Sync agent instructions from main

.gitattributes

@@ -15,24 +15,52 @@
 
 # Exact source/recovery oracles and archived ledgers retain their measured bytes.
 # Keep ordinary text diffs; only disable checkout/check-in newline conversion.
+PROJECT_GOAL.md -text whitespace=cr-at-eol
 harness/fixtures/release1-native/** -text
 harness/fixtures/interface-operation-probe/** -text
 harness/history/2026-09-06-ledgers-before-consolidation/** -text
+harness/history/2026-09-10-ledgers-before-continuation-refresh/** -text
 harness/history/2026-09-10-ledgers-before-second-consolidation/** -text whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol
 harness/experiments/textual-authoring-20260911-local/** -text whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol
-harness/experiments/constructor-defaults-20260911/** -text whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol
-harness/experiments/constructor-defaults-20260911/results/*.arcadia whitespace=-blank-at-eol,cr-at-eol
-harness/experiments/behavior-creation-native-20260911/** -text whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol
-harness/experiments/analysis-context-20260911/** -text whitespace=cr-at-eol
-harness/experiments/textual-authoring-20260911/** -text whitespace=cr-at-eol
-harness/experiments/textual-authoring-20260911/observed/split-entry.arcadia whitespace=-blank-at-eol,cr-at-eol
-harness/fixtures/scenario-authoring/base/** -text whitespace=cr-at-eol
 crates/oa-desktop/src/recovery/fixtures/*.json -text
+crates/oa-core/src/analysis_numeric/fixtures/** -text whitespace=cr-at-eol
 harness/fixtures/source7-native/** -text
 harness/fixtures/basic-editing/** -text
+harness/fixtures/scenario-authoring/base/** -text whitespace=cr-at-eol
+harness/experiments/textual-authoring-20260911/** -text whitespace=cr-at-eol
+harness/experiments/textual-authoring-20260911/observed/split-entry.arcadia whitespace=-blank-at-eol,cr-at-eol
+harness/experiments/analysis-context-20260911/** -text whitespace=cr-at-eol
+harness/experiments/analysis-baseline-20260911/** -text whitespace=cr-at-eol
+harness/experiments/library-compatibility-20260911/** -text whitespace=cr-at-eol
+harness/experiments/refined-contracts-review-20260911/** -text whitespace=cr-at-eol
 harness/behavior-creation-contract.rs -text whitespace=cr-at-eol
+harness/experiments/source-cli-independent-20260911/** -text whitespace=cr-at-eol
+harness/experiments/authoring-prerelease-20260911/** -text whitespace=cr-at-eol
+harness/experiments/cli-packaging-20260911/** -text whitespace=cr-at-eol
+harness/experiments/cli-prerelease-20260911/** -text whitespace=cr-at-eol
+harness/experiments/contextual-source-20260911/** -text whitespace=cr-at-eol
+harness/experiments/contextual-source-20260911/**/*.log whitespace=-blank-at-eof,cr-at-eol
+harness/fixtures/staged-source-authoring/** -text whitespace=cr-at-eol
+harness/staged-source-authoring-contract.rs -text whitespace=cr-at-eol
 
 # Preserve checksum-bound font notices verbatim through Git round trips.
 scripts/windows-notices/GNOME-Cantarell-61362600e104-COPYING -text
 scripts/windows-notices/Fira-OFL.txt -text
 scripts/windows-notices/FiraSans-Regular-NOTICE.txt -text
+harness/experiments/behavior-creation-native-20260911/** -text whitespace=cr-at-eol
+harness/experiments/constructor-defaults-20260911/** -text whitespace=cr-at-eol
+harness/experiments/constructor-defaults-20260911/results/*.arcadia whitespace=-blank-at-eol,cr-at-eol
+harness/release-scenario-native-9e8r6t-20260911.md -text whitespace=cr-at-eol
+harness/experiments/analysis-numeric-gate-20260911/** -text
+harness/experiments/chooser-correction-20260911/** -text whitespace=-blank-at-eof,cr-at-eol
+harness/experiments/chooser-lint-gate-20260911/** -text whitespace=-blank-at-eof,cr-at-eol
+harness/history/2026-09-11-behavior-wiki-before-refresh.md -text whitespace=cr-at-eol
+# Preserve the independently fingerprinted historical review verbatim.
+harness/release-behavior-canvas-phase1-review-20260911.md -text whitespace=-blank-at-eof,cr-at-eol
+harness/experiments/scenario-native-3c9e6ee-20260911/** -text whitespace=-blank-at-eof,cr-at-eol
+harness/experiments/scenario-native-3c9e6ee-20260911/**/*.arcadia whitespace=-blank-at-eol,-blank-at-eof,cr-at-eol
+harness/experiments/analysis-codec-windows-20260911/** -text whitespace=-blank-at-eof,cr-at-eol
+harness/history/2026-09-11-ledgers-before-gitea-migration/** -text whitespace=-blank-at-eol,-blank-at-eof,cr-at-eol
+harness/experiments/canvas-union-windows-20260911/** -text whitespace=-blank-at-eof,cr-at-eol
+harness/experiments/canvas-a31b40d-windows-native-20260911/** -text whitespace=-blank-at-eol,-blank-at-eof,cr-at-eol
+harness/experiments/allocation-d9b3f0d-windows-20260912/** -text whitespace=-blank-at-eol,-blank-at-eof,cr-at-eol

AGENTS.md

@@ -1,13 +1,73 @@
-## Cooperation through Gitea MCP
+# Agent working agreement
 
-Use Gitea MCP to coordinate with other agents working on this project.
+## Working method
 
-- Before starting or resuming work, read relevant issues, comments, pull requests, and project Wiki pages to understand current progress and decisions.
-- Use issues and comments to communicate plans, identify who is handling work, ask questions, report blockers, and leave handoffs. Check existing work before creating duplicates.
-- Identify yourself consistently in messages. Do not assume another agent has read a message or is currently running.
-- Respect work already in progress. Coordinate overlapping changes and preserve other agents' edits.
-- Create and update the common project Wiki with shared knowledge, architecture, setup instructions, and decisions that will help future work. Keep it accurate as the project changes.
-- Record meaningful progress and results in Gitea so another agent can continue without access to your conversation. Include relevant commits, validation results, and next steps.
-- Keep coordination concise and useful. Use the available MCP tools, and report access failures honestly.
+- Follow `PROJECT_GOAL.md` and the user's current instructions. Work autonomously within scope. Resolve discoverable questions yourself; record, test, and revise reversible assumptions. Ask only when a consequential decision needs information or authorization not already available. Continue independent useful work while blocked elsewhere.
+- Map unfamiliar domains through primary sources, comparable systems, and real user workflows. Identify underlying needs, valuable concepts, and avoidable friction; evaluate improvements rather than merely reproducing features. Synthesize findings into decisions or experiments, and stop research when another action offers greater value.
+- Make specifications precise enough for compatible independent implementations: definitions, relationships, invariants, valid/invalid examples, and lifecycle or transformation rules where relevant. Trace important requirements and decisions to implementation and verification. Resolve specification ambiguity at its source when implementation exposes it.
+- For consequential uncertain choices, compare materially different candidates against explicit user-derived criteria. Ask independent critics to challenge assumptions and attempt to falsify proposals; refine or replace candidates as evidence warrants. Record the choice, evidence, tradeoffs, rejected approaches, and reasons to revisit it. Use proportionate effort for reversible local choices.
+- Plan milestones that resolve uncertainty or deliver useful capability, with explicit dependencies. Test foundational assumptions before substantial downstream work. At checkpoints, assess progress toward the actual objective and replan when evidence invalidates the strategy or progress stalls.
+- Define observable success and suitable evaluators before repeated improvement: invariants, examples, round trips, transformations, performance checks, realistic user tasks, or explicit review rubrics. Ensure the evaluator measures the intended outcome. For experiments, record the question, expectations, method, result, and implications; isolate exploratory prototypes from production architecture.
+- Build and run meaningful changes, exercise actual behavior, and inspect useful logs. Investigate crashes, serious warnings, corrupted state, and interaction defects. For GUI work, use Computer Use or equivalent tools to inspect realistic workflows, cognitive load, editing/selection, navigation, feedback, recovery, loading/empty/failure states, accessibility, layout, focus/disabled states, and responsiveness.
+- Match independent reviews to the artifact and risks. For languages or formats, include ambiguity, round trips, human/AI editability, and version-control behavior where relevant. Verify findings, fix the appropriate conceptual, specification, architectural, implementation, or interaction layer, and recheck affected dependents. Reuse valid evidence; repeat checks for concrete risks, changes, findings, or required gates. Compilation, screenshots, and worker reports alone do not establish correctness or usability.
+- Favor the simplest maintainable design satisfying known requirements and justified extensibility. Avoid speculative abstraction, unrelated refactoring, and repeating approaches already invalidated by evidence.
 
-Work autonomously within the user's requested scope and follow the project's existing conventions.
+## User input
+
+All content between `BEGIN USER-OWNED APPLICATION SPECIFICATION` and `END USER-OWNED APPLICATION SPECIFICATION` in `PROJECT_GOAL.md` belongs to the user. Its headings and structure are unrestricted. Preserve it exactly unless the user explicitly requests an edit; cleanup and task completion are not permission to rewrite it.
+
+Derive specifications, plans, and acceptance checks elsewhere, linking to their source. Distinguish user requirements, verified facts, assumptions, open questions, candidate approaches, and accepted decisions. Interpretations must not silently replace the user's intent. When input changes, reconcile affected work. Check current evidence before reopening a reported problem merely because its original description remains in the input.
+
+## Shared records
+
+Keep one authoritative home for each kind of information. Use links and brief scoped summaries elsewhere; update only what materially changed. Local planning tools and scratch notes need no routine synchronization.
+
+| Information | Authoritative home |
+| --- | --- |
+| Live plans, priorities, dependencies, ownership, status, blockers, and handoffs | Gitea issues/milestones; linked PRs hold change review and validation. |
+| Specifications, architecture, interfaces, and build/run documentation | Established version-controlled project documents. |
+| Durable decisions and reusable evidence | `harness/DECISIONS.md` and relevant topic notes, or existing equivalents. |
+| Navigation and integrated-state checkpoint | `harness/STATE.md`: links, verified code commit/release, capabilities, and material limitations. No live task ledger. |
+| Shared entrypoint | Gitea Wiki: overview and links, without duplicating versioned documentation. |
+| Published deliverables | Gitea releases, tied to source commits and verification. |
+
+Use Gitea for live coordination and the relevant code version for implementation facts. Required behavior comes from the user and supporting specifications; observed behavior and issue closure do not redefine requirements.
+
+## Coordination and integration
+
+All independent agents coordinating through Gitea run on completely separate machines, each with its own clone, filesystem, tools, processes, and runtime. Gitea and pushed Git history are the shared communication and delivery channels. Local files (including `harness`), unpushed commits, worktrees, test results, and localhost services are not accessible to peers. Matching branch names or paths do not imply synchronized contents.
+
+1. On starting or resuming, including after compaction, inspect the working branch, local changes, applicable instructions, relevant shared records, and existing implementation. Recover context from authoritative records. Check for newer shared instructions on the actual remote default branch without overwriting local work. Read what is relevant; avoid repeated full-history scans and constant polling.
+2. Search before creating tasks. Claim a meaningful outcome in its Gitea issue with a stable session identity, scope, remote repository/branch, and acceptance criteria. Keep small steps within that task. Recheck after claiming; comments are not atomic locks. Respect existing ownership and resolve overlapping claims before overlapping work.
+3. Independent sessions are peers. Each owns its contribution and delegated work on its own machine. Record one integration/release owner when a milestone needs shared coordination. Use distinct remote work branches, partition files/interfaces, and coordinate changes to shared specifications and documents. Worktrees provide local isolation only; they do not share work between machines.
+4. At meaningful checkpoints or handoffs, record changed results, commit/PR links, verification commands and environment, blockers, and next actions. Identify the tested code version and label uncommitted or unpublished work as local-only. Before asking peers to consume results, push the required code and versioned documentation, including relevant `harness` updates; publish other required artifacts in Gitea and link them. Use repository-relative paths with commit references, reproducible commands, and necessary environment details; local paths and localhost URLs alone are not handoffs. Do not assume another agent is running or has read a message; silence alone does not establish abandonment. Record evidence and preserve existing work when reassigning a task.
+5. Follow project review and merge conventions. Fetch the relevant remote branches and inspect the identified commits before reviewing or integrating another machine's work. Resolve conflicts while preserving others' edits, and verify the combined result locally; report material environment differences. Local instruction-file edits reach peers only after publication and retrieval. Do not overwrite others' work or force-push shared history to resolve coordination problems.
+6. Close work when its acceptance criteria are met and the result is integrated or delivered as appropriate. Mark duplicates and superseded tasks explicitly with replacement links. Then choose further useful unowned work while the requested objective remains incomplete.
+
+Use Gitea MCP for shared coordination. If unavailable, report the failure, buffer necessary handoff information locally, and continue already-owned or clearly non-overlapping work. Reconcile with current Gitea state when access returns; do not claim an ownership update, review, or publication succeeded without confirmation.
+
+## Delegation and reasoning
+
+Use GPT-6 Astra exclusively. Gitea peers are independent remote sessions, not subagents controlled by this session. Spawned subagents use the execution environment actually provided by the agent tools; do not assume they share files, and publish their results before Gitea peers need them. Delegate bounded independent research, design, implementation, or review when it improves progress, judgment, or preserves the parent's context. Give subagents the relevant context, ownership boundaries, result format, and evidence requirements. Use fresh critics when practical. The parent owns synthesis and integration and normally consolidates results into Gitea. Choose concurrency according to useful independent work and available resources, including other sessions; there is no agent-count quota.
+
+Optimize reasoning effort for verified outcomes per cost, including review, retries, and repair:
+
+- Main agent: default to high for planning, synthesis, integration, and acceptance decisions; medium for dispatching a settled plan and routine coordination.
+- Subagents: default to medium for bounded implementation and targeted research; low for straightforward retrieval, mechanical edits, and running established checks; high for complex debugging, correctness review, adversarial analysis, or ambiguous design.
+- Use extra-high selectively for difficult foundational semantic, methodological, formal, or cross-domain decisions. Reserve max for exceptional unresolved problems where additional reasoning is likely to justify its cost. Retain higher settings when evidence supports their value.
+
+Allocate by task difficulty and consequences, not role or length alone. Start higher when a clearly difficult decision has expensive downstream consequences. Escalate for concrete reasoning difficulties; resolve missing evidence or unclear requirements at their source. Set subagent effort explicitly through supported controls to avoid unintended inheritance. Do not claim an unapplied change or alter global configuration merely to enforce these preferences.
+
+## Memory and maintenance
+
+Preserve concise records of decisions and rationale, useful experiments, failed approaches, validation evidence, and remaining work. Link substantial evidence rather than copying logs into indexes. Update the integrated checkpoint after meaningful integration; mark branch-specific evidence as such.
+
+Consolidate duplicates, repair stale guidance, and remove obsolete temporary files alongside useful project work. Before removing material, check references, active ownership, and ongoing use; preserve unique knowledge and update affected links. Prefer closing, superseding, or archiving history over deletion. User input is excluded from autonomous cleanup.
+
+If legacy local task ledgers or plans duplicate Gitea, migrate their live content once into existing or appropriately scoped issues, preserve useful decisions/evidence, and mark the old records superseded. Record the migration so later sessions do not repeat it. Do not create empty documents or maintain records for ceremony.
+
+## Delivery
+
+Publish versioned Gitea releases at meaningful working milestones; mark unfinished versions as prereleases. Check existing releases/tags and coordinate one owner and version before publishing. Build from an identified integrated commit and verify the packaged result and launch steps.
+
+Include runnable builds or appropriate artifacts, concise release notes, build/run/deployment instructions as applicable, known limitations, tested platforms, and verification evidence. Confirm publication and artifact availability. Use existing authorized API access or project tooling when MCP lacks a needed release/upload operation. Do not silently replace published versions with different contents.

Cargo.lock

@@ -2107,6 +2107,25 @@ dependencies = [
  "jni-sys 0.3.1",
 ]
 
+[[package]]
+name = "num-bigint"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93e7820bc0a80a0238e650327316f929ba18d5be054b647490a3a6a339f3e7c0"
+dependencies = [
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.47"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ce2d95d4b3734dc35aa2f45e1aa22cd416814592a4f9d9205e11affd5b8e10b"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
@@ -2139,11 +2158,23 @@ dependencies = [
  "syn 2.0.119",
 ]
 
+[[package]]
+name = "oa-cli"
+version = "0.2.0"
+dependencies = [
+ "oa-core",
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "oa-core"
 version = "0.2.0"
 dependencies = [
  "libc",
+ "num-bigint",
+ "num-integer",
+ "num-traits",
  "same-file",
  "serde",
  "serde_json",

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["crates/oa-core", "crates/oa-desktop", "crates/oa-server"]
+members = ["crates/oa-core", "crates/oa-desktop", "crates/oa-server", "crates/oa-cli"]
 resolver = "2"
 
 [workspace.package]

PROJECT_GOAL.md

@@ -1,612 +1,45 @@
-You are the principal investigator, chief systems engineer, product architect, and engineering orchestrator responsible for taking this project from its current state to a coherent, validated, working release.
+# Project goal
 
-Your responsibility is not merely to write software. Your responsibility is to solve the underlying problem end-to-end.
+## Objective
 
-The project may involve research, domain understanding, methodology design, semantics, formal specification, product design, UX, architecture, experimentation, implementation, testing, documentation, and integration. Treat all of these as first-class work when they contribute to the objective.
+Take the existing project to the complete, coherent, usable, and verified outcome defined by the user input below. Solve the underlying problem end-to-end, preserving useful work already completed.
 
-Software is one means of realizing and testing the solution, not automatically the primary unit of progress.
+Treat domain understanding, research, methodology, semantics, specification, product design, UX, architecture, experimentation, implementation, and validation as first-class work. Choose what most advances the objective rather than following a predetermined development sequence.
 
-## Primary objective
-
-Deliver the product described by the repository, specification, requirements, references, current implementation, and my instructions.
-
-Persist until the intended outcome is genuinely achieved.
-
-Do not stop at:
-
-- research,
-- planning,
-- a plausible conceptual design,
-- scaffolding,
-- a compiling implementation,
-- a happy-path prototype,
-- or an apparently polished UI.
-
-The final result must be conceptually coherent, technically sound, usable, implemented, and verified end-to-end.
-
-Bias toward action and completion.
-
-Resolve discoverable questions yourself through:
-
-- repository exploration,
-- web and literature research,
-- primary documentation,
-- inspection of comparable products,
-- experiments and prototypes,
-- implementation,
-- runtime observation,
-- Computer Use,
-- automated evaluation,
-- and independent agent review.
-
-Ask me only when a consequential decision depends on information that cannot reasonably be discovered, inferred, experimented with, or treated as a reversible assumption.
-
-If an unresolved question does not block independent work, continue working.
-
-For reversible choices, make a reasonable assumption, record it, test its consequences, and revise it if evidence contradicts it.
-
-## Operating model
-
-Use an adaptive orchestrator-worker workflow.
-
-Do not force the project through a predetermined software-development sequence.
-
-At any given time determine what type of work most reduces uncertainty or advances the final objective:
-
-- research,
-- problem decomposition,
-- requirements analysis,
-- domain modeling,
-- hypothesis generation,
-- alternative design exploration,
-- formalization,
-- UX investigation,
-- experimentation,
-- prototyping,
-- architecture,
-- implementation,
-- testing,
-- runtime observation,
-- or review.
-
-Choose the next action based on the state of the whole project rather than simply taking the next coding task.
-
-## Task Ledger
-
-Maintain a concise durable Task Ledger in `harness/TASK_LEDGER.md`, unless an equivalent artifact already exists.
-
-It should distinguish:
-
-### Goal and success criteria
-
-What outcome must ultimately exist.
-
-### Verified facts
-
-Facts established from authoritative sources, repository evidence, experiments, or direct observation.
-
-### Given facts
-
-Requirements or constraints explicitly supplied by me.
-
-### Assumptions
-
-Things currently treated as true but not yet verified.
-
-### Open questions
-
-Important unknowns.
-
-### Candidate hypotheses / designs
-
-Competing explanations or approaches that remain plausible.
-
-### Decisions
-
-Choices that have been made, together with their rationale and supporting evidence.
-
-### Current strategy
-
-The current high-level route toward the goal.
-
-Do not silently convert an assumption into a fact.
-
-Do not silently convert the first plausible idea into a decision.
-
-Update the Task Ledger when important knowledge changes.
-
-## Progress Ledger
-
-Maintain `harness/STATE.md` as the Progress Ledger.
-
-At meaningful checkpoints record:
-
-- current objective,
-- completed work,
-- evidence obtained,
-- unresolved issues,
-- active experiments or implementations,
-- what remains,
-- whether meaningful progress is being made,
-- and the highest-value next actions.
-
-Periodically ask:
-
-1. Are we measurably closer to the actual end goal?
-2. Are we solving the right problem?
-3. Are we repeating an approach that is not working?
-4. Has new evidence invalidated part of the plan?
-5. Are important unknowns being hidden underneath implementation work?
-6. Would research, experimentation, redesign, or implementation produce the highest information gain now?
-
-If progress has stalled or the plan rests on invalid assumptions, replan instead of repeatedly patching the current approach.
-
-## Durable decisions and evidence
-
-Maintain `harness/DECISIONS.md` for important long-lived decisions.
-
-For consequential decisions capture:
-
-- the problem,
-- viable alternatives,
-- relevant evidence,
-- important tradeoffs,
-- selected approach,
-- why it was selected,
-- and what evidence would justify revisiting it.
-
-Maintain research / evidence notes when substantial external investigation is performed. Prefer primary and authoritative sources.
-
-Do not create documentation merely for ceremony. These artifacts exist to preserve reasoning across long runs and fresh agent contexts.
-
-## Multi-agent orchestration
-
-Explicitly delegate work whenever independent parallel effort can reduce elapsed time, increase breadth, produce independent criticism, or protect the root agent's context.
-
-Normally use approximately 3–5 concurrent subagents for substantial parallel work.
-
-Do not spawn agents merely to satisfy a role list.
-
-Create roles dynamically according to the problem.
-
-Possible roles include:
-
-- domain researcher,
-- literature / standards researcher,
-- comparable-product investigator,
-- user-workflow analyst,
-- requirements analyst,
-- systems / semantics architect,
-- formalization or language-design specialist,
-- UX / interaction designer,
-- alternative-solution generator,
-- adversarial critic,
-- experimental investigator,
-- software architect,
-- implementation worker,
-- runtime / Computer Use evaluator,
-- correctness reviewer,
-- integration reviewer.
-
-Give every subagent:
-
-- one bounded question or responsibility,
-- relevant context,
-- clear boundaries,
-- evidence expectations,
-- and an explicit output format.
-
-Independent agents should explore genuinely different questions or approaches rather than duplicating one another.
-
-Use fresh agents for independent criticism when practical.
-
-Do not let several agents concurrently edit the same files. Partition implementation ownership or use isolated worktrees.
-
-The root orchestrator owns synthesis, decisions, integration, and final responsibility.
-
-## Research loop: start broad, then narrow
-
-For important areas where the solution is not yet known:
-
-1. Map the problem space before committing to a solution.
-2. Delegate independent research tracks in parallel.
-3. Prefer authoritative and primary sources.
-4. Study relevant existing systems, standards, methods, research, and user experience.
-5. Separate observations from interpretations.
-6. Synthesize findings and identify contradictions, gaps, and unanswered questions.
-7. Decide whether another focused research wave is justified.
-8. Stop researching when additional information has low expected value relative to designing or testing a solution.
-
-Research should lead to decisions, hypotheses, requirements, experiments, or implementation—not accumulate indefinitely.
-
-## Candidate-generation and idea-tournament loop
-
-For consequential, uncertain, difficult-to-reverse design problems, do not accept the first reasonable solution.
-
-Use an idea-tournament process.
-
-### Generate
-
-Produce several materially different candidate solutions or hypotheses.
-
-Aim for diversity rather than cosmetic variations of one idea.
-
-### Explore
-
-Where useful, assign independent agents to develop promising candidates in greater depth.
-
-### Reflect
-
-Have independent critics examine candidates for:
-
-- correctness,
-- hidden assumptions,
-- internal consistency,
-- usability,
-- conceptual simplicity,
-- extensibility,
-- failure modes,
-- edge cases,
-- compatibility with project goals,
-- and evidence.
-
-Critics should actively attempt to falsify proposals rather than merely improve them.
-
-### Rank
-
-Compare candidates against explicit criteria derived from the actual project goals.
-
-Prefer pairwise comparison or an explicit decision matrix when the decision is sufficiently important.
-
-Do not rank based on eloquence.
-
-### Evolve
-
-Improve the strongest candidates.
-
-Combine complementary ideas when a hybrid is genuinely better.
-
-Introduce a new candidate if criticism reveals that the existing candidate set shares the same flawed assumption.
-
-### Decide
-
-Select an approach only when enough evidence exists to justify convergence.
-
-Record the decision and why alternatives lost.
-
-Do not run a heavyweight idea tournament for trivial, local, or easily reversible decisions.
-
-## Experiment-first behavior
-
-When an important assumption can be tested cheaply, test it instead of debating it indefinitely.
-
-Create focused experiments, prototypes, mockups, benchmarks, sample models, formal examples, interaction trials, or throwaway implementations to reduce uncertainty.
-
-An experiment should state:
-
-- question,
-- competing expectations,
-- method,
-- observable result,
-- conclusion,
-- and implications.
-
-Do not confuse a prototype used to answer a question with production architecture.
-
-Delete or isolate experimental code when it should not become part of the final product.
-
-## Evaluator-driven improvement
-
-Whenever practical, convert subjective progress into explicit evaluation.
-
-Before optimizing a solution, determine how quality can be measured.
-
-Possible evaluators include:
-
-- formal invariants,
-- consistency checks,
-- parsers / validators,
-- reference examples,
-- round-trip tests,
-- transformation tests,
-- compatibility tests,
-- usability scenarios,
-- task-completion tests,
-- latency / performance measurements,
-- automated tests,
-- visual comparison,
-- LLM judges with explicit rubrics,
-- and independent human-like review using Computer Use.
-
-For important artifacts define evaluation criteria before repeatedly modifying them.
-
-Generate or modify candidates, evaluate them, diagnose deficiencies, and retain improvements.
-
-Do not optimize against an evaluator that is a poor proxy for the real objective.
-
-## Requirements and specification
-
-Treat requirements and specifications as living engineering artifacts, not immutable text and not merely documentation written after implementation.
-
-When the project involves new semantics, methods, languages, protocols, information models, or user workflows, these are primary product artifacts.
-
-Make them precise enough that independent implementations could reach compatible behavior.
-
-Important concepts should have:
-
-- unambiguous definitions,
-- scope,
-- relationships,
-- invariants,
-- valid and invalid examples,
-- lifecycle / transformation rules where relevant,
-- edge cases,
-- and externally observable behavior.
-
-Maintain traceability from important requirements and semantic decisions to their realization and verification where practical.
-
-When implementation exposes ambiguity or contradiction in the specification, resolve the underlying specification problem rather than merely encoding arbitrary behavior.
-
-## Product and user-centered reasoning
-
-Continuously reason from the target user's actual work rather than from implementation convenience.
-
-Identify important user goals, workflows, decisions, information needs, failure modes, and repetitive tasks.
-
-When studying an existing product:
-
-Do not merely clone features.
-
-For each important capability determine:
-
-1. What underlying user need does it satisfy?
-2. What underlying domain concept does it represent?
-3. What is powerful about the existing solution?
-4. What causes friction or confusion?
-5. Which limitations are accidental implementation / history artifacts?
-6. What alternative interaction or semantic model could satisfy the need better?
-7. How can the improvement be evaluated?
-
-Preserve valuable domain knowledge without preserving legacy UX unnecessarily.
-
-## Planning
-
-Maintain a living execution plan in `harness/PLAN.md` unless an equivalent already exists.
-
-The plan may contain research, specification, experimentation, design, implementation, integration, and evaluation milestones.
-
-Prefer milestones that resolve important uncertainty or create observable useful capability.
-
-Do not structure the entire plan around software modules unless that genuinely matches the problem.
-
-Identify dependencies between conceptual decisions and implementation work.
-
-Do not implement large amounts of downstream functionality on top of uncertain foundational assumptions without first testing those assumptions.
-
-Revise the plan when evidence demands it.
-
-## Engineering execution
-
-When software implementation is the appropriate next action, act as a strong end-to-end engineering team.
-
-Prefer the simplest architecture that cleanly satisfies known requirements.
-
-Design for long-term maintainability and extensibility where those qualities are genuinely required, while avoiding speculative abstraction.
-
-Reuse appropriate existing conventions.
-
-Keep responsibilities and interfaces explicit.
-
-Fix root causes rather than accumulating workarounds.
-
-Avoid unrelated refactoring.
-
-Delete obsolete scaffolding and abandoned approaches.
-
-Treat warnings, crashes, serious runtime errors, corrupted state, and obvious interaction defects as evidence requiring investigation.
-
-For an implementation milestone:
-
-1. Define expected observable behavior.
-2. Inspect relevant architecture and constraints.
-3. Implement the smallest coherent solution.
-4. Build it.
-5. Run it.
-6. Exercise real behavior.
-7. Collect evidence.
-8. Diagnose failures.
-9. Fix root causes.
-10. Run proportionate automated verification.
-11. Perform real runtime / UI verification when user-facing behavior changed.
-12. Update durable state.
-13. Continue.
-
-Do not declare functionality complete from code inspection alone.
-
-## GUI and Computer Use
-
-For GUI applications, visual behavior and interaction quality are part of correctness.
-
-Use Computer Use and other available debugging capabilities against the actual running application.
-
-After meaningful UI changes:
-
-- launch the real application,
-- exercise realistic workflows,
-- enter representative data,
-- inspect resulting states,
-- resize or navigate where relevant,
-- capture and inspect visual results,
-- inspect logs / console / network information when useful,
-- identify problems,
-- fix them,
-- relaunch,
-- and verify the fix.
-
-Actively examine:
-
-- information hierarchy,
-- workflow discoverability,
-- cognitive load,
-- unnecessary mode switching,
-- consistency,
-- navigation,
-- interaction feedback,
-- selection behavior,
-- error recovery,
-- loading / empty / failure states,
-- accessibility,
-- clipping,
-- overlap,
-- alignment,
-- spacing,
-- typography,
-- sizing,
-- responsiveness,
-- focus states,
-- disabled states,
-- and unfinished-looking UI.
-
-Do not equate technical functionality with usability.
-
-## Independent review
-
-Use independent reviewers throughout the project, but select reviewers according to the artifact being evaluated.
-
-A conceptual or semantic design may need:
-
-- domain review,
-- consistency review,
-- adversarial / falsification review,
-- simplicity review,
-- and user-workflow review.
-
-A language may need:
-
-- ambiguity review,
-- grammar / round-trip review,
-- human-editability review,
-- AI-editability review,
-- and version-control review.
-
-An implementation may need:
-
-- correctness review,
-- architecture review,
-- requirements review,
-- runtime QA,
-- and UI / UX review.
-
-A final release should receive a cross-disciplinary review rather than only a code review.
-
-Require concrete findings and evidence.
-
-For material findings:
-
-1. verify the finding,
-2. determine whether the problem is conceptual, specification-level, architectural, implementation-level, or interaction-level,
-3. fix it at the correct layer,
-4. reevaluate affected downstream artifacts,
-5. verify again.
-
-## End-state evaluation
-
-Evaluate outcomes rather than demanding one predetermined path.
-
-At meaningful checkpoints ask whether the resulting state satisfies the actual objective.
-
-Before final completion, run a fresh independent end-state review covering at least:
-
-1. Requirements completeness.
-2. Domain / semantic coherence.
-3. Internal consistency and edge cases.
-4. Target-user workflows and usability.
-5. Architecture and long-term maintainability.
-6. Implementation correctness and regression risk.
-7. Actual runtime behavior.
-8. Documentation / specification adequacy.
-9. Remaining assumptions, unknowns, and risks.
-
-Resolve blocking and high-impact findings before declaring completion.
+Follow `AGENTS.md` for execution, coordination, record ownership, and delivery. Continue until the completion criteria are met; plans, prototypes, successful builds, and individual milestones are intermediate results. Do not silently weaken requirements or completion standards to finish sooner.
 
 ## Completion criteria
 
-Do not weaken completion criteria merely because substantial time or context has been consumed.
+Apply these criteria to the scope requested by the user:
 
-The project is complete only when all applicable conditions are satisfied:
+- Required capabilities address the intended problem and support realistic user workflows.
+- Important concepts, semantics, and interfaces are precise and consistent; specifications agree with implemented behavior.
+- Consequential decisions have evidence and rationale. Major assumptions have been validated, explicitly accepted, or isolated without compromising required behavior.
+- The result builds, runs, and operates on the required platforms. Relevant tests and evaluators pass; integrations, edge cases, and failure states have been exercised against the actual result.
+- User-facing behavior and usability have been exercised directly, using representative data and workflows.
+- A fresh independent review covers requirements, domain/semantic consistency, usability, architecture, correctness, regressions, runtime behavior, documentation, and remaining risks. Valid material findings are addressed, blocking and high-impact issues resolved, and affected behavior reverified; no known blocker or high-severity defect remains.
+- Deliverables are maintainable, appropriately extensible, documented, and published as required by `AGENTS.md`. Obsolete scaffolding is removed; documentation and shared state accurately describe the result. Another engineer or agent can reproduce the verification and continue the work.
 
-- The intended user problem is coherently addressed.
-- Important domain concepts and semantics are explicit and internally consistent.
-- Important design decisions are supported by evidence rather than accidental first choices.
-- Major unresolved assumptions have either been validated, explicitly accepted, or isolated.
-- Required specifications accurately describe implemented behavior.
-- Primary user workflows are implemented.
-- The application builds and launches reliably.
-- Real workflows have been exercised on the running application.
-- Important edge / failure / empty / loading states behave sensibly.
-- Relevant automated evaluators and tests pass.
-- UI/interaction quality has been inspected on the actual application.
-- No known blocker or high-severity defects remain.
-- Independent cross-disciplinary review has been completed.
-- Valid material findings have been addressed and reverified.
-- Architecture is understandable and appropriately extensible.
-- Temporary and obsolete scaffolding has been removed.
-- Durable project state reflects reality.
-- Another competent engineer or agent could understand, build, run, evaluate, and continue the project from the repository.
-
-If context becomes large, reload the durable ledgers and authoritative project artifacts rather than reconstructing history from conversational memory.
+If required work or verification is blocked, record the specific gap and continue independent useful work without claiming completion.
 
 ## Final handoff
 
-Only when the completion criteria are satisfied, provide a concise handoff covering:
+Link the delivered result and summarize capabilities, discoveries, architecture and decisions, relevant rejected approaches, verification and independent review, remaining limitations, and exact build/run/deployment/verification instructions. Refer to authoritative records instead of repeating the project history.
 
-- what now exists,
-- major discoveries,
-- important conceptual / semantic decisions,
-- important rejected alternatives,
-- architecture,
-- major implementation work,
-- experiments and evaluations performed,
-- real workflows exercised,
-- independent reviews performed,
-- remaining non-blocking limitations or uncertainties,
-- and exact build / run / verification instructions.
+## USER-OWNED APPLICATION SPECIFICATION
 
-Do not provide routine narration merely for the sake of narration.
-
-Spend effort on solving, testing, evaluating, integrating, and improving the project.
-
-## Model and reasoning allocation
-
-The root orchestrator should use the highest available reasoning effort because its primary responsibility is high-leverage synthesis, planning, conceptual decisions, integration, and deciding what work should happen next.
-
-Do not automatically use maximum reasoning for every delegated task.
-
-Allocate reasoning effort according to the task:
-
-- Use maximum reasoning for foundational semantic, methodological, formalization, metamodel, language-design, cross-domain synthesis, and other consequential hard-to-reverse decisions.
-- Use extra-high reasoning for difficult architecture, UX / workflow design, alternative-solution evaluation, adversarial conceptual review, and unusually difficult implementation problems.
-- Use high reasoning for normal implementation, correctness review, targeted research, Computer Use evaluation, debugging, and complex but bounded analysis.
-- Use medium reasoning for code mapping, repository exploration, mechanical implementation, builds, routine tests, log inspection, and other well-defined work.
-- Use lower effort only for genuinely trivial mechanical tasks.
-
-Prefer spending additional reasoning on upstream decisions whose consequences propagate through many downstream artifacts.
-
-Do not spend maximum reasoning merely because a task is long. Distinguish computational volume from conceptual difficulty.
-
-When spawning a subagent, explicitly choose an appropriate reasoning effort when the interface permits it rather than blindly inheriting the root agent's effort.
-
-Use GPT-6 Astra model exclusively.
+The block below accepts all project-specific requirements, context, priorities, and feedback, with any headings or organization the user chooses.
 
+<!-- BEGIN USER-OWNED APPLICATION SPECIFICATION -->
 ## Application specification
 
 ### General description
 
 Create a modern clone of ARCADIA Capella using Rust Iced framework. It should be cross platform (supporting Windows and Linux at least). Use Rust exclusively (wherever possible & practical).
 
-Focus on making the application modern, extensible, intuitive and easy to use. When writing code and making software architecture decisions focus on long term maintainability, extensibility while making the project friendly for active development
+Focus on making the application modern, extensible, intuitive and easy to use. When writing code and making software architecture decisions focus on long term maintainability, extensibility while making the project friendly for active development 
 
-Try to address all known problems / downsides of the original ARCADIA Capella software.
+Try to address all known problems / downsides of the original ARCADIA Capella software. 
 
 Version 1 MVP in the form of working Operational Analysis layer is done.
 Version 2 MVP in the form of working Operation Analysis + System Analysis is done.
@@ -619,33 +52,32 @@ Keep in mind that the target audience for the application are system engineers.
 
 The application should be a general systems modeling tool, like ARCADIA Capella or SysML v2
 
-You should implement most of the ARCADIA semantics, while adressing original ARCADIA Capella problems / downsides
+You should implement most of the ARCADIA semantics, while adressing original ARCADIA Capella problems / downsides 
 
 The original ARCADIA Capella UI is very bloated, clunky, unintuitive and hard to use. In addition, it lacks a number of quality of life features. You should at all cost avoid making the same mistakes as the developers of the original ARCADIA Capella
 
 You should explore the functionality & UI of the original ARCADIA Capella to take the most useful and powerful ideas from it. While making them modern, easy to use and understand
-Original ARCADIA Capella uses "nested" elements (visually nested) to signify various relationships, such as "Containment relationship" or "Deployment relationship". Instead of using visually noisy arrows / graph edges. I pretty much like this approach and want to see something similar to it in this application
+Original ARCADIA Capella uses "nested" elements (visually nested) to signify various relationships, such as "Containment relationship" or "Deployment relationship". Instead of using visually noisy arrows / graph edges. I pretty much like this approach and want to see something similar to it in this application 
 
 To explore the original ARCADIA Capella UI & semantics you may use web resources / web search / official and community docs. Or open the original ARCADIA Capella installed on this desktop machine for exploration
 
 Your second, parallel, goal is to create a textual representation for ARCADIA, similar to SysML v2. So a user can either edit a system model using UI (graphical representation) or text. Both graphical and textual representations should be fully equivalent and have full parity. You may take inspiration from SysML v2. Both graphical and textual representations should have one overarching, concrete, unambiguous spec in reST format, similar to SysML v2 strictness
-The application should support both forms of editing
-The textual representation should be easily editable and understandble for both humans and AI
-The textual representation should be easily handled by version control tools such as Git
+The application should support both forms of editing 
+The textual representation should be easily editable and understandble for both humans and AI 
+The textual representation should be easily handled by version control tools such as Git 
 The underlying semantics of the textual / graphical representation should support traceability of various development artifacts (for example - code, CAD files, electrical schematics, Docx files and anything in between)
 The textual representation editor should have syntax highlighting and linting
 
-The project should also have a backend server / service that you can deploy. The backend server purpose is to give programmatic access to stored system models. So, there also should be a clear REST API for querying, editing and working with models. The purpose of the REST API is to allow automation, scripting and AI-driven workflows
-An example could be - writing custom plugins for various domain specific software (version control software, CAD software etc...) to establish traceability between development artifacts and a system model
+The project should also have a backend server / service that you can deploy. The backend server purpose is to give programmatic access to stored system models. So, there also should be a clear REST API for querying, editing and working with models. The purpose of the REST API is to allow automation, scripting and AI-driven workflows 
+An example could be - writing custom plugins for various domain specific software (version control software, CAD software etc...) to establish traceability between development artifacts and a system model 
 
 The desktop application should contain built-in guide / help / tutorial with clear and concise info on modeling concepts, underlying semantics, common modeling scenarios and application features / how to use the app. It should be easy to navigate and explore
 
-@Computer
+@Computer 
 
 ### Semantic model / metamodel
 
 Requirements:
-
 - Textual notation.
 - Graphical notation.
 - Constraints and calculations.
@@ -658,7 +90,6 @@ Requirements:
 #### Textual notation
 
 Requirements:
-
 - Should not have visual noise and clutter.
 - Should have means to reduce cognitive load when developing system models.
 - Should be easily editable by humans. And AI agents.
@@ -672,8 +103,9 @@ Long, homogeneous lists in the UI that require user to scroll far or search for
 
 ## Active issues / current guidance
 
-Right now, the behavior & scenarios UI is hard to use. It contains static / uneditable diagrams, which is highly dubious. In addition, user workflow with the behavior & scenarios UI differ significantly from the other UIs - you can't edit diagrams and instead suppose to click on menus for model development
+Right now, the behavior & scenarios UI is hard to use. It contains static / uneditable diagrams, which is highly dubious. In addition, user workflow with the behavior & scenarios UI differ significantly from the other UIs - you can't edit diagrams and instead suppose to click on menus for model development 
 
----
+--- 
 
-The current project state is nowhere near the usability of the original ARCADIA Capella (despite its downfalls) or its functionality / semantics. You should focus on that by studying original ARCADIA Capella very closely and implementing its features in a modern, ergonomic and easy to use way
+The current project state is nowhere near the usability of the original ARCADIA Capella (despite its downfalls) or its functionality / semantics. You should focus on that by studying original ARCADIA Capella very closely and implementing its features in a modern, ergonomic and easy to use way
+<!-- END USER-OWNED APPLICATION SPECIFICATION -->

README.md

@@ -18,7 +18,7 @@ From the repository root:
 cargo run --locked -p oa-desktop --bin arcadia-studio
 ```
 
-Build both desktop and server release executables:
+Build the desktop, server and source CLI release executables:
 
 ```sh
 cargo build --release --workspace --locked
@@ -51,6 +51,21 @@ The earlier V2 package record describes `dist/ArcadiaStudio-Windows.zip` and `di
 
 The current [Windows packaging instructions](docs/windows-packaging.md) stage both executables, verify their runtime DLL dependencies, and produce an archive with checksums and provenance. Native acceptance fixtures and independent expected results are retained in [the release fixture directory](harness/fixtures/release1-native/README.md).
 
+## Work with source files from the command line
+
+The `arcadia` CLI checks an explicit `.arcadia` entry file and its includes without
+starting the desktop or server:
+
+```sh
+cargo run --locked -p oa-cli --bin arcadia -- check examples/text-first/project.arcadia
+```
+
+`stabilize ROOT` previews the identities needed for persistent editing;
+`rename-alias ROOT OLD NEW` previews an alias change and its references. Add
+`--write` to save that invocation's candidate, or `--json` for structured
+diagnostics and changed-file text/diffs. Preview leaves files untouched.
+See [source CLI commands](docs/source-cli.md) for examples and exit codes.
+
 ## Model operational needs and system responsibilities
 
 The desktop starts at **Home**, where you can create a model, open a local project, continue recent files or recover retained work. Missing recent files stay visible with **Locate**; **Remove** only forgets their history entry. Choose **Explore rescue example** for a model combining people, an organization, a System of Interest, information and physical exchange items, normal/degraded behavior and code/CAD evidence.

crates/oa-cli/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "oa-cli"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+rust-version.workspace = true
+
+[[bin]]
+name = "arcadia"
+path = "src/main.rs"
+
+[dependencies]
+oa-core = { path = "../oa-core" }
+serde.workspace = true
+serde_json.workspace = true

crates/oa-cli/src/lib.rs

@@ -0,0 +1,451 @@
+//! Source-only authoring. Preparation captures bytes; only core owns disk writes.
+use oa_core::{
+    Command, language,
+    persistence::MigrationReport,
+    prepare_command,
+    source_files::{self, DiskProject, SourceFileError},
+    source_project::{self, CompiledSourceProject, ProjectLimits, SourceDiagnostic},
+    validation::Severity,
+};
+use serde::Serialize;
+use std::path::{Path, PathBuf};
+
+pub const LIMITS: ProjectLimits = ProjectLimits {
+    max_files: 256,
+    max_include_depth: 32,
+    max_include_edges: 1024,
+    model: language::ParseLimits {
+        max_source_bytes: 64 * 1024 * 1024,
+        max_graph_objects: 100_000,
+        max_records: 250_000,
+        max_step_references: 500_000,
+    },
+};
+
+#[derive(Debug, Clone)]
+pub enum Operation {
+    Check,
+    Stabilize,
+    RenameAlias { old: String, new: String },
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct Location {
+    pub path: String,
+    /// Half-open UTF-8 byte offsets. Line/column are one-based Unicode scalars.
+    pub start: usize,
+    pub end: usize,
+    pub line: Option<usize>,
+    pub column: Option<usize>,
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct Diagnostic {
+    pub severity: String,
+    pub code: String,
+    pub message: String,
+    pub coordinate_space: String,
+    pub location: Option<Location>,
+    pub related: Vec<Location>,
+    pub object_id: Option<String>,
+    pub field: Option<String>,
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct Change {
+    pub path: String,
+    /// Exact captured and proposed UTF-8 text, including line endings.
+    pub before: String,
+    pub after: String,
+    pub diff: String,
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct Report {
+    pub format_version: u32,
+    pub entry: String,
+    pub operation: String,
+    pub status: String,
+    pub exit_code: u8,
+    /// True only after a successful changed save. False on failure does not
+    /// promise rollback: consult the specific error/recovery outcome.
+    pub written: bool,
+    pub diagnostics: Vec<Diagnostic>,
+    pub changes: Vec<Change>,
+    pub identities_to_stabilize: usize,
+    pub migration: Option<MigrationReport>,
+    pub notes: Vec<String>,
+}
+
+impl Report {
+    pub fn failure(
+        entry: &Path,
+        operation: &str,
+        exit_code: u8,
+        code: &str,
+        message: String,
+    ) -> Self {
+        let mut report = Self::empty(entry, operation);
+        report.fail(exit_code, code, message);
+        report
+    }
+
+    fn empty(entry: &Path, operation: &str) -> Self {
+        Self {
+            format_version: 1,
+            entry: entry.to_string_lossy().into_owned(),
+            operation: operation.into(),
+            status: "checked".into(),
+            exit_code: 0,
+            written: false,
+            diagnostics: vec![],
+            changes: vec![],
+            identities_to_stabilize: 0,
+            migration: None,
+            notes: vec![],
+        }
+    }
+
+    fn fail(&mut self, exit_code: u8, code: &str, message: String) {
+        self.status = "rejected".into();
+        self.exit_code = exit_code;
+        self.diagnostics.push(Diagnostic {
+            severity: "error".into(),
+            code: code.into(),
+            message,
+            coordinate_space: "operation".into(),
+            location: None,
+            related: vec![],
+            object_id: None,
+            field: None,
+        });
+    }
+}
+
+fn located(issue: SourceDiagnostic, space: &str) -> Diagnostic {
+    let d = issue.diagnostic;
+    Diagnostic {
+        severity: match d.severity {
+            Severity::Error => "error",
+            Severity::Warning => "warning",
+        }
+        .into(),
+        code: d.code,
+        message: d.message,
+        coordinate_space: space.into(),
+        location: Some(Location {
+            path: issue.path,
+            start: d.span.start,
+            end: d.span.end,
+            line: Some(d.line),
+            column: Some(d.column),
+        }),
+        related: issue
+            .related
+            .into_iter()
+            .map(|at| Location {
+                path: at.path,
+                start: at.span.start,
+                end: at.span.end,
+                line: None,
+                column: None,
+            })
+            .collect(),
+        object_id: d.object_id.map(|id| id.to_string()),
+        field: d.field,
+    }
+}
+
+fn disk_error(report: &mut Report, error: SourceFileError) {
+    let code = match &error {
+        SourceFileError::Conflict(_) => "external_change",
+        SourceFileError::RecoveryRequired(_) => "recovery_required",
+        SourceFileError::RecoveryFailed { .. } => "recovery_failed",
+        SourceFileError::Path(_) => "unsafe_path",
+        SourceFileError::Limit(_) => "source_limit",
+        SourceFileError::UnknownExpectation(_) => "unknown_disk_expectation",
+        SourceFileError::Invalid(_) => "invalid_save_candidate",
+        SourceFileError::Io { .. } => "io_error",
+    };
+    report.fail(3, code, error.to_string());
+}
+
+/// A candidate owns its original expectations and is consumed by saving.
+/// Callers cannot replace its source/model/expectations after preparation.
+pub struct Prepared {
+    report: Report,
+    snapshot: DiskProject,
+    compiled: CompiledSourceProject,
+    mutable: bool,
+}
+
+impl Prepared {
+    pub fn report(&self) -> &Report {
+        &self.report
+    }
+
+    pub fn into_report(self) -> Report {
+        self.report
+    }
+
+    pub fn write(mut self) -> Report {
+        if !self.mutable {
+            self.report
+                .fail(2, "usage", "check/lint does not accept --write".into());
+            return self.report;
+        }
+        match source_files::save_project(&self.snapshot, &self.compiled, LIMITS) {
+            Ok(_) => {
+                self.report.written = !self.report.changes.is_empty();
+                self.report.status = if self.report.written {
+                    "written"
+                } else {
+                    "unchanged"
+                }
+                .into();
+            }
+            Err(error) => disk_error(&mut self.report, error),
+        }
+        self.report
+    }
+}
+
+pub fn prepare(entry: &Path, operation: Operation) -> Result<Prepared, Box<Report>> {
+    let name = match operation {
+        Operation::Check => "check",
+        Operation::Stabilize => "stabilize",
+        Operation::RenameAlias { .. } => "rename-alias",
+    };
+    let mut report = Report::empty(entry, name);
+    let snapshot = source_files::load_project(entry, LIMITS).map_err(|error| {
+        disk_error(&mut report, error);
+        Box::new(report.clone())
+    })?;
+    let raw = snapshot.reachable_bundle();
+    // The loader may include warnings from stabilized compilation. Only its
+    // discovery/IO diagnostics are authoritative on the original bytes.
+    let mut diagnostics: Vec<_> = snapshot
+        .diagnostics
+        .iter()
+        .filter(|d| {
+            matches!(
+                d.diagnostic.code.as_str(),
+                "pending_save"
+                    | "source_encoding"
+                    | "source_limit"
+                    | "invalid_path"
+                    | "missing_include"
+                    | "project_limit"
+            )
+        })
+        .cloned()
+        .collect();
+    for diagnostic in source_project::lint_bundle(&raw, LIMITS) {
+        if !diagnostics.contains(&diagnostic) {
+            diagnostics.push(diagnostic);
+        }
+    }
+    let disk_refusal = snapshot.diagnostics.iter().any(|d| {
+        matches!(
+            d.diagnostic.code.as_str(),
+            "pending_save" | "missing_include" | "invalid_path"
+        )
+    });
+    let invalid = diagnostics
+        .iter()
+        .any(|d| d.diagnostic.severity == Severity::Error);
+    report.diagnostics = diagnostics
+        .into_iter()
+        .map(|d| located(d, "input"))
+        .collect();
+    if invalid {
+        // Do not run declaration analysis or any updater on invalid raw text.
+        // Failed lint may also have allocated provisional object identities.
+        for diagnostic in &mut report.diagnostics {
+            diagnostic.object_id = None;
+        }
+        report.status = "invalid".into();
+        report.exit_code = if disk_refusal { 3 } else { 1 };
+        return Err(Box::new(report));
+    }
+    let explicit_ids: std::collections::BTreeSet<_> = raw
+        .files
+        .values()
+        .flat_map(|text| language::analyze(text).declarations)
+        .filter_map(|d| d.id.map(|id| id.to_string()))
+        .collect();
+    for diagnostic in &mut report.diagnostics {
+        if diagnostic
+            .object_id
+            .as_ref()
+            .is_some_and(|id| !explicit_ids.contains(id))
+        {
+            diagnostic.object_id = None;
+        }
+    }
+    let mut compiled = source_project::compile_bundle(&raw, LIMITS).map_err(|diagnostics| {
+        report.status = "invalid".into();
+        report.exit_code = 1;
+        report
+            .diagnostics
+            .extend(diagnostics.into_iter().map(|d| located(d, "candidate")));
+        Box::new(report.clone())
+    })?;
+    report.identities_to_stabilize = raw
+        .files
+        .values()
+        .map(|text| {
+            language::analyze(text)
+                .declarations
+                .into_iter()
+                .filter(|d| d.id.is_none())
+                .count()
+        })
+        .sum();
+    report.migration = compiled.decoded.migration.clone();
+    let mutable = !matches!(operation, Operation::Check);
+    if let Operation::RenameAlias { old, new } = operation {
+        let project = &compiled.decoded.project;
+        let Some((id, _)) = project
+            .identities()
+            .into_iter()
+            .find(|(_, alias)| *alias == old)
+        else {
+            report.fail(
+                1,
+                "unknown_alias",
+                format!("No declaration has alias '{old}'."),
+            );
+            return Err(Box::new(report));
+        };
+        let command = prepare_command(project, &Command::SetAlias(id, new)).map_err(|error| {
+            report.fail(1, "semantic_command_rejected", error.to_string());
+            Box::new(report.clone())
+        })?;
+        compiled = source_project::update_bundle_with_identity_map(
+            &compiled,
+            &command.project,
+            &command.identity_map,
+            LIMITS,
+        )
+        .map_err(|diagnostics| {
+            report.status = "invalid".into();
+            report.exit_code = 1;
+            report
+                .diagnostics
+                .extend(diagnostics.into_iter().map(|d| located(d, "candidate")));
+            Box::new(report.clone())
+        })?;
+    }
+    if mutable {
+        for (path, after) in &compiled.bundle.files {
+            let before = raw.files.get(path).cloned().unwrap_or_default();
+            if &before != after {
+                report.changes.push(Change {
+                    path: path.clone(),
+                    diff: unified_diff(path, &before, after),
+                    before,
+                    after: after.clone(),
+                });
+            }
+        }
+        report.status = "preview".into();
+        report.notes.push("This invocation's complete proposed changed-file texts and diffs are reported. Without --write nothing is saved; a later invocation may allocate different missing UUIDs. This is not a saved plan or a digest of unchanged dependencies.".into());
+    }
+    report.notes.push("Diagnostic object IDs are omitted for declarations without authored IDs; lint's temporary identities are not the candidate's identities.".into());
+    report.notes.push("Disk writes use the core journal/conflict checks. This is not cross-process atomic visibility or a power-loss durability guarantee; pending saves are never implicitly recovered. A failed write may require explicit journal recovery.".into());
+    Ok(Prepared {
+        report,
+        snapshot,
+        compiled,
+        mutable,
+    })
+}
+
+/// One bounded hunk per file: common prefix/suffix plus three context lines.
+/// Linear in input size; no quadratic LCS allocation for large modules.
+fn unified_diff(path: &str, before: &str, after: &str) -> String {
+    let a: Vec<_> = before.split_inclusive('\n').collect();
+    let b: Vec<_> = after.split_inclusive('\n').collect();
+    let prefix = a.iter().zip(&b).take_while(|(a, b)| a == b).count();
+    let suffix = a[prefix..]
+        .iter()
+        .rev()
+        .zip(b[prefix..].iter().rev())
+        .take_while(|(a, b)| a == b)
+        .count();
+    let start = prefix.saturating_sub(3);
+    let a_end = (a.len() - suffix + 3).min(a.len());
+    let b_end = (b.len() - suffix + 3).min(b.len());
+    let a_start = if a_end == start { start } else { start + 1 };
+    let b_start = if b_end == start { start } else { start + 1 };
+    let mut out = format!(
+        "--- a/{path}\n+++ b/{path}\n@@ -{a_start},{} +{b_start},{} @@\n",
+        a_end - start,
+        b_end - start
+    );
+    let mut emit = |prefix: char, line: &str| {
+        out.push(prefix);
+        out.push_str(line);
+        if !line.ends_with('\n') {
+            out.push_str("\n\\ No newline at end of file\n");
+        }
+    };
+    for line in &a[start..prefix] {
+        emit(' ', line);
+    }
+    for line in &a[prefix..a.len() - suffix] {
+        emit('-', line);
+    }
+    for line in &b[prefix..b.len() - suffix] {
+        emit('+', line);
+    }
+    for line in &a[a.len() - suffix..a_end] {
+        emit(' ', line);
+    }
+    out
+}
+
+pub struct Arguments {
+    pub entry: PathBuf,
+    pub operation: Operation,
+    pub write: bool,
+    pub json: bool,
+}
+
+pub const HELP: &str = "arcadia check ROOT [--json]\narcadia lint ROOT [--json]\narcadia stabilize ROOT [--write] [--json]\narcadia rename-alias ROOT OLD NEW [--write] [--json]\n\nROOT is an explicit .arcadia entry file; includes resolve relative to it.\nMutation commands preview by default. --write applies this invocation's candidate.\nMissing UUIDs in a preview are provisional until written. No canonical formatting.\nExit: 0 valid/success (engineering warnings allowed), 1 invalid source or semantic\ncommand rejection, 2 usage, 3 disk/path/conflict/pending-journal/output failure.\nNo implicit journal recovery. Limits: 64 MiB, 256 files, include depth32/edges1024,\n100000 graph objects, 250000 records, 500000 ordered references.\n";
+
+pub fn arguments(args: &[std::ffi::OsString]) -> Result<Arguments, String> {
+    let mut positional = Vec::new();
+    let (mut write, mut json) = (false, false);
+    for arg in args {
+        if arg == "--write" && !write {
+            write = true;
+        } else if arg == "--json" && !json {
+            json = true;
+        } else if arg.to_string_lossy().starts_with('-') {
+            return Err(format!(
+                "Unknown or repeated option: {}",
+                arg.to_string_lossy()
+            ));
+        } else {
+            positional.push(arg);
+        }
+    }
+    let command = positional.first().and_then(|s| s.to_str()).unwrap_or("");
+    let operation = match (command, positional.len()) {
+        ("check" | "lint", 2) if !write => Operation::Check,
+        ("stabilize", 2) => Operation::Stabilize,
+        ("rename-alias", 4) => Operation::RenameAlias {
+            old: positional[2].to_str().ok_or("Alias must be UTF-8")?.into(),
+            new: positional[3].to_str().ok_or("Alias must be UTF-8")?.into(),
+        },
+        _ => return Err(HELP.into()),
+    };
+    Ok(Arguments {
+        entry: PathBuf::from(positional[1]),
+        operation,
+        write,
+        json,
+    })
+}

crates/oa-cli/src/main.rs

@@ -0,0 +1,102 @@
+use oa_cli::{Report, arguments, prepare};
+use std::{
+    io::{self, Write},
+    path::Path,
+    process::ExitCode,
+};
+
+fn human_report(report: &Report, show_diff: bool) -> io::Result<()> {
+    let mut err = io::stderr().lock();
+    for d in &report.diagnostics {
+        let at = d
+            .location
+            .as_ref()
+            .map(|l| {
+                format!(
+                    "{}:{}:{}",
+                    l.path,
+                    l.line.unwrap_or(0),
+                    l.column.unwrap_or(0)
+                )
+            })
+            .unwrap_or_else(|| report.entry.clone());
+        writeln!(
+            err,
+            "{at}: {}[{}] ({}): {}",
+            d.severity, d.code, d.coordinate_space, d.message
+        )?;
+    }
+    writeln!(
+        err,
+        "{}: {} file changes; {} identities to stabilize",
+        report.status,
+        report.changes.len(),
+        report.identities_to_stabilize
+    )?;
+    if let Some(migration) = &report.migration {
+        writeln!(
+            err,
+            "Source migration: schema {} → {} (separate from identity stabilization)",
+            migration.from_schema, migration.to_schema
+        )?;
+    }
+    for note in &report.notes {
+        writeln!(err, "{note}")?;
+    }
+    if show_diff {
+        let mut out = io::stdout().lock();
+        for change in &report.changes {
+            write!(out, "{}", change.diff)?;
+        }
+        out.flush()?;
+    }
+    err.flush()
+}
+
+fn run() -> io::Result<u8> {
+    let args: Vec<_> = std::env::args_os().skip(1).collect();
+    if args.len() == 1 && (args[0] == "--help" || args[0] == "-h") {
+        io::stdout().write_all(oa_cli::HELP.as_bytes())?;
+        return Ok(0);
+    }
+    if args.len() == 1 && args[0] == "--version" {
+        writeln!(io::stdout(), "arcadia {}", env!("CARGO_PKG_VERSION"))?;
+        return Ok(0);
+    }
+    let json = args.iter().any(|a| a == "--json");
+    let mut displayed = false;
+    let report = match arguments(&args) {
+        Err(error) => Report::failure(Path::new(""), "usage", 2, "usage", error),
+        Ok(args) => match prepare(&args.entry, args.operation) {
+            Err(report) => *report,
+            Ok(prepared) => {
+                if args.write {
+                    if !args.json {
+                        human_report(prepared.report(), true)?;
+                        displayed = true;
+                    }
+                    prepared.write()
+                } else {
+                    prepared.into_report()
+                }
+            }
+        },
+    };
+    if json {
+        serde_json::to_writer_pretty(io::stdout().lock(), &report)?;
+        writeln!(io::stdout())?;
+    } else {
+        human_report(&report, !displayed)?;
+    }
+    Ok(report.exit_code)
+}
+
+fn main() -> ExitCode {
+    match run() {
+        Ok(code) => ExitCode::from(code),
+        Err(error) => {
+            let _ = writeln!(io::stderr(), "Output failed: {error}");
+            ExitCode::from(3)
+        }
+    }
+}

crates/oa-cli/tests/source_cli.rs

@@ -0,0 +1,425 @@
+use oa_cli::{LIMITS, Operation, Prepared, prepare};
+use oa_core::{Id, Project, source_files, source_project};
+use serde_json::Value;
+use std::{
+    collections::BTreeMap,
+    fs,
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+struct Fixture(PathBuf);
+impl Fixture {
+    fn new() -> Self {
+        let path = std::env::temp_dir().join(format!("arcadia-cli-test-{}", Id::new_v4()));
+        fs::create_dir(&path).unwrap();
+        Self(path)
+    }
+    fn put(&self, name: &str, text: &str) {
+        let path = self.0.join(name);
+        fs::create_dir_all(path.parent().unwrap()).unwrap();
+        fs::write(path, text).unwrap();
+    }
+    fn entry(&self) -> PathBuf {
+        self.0.join("project.arcadia")
+    }
+    fn read(&self, name: &str) -> String {
+        fs::read_to_string(self.0.join(name)).unwrap()
+    }
+    fn prepare(&self, op: Operation) -> Prepared {
+        prepare(&self.entry(), op).unwrap_or_else(|report| panic!("{report:#?}"))
+    }
+    fn model(&self) -> Project {
+        let disk = source_files::load_project(&self.entry(), LIMITS).unwrap();
+        source_project::compile_bundle(&disk.reachable_bundle(), LIMITS)
+            .unwrap()
+            .decoded
+            .project
+    }
+    fn cli(&self, args: &[&str]) -> (i32, Value) {
+        let mut command = Command::new(env!("CARGO_BIN_EXE_arcadia"));
+        command
+            .arg(args[0])
+            .arg(self.entry())
+            .args(&args[1..])
+            .arg("--json");
+        let output = command.output().unwrap();
+        assert!(
+            output.stderr.is_empty(),
+            "{}",
+            String::from_utf8_lossy(&output.stderr)
+        );
+        (
+            output.status.code().unwrap(),
+            serde_json::from_slice(&output.stdout).unwrap(),
+        )
+    }
+}
+impl Drop for Fixture {
+    fn drop(&mut self) {
+        let _ = fs::remove_dir_all(&self.0);
+    }
+}
+
+const SIMPLE: &str = "// 雨: authored defaults stay omitted\r\narcadia 7;\r\nproject rescue \"Rescue\" {\r\n    oa_entity team \"Team\" {}\r\n}\r\n";
+
+#[test]
+fn complete_alarm_example_preview_then_write_and_fixed_point() {
+    let fixture = Fixture::new();
+    let source = include_str!(
+        "../../../harness/experiments/textual-authoring-20260911/alarm-response.arcadia"
+    );
+    fixture.put("project.arcadia", source);
+    let (code, check) = fixture.cli(&["check"]);
+    assert_eq!(code, 0);
+    assert_eq!(check["diagnostics"], serde_json::json!([]));
+    let (code, preview) = fixture.cli(&["stabilize"]);
+    assert_eq!(code, 0);
+    assert_eq!(preview["identities_to_stabilize"], 40);
+    assert_eq!(preview["status"], "preview");
+    assert_eq!(fixture.read("project.arcadia"), source);
+    assert!(
+        preview["changes"][0]["diff"]
+            .as_str()
+            .unwrap()
+            .contains("+project alarm_response")
+    );
+    let (code, written) = fixture.cli(&["stabilize", "--write"]);
+    assert_eq!(code, 0);
+    let saved = fixture.read("project.arcadia");
+    assert_eq!(written["changes"][0]["after"], saved);
+    let project = fixture.model();
+    assert_eq!(project.identities().len(), 40);
+    let mut stripped = saved.clone();
+    for (id, _) in project.identities() {
+        stripped = stripped.replace(&format!(" id \"{id}\""), "");
+    }
+    assert_eq!(stripped, source, "only identity clauses may be inserted");
+    let (code, again) = fixture.cli(&["stabilize", "--write"]);
+    assert_eq!(code, 0);
+    assert_eq!(again["changes"], serde_json::json!([]));
+    assert_eq!(again["status"], "unchanged");
+    assert_eq!(fixture.model(), project);
+    assert_eq!(fixture.read("project.arcadia"), saved);
+}
+
+#[test]
+fn captured_candidate_exact_write_preserves_crlf_comments_and_noop_metadata() {
+    let fixture = Fixture::new();
+    fixture.put("project.arcadia", SIMPLE);
+    let candidate = fixture.prepare(Operation::Stabilize);
+    let expected = candidate.report().changes[0].after.clone();
+    assert_eq!(candidate.report().identities_to_stabilize, 2);
+    assert_eq!(fixture.read("project.arcadia"), SIMPLE);
+    assert_eq!(candidate.write().exit_code, 0);
+    assert_eq!(fixture.read("project.arcadia"), expected);
+    assert!(expected.contains("// 雨: authored defaults stay omitted\r\n"));
+    assert!(!expected.contains("description"));
+    let metadata = fs::metadata(fixture.entry()).unwrap().modified().unwrap();
+    let report = fixture.prepare(Operation::Stabilize).write();
+    assert_eq!(report.status, "unchanged");
+    assert!(!report.written);
+    assert_eq!(
+        fs::metadata(fixture.entry()).unwrap().modified().unwrap(),
+        metadata
+    );
+    assert_eq!(fs::read_dir(&fixture.0).unwrap().count(), 1);
+}
+
+#[test]
+fn alias_rename_across_modules_changes_only_live_tokens_and_retains_all_identity() {
+    let fixture = Fixture::new();
+    fixture.put("project.arcadia", "arcadia 7; project rescue \"Rescue\" { include \"participants.arcadia\"; include \"work.arcadia\"; }\n");
+    fixture.put(
+        "participants.arcadia",
+        "// @team is quoted documentation\noa_entity team \"Team @team\" {}\n",
+    );
+    fixture.put("work.arcadia", "oa_activity assess \"Assess\" {}\noa_activity report \"Report\" {}\nallocation assigned \"Assigned\" { source @team; target @assess; }\ninteraction transfer \"Transfer\" { source @assess; target @report; }\n");
+    assert_eq!(fixture.prepare(Operation::Stabilize).write().exit_code, 0);
+    let before = fixture.model();
+    let original: BTreeMap<_, _> = ["project.arcadia", "participants.arcadia", "work.arcadia"]
+        .into_iter()
+        .map(|p| (p, fixture.read(p)))
+        .collect();
+    let team = before
+        .identities()
+        .into_iter()
+        .find(|(_, alias)| *alias == "team")
+        .unwrap()
+        .0;
+    let candidate = fixture.prepare(Operation::RenameAlias {
+        old: "team".into(),
+        new: "rescue_team".into(),
+    });
+    assert_eq!(candidate.report().changes.len(), 2);
+    assert_eq!(fixture.model(), before, "preview cannot mutate");
+    assert_eq!(candidate.write().exit_code, 0);
+    let mut expected = before;
+    expected.elements.get_mut(&team).unwrap().alias = "rescue_team".into();
+    assert_eq!(fixture.model(), expected);
+    assert_eq!(fixture.read("project.arcadia"), original["project.arcadia"]);
+    assert_eq!(
+        fixture.read("participants.arcadia"),
+        original["participants.arcadia"].replacen("oa_entity team ", "oa_entity rescue_team ", 1)
+    );
+    assert_eq!(
+        fixture.read("work.arcadia"),
+        original["work.arcadia"].replace("source @team;", "source @rescue_team;")
+    );
+}
+
+#[test]
+fn invalid_unicode_raw_edit_is_located_and_never_stabilized_or_written() {
+    let fixture = Fixture::new();
+    let raw = "arcadia 7; project p \"雨\" {\n oa_activity a \"A\" {}\n allocation alloc \"Alloc\" { source @missing; target @a; }\n}\n";
+    fixture.put("project.arcadia", raw);
+    for command in [
+        vec!["check"],
+        vec!["stabilize", "--write"],
+        vec!["rename-alias", "a", "b", "--write"],
+    ] {
+        let (code, report) = fixture.cli(&command);
+        assert_eq!(code, 1);
+        assert_eq!(fixture.read("project.arcadia"), raw);
+        let diagnostics = report["diagnostics"].as_array().unwrap();
+        assert!(!diagnostics.is_empty());
+        for d in diagnostics {
+            assert_eq!(d["coordinate_space"], "input");
+            let at = &d["location"];
+            let start = at["start"].as_u64().unwrap() as usize;
+            assert!(raw.is_char_boundary(start));
+            assert_eq!(
+                at["line"].as_u64().unwrap() as usize,
+                raw[..start].bytes().filter(|b| *b == b'\n').count() + 1
+            );
+            let line = raw[..start]
+                .rsplit_once('\n')
+                .map_or(&raw[..start], |(_, tail)| tail);
+            assert_eq!(
+                at["column"].as_u64().unwrap() as usize,
+                line.chars().count() + 1
+            );
+        }
+    }
+}
+
+#[test]
+fn missing_id_warning_uses_raw_location_and_never_exposes_ephemeral_lint_id() {
+    let fixture = Fixture::new();
+    let raw = "arcadia 7;\nproject p \"雨\" {\n    oa_activity work \"Work\" {}\n}\n";
+    fixture.put("project.arcadia", raw);
+    let (code, result) = fixture.cli(&["lint"]);
+    assert_eq!(code, 0, "engineering warnings do not reject admission");
+    let warning = result["diagnostics"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .find(|d| d["code"] == "work_without_behavior_context")
+        .unwrap();
+    assert_eq!(warning["severity"], "warning");
+    assert_eq!(
+        warning["location"]["start"],
+        raw.find("oa_activity").unwrap()
+    );
+    assert_eq!(warning["location"]["line"], 3);
+    assert_eq!(warning["location"]["column"], 5);
+    assert!(warning["object_id"].is_null());
+    assert_eq!(fixture.read("project.arcadia"), raw);
+}
+
+#[test]
+fn captured_dependency_change_refuses_all_writes_even_on_noop() {
+    let fixture = Fixture::new();
+    fixture.put("project.arcadia", SIMPLE);
+    let pending = fixture.prepare(Operation::Stabilize);
+    let external = format!("{SIMPLE}// editor changed this\n");
+    fixture.put("project.arcadia", &external);
+    let result = pending.write();
+    assert_eq!(result.exit_code, 3);
+    assert_eq!(result.diagnostics.last().unwrap().code, "external_change");
+    assert_eq!(fixture.read("project.arcadia"), external);
+    assert_eq!(fixture.prepare(Operation::Stabilize).write().exit_code, 0);
+    let noop = fixture.prepare(Operation::Stabilize);
+    assert!(noop.report().changes.is_empty());
+    let latest = format!("{}// another edit\n", fixture.read("project.arcadia"));
+    fixture.put("project.arcadia", &latest);
+    assert_eq!(noop.write().exit_code, 3);
+    assert_eq!(fixture.read("project.arcadia"), latest);
+}
+
+#[test]
+fn pending_journal_refuses_read_preview_and_write_without_recovery() {
+    let fixture = Fixture::new();
+    fixture.put("project.arcadia", SIMPLE);
+    assert_eq!(fixture.prepare(Operation::Stabilize).write().exit_code, 0);
+    let noop = fixture.prepare(Operation::Stabilize);
+    let source = fixture.read("project.arcadia");
+    // An opaque incomplete journal must never be interpreted/recovered by CLI.
+    let journal = fixture.0.join(".arcadia-save-project.arcadia.journal");
+    fs::create_dir(&journal).unwrap();
+    fs::write(journal.join("sentinel"), b"retain").unwrap();
+    for op in [Operation::Check, Operation::Stabilize] {
+        let report = prepare(&fixture.entry(), op).err().unwrap();
+        assert_eq!(report.exit_code, 3);
+        assert!(report.diagnostics.iter().any(|d| d.code == "pending_save"));
+    }
+    assert_eq!(
+        noop.write().exit_code,
+        3,
+        "saver must recheck after preview"
+    );
+    assert_eq!(fixture.read("project.arcadia"), source);
+    assert_eq!(fs::read(journal.join("sentinel")).unwrap(), b"retain");
+}
+
+#[test]
+fn rejected_alias_and_same_alias_preserve_source() {
+    let fixture = Fixture::new();
+    fixture.put("project.arcadia", SIMPLE);
+    assert_eq!(fixture.prepare(Operation::Stabilize).write().exit_code, 0);
+    let source = fixture.read("project.arcadia");
+    for (old, new) in [
+        ("team", "rescue"),
+        ("team", "invalid alias"),
+        ("absent", "valid"),
+    ] {
+        let (code, result) = fixture.cli(&["rename-alias", old, new, "--write"]);
+        assert_eq!(code, 1);
+        assert_eq!(result["status"], "rejected");
+        assert_eq!(fixture.read("project.arcadia"), source);
+    }
+    let (code, result) = fixture.cli(&["rename-alias", "team", "team", "--write"]);
+    assert_eq!(code, 0);
+    assert_eq!(result["status"], "unchanged");
+    assert_eq!(fixture.read("project.arcadia"), source);
+}
+
+#[test]
+fn rename_shows_missing_identity_and_separate_source_migration() {
+    let fixture = Fixture::new();
+    let old = "// retain\narcadia 5; project p \"P\" { oa_entity team \"Team\" {} }\n";
+    fixture.put("project.arcadia", old);
+    let candidate = fixture.prepare(Operation::RenameAlias {
+        old: "team".into(),
+        new: "crew".into(),
+    });
+    let report = candidate.report();
+    assert_eq!(report.identities_to_stabilize, 2);
+    assert_eq!(report.migration.as_ref().unwrap().from_schema, 5);
+    assert_eq!(report.migration.as_ref().unwrap().to_schema, 7);
+    assert!(report.changes[0].diff.contains("-arcadia 5;"));
+    assert!(report.changes[0].diff.contains("+arcadia 7;"));
+    assert!(report.changes[0].after.contains("oa_entity crew"));
+    assert_eq!(fixture.read("project.arcadia"), old);
+    assert_eq!(candidate.write().exit_code, 0);
+}
+
+#[test]
+fn entry_is_explicit_and_machine_readable_usage_errors_do_not_write() {
+    let fixture = Fixture::new();
+    fixture.put("project.arcadia", SIMPLE);
+    let output = Command::new(env!("CARGO_BIN_EXE_arcadia"))
+        .current_dir(&fixture.0)
+        .args(["check", "--json"])
+        .output()
+        .unwrap();
+    assert_eq!(output.status.code(), Some(2));
+    let error: Value = serde_json::from_slice(&output.stdout).unwrap();
+    assert_eq!(error["diagnostics"][0]["code"], "usage");
+    assert_eq!(fixture.read("project.arcadia"), SIMPLE);
+    let (code, _) = fixture.cli(&["check", "--write"]);
+    assert_eq!(code, 2);
+    assert!(Path::new(env!("CARGO_BIN_EXE_arcadia")).is_file());
+}
+
+#[test]
+fn loader_encoding_missing_dependency_and_invalid_old_source_keep_original_bytes() {
+    let fixture = Fixture::new();
+    let entry = "arcadia 7; project p \"P\" { include \"part.arcadia\"; }";
+    fixture.put("project.arcadia", entry);
+    let (code, report) = fixture.cli(&["stabilize", "--write"]);
+    assert_eq!(code, 3, "a disk dependency could not be read");
+    assert!(
+        report["diagnostics"]
+            .as_array()
+            .unwrap()
+            .iter()
+            .any(|d| d["code"] == "missing_include")
+    );
+    fs::write(fixture.0.join("part.arcadia"), [0xff, 0xfe]).unwrap();
+    let (code, report) = fixture.cli(&["stabilize", "--write"]);
+    assert_eq!(code, 1, "invalid encoding is invalid raw source");
+    assert!(
+        report["diagnostics"]
+            .as_array()
+            .unwrap()
+            .iter()
+            .any(|d| d["code"] == "source_encoding")
+    );
+    assert_eq!(fixture.read("project.arcadia"), entry);
+    assert_eq!(
+        fs::read(fixture.0.join("part.arcadia")).unwrap(),
+        [0xff, 0xfe]
+    );
+    for raw in [
+        "arcadia 5; project p \"P\" { oa_entity a \"A\" { ??? } }",
+        "arcadia 2; project p \"P\" {}",
+    ] {
+        fixture.put("project.arcadia", raw);
+        let (code, _) = fixture.cli(&["stabilize", "--write"]);
+        assert_eq!(code, 1);
+        assert_eq!(fixture.read("project.arcadia"), raw);
+    }
+}
+
+#[test]
+fn non_element_alias_detached_file_and_unchanged_dependency_conflict() {
+    let fixture = Fixture::new();
+    fixture.put("project.arcadia", "arcadia 7; project p \"P\" { include \"part.arcadia\"; oa_activity a \"A\" {} allocation responsible \"Responsible\" { source @ // keep edge comment\nteam; target @a; } }");
+    fixture.put("part.arcadia", "oa_entity team \"Team\" {}");
+    fixture.put(
+        "detached.arcadia",
+        "invalid detached draft must stay exact 雨",
+    );
+    assert_eq!(fixture.prepare(Operation::Stabilize).write().exit_code, 0);
+    let before = fixture.model();
+    let relation = before
+        .identities()
+        .into_iter()
+        .find(|(_, alias)| *alias == "responsible")
+        .unwrap()
+        .0;
+    let (code, _) = fixture.cli(&["rename-alias", "responsible", "performs", "--write"]);
+    assert_eq!(code, 0);
+    let mut expected = before;
+    expected.relations.get_mut(&relation).unwrap().alias = "performs".into();
+    assert_eq!(fixture.model(), expected);
+    assert!(
+        fixture
+            .read("project.arcadia")
+            .contains("@ // keep edge comment\nteam")
+    );
+    let captured = fixture.prepare(Operation::RenameAlias {
+        old: "p".into(),
+        new: "rescue".into(),
+    });
+    assert!(
+        captured
+            .report()
+            .changes
+            .iter()
+            .all(|c| c.path != "part.arcadia")
+    );
+    let root_before = fixture.read("project.arcadia");
+    fixture.put("part.arcadia", "// external unchanged-dependency edit\n");
+    assert_eq!(captured.write().exit_code, 3);
+    assert_eq!(fixture.read("project.arcadia"), root_before);
+    assert_eq!(
+        fixture.read("part.arcadia"),
+        "// external unchanged-dependency edit\n"
+    );
+    assert_eq!(
+        fixture.read("detached.arcadia"),
+        "invalid detached draft must stay exact 雨"
+    );
+}

crates/oa-core/Cargo.toml

@@ -12,6 +12,9 @@ uuid.workspace = true
 thiserror.workspace = true
 tempfile = "3"
 same-file = "1"
+num-bigint = "0.5.1"
+num-integer = "0.1.47"
+num-traits = "0.2.19"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 libc = "0.2"

crates/oa-core/src/analysis_numeric.rs

@@ -0,0 +1,103 @@
+//! Exact numeric foundation for analysis; no model, expression, or package resolver.
+//!
+//! Values use reduced rational coordinates. All nontrivial arithmetic takes one
+//! request-local [WorkMeter]. The future evaluator must also charge *expanded*
+//! expression/call/property/list/target visits and retain the same logical walk on
+//! cache hits. Stored AST size is not a dynamic execution limit.
+//!
+//! Approximate engineering functions/irrational unit scales require a subsequent
+//! explicit numeric profile; rationals do not implement degree/radian conversion
+//! or transcendental mathematics.
+
+mod dimension;
+mod exact;
+mod meter;
+mod quantity;
+
+pub use dimension::{Dimension, DimensionAxis};
+pub use exact::{Exact, ExactWire};
+pub use meter::{
+    EvaluationStep, NumericOperation, WorkExhaustion, WorkLimits, WorkMeter, WorkResource,
+    WorkSite, WorkUsage,
+};
+pub use quantity::{NumericType, NumericValue, ResolvedKind, Unit};
+
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+
+/// Profile identity includes the accounting rules, not crate-internal timing.
+pub const WORK_PROFILE: &str = "Q1-logical-work-1";
+pub const MAX_COMPONENT_BITS: u64 = 4096;
+/// Cross products require 8192 bits; their sum can require one additional bit.
+pub const MAX_INTERMEDIATE_BITS: u64 = 8193;
+pub const MAX_COMPONENT_DIGITS: usize = 1234;
+pub const MAX_DECIMAL_EXPONENT: i32 = 128;
+pub const MAX_INTEGER_POWER: i8 = 16;
+/// Includes ratio punctuation/whitespace without permitting unbounded scanning.
+pub const MAX_LITERAL_BYTES: usize = 2 * MAX_COMPONENT_DIGITS + 32;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum NumberComponent {
+    Numerator,
+    Denominator,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Error, Serialize, Deserialize)]
+pub enum NumericLimit {
+    #[error("request work exhausted: {0}")]
+    Work(WorkExhaustion),
+    #[error("{component:?} uses {bits} bits, above the {limit}-bit {stage} limit")]
+    Bits {
+        component: NumberComponent,
+        bits: u64,
+        limit: u64,
+        stage: String,
+    },
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Error, Serialize, Deserialize)]
+pub enum NumericError {
+    #[error("numeric limit: {0}")]
+    Limit(NumericLimit),
+    #[error("invalid numeric literal")]
+    InvalidLiteral,
+    #[error("numeric literal exceeds its digit or byte limit")]
+    LiteralTooLong,
+    #[error("decimal exponent is outside -128 through 128")]
+    DecimalExponent,
+    #[error("wire rational is not in canonical reduced form")]
+    NonCanonicalWire,
+    #[error("rational denominator is zero")]
+    ZeroDenominator,
+    #[error("division by zero")]
+    DivisionByZero,
+    #[error("zero to the power zero is undefined in this profile")]
+    ZeroPowerZero,
+    #[error("integer power is outside -16 through 16")]
+    IntegerPower,
+    #[error("dimension exponent at {axis:?} is outside -32 through 32: {value}")]
+    DimensionExponent { axis: DimensionAxis, value: i32 },
+    #[error("unit scale must be strictly positive")]
+    UnitScale,
+    #[error("a linear unit must have zero offset")]
+    LinearOffset,
+    #[error("an affine point must have a distinct linear difference kind")]
+    DifferenceKind,
+    #[error("numeric kinds or dimensions are incompatible")]
+    IncompatibleTypes,
+    #[error("operation is not defined for affine points")]
+    AffineOperation,
+    #[error("AsKind requires an anonymous matching dimension and a linear target")]
+    KindAssertion,
+    #[error("request work limits exceed the provisional reference ceilings")]
+    InvalidWorkLimits,
+}
+
+impl NumericError {
+    pub fn is_terminal_work_exhaustion(&self) -> bool {
+        matches!(self, Self::Limit(NumericLimit::Work(_)))
+    }
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-core/src/analysis_numeric/dimension.rs

@@ -0,0 +1,107 @@
+use super::NumericError;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum DimensionAxis {
+    Length,
+    Mass,
+    Time,
+    ElectricCurrent,
+    Temperature,
+    Amount,
+    LuminousIntensity,
+}
+
+impl DimensionAxis {
+    pub const ALL: [Self; 7] = [
+        Self::Length,
+        Self::Mass,
+        Self::Time,
+        Self::ElectricCurrent,
+        Self::Temperature,
+        Self::Amount,
+        Self::LuminousIntensity,
+    ];
+}
+
+/// SI base-dimension vector in DimensionAxis::ALL order, each entry -32..=32.
+/// This is a dimension, never a nominal quantity-kind compatibility proof.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(try_from = "[i16; 7]", into = "[i16; 7]")]
+pub struct Dimension([i16; 7]);
+
+impl Dimension {
+    pub const ZERO: Self = Self([0; 7]);
+
+    pub fn new(exponents: [i16; 7]) -> Result<Self, NumericError> {
+        for (index, value) in exponents.iter().copied().enumerate() {
+            if !(-32..=32).contains(&value) {
+                return Err(NumericError::DimensionExponent {
+                    axis: DimensionAxis::ALL[index],
+                    value: i32::from(value),
+                });
+            }
+        }
+        Ok(Self(exponents))
+    }
+
+    pub fn exponents(self) -> [i16; 7] {
+        self.0
+    }
+
+    pub fn is_dimensionless(self) -> bool {
+        self == Self::ZERO
+    }
+
+    pub fn checked_product(self, rhs: Self) -> Result<Self, NumericError> {
+        self.combine(rhs, 1)
+    }
+
+    pub fn checked_quotient(self, rhs: Self) -> Result<Self, NumericError> {
+        self.combine(rhs, -1)
+    }
+
+    pub fn checked_power(self, exponent: i8) -> Result<Self, NumericError> {
+        if !(-super::MAX_INTEGER_POWER..=super::MAX_INTEGER_POWER).contains(&exponent) {
+            return Err(NumericError::IntegerPower);
+        }
+        let mut output = [0; 7];
+        for (index, value) in self.0.iter().enumerate() {
+            output[index] = Self::checked_exponent(index, i32::from(*value) * i32::from(exponent))?;
+        }
+        Ok(Self(output))
+    }
+
+    fn combine(self, rhs: Self, sign: i32) -> Result<Self, NumericError> {
+        let mut output = [0; 7];
+        for (index, value) in self.0.iter().enumerate() {
+            output[index] =
+                Self::checked_exponent(index, i32::from(*value) + sign * i32::from(rhs.0[index]))?;
+        }
+        Ok(Self(output))
+    }
+
+    fn checked_exponent(index: usize, value: i32) -> Result<i16, NumericError> {
+        if !(-32..=32).contains(&value) {
+            return Err(NumericError::DimensionExponent {
+                axis: DimensionAxis::ALL[index],
+                value,
+            });
+        }
+        Ok(value as i16)
+    }
+}
+
+impl TryFrom<[i16; 7]> for Dimension {
+    type Error = NumericError;
+
+    fn try_from(value: [i16; 7]) -> Result<Self, Self::Error> {
+        Self::new(value)
+    }
+}
+
+impl From<Dimension> for [i16; 7] {
+    fn from(value: Dimension) -> Self {
+        value.0
+    }
+}

crates/oa-core/src/analysis_numeric/exact.rs

@@ -0,0 +1,469 @@
+use super::meter::{normalization_cost, parse_cost, product_cost, sum_cost, words};
+use super::{
+    MAX_COMPONENT_BITS, MAX_COMPONENT_DIGITS, MAX_DECIMAL_EXPONENT, MAX_INTEGER_POWER,
+    MAX_INTERMEDIATE_BITS, MAX_LITERAL_BYTES, NumberComponent, NumericError, NumericLimit,
+    NumericOperation, WorkLimits, WorkMeter,
+};
+use num_bigint::BigInt;
+use num_integer::Integer;
+use num_traits::{One, Signed, Zero};
+use serde::{Deserialize, Serialize};
+use std::cmp::Ordering;
+
+/// The interchange representation deliberately does not use num-bigint's serde
+/// format or JSON numeric values. Duplicate/missing/unknown fields reject.
+/// Its derived decoder allocates String fields before numeric validation; a
+/// transport/document adapter must bound the encoded envelope and decoded text.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct ExactWire {
+    pub numerator: String,
+    pub denominator: String,
+}
+
+/// Reduced rational with positive denominator and <=4096-bit components.
+///
+/// There are no unmetered arithmetic/ordering traits. Eq is structural equality
+/// of already normalized bounded values, not an expression comparison API.
+/// Standalone serde admission bounds the subsequent BigInt validation, not the
+/// preceding String decoding. Document adapters must bound encoded/decoded input
+/// and aggregate admission work. Evaluation uses one explicit WorkMeter.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(try_from = "ExactWire", into = "ExactWire")]
+pub struct Exact {
+    numerator: BigInt,
+    denominator: BigInt,
+}
+
+impl Exact {
+    pub fn from_integer(value: i64) -> Self {
+        Self {
+            numerator: BigInt::from(value),
+            denominator: BigInt::one(),
+        }
+    }
+
+    pub fn is_zero(&self) -> bool {
+        self.numerator.is_zero()
+    }
+
+    pub fn is_positive(&self) -> bool {
+        self.numerator.is_positive()
+    }
+
+    pub fn component_bits(&self) -> (u64, u64) {
+        (self.numerator.bits(), self.denominator.bits())
+    }
+
+    pub fn to_wire(&self) -> ExactWire {
+        ExactWire {
+            numerator: self.numerator.to_string(),
+            denominator: self.denominator.to_string(),
+        }
+    }
+
+    /// Canonical *literal* spelling, not a generic expression formatter.
+    /// Negative literal nodes use ratio(-n,d), even when d=1. A leading minus
+    /// belongs to the future expression parser's UnaryNegate node instead.
+    pub fn canonical_literal(&self) -> String {
+        if self.denominator.is_one() && !self.numerator.is_negative() {
+            self.numerator.to_string()
+        } else {
+            format!("ratio({}, {})", self.numerator, self.denominator)
+        }
+    }
+
+    pub fn from_wire(wire: &ExactWire, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        let n_digits = wire_digits(&wire.numerator, true)?;
+        let d_digits = wire_digits(&wire.denominator, false)?;
+        let n_bound = decimal_bits(n_digits.len());
+        let d_bound = decimal_bits(d_digits.len());
+        meter.numeric(
+            NumericOperation::ParseWire,
+            parse_cost(n_digits.len(), n_bound)
+                + parse_cost(d_digits.len(), d_bound)
+                + normalization_cost(n_bound, d_bound),
+        )?;
+        let numerator = parse_integer(&wire.numerator)?;
+        let denominator = parse_integer(&wire.denominator)?;
+        Self::check_bits(&numerator, &denominator, MAX_COMPONENT_BITS, "wire")?;
+        if denominator.is_zero() {
+            return Err(NumericError::ZeroDenominator);
+        }
+        if !numerator.gcd(&denominator).is_one() {
+            return Err(NumericError::NonCanonicalWire);
+        }
+        Ok(Self {
+            numerator,
+            denominator,
+        })
+    }
+
+    /// Reads one unsigned decimal/integer atom or a ratio(n,d) literal only.
+    /// It does not parse expressions, unary operators, units, calls or names.
+    /// Source ratios/decimals may reduce; wire values must already be canonical.
+    pub fn parse_literal(source: &str, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        if source.len() > MAX_LITERAL_BYTES {
+            return Err(NumericError::LiteralTooLong);
+        }
+        let source = trim_ascii(source);
+        if let Some(body) = source.strip_prefix("ratio(") {
+            let body = body.strip_suffix(')').ok_or(NumericError::InvalidLiteral)?;
+            let (n, d) = body.split_once(',').ok_or(NumericError::InvalidLiteral)?;
+            return Self::parse_ratio(trim_ascii(n), trim_ascii(d), meter);
+        }
+        Self::parse_decimal(source, meter)
+    }
+
+    fn parse_ratio(n: &str, d: &str, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        let n_digits = source_integer_digits(n, true)?;
+        let d_digits = source_integer_digits(d, false)?;
+        let n_bound = decimal_bits(n_digits.len());
+        let d_bound = decimal_bits(d_digits.len());
+        Self::check_estimates(n_bound, d_bound)?;
+        meter.numeric(
+            NumericOperation::ParseLiteral,
+            parse_cost(n_digits.len(), n_bound)
+                + parse_cost(d_digits.len(), d_bound)
+                + normalization_cost(n_bound, d_bound),
+        )?;
+        Self::normalize_precharged(parse_integer(n)?, parse_integer(d)?)
+    }
+
+    fn parse_decimal(source: &str, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        let mut parts = source.split(['e', 'E']);
+        let mantissa = parts.next().ok_or(NumericError::InvalidLiteral)?;
+        let exponent = match parts.next() {
+            Some(text) => parse_exponent(text)?,
+            None => 0,
+        };
+        if parts.next().is_some() {
+            return Err(NumericError::InvalidLiteral);
+        }
+        let (whole, fraction) = match mantissa.split_once('.') {
+            Some((whole, fraction)) if !fraction.is_empty() => (whole, fraction),
+            Some(_) => return Err(NumericError::InvalidLiteral),
+            None => (mantissa, ""),
+        };
+        source_integer_digits(whole, false)?;
+        if !fraction.bytes().all(|byte| byte.is_ascii_digit()) {
+            return Err(NumericError::InvalidLiteral);
+        }
+        let digit_count = whole.len() + fraction.len();
+        if digit_count > MAX_COMPONENT_DIGITS {
+            return Err(NumericError::LiteralTooLong);
+        }
+        let adjustment = exponent - fraction.len() as i32;
+        let power = adjustment.unsigned_abs();
+        let mantissa_bound = decimal_bits(digit_count);
+        let scale_bound = decimal_bits(power as usize + 1);
+        let (n_bound, d_bound) = if adjustment >= 0 {
+            (mantissa_bound + scale_bound, 1)
+        } else {
+            (mantissa_bound, scale_bound)
+        };
+        Self::check_estimates(n_bound, d_bound)?;
+        // Fixed logical allowance for constructing 10^power; independent of
+        // num-bigint's selected multiplication/exponentiation implementation.
+        let power_steps = 1 + 2 * u64::from(u32::BITS - power.leading_zeros());
+        meter.numeric(
+            NumericOperation::ParseLiteral,
+            parse_cost(digit_count, mantissa_bound)
+                + power_steps * product_cost(scale_bound, scale_bound)
+                + product_cost(mantissa_bound, scale_bound)
+                + normalization_cost(n_bound, d_bound),
+        )?;
+        let digits = format!("{whole}{fraction}");
+        let mut numerator = parse_integer(&digits)?;
+        let scale = BigInt::from(10_u8).pow(power);
+        let denominator = if adjustment >= 0 {
+            numerator *= scale;
+            BigInt::one()
+        } else {
+            scale
+        };
+        Self::normalize_precharged(numerator, denominator)
+    }
+
+    pub fn add(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        self.add_or_subtract(rhs, false, meter)
+    }
+
+    pub fn subtract(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        self.add_or_subtract(rhs, true, meter)
+    }
+
+    fn add_or_subtract(
+        &self,
+        rhs: &Self,
+        subtract: bool,
+        meter: &mut WorkMeter,
+    ) -> Result<Self, NumericError> {
+        let (a, b) = self.component_bits();
+        let (c, d) = rhs.component_bits();
+        let left_bound = a + d;
+        let right_bound = c + b;
+        let n_bound = left_bound.max(right_bound) + 1;
+        let d_bound = b + d;
+        Self::check_estimates(n_bound, d_bound)?;
+        meter.numeric(
+            if subtract {
+                NumericOperation::Subtract
+            } else {
+                NumericOperation::Add
+            },
+            product_cost(a, d)
+                + product_cost(c, b)
+                + sum_cost(left_bound, right_bound)
+                + product_cost(b, d)
+                + normalization_cost(n_bound, d_bound),
+        )?;
+        let left = &self.numerator * &rhs.denominator;
+        let right = &rhs.numerator * &self.denominator;
+        let numerator = if subtract { left - right } else { left + right };
+        let denominator = &self.denominator * &rhs.denominator;
+        Self::normalize_precharged(numerator, denominator)
+    }
+
+    pub fn multiply(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        let (a, b) = self.component_bits();
+        let (c, d) = rhs.component_bits();
+        Self::check_estimates(a + c, b + d)?;
+        meter.numeric(
+            NumericOperation::Multiply,
+            product_cost(a, c) + product_cost(b, d) + normalization_cost(a + c, b + d),
+        )?;
+        Self::normalize_precharged(
+            &self.numerator * &rhs.numerator,
+            &self.denominator * &rhs.denominator,
+        )
+    }
+
+    pub fn divide(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        let (a, b) = self.component_bits();
+        let (c, d) = rhs.component_bits();
+        Self::check_estimates(a + d, b + c)?;
+        meter.numeric(
+            NumericOperation::Divide,
+            product_cost(a, d) + product_cost(b, c) + normalization_cost(a + d, b + c),
+        )?;
+        if rhs.is_zero() {
+            return Err(NumericError::DivisionByZero);
+        }
+        Self::normalize_precharged(
+            &self.numerator * &rhs.denominator,
+            &self.denominator * &rhs.numerator,
+        )
+    }
+
+    pub fn compare(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Ordering, NumericError> {
+        let (a, b) = self.component_bits();
+        let (c, d) = rhs.component_bits();
+        Self::check_estimates((a + d).max(c + b), 1)?;
+        meter.numeric(
+            NumericOperation::Compare,
+            product_cost(a, d) + product_cost(c, b) + sum_cost(a + d, c + b),
+        )?;
+        Ok((&self.numerator * &rhs.denominator).cmp(&(&rhs.numerator * &self.denominator)))
+    }
+
+    pub fn negated(&self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.numeric(NumericOperation::Negate, self.copy_cost())?;
+        Ok(Self {
+            numerator: -&self.numerator,
+            denominator: self.denominator.clone(),
+        })
+    }
+
+    pub fn absolute(&self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.numeric(NumericOperation::Absolute, self.copy_cost())?;
+        Ok(Self {
+            numerator: self.numerator.abs(),
+            denominator: self.denominator.clone(),
+        })
+    }
+
+    pub fn reciprocal(&self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.numeric(NumericOperation::Reciprocal, self.copy_cost())?;
+        if self.is_zero() {
+            return Err(NumericError::DivisionByZero);
+        }
+        Ok(Self {
+            numerator: if self.numerator.is_negative() {
+                -&self.denominator
+            } else {
+                self.denominator.clone()
+            },
+            denominator: self.numerator.abs(),
+        })
+    }
+
+    /// Fixed left-to-right repeated multiplication, at most 16 multiplications.
+    /// Each reduced stage obeys the same component bound; no large power is
+    /// allocated and subsequently discarded after discovering it is oversized.
+    pub fn power(&self, exponent: i8, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.numeric(NumericOperation::Power, self.copy_cost())?;
+        if !(-MAX_INTEGER_POWER..=MAX_INTEGER_POWER).contains(&exponent) {
+            return Err(NumericError::IntegerPower);
+        }
+        if self.is_zero() && exponent == 0 {
+            return Err(NumericError::ZeroPowerZero);
+        }
+        let factor = if exponent < 0 {
+            self.reciprocal(meter)?
+        } else {
+            self.clone()
+        };
+        let mut value = Self::from_integer(1);
+        for _ in 0..exponent.unsigned_abs() {
+            value = value.multiply(&factor, meter)?;
+        }
+        Ok(value)
+    }
+
+    pub(super) fn copy_cost(&self) -> u64 {
+        let (n, d) = self.component_bits();
+        1 + words(n) + words(d)
+    }
+
+    fn normalize_precharged(
+        mut numerator: BigInt,
+        mut denominator: BigInt,
+    ) -> Result<Self, NumericError> {
+        Self::check_bits(
+            &numerator,
+            &denominator,
+            MAX_INTERMEDIATE_BITS,
+            "intermediate",
+        )?;
+        if denominator.is_zero() {
+            return Err(NumericError::ZeroDenominator);
+        }
+        if denominator.is_negative() {
+            numerator = -numerator;
+            denominator = -denominator;
+        }
+        let gcd = numerator.gcd(&denominator);
+        numerator /= &gcd;
+        denominator /= gcd;
+        Self::check_bits(&numerator, &denominator, MAX_COMPONENT_BITS, "reduced")?;
+        Ok(Self {
+            numerator,
+            denominator,
+        })
+    }
+
+    fn check_estimates(n: u64, d: u64) -> Result<(), NumericError> {
+        Self::check_bit_count(
+            n,
+            NumberComponent::Numerator,
+            MAX_INTERMEDIATE_BITS,
+            "predicted",
+        )?;
+        Self::check_bit_count(
+            d,
+            NumberComponent::Denominator,
+            MAX_INTERMEDIATE_BITS,
+            "predicted",
+        )
+    }
+
+    fn check_bits(n: &BigInt, d: &BigInt, limit: u64, stage: &str) -> Result<(), NumericError> {
+        Self::check_bit_count(n.bits(), NumberComponent::Numerator, limit, stage)?;
+        Self::check_bit_count(d.bits(), NumberComponent::Denominator, limit, stage)
+    }
+
+    fn check_bit_count(
+        bits: u64,
+        component: NumberComponent,
+        limit: u64,
+        stage: &str,
+    ) -> Result<(), NumericError> {
+        if bits > limit {
+            return Err(NumericError::Limit(NumericLimit::Bits {
+                component,
+                bits,
+                limit,
+                stage: stage.to_owned(),
+            }));
+        }
+        Ok(())
+    }
+}
+
+impl TryFrom<ExactWire> for Exact {
+    type Error = NumericError;
+
+    fn try_from(value: ExactWire) -> Result<Self, Self::Error> {
+        // BigInt validation is bounded after ExactWire strings have decoded.
+        // The adapter owns envelope/text/aggregate admission bounds and must not
+        // reset evaluation meters.
+        Self::from_wire(&value, &mut WorkMeter::new(WorkLimits::REFERENCE))
+    }
+}
+
+impl From<Exact> for ExactWire {
+    fn from(value: Exact) -> Self {
+        value.to_wire()
+    }
+}
+
+fn trim_ascii(text: &str) -> &str {
+    text.trim_matches(|ch: char| ch.is_ascii_whitespace())
+}
+
+fn source_integer_digits(text: &str, signed: bool) -> Result<&str, NumericError> {
+    let digits = if signed {
+        text.strip_prefix('-').unwrap_or(text)
+    } else {
+        text
+    };
+    if digits.len() > MAX_COMPONENT_DIGITS {
+        return Err(NumericError::LiteralTooLong);
+    }
+    if digits.is_empty() || !digits.bytes().all(|byte| byte.is_ascii_digit()) {
+        return Err(NumericError::InvalidLiteral);
+    }
+    Ok(digits)
+}
+
+fn wire_digits(text: &str, signed: bool) -> Result<&str, NumericError> {
+    let digits = source_integer_digits(text, signed).map_err(|error| match error {
+        NumericError::LiteralTooLong => error,
+        _ => NumericError::NonCanonicalWire,
+    })?;
+    if (digits.len() > 1 && digits.starts_with('0')) || (text.starts_with('-') && digits == "0") {
+        return Err(NumericError::NonCanonicalWire);
+    }
+    Ok(digits)
+}
+
+fn parse_integer(text: &str) -> Result<BigInt, NumericError> {
+    BigInt::parse_bytes(text.as_bytes(), 10).ok_or(NumericError::InvalidLiteral)
+}
+
+fn parse_exponent(text: &str) -> Result<i32, NumericError> {
+    let (negative, digits) = if let Some(digits) = text.strip_prefix('-') {
+        (true, digits)
+    } else {
+        (false, text.strip_prefix('+').unwrap_or(text))
+    };
+    if digits.is_empty() || !digits.bytes().all(|byte| byte.is_ascii_digit()) {
+        return Err(NumericError::InvalidLiteral);
+    }
+    let mut value = 0_i32;
+    for digit in digits.bytes() {
+        value = value * 10 + i32::from(digit - b'0');
+        if value > MAX_DECIMAL_EXPONENT {
+            return Err(NumericError::DecimalExponent);
+        }
+    }
+    Ok(if negative { -value } else { value })
+}
+
+fn decimal_bits(digits: usize) -> u64 {
+    // 3.322 exceeds log2(10); dimensions are bounded before this conversion.
+    (digits as u64 * 3322).div_ceil(1000).max(1)
+}

crates/oa-core/src/analysis_numeric/fixtures/r7-literal-boundaries.json

@@ -0,0 +1,32 @@
+[
+  {
+    "canonical_source": "1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+    "expression": {
+      "Number": {
+        "denominator": "1",
+        "numerator": "1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+      }
+    },
+    "name": "ten_to_300"
+  },
+  {
+    "canonical_source": "ratio(1, 522194440706576253345876355358312191289982124523691890192116741641976953985778728424413405967498779170445053357219631418993786719092896803631618043925682638972978488271854999170180795067191859157214035005927973113188159419698856372836167342172293308748403954352901852035642024370059304557233988891799014503343469488440893892973452815095130470299789726716411734651513348221529512507986199933857107770846917779942645743159118957217248367043905936319748237550094520674504208530837546834166925275516486044134775384991808184705966507606898412918594045916828375610659246423184062775112999150206172392431297837246097308511903252956622805412865917690043804311051417135098849101156584508839003337597742539960818209685142687562392007453579567729991395256699805775897135553415567045292136442139895777424891477161767258532611634530697452993846501061481697843891439474220308003706472837459911525285821188577408160690315522951458068463354171428220365223949985950890732881736611925133626529949897998045399734600887312408859224933727829625089164535236559716582775403784110923285873186648442456409760158728501220463308455437074192539205964902261490928669488824051563042951500651206733594863336608245755565801460390869016718045121902354170201577095168)",
+    "expression": {
+      "Number": {
+        "denominator": "522194440706576253345876355358312191289982124523691890192116741641976953985778728424413405967498779170445053357219631418993786719092896803631618043925682638972978488271854999170180795067191859157214035005927973113188159419698856372836167342172293308748403954352901852035642024370059304557233988891799014503343469488440893892973452815095130470299789726716411734651513348221529512507986199933857107770846917779942645743159118957217248367043905936319748237550094520674504208530837546834166925275516486044134775384991808184705966507606898412918594045916828375610659246423184062775112999150206172392431297837246097308511903252956622805412865917690043804311051417135098849101156584508839003337597742539960818209685142687562392007453579567729991395256699805775897135553415567045292136442139895777424891477161767258532611634530697452993846501061481697843891439474220308003706472837459911525285821188577408160690315522951458068463354171428220365223949985950890732881736611925133626529949897998045399734600887312408859224933727829625089164535236559716582775403784110923285873186648442456409760158728501220463308455437074192539205964902261490928669488824051563042951500651206733594863336608245755565801460390869016718045121902354170201577095168",
+        "numerator": "1"
+      }
+    },
+    "name": "one_over_two_to_4095"
+  },
+  {
+    "canonical_source": "ratio(-1044388881413152506691752710716624382579964249047383780384233483283953907971557456848826811934997558340890106714439262837987573438185793607263236087851365277945956976543709998340361590134383718314428070011855946226376318839397712745672334684344586617496807908705803704071284048740118609114467977783598029006686938976881787785946905630190260940599579453432823469303026696443059025015972399867714215541693835559885291486318237914434496734087811872639496475100189041349008417061675093668333850551032972088269550769983616369411933015213796825837188091833656751221318492846368125550225998300412344784862595674492194617023806505913245610825731835380087608622102834270197698202313169017678006675195485079921636419370285375124784014907159135459982790513399611551794271106831134090584272884279791554849782954323534517065223269061394905987693002122963395687782878948440616007412945674919823050571642377154816321380631045902916136926708342856440730447899971901781465763473223850267253059899795996090799469201774624817718449867455659250178329070473119433165550807568221846571746373296884912819520317457002440926616910874148385078411929804522981857338977648103126085903001302413467189726673216491511131602920781738033436090243804708340403154190335, 1)",
+    "expression": {
+      "Number": {
+        "denominator": "1",
+        "numerator": "-1044388881413152506691752710716624382579964249047383780384233483283953907971557456848826811934997558340890106714439262837987573438185793607263236087851365277945956976543709998340361590134383718314428070011855946226376318839397712745672334684344586617496807908705803704071284048740118609114467977783598029006686938976881787785946905630190260940599579453432823469303026696443059025015972399867714215541693835559885291486318237914434496734087811872639496475100189041349008417061675093668333850551032972088269550769983616369411933015213796825837188091833656751221318492846368125550225998300412344784862595674492194617023806505913245610825731835380087608622102834270197698202313169017678006675195485079921636419370285375124784014907159135459982790513399611551794271106831134090584272884279791554849782954323534517065223269061394905987693002122963395687782878948440616007412945674919823050571642377154816321380631045902916136926708342856440730447899971901781465763473223850267253059899795996090799469201774624817718449867455659250178329070473119433165550807568221846571746373296884912819520317457002440926616910874148385078411929804522981857338977648103126085903001302413467189726673216491511131602920781738033436090243804708340403154190335"
+      }
+    },
+    "name": "negative_4096_bit_bound"
+  }
+]

crates/oa-core/src/analysis_numeric/meter.rs

@@ -0,0 +1,240 @@
+use super::{NumericError, NumericLimit};
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+
+/// Every event is charged once per dynamic occurrence, before entering it.
+///
+/// A Call expression therefore charges Expression and CalculationEntry; a
+/// Property read charges Expression and PropertyBinding. List element visits
+/// are additional to evaluation of their expressions. Only executed branches
+/// are charged. Targets are sorted by category (properties, then checks), then
+/// stable UUID bytes, by the integrating evaluator.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum EvaluationStep {
+    Target,
+    Expression,
+    CalculationEntry,
+    PropertyBinding,
+    ListElement,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum NumericOperation {
+    ParseWire,
+    ParseLiteral,
+    Add,
+    Subtract,
+    Multiply,
+    Divide,
+    Compare,
+    Negate,
+    Absolute,
+    Reciprocal,
+    Power,
+    KindAssertion,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum WorkResource {
+    DynamicEvents,
+    NumericUnits,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum WorkSite {
+    Evaluation(EvaluationStep),
+    Numeric(NumericOperation),
+}
+
+/// Failed reservations consume no partial charge. The first failure is latched.
+#[derive(Debug, Clone, PartialEq, Eq, Error, Serialize, Deserialize)]
+#[error("{resource:?}: used {used}, requested {requested}, limit {limit}, at {site:?}")]
+pub struct WorkExhaustion {
+    pub resource: WorkResource,
+    pub used: u64,
+    pub requested: u64,
+    pub limit: u64,
+    pub site: WorkSite,
+}
+
+/// Provisional calibration ceilings, not measured execution-time guarantees.
+///
+/// Effective limits, profile identity, capture, targets and context must all be
+/// recorded in request/result/frozen identity. A caller may lower these ceilings.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(try_from = "WorkLimitsWire", into = "WorkLimitsWire")]
+pub struct WorkLimits {
+    dynamic_events: u64,
+    numeric_units: u64,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct WorkLimitsWire {
+    dynamic_events: u64,
+    numeric_units: u64,
+}
+
+impl WorkLimits {
+    pub const REFERENCE: Self = Self {
+        dynamic_events: 1_000_000,
+        numeric_units: 50_000_000,
+    };
+
+    pub fn new(dynamic_events: u64, numeric_units: u64) -> Result<Self, NumericError> {
+        if dynamic_events > Self::REFERENCE.dynamic_events
+            || numeric_units > Self::REFERENCE.numeric_units
+        {
+            return Err(NumericError::InvalidWorkLimits);
+        }
+        Ok(Self {
+            dynamic_events,
+            numeric_units,
+        })
+    }
+
+    pub fn dynamic_events(self) -> u64 {
+        self.dynamic_events
+    }
+
+    pub fn numeric_units(self) -> u64 {
+        self.numeric_units
+    }
+}
+
+impl TryFrom<WorkLimitsWire> for WorkLimits {
+    type Error = NumericError;
+
+    fn try_from(value: WorkLimitsWire) -> Result<Self, Self::Error> {
+        Self::new(value.dynamic_events, value.numeric_units)
+    }
+}
+
+impl From<WorkLimits> for WorkLimitsWire {
+    fn from(value: WorkLimits) -> Self {
+        Self {
+            dynamic_events: value.dynamic_events,
+            numeric_units: value.numeric_units,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct WorkUsage {
+    pub dynamic_events: u64,
+    pub numeric_units: u64,
+}
+
+/// Intentionally neither Clone nor Default: pass the same mutable meter through
+/// every target, numeric operation and expanded call in one evaluation request.
+///
+/// Exhaustion is terminal. Integrators must stop traversing siblings/targets and
+/// mark already collected causes as incomplete. Replaying an aggregate cache
+/// cost is insufficient if it changes the exact exhaustion location; initially
+/// retain logical traversal even when numerical values come from a cache.
+#[derive(Debug)]
+pub struct WorkMeter {
+    limits: WorkLimits,
+    usage: WorkUsage,
+    exhausted: Option<WorkExhaustion>,
+}
+
+impl WorkMeter {
+    pub fn new(limits: WorkLimits) -> Self {
+        Self {
+            limits,
+            usage: WorkUsage::default(),
+            exhausted: None,
+        }
+    }
+
+    pub fn limits(&self) -> WorkLimits {
+        self.limits
+    }
+
+    pub fn usage(&self) -> WorkUsage {
+        self.usage
+    }
+
+    pub fn exhaustion(&self) -> Option<&WorkExhaustion> {
+        self.exhausted.as_ref()
+    }
+
+    pub fn ensure_active(&self) -> Result<(), NumericError> {
+        match &self.exhausted {
+            Some(failure) => Err(NumericError::Limit(NumericLimit::Work(failure.clone()))),
+            None => Ok(()),
+        }
+    }
+
+    pub fn visit(&mut self, step: EvaluationStep) -> Result<(), NumericError> {
+        self.reserve(WorkResource::DynamicEvents, 1, WorkSite::Evaluation(step))
+    }
+
+    pub(super) fn numeric(
+        &mut self,
+        operation: NumericOperation,
+        units: u64,
+    ) -> Result<(), NumericError> {
+        self.reserve(
+            WorkResource::NumericUnits,
+            units,
+            WorkSite::Numeric(operation),
+        )
+    }
+
+    fn reserve(
+        &mut self,
+        resource: WorkResource,
+        requested: u64,
+        site: WorkSite,
+    ) -> Result<(), NumericError> {
+        self.ensure_active()?;
+        let (used, limit) = match resource {
+            WorkResource::DynamicEvents => (self.usage.dynamic_events, self.limits.dynamic_events),
+            WorkResource::NumericUnits => (self.usage.numeric_units, self.limits.numeric_units),
+        };
+        // Subtraction is safe: only successful reservations update usage.
+        if requested > limit - used {
+            let failure = WorkExhaustion {
+                resource,
+                used,
+                requested,
+                limit,
+                site,
+            };
+            self.exhausted = Some(failure.clone());
+            return Err(NumericError::Limit(NumericLimit::Work(failure)));
+        }
+        match resource {
+            WorkResource::DynamicEvents => self.usage.dynamic_events += requested,
+            WorkResource::NumericUnits => self.usage.numeric_units += requested,
+        }
+        Ok(())
+    }
+}
+
+// Logical 64-bit words are platform independent. These are deterministic
+// accounting weights, not a claim about num-bigint's internal algorithm/timing.
+pub(super) fn words(bits: u64) -> u64 {
+    bits.max(1).div_ceil(64)
+}
+
+pub(super) fn product_cost(a_bits: u64, b_bits: u64) -> u64 {
+    1 + words(a_bits) * words(b_bits)
+}
+
+pub(super) fn sum_cost(a_bits: u64, b_bits: u64) -> u64 {
+    1 + words(a_bits.max(b_bits))
+}
+
+pub(super) fn normalization_cost(n_bits: u64, d_bits: u64) -> u64 {
+    let width = words(n_bits.max(d_bits));
+    // 64*w² for GCD plus 2*w² for the two quotient operations.
+    1 + 66 * width * width
+}
+
+pub(super) fn parse_cost(digits: usize, estimated_bits: u64) -> u64 {
+    1 + digits as u64 * words(estimated_bits)
+}

crates/oa-core/src/analysis_numeric/quantity.rs

@@ -0,0 +1,378 @@
+use super::{Dimension, Exact, MAX_INTEGER_POWER, NumericError, NumericOperation, WorkMeter};
+use std::cmp::Ordering;
+
+/// K is supplied by the common resolver's verified nominal compatibility
+/// relation. It is not inferred from dimension/name/symbol/archive bytes here.
+/// Coordinate basis/algebra/difference-kind closure must be part of that proof.
+/// Exact definition references and pins remain the caller's provenance.
+/// K must be a bounded, cheap-to-clone/compare verified handle. Constructing or
+/// comparing an unbounded rooted contract graph is resolver admission work and
+/// must not be hidden inside K's Clone/Eq implementations. Rust trait bounds do
+/// not enforce this resource contract.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ResolvedKind<K> {
+    key: K,
+    dimension: Dimension,
+    difference: Option<K>,
+}
+
+impl<K> ResolvedKind<K> {
+    pub fn linear(key: K, dimension: Dimension) -> Self {
+        Self {
+            key,
+            dimension,
+            difference: None,
+        }
+    }
+
+    pub fn key(&self) -> &K {
+        &self.key
+    }
+
+    pub fn dimension(&self) -> Dimension {
+        self.dimension
+    }
+
+    pub fn is_affine(&self) -> bool {
+        self.difference.is_some()
+    }
+}
+
+impl<K: Clone + Eq> ResolvedKind<K> {
+    pub fn affine(key: K, difference: &Self) -> Result<Self, NumericError> {
+        if difference.is_affine() || key == difference.key {
+            return Err(NumericError::DifferenceKind);
+        }
+        Ok(Self {
+            key,
+            dimension: difference.dimension,
+            difference: Some(difference.key.clone()),
+        })
+    }
+
+    pub fn difference_kind(&self) -> Option<Self> {
+        self.difference
+            .as_ref()
+            .map(|key| Self::linear(key.clone(), self.dimension))
+    }
+}
+
+/// Canonical coordinate = magnitude * scale + offset.
+/// Unit symbols and display preferences are outside this numeric representation.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Unit<K> {
+    kind: ResolvedKind<K>,
+    scale: Exact,
+    offset: Exact,
+}
+
+impl<K: Clone + Eq> Unit<K> {
+    pub fn new(kind: ResolvedKind<K>, scale: Exact, offset: Exact) -> Result<Self, NumericError> {
+        if !scale.is_positive() {
+            return Err(NumericError::UnitScale);
+        }
+        if !kind.is_affine() && !offset.is_zero() {
+            return Err(NumericError::LinearOffset);
+        }
+        Ok(Self {
+            kind,
+            scale,
+            offset,
+        })
+    }
+
+    pub fn kind(&self) -> &ResolvedKind<K> {
+        &self.kind
+    }
+
+    pub fn scale(&self) -> &Exact {
+        &self.scale
+    }
+
+    pub fn offset(&self) -> &Exact {
+        &self.offset
+    }
+
+    /// Fixed multiply-then-add path. Each reduced arithmetic stage is bounded.
+    /// A mathematically cancelling wider intermediate still reports NumericLimit;
+    /// replacing this path with a fused operation requires a new work profile.
+    pub fn to_canonical(
+        &self,
+        magnitude: &Exact,
+        meter: &mut WorkMeter,
+    ) -> Result<Exact, NumericError> {
+        magnitude
+            .multiply(&self.scale, meter)?
+            .add(&self.offset, meter)
+    }
+
+    /// Fixed subtract-then-divide path; never rounds a coordinate.
+    pub fn from_canonical(
+        &self,
+        coordinate: &Exact,
+        meter: &mut WorkMeter,
+    ) -> Result<Exact, NumericError> {
+        coordinate
+            .subtract(&self.offset, meter)?
+            .divide(&self.scale, meter)
+    }
+
+    pub fn convert(
+        &self,
+        magnitude: &Exact,
+        target: &Self,
+        meter: &mut WorkMeter,
+    ) -> Result<Exact, NumericError> {
+        meter.ensure_active()?;
+        if self.kind != target.kind {
+            return Err(NumericError::IncompatibleTypes);
+        }
+        target.from_canonical(&self.to_canonical(magnitude, meter)?, meter)
+    }
+}
+
+/// Internal numerical types. Boolean/list/check semantics belong to the common
+/// expression evaluator. Anonymous zero dimension normalizes to Number.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum NumericType<K> {
+    Number,
+    Named(ResolvedKind<K>),
+    Anonymous(Dimension),
+}
+
+impl<K> NumericType<K> {
+    pub fn dimension(&self) -> Dimension {
+        match self {
+            Self::Number => Dimension::ZERO,
+            Self::Named(kind) => kind.dimension,
+            Self::Anonymous(dimension) => *dimension,
+        }
+    }
+
+    pub fn is_affine(&self) -> bool {
+        matches!(self, Self::Named(kind) if kind.is_affine())
+    }
+
+    fn anonymous(dimension: Dimension) -> Self {
+        if dimension.is_dimensionless() {
+            Self::Number
+        } else {
+            Self::Anonymous(dimension)
+        }
+    }
+
+    fn normalized(self) -> Self {
+        match self {
+            Self::Anonymous(dimension) => Self::anonymous(dimension),
+            other => other,
+        }
+    }
+}
+
+/// A canonical rational coordinate with an internal numerical type.
+///
+/// Derived Eq compares stored representation. Formal equality/ordering must call
+/// compare(), which rejects mismatched nominal kinds instead of treating them
+/// as a false predicate. Public property output must still check its declared
+/// type and anchor the result to that declaration's exact definition reference.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct NumericValue<K> {
+    value_type: NumericType<K>,
+    coordinate: Exact,
+}
+
+impl<K: Clone + Eq> NumericValue<K> {
+    pub fn new(value_type: NumericType<K>, coordinate: Exact) -> Self {
+        Self {
+            value_type: value_type.normalized(),
+            coordinate,
+        }
+    }
+
+    pub fn number(coordinate: Exact) -> Self {
+        Self::new(NumericType::Number, coordinate)
+    }
+
+    pub fn from_unit(
+        magnitude: &Exact,
+        unit: &Unit<K>,
+        meter: &mut WorkMeter,
+    ) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        Ok(Self::new(
+            NumericType::Named(unit.kind.clone()),
+            unit.to_canonical(magnitude, meter)?,
+        ))
+    }
+
+    pub fn value_type(&self) -> &NumericType<K> {
+        &self.value_type
+    }
+
+    pub fn coordinate(&self) -> &Exact {
+        &self.coordinate
+    }
+
+    pub fn display_in(&self, unit: &Unit<K>, meter: &mut WorkMeter) -> Result<Exact, NumericError> {
+        meter.ensure_active()?;
+        if !matches!(&self.value_type, NumericType::Named(kind) if kind == &unit.kind) {
+            return Err(NumericError::IncompatibleTypes);
+        }
+        unit.from_canonical(&self.coordinate, meter)
+    }
+
+    pub fn add(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        let output = self.additive_type(rhs, false)?;
+        Ok(Self::new(
+            output,
+            self.coordinate.add(&rhs.coordinate, meter)?,
+        ))
+    }
+
+    pub fn subtract(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        let output = self.additive_type(rhs, true)?;
+        Ok(Self::new(
+            output,
+            self.coordinate.subtract(&rhs.coordinate, meter)?,
+        ))
+    }
+
+    fn additive_type(&self, rhs: &Self, subtract: bool) -> Result<NumericType<K>, NumericError> {
+        use NumericType::{Anonymous, Named, Number};
+        match (&self.value_type, &rhs.value_type) {
+            (Number, Number) => Ok(Number),
+            (Anonymous(left), Anonymous(right)) if left == right => Ok(Anonymous(*left)),
+            (Named(left), Named(right)) => match (&left.difference, &right.difference) {
+                (None, None) if left == right => Ok(Named(left.clone())),
+                (Some(difference), Some(_)) if subtract && left == right => Ok(Named(
+                    ResolvedKind::linear(difference.clone(), left.dimension),
+                )),
+                (Some(difference), None)
+                    if difference == &right.key && left.dimension == right.dimension =>
+                {
+                    Ok(Named(left.clone()))
+                }
+                (None, Some(difference))
+                    if !subtract
+                        && difference == &left.key
+                        && left.dimension == right.dimension =>
+                {
+                    Ok(Named(right.clone()))
+                }
+                _ => Err(NumericError::IncompatibleTypes),
+            },
+            _ => Err(NumericError::IncompatibleTypes),
+        }
+    }
+
+    pub fn multiply(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        let output = self.multiplicative_type(rhs, false)?;
+        Ok(Self::new(
+            output,
+            self.coordinate.multiply(&rhs.coordinate, meter)?,
+        ))
+    }
+
+    pub fn divide(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        let output = self.multiplicative_type(rhs, true)?;
+        Ok(Self::new(
+            output,
+            self.coordinate.divide(&rhs.coordinate, meter)?,
+        ))
+    }
+
+    fn multiplicative_type(
+        &self,
+        rhs: &Self,
+        divide: bool,
+    ) -> Result<NumericType<K>, NumericError> {
+        use NumericType::Number;
+        if self.value_type.is_affine() || rhs.value_type.is_affine() {
+            return Err(NumericError::AffineOperation);
+        }
+        match (&self.value_type, &rhs.value_type) {
+            (Number, Number) => Ok(Number),
+            (_, Number) => Ok(self.value_type.clone()),
+            (Number, _) if !divide => Ok(rhs.value_type.clone()),
+            _ => {
+                let left = self.value_type.dimension();
+                let right = rhs.value_type.dimension();
+                let dimension = if divide {
+                    left.checked_quotient(right)?
+                } else {
+                    left.checked_product(right)?
+                };
+                Ok(NumericType::anonymous(dimension))
+            }
+        }
+    }
+
+    pub fn negated(&self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        if self.value_type.is_affine() {
+            return Err(NumericError::AffineOperation);
+        }
+        Ok(Self::new(
+            self.value_type.clone(),
+            self.coordinate.negated(meter)?,
+        ))
+    }
+
+    pub fn absolute(&self, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        if self.value_type.is_affine() {
+            return Err(NumericError::AffineOperation);
+        }
+        Ok(Self::new(
+            self.value_type.clone(),
+            self.coordinate.absolute(meter)?,
+        ))
+    }
+
+    pub fn power(&self, exponent: i8, meter: &mut WorkMeter) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        if !(-MAX_INTEGER_POWER..=MAX_INTEGER_POWER).contains(&exponent) {
+            return Err(NumericError::IntegerPower);
+        }
+        if self.value_type.is_affine() {
+            return Err(NumericError::AffineOperation);
+        }
+        let output = match exponent {
+            0 => NumericType::Number,
+            1 => self.value_type.clone(),
+            _ => NumericType::anonymous(self.value_type.dimension().checked_power(exponent)?),
+        };
+        Ok(Self::new(output, self.coordinate.power(exponent, meter)?))
+    }
+
+    pub fn compare(&self, rhs: &Self, meter: &mut WorkMeter) -> Result<Ordering, NumericError> {
+        meter.ensure_active()?;
+        if self.value_type != rhs.value_type {
+            return Err(NumericError::IncompatibleTypes);
+        }
+        self.coordinate.compare(&rhs.coordinate, meter)
+    }
+
+    pub fn as_kind(
+        &self,
+        target: &ResolvedKind<K>,
+        meter: &mut WorkMeter,
+    ) -> Result<Self, NumericError> {
+        meter.ensure_active()?;
+        if target.is_affine()
+            || matches!(self.value_type, NumericType::Named(_))
+            || self.value_type.dimension() != target.dimension
+        {
+            return Err(NumericError::KindAssertion);
+        }
+        meter.numeric(NumericOperation::KindAssertion, self.coordinate.copy_cost())?;
+        Ok(Self::new(
+            NumericType::Named(target.clone()),
+            self.coordinate.clone(),
+        ))
+    }
+}

crates/oa-core/src/analysis_numeric/tests.rs

@@ -0,0 +1,804 @@
+use super::*;
+use num_bigint::BigInt;
+use num_traits::One;
+use std::cmp::Ordering;
+
+fn meter() -> WorkMeter {
+    WorkMeter::new(WorkLimits::REFERENCE)
+}
+
+fn exact(n: impl ToString, d: impl ToString) -> Exact {
+    Exact::from_wire(
+        &ExactWire {
+            numerator: n.to_string(),
+            denominator: d.to_string(),
+        },
+        &mut meter(),
+    )
+    .unwrap()
+}
+
+fn source(text: &str) -> Exact {
+    Exact::parse_literal(text, &mut meter()).unwrap()
+}
+
+fn assert_fraction(value: &Exact, n: impl ToString, d: impl ToString) {
+    assert_eq!(
+        value.to_wire(),
+        ExactWire {
+            numerator: n.to_string(),
+            denominator: d.to_string(),
+        }
+    );
+}
+
+// Independent bounded i128 oracle. It does not call the production Exact/GCD
+// implementation when deriving expected arithmetic or ordering.
+fn small_fraction(mut n: i128, mut d: i128) -> (i128, i128) {
+    assert_ne!(d, 0);
+    if d < 0 {
+        n = -n;
+        d = -d;
+    }
+    let (mut a, mut b) = (n.abs(), d);
+    while b != 0 {
+        (a, b) = (b, a % b);
+    }
+    (n / a, d / a)
+}
+
+#[test]
+fn arithmetic_matches_independent_small_integer_oracle() {
+    for a in [-5_i128, -2, 0, 1, 4] {
+        for b in [1_i128, 2, 3, 7] {
+            for c in [-5_i128, -2, 0, 1, 4] {
+                for d in [1_i128, 2, 3, 7] {
+                    let (an, ad) = small_fraction(a, b);
+                    let (bn, bd) = small_fraction(c, d);
+                    let left = exact(an, ad);
+                    let right = exact(bn, bd);
+                    let mut work = meter();
+                    let (n, den) = small_fraction(a * d + c * b, b * d);
+                    assert_fraction(&left.add(&right, &mut work).unwrap(), n, den);
+                    let (n, den) = small_fraction(a * d - c * b, b * d);
+                    assert_fraction(&left.subtract(&right, &mut work).unwrap(), n, den);
+                    let (n, den) = small_fraction(a * c, b * d);
+                    assert_fraction(&left.multiply(&right, &mut work).unwrap(), n, den);
+                    if c != 0 {
+                        let (n, den) = small_fraction(a * d, b * c);
+                        assert_fraction(&left.divide(&right, &mut work).unwrap(), n, den);
+                    } else {
+                        assert_eq!(
+                            left.divide(&right, &mut work),
+                            Err(NumericError::DivisionByZero)
+                        );
+                    }
+                    assert_eq!(
+                        left.compare(&right, &mut work).unwrap(),
+                        (a * d).cmp(&(c * b))
+                    );
+                }
+            }
+        }
+    }
+}
+
+#[test]
+fn decimals_are_exact_and_source_ratios_reduce() {
+    assert_fraction(
+        &source("0.1").add(&source("0.2"), &mut meter()).unwrap(),
+        3,
+        10,
+    );
+    assert_fraction(&source("0.50"), 1, 2);
+    assert_fraction(&source("12.50e-2"), 1, 8);
+    assert_fraction(&source("1e+3"), 1000, 1);
+    assert_fraction(&source("0001.2500"), 5, 4);
+    assert_fraction(&source(" ratio( -6, 8 ) "), -3, 4);
+    assert_fraction(&source("ratio(-0, 27)"), 0, 1);
+    assert_eq!(source("0.5").canonical_literal(), "ratio(1, 2)");
+    assert_eq!(source("42").canonical_literal(), "42");
+}
+
+#[test]
+fn powers_and_signs_have_explicit_domains() {
+    let x = exact(-2, 3);
+    assert_fraction(&x.power(3, &mut meter()).unwrap(), -8, 27);
+    assert_fraction(&x.power(-3, &mut meter()).unwrap(), -27, 8);
+    assert_fraction(&x.power(0, &mut meter()).unwrap(), 1, 1);
+    assert_fraction(&x.absolute(&mut meter()).unwrap(), 2, 3);
+    assert_fraction(&x.negated(&mut meter()).unwrap(), 2, 3);
+    assert_fraction(&x.reciprocal(&mut meter()).unwrap(), -3, 2);
+    let zero = Exact::from_integer(0);
+    assert_eq!(
+        zero.power(0, &mut meter()),
+        Err(NumericError::ZeroPowerZero)
+    );
+    assert_eq!(
+        zero.power(-1, &mut meter()),
+        Err(NumericError::DivisionByZero)
+    );
+    assert_eq!(x.power(17, &mut meter()), Err(NumericError::IntegerPower));
+    assert_eq!(
+        x.power(i8::MIN, &mut meter()),
+        Err(NumericError::IntegerPower)
+    );
+}
+
+#[test]
+fn canonical_wire_rejects_both_component_noncanonical_forms() {
+    for (n, d) in [
+        ("+1", "1"),
+        ("01", "1"),
+        ("-0", "1"),
+        ("1", "+1"),
+        ("1", "-1"),
+        ("1", "01"),
+        ("2", "4"),
+        ("0", "3"),
+        ("", "1"),
+        ("1", ""),
+        ("1.0", "1"),
+        ("1", "1.0"),
+        ("1e1", "1"),
+        ("1", "1e1"),
+        (" 1", "1"),
+        ("1", "1 "),
+    ] {
+        assert!(
+            Exact::from_wire(
+                &ExactWire {
+                    numerator: n.into(),
+                    denominator: d.into()
+                },
+                &mut meter(),
+            )
+            .is_err(),
+            "accepted {n}/{d}"
+        );
+    }
+    assert_eq!(
+        Exact::from_wire(
+            &ExactWire {
+                numerator: "1".into(),
+                denominator: "0".into()
+            },
+            &mut meter()
+        ),
+        Err(NumericError::ZeroDenominator)
+    );
+    assert_fraction(&exact(0, 1), 0, 1);
+    assert_fraction(&exact(-1, 2), -1, 2);
+}
+
+#[test]
+fn serde_uses_closed_canonical_string_wire() {
+    let value = exact(-3, 7);
+    let encoded = serde_json::to_value(&value).unwrap();
+    assert_eq!(
+        encoded,
+        serde_json::json!({"numerator":"-3","denominator":"7"})
+    );
+    assert_eq!(serde_json::from_value::<Exact>(encoded).unwrap(), value);
+    for invalid in [
+        r#"{"numerator":1,"denominator":"2"}"#,
+        r#"{"numerator":"1","denominator":2}"#,
+        r#"{"numerator":"1","denominator":"2","other":0}"#,
+        r#"{"numerator":"1","numerator":"2","denominator":"3"}"#,
+        r#"{"numerator":"1"}"#,
+        r#"{"numerator":"2","denominator":"4"}"#,
+    ] {
+        assert!(serde_json::from_str::<Exact>(invalid).is_err(), "{invalid}");
+    }
+}
+
+#[test]
+fn literal_reader_does_not_fold_expression_unary_minus() {
+    assert_eq!(
+        Exact::parse_literal("-2", &mut meter()),
+        Err(NumericError::InvalidLiteral)
+    );
+    let negative_literal = source("ratio(-2, 1)");
+    assert_eq!(negative_literal.canonical_literal(), "ratio(-2, 1)");
+    assert_eq!(source("2").negated(&mut meter()).unwrap(), negative_literal);
+    // Equality of coordinates does not claim AST equality. The expression
+    // parser must preserve UnaryNegate independently of its operand literal.
+    assert_eq!(source("2").canonical_literal(), "2");
+}
+
+#[test]
+fn literal_syntax_and_decimal_exponent_are_bounded() {
+    for invalid in [
+        "",
+        "-",
+        "+1",
+        ".5",
+        "1.",
+        "1.2.3",
+        "1e",
+        "1ee2",
+        "1e+-2",
+        "1_000",
+        "NaN",
+        "Infinity",
+        "1/2",
+        "ratio(1)",
+        "ratio(1,2,3)",
+        "ratio(1,-2)",
+        "ratio(+1,2)",
+        "ratio(1,2) + 1",
+        "１２",
+    ] {
+        assert!(
+            Exact::parse_literal(invalid, &mut meter()).is_err(),
+            "{invalid}"
+        );
+    }
+    for invalid in ["1e129", "1e-129", "1e9999999999999999999999"] {
+        assert_eq!(
+            Exact::parse_literal(invalid, &mut meter()),
+            Err(NumericError::DecimalExponent)
+        );
+    }
+    assert!(Exact::parse_literal("1e128", &mut meter()).is_ok());
+    assert!(Exact::parse_literal("1e-128", &mut meter()).is_ok());
+    assert_eq!(
+        Exact::parse_literal(&"1".repeat(MAX_COMPONENT_DIGITS + 1), &mut meter()),
+        Err(NumericError::LiteralTooLong)
+    );
+    assert_eq!(
+        Exact::parse_literal(&" ".repeat(MAX_LITERAL_BYTES + 1), &mut meter()),
+        Err(NumericError::LiteralTooLong)
+    );
+}
+
+#[test]
+fn full_independent_r7_packets_round_trip_as_literals_and_wire() {
+    let packets: serde_json::Value =
+        serde_json::from_str(include_str!("fixtures/r7-literal-boundaries.json")).unwrap();
+    for packet in packets.as_array().unwrap() {
+        let wire: ExactWire =
+            serde_json::from_value(packet["expression"]["Number"].clone()).unwrap();
+        let expected = Exact::from_wire(&wire, &mut meter()).unwrap();
+        let spelling = packet["canonical_source"].as_str().unwrap();
+        assert_eq!(expected.canonical_literal(), spelling);
+        assert_eq!(
+            Exact::parse_literal(spelling, &mut meter()).unwrap(),
+            expected
+        );
+        let serialized = serde_json::to_string(&expected).unwrap();
+        assert_eq!(
+            serde_json::from_str::<Exact>(&serialized).unwrap(),
+            expected
+        );
+        assert_eq!(expected.to_wire(), wire);
+    }
+}
+
+#[test]
+fn full_8193_bit_sum_intermediate_can_reduce_to_admitted_value() {
+    // N=(2^4096)-1, D=N-1. gcd(N,D)=1 and D is even.
+    // N/D + N/D = N/(D/2), although its un-reduced numerator needs 8193 bits.
+    let n = (BigInt::one() << 4096_usize) - 1_u8;
+    let d = &n - 1_u8;
+    let value = exact(&n, &d);
+    let result = value.add(&value, &mut meter()).unwrap();
+    assert_fraction(&result, &n, &d / 2_u8);
+}
+
+#[test]
+fn cross_products_cancel_before_reduced_component_limit() {
+    let n = BigInt::one() << 4095_usize;
+    let d = &n - 1_u8;
+    let left = exact(&n, &d);
+    let right = exact(&d, &n);
+    assert_fraction(&left.multiply(&right, &mut meter()).unwrap(), 1, 1);
+    assert_fraction(
+        &left
+            .add(&left.negated(&mut meter()).unwrap(), &mut meter())
+            .unwrap(),
+        0,
+        1,
+    );
+}
+
+#[test]
+fn both_reduced_component_overflows_are_reported() {
+    let n = BigInt::one() << 4095_usize;
+    let mut work = meter();
+    let failure = exact(&n, 1)
+        .multiply(&Exact::from_integer(2), &mut work)
+        .unwrap_err();
+    assert!(matches!(
+        failure,
+        NumericError::Limit(NumericLimit::Bits {
+            component: NumberComponent::Numerator,
+            bits: 4097,
+            ..
+        })
+    ));
+    assert!(work.exhaustion().is_none());
+    let failure = exact(1, &n)
+        .divide(&Exact::from_integer(2), &mut work)
+        .unwrap_err();
+    assert!(matches!(
+        failure,
+        NumericError::Limit(NumericLimit::Bits {
+            component: NumberComponent::Denominator,
+            bits: 4097,
+            ..
+        })
+    ));
+    // Value overflow is a nonterminal supported-operation failure; fuel
+    // exhaustion, in contrast, terminates the entire request.
+    assert_fraction(&source("1").add(&source("1"), &mut work).unwrap(), 2, 1);
+}
+
+#[test]
+fn wire_rejects_4097_bits_before_gcd_can_reduce_them() {
+    let oversized = (BigInt::one() << 4096_usize).to_string();
+    for wire in [
+        ExactWire {
+            numerator: oversized.clone(),
+            denominator: "1".into(),
+        },
+        ExactWire {
+            numerator: "1".into(),
+            denominator: oversized.clone(),
+        },
+        ExactWire {
+            numerator: oversized.clone(),
+            denominator: oversized,
+        },
+    ] {
+        assert!(matches!(
+            Exact::from_wire(&wire, &mut meter()),
+            Err(NumericError::Limit(NumericLimit::Bits { stage, .. })) if stage == "wire"
+        ));
+    }
+}
+
+#[test]
+fn numeric_precharge_precedes_big_integer_result_allocation() {
+    let n = BigInt::one() << 4095_usize;
+    let left = exact(&n, 1);
+    let mut work = WorkMeter::new(WorkLimits::new(10, 0).unwrap());
+    let failure = left
+        .multiply(&Exact::from_integer(2), &mut work)
+        .unwrap_err();
+    assert!(failure.is_terminal_work_exhaustion());
+    assert_eq!(work.usage().numeric_units, 0);
+    assert!(matches!(
+        work.exhaustion().unwrap().site,
+        WorkSite::Numeric(NumericOperation::Multiply)
+    ));
+    // With available fuel the same operation reaches the 4097-bit result check.
+    assert!(matches!(
+        left.multiply(&Exact::from_integer(2), &mut meter()),
+        Err(NumericError::Limit(NumericLimit::Bits { .. }))
+    ));
+    let too_wide_wire = ExactWire {
+        numerator: (BigInt::one() << 4096_usize).to_string(),
+        denominator: "1".into(),
+    };
+    let mut parse_work = WorkMeter::new(WorkLimits::new(0, 0).unwrap());
+    assert!(
+        Exact::from_wire(&too_wide_wire, &mut parse_work)
+            .unwrap_err()
+            .is_terminal_work_exhaustion()
+    );
+}
+
+#[test]
+fn provisional_limits_and_effective_limits_round_trip() {
+    let limits = WorkLimits::new(500, 2000).unwrap();
+    let encoded = serde_json::to_value(limits).unwrap();
+    assert_eq!(
+        encoded,
+        serde_json::json!({"dynamic_events":500,"numeric_units":2000})
+    );
+    assert_eq!(
+        serde_json::from_value::<WorkLimits>(encoded).unwrap(),
+        limits
+    );
+    assert_eq!(
+        WorkLimits::new(1_000_001, 0),
+        Err(NumericError::InvalidWorkLimits)
+    );
+    assert_eq!(
+        WorkLimits::new(0, 50_000_001),
+        Err(NumericError::InvalidWorkLimits)
+    );
+    assert!(
+        serde_json::from_str::<WorkLimits>(r#"{"dynamic_events":1000001,"numeric_units":0}"#)
+            .is_err()
+    );
+}
+
+#[test]
+fn exact_accounting_boundary_and_terminal_failure_are_stable() {
+    // One-word addition: three products at 2, one sum at 2,
+    // normalization at 67 => 75 logical numeric units.
+    let mut work = WorkMeter::new(WorkLimits::new(4, 75).unwrap());
+    assert_fraction(&exact(1, 2).add(&exact(1, 3), &mut work).unwrap(), 5, 6);
+    assert_eq!(work.usage().numeric_units, 75);
+    assert!(work.exhaustion().is_none());
+    let first = Exact::from_integer(1).negated(&mut work).unwrap_err();
+    let at_failure = work.usage();
+    assert_eq!(
+        work.exhaustion().unwrap(),
+        &WorkExhaustion {
+            resource: WorkResource::NumericUnits,
+            used: 75,
+            requested: 3,
+            limit: 75,
+            site: WorkSite::Numeric(NumericOperation::Negate),
+        }
+    );
+    assert_eq!(work.visit(EvaluationStep::Target).unwrap_err(), first);
+    assert_eq!(
+        Exact::from_integer(1)
+            .divide(&Exact::from_integer(0), &mut work)
+            .unwrap_err(),
+        first
+    );
+    assert_eq!(
+        work.numeric(NumericOperation::Compare, 0).unwrap_err(),
+        first
+    );
+    assert_eq!(work.usage(), at_failure);
+}
+
+#[test]
+fn zero_cost_and_maximum_reservation_do_not_underflow_or_reactivate() {
+    let mut work = WorkMeter::new(WorkLimits::new(0, 0).unwrap());
+    work.numeric(NumericOperation::Compare, 0).unwrap();
+    let failure = work
+        .numeric(NumericOperation::Multiply, u64::MAX)
+        .unwrap_err();
+    assert!(failure.is_terminal_work_exhaustion());
+    assert_eq!(work.usage(), WorkUsage::default());
+    assert_eq!(
+        work.numeric(NumericOperation::Compare, 0).unwrap_err(),
+        failure
+    );
+    let mut dynamic = WorkMeter::new(WorkLimits::new(0, 5).unwrap());
+    assert!(dynamic.visit(EvaluationStep::Target).is_err());
+    assert_eq!(dynamic.usage(), WorkUsage::default());
+}
+
+#[test]
+fn multiple_targets_share_one_aggregate_meter() {
+    let mut work = WorkMeter::new(WorkLimits::new(3, 50).unwrap());
+    work.visit(EvaluationStep::Target).unwrap();
+    work.visit(EvaluationStep::Expression).unwrap();
+    work.visit(EvaluationStep::Target).unwrap();
+    let failure = work.visit(EvaluationStep::Expression).unwrap_err();
+    assert!(failure.is_terminal_work_exhaustion());
+    assert_eq!(work.usage().dynamic_events, 3);
+}
+
+// A direct bounded call-tree workload, not an expression interpreter/dialect.
+fn expanded_calls(
+    depth: u8,
+    x: u64,
+    work: &mut WorkMeter,
+    entered: &mut u64,
+) -> Result<u64, NumericError> {
+    work.visit(EvaluationStep::CalculationEntry)?;
+    *entered += 1;
+    if depth == 0 {
+        return Ok(x);
+    }
+    let left = expanded_calls(depth - 1, 2 * x, work, entered)?;
+    let right = expanded_calls(depth - 1, 2 * x + 1, work, entered)?;
+    Ok(left + right)
+}
+
+#[test]
+fn c1_expanded_call_witness_terminates_at_dynamic_limit() {
+    let mut work = WorkMeter::new(WorkLimits::new(10_000, 0).unwrap());
+    let mut entered = 0;
+    let failure = expanded_calls(30, 0, &mut work, &mut entered).unwrap_err();
+    assert!(failure.is_terminal_work_exhaustion());
+    assert_eq!(entered, 10_000);
+    assert_eq!(work.usage().dynamic_events, 10_000);
+    assert_eq!(
+        work.exhaustion().unwrap().site,
+        WorkSite::Evaluation(EvaluationStep::CalculationEntry)
+    );
+    // Nearby finite control: 63 invocations, leaves 0..31, sum 496.
+    let mut bounded = WorkMeter::new(WorkLimits::new(63, 0).unwrap());
+    let mut entered = 0;
+    assert_eq!(
+        expanded_calls(5, 0, &mut bounded, &mut entered).unwrap(),
+        496
+    );
+    assert_eq!(entered, 63);
+    assert!(bounded.exhaustion().is_none());
+}
+
+fn dim(value: [i16; 7]) -> Dimension {
+    Dimension::new(value).unwrap()
+}
+
+fn linear(key: &str, dimension: Dimension) -> ResolvedKind<String> {
+    ResolvedKind::linear(key.to_owned(), dimension)
+}
+
+fn named(n: i64, kind: &ResolvedKind<String>) -> NumericValue<String> {
+    NumericValue::new(NumericType::Named(kind.clone()), Exact::from_integer(n))
+}
+
+#[test]
+fn dimensions_use_checked_seven_axis_integer_algebra() {
+    let length = dim([1, 0, 0, 0, 0, 0, 0]);
+    let mass = dim([0, 1, 0, 0, 0, 0, 0]);
+    let time = dim([0, 0, 1, 0, 0, 0, 0]);
+    assert_eq!(
+        mass.checked_product(length)
+            .unwrap()
+            .checked_quotient(time.checked_power(2).unwrap())
+            .unwrap(),
+        dim([1, 1, -2, 0, 0, 0, 0])
+    );
+    assert!(time.checked_quotient(time).unwrap().is_dimensionless());
+    assert!(matches!(
+        dim([32, 0, 0, 0, 0, 0, 0]).checked_product(length),
+        Err(NumericError::DimensionExponent {
+            axis: DimensionAxis::Length,
+            value: 33
+        })
+    ));
+    assert!(dim([0, 0, -32, 0, 0, 0, 0]).checked_quotient(time).is_err());
+    assert!(length.checked_power(i8::MIN).is_err());
+    assert!(Dimension::new([33, 0, 0, 0, 0, 0, 0]).is_err());
+    assert_eq!(
+        serde_json::to_value(time).unwrap(),
+        serde_json::json!([0, 0, 1, 0, 0, 0, 0])
+    );
+    for invalid in ["[0,0,33,0,0,0,0]", "[0,0,1]", "[0,0,1,0,0,0,0,0]"] {
+        assert!(serde_json::from_str::<Dimension>(invalid).is_err());
+    }
+}
+
+#[test]
+fn duration_unit_coordinates_are_exact_and_nominal() {
+    let duration = linear("duration", dim([0, 0, 1, 0, 0, 0, 0]));
+    let s = Unit::new(duration.clone(), source("1"), source("0")).unwrap();
+    let ms = Unit::new(duration.clone(), source("0.001"), source("0")).unwrap();
+    assert_fraction(&ms.convert(&source("750"), &s, &mut meter()).unwrap(), 3, 4);
+    let receive = NumericValue::from_unit(&source("750"), &ms, &mut meter()).unwrap();
+    let dispatch = NumericValue::from_unit(&source("1"), &s, &mut meter()).unwrap();
+    let total = receive.add(&dispatch, &mut meter()).unwrap();
+    assert_fraction(total.coordinate(), 7, 4);
+    assert_fraction(&total.display_in(&ms, &mut meter()).unwrap(), 1750, 1);
+    let different = Unit::new(
+        linear("different-kind", duration.dimension()),
+        source("1"),
+        source("0"),
+    )
+    .unwrap();
+    assert_eq!(
+        ms.convert(&source("750"), &different, &mut meter()),
+        Err(NumericError::IncompatibleTypes)
+    );
+    let inconsistent = Unit::new(
+        linear("duration", dim([1, 0, 0, 0, 0, 0, 0])),
+        source("1"),
+        source("0"),
+    )
+    .unwrap();
+    assert!(
+        ms.convert(&source("1"), &inconsistent, &mut meter())
+            .is_err()
+    );
+    assert!(Unit::new(duration.clone(), source("0"), source("0")).is_err());
+    assert!(Unit::new(duration.clone(), source("ratio(-1,1)"), source("0")).is_err());
+    assert_eq!(
+        Unit::new(duration, source("1"), source("1")).unwrap_err(),
+        NumericError::LinearOffset
+    );
+}
+
+#[test]
+fn affine_point_and_difference_arithmetic_has_distinct_kinds() {
+    let interval = linear("temperature-difference", dim([0, 0, 0, 0, 1, 0, 0]));
+    let point = ResolvedKind::affine("temperature-point".to_owned(), &interval).unwrap();
+    let celsius = Unit::new(point.clone(), source("1"), source("273.15")).unwrap();
+    let fahrenheit = Unit::new(
+        point.clone(),
+        source("ratio(5,9)"),
+        source("ratio(45967,180)"),
+    )
+    .unwrap();
+    let kelvin_interval = Unit::new(interval.clone(), source("1"), source("0")).unwrap();
+    assert_fraction(
+        &celsius
+            .convert(&source("0"), &fahrenheit, &mut meter())
+            .unwrap(),
+        32,
+        1,
+    );
+    assert_fraction(
+        &fahrenheit
+            .convert(&source("70"), &celsius, &mut meter())
+            .unwrap(),
+        190,
+        9,
+    );
+    let p20 = NumericValue::from_unit(&source("20"), &celsius, &mut meter()).unwrap();
+    let p10 = NumericValue::from_unit(&source("10"), &celsius, &mut meter()).unwrap();
+    let difference = p20.subtract(&p10, &mut meter()).unwrap();
+    assert_eq!(
+        difference.value_type(),
+        &NumericType::Named(interval.clone())
+    );
+    assert_fraction(
+        &difference
+            .display_in(&kelvin_interval, &mut meter())
+            .unwrap(),
+        10,
+        1,
+    );
+    let delta5 = named(5, &interval);
+    let p25 = p20.add(&delta5, &mut meter()).unwrap();
+    assert_fraction(&p25.display_in(&celsius, &mut meter()).unwrap(), 25, 1);
+    assert_eq!(delta5.add(&p20, &mut meter()).unwrap(), p25);
+    assert!(p20.add(&p10, &mut meter()).is_err());
+    assert!(delta5.subtract(&p20, &mut meter()).is_err());
+    assert_eq!(
+        p20.power(1, &mut meter()),
+        Err(NumericError::AffineOperation)
+    );
+    assert_eq!(
+        p20.negated(&mut meter()),
+        Err(NumericError::AffineOperation)
+    );
+    assert_eq!(p20.compare(&p10, &mut meter()).unwrap(), Ordering::Greater);
+    assert!(p20.display_in(&kelvin_interval, &mut meter()).is_err());
+    assert!(ResolvedKind::affine(interval.key().clone(), &interval).is_err());
+    assert!(ResolvedKind::affine("other".to_owned(), &point).is_err());
+}
+
+#[test]
+fn affine_conversion_rejects_a_wider_stage_even_when_the_final_value_would_fit() {
+    // A fused coordinate calculation 2*m-m equals m, where m=2^4095 fits.
+    // The fixed multiply stage produces 2^4096, so it must fail before offset
+    // cancellation. The inverse path likewise rejects (m-(-m))/2 at subtraction.
+    let large = BigInt::one() << 4095_usize;
+    let magnitude = exact(&large, 1);
+    let interval = linear("temperature-interval", dim([0, 0, 0, 0, 1, 0, 0]));
+    let point = ResolvedKind::affine("temperature-point".to_owned(), &interval).unwrap();
+    let unit = Unit::new(point, Exact::from_integer(2), exact(-&large, 1)).unwrap();
+    let mut work = meter();
+    for outcome in [
+        unit.to_canonical(&magnitude, &mut work),
+        unit.from_canonical(&magnitude, &mut work),
+    ] {
+        assert!(matches!(
+            outcome,
+            Err(NumericError::Limit(NumericLimit::Bits {
+                component: NumberComponent::Numerator,
+                bits: 4097,
+                limit: MAX_COMPONENT_BITS,
+                ..
+            }))
+        ));
+    }
+    assert!(work.exhaustion().is_none());
+    let half = exact(&large >> 1_usize, 1);
+    assert_fraction(&unit.to_canonical(&half, &mut work).unwrap(), 0, 1);
+    assert_eq!(
+        unit.from_canonical(&Exact::from_integer(0), &mut work)
+            .unwrap(),
+        half
+    );
+}
+
+#[test]
+fn r6_anonymous_compound_energy_needs_one_outer_assertion() {
+    let force = linear("force", dim([1, 1, -2, 0, 0, 0, 0]));
+    let length = linear("length", dim([1, 0, 0, 0, 0, 0, 0]));
+    let energy = linear("energy", dim([2, 1, -2, 0, 0, 0, 0]));
+    let a = named(3, &force)
+        .multiply(&named(4, &length), &mut meter())
+        .unwrap();
+    let b = named(2, &force)
+        .multiply(&named(7, &length), &mut meter())
+        .unwrap();
+    assert_eq!(a.value_type(), &NumericType::Anonymous(energy.dimension()));
+    let sum = a.add(&b, &mut meter()).unwrap();
+    let result = sum.as_kind(&energy, &mut meter()).unwrap();
+    assert_fraction(result.coordinate(), 26, 1);
+    assert_eq!(result.value_type(), &NumericType::Named(energy.clone()));
+    assert_eq!(a.compare(&b, &mut meter()).unwrap(), Ordering::Less);
+    assert!(result.add(&sum, &mut meter()).is_err());
+    assert_eq!(
+        result.as_kind(&energy, &mut meter()),
+        Err(NumericError::KindAssertion)
+    );
+}
+
+#[test]
+fn anonymous_product_then_quotient_closes_and_preserves_scaling() {
+    let mass = linear("mass", dim([0, 1, 0, 0, 0, 0, 0]));
+    let length = linear("length", dim([1, 0, 0, 0, 0, 0, 0]));
+    let time = linear("duration", dim([0, 0, 1, 0, 0, 0, 0]));
+    let momentum = linear("momentum", dim([1, 1, -1, 0, 0, 0, 0]));
+    let result = named(2, &mass)
+        .multiply(&named(3, &length), &mut meter())
+        .unwrap()
+        .divide(&named(2, &time), &mut meter())
+        .unwrap()
+        .as_kind(&momentum, &mut meter())
+        .unwrap();
+    assert_fraction(result.coordinate(), 3, 1);
+    let scalar = NumericValue::number(source("2"));
+    let scaled = scalar.multiply(&named(3, &time), &mut meter()).unwrap();
+    assert_eq!(scaled.value_type(), &NumericType::Named(time.clone()));
+    assert_fraction(scaled.coordinate(), 6, 1);
+    assert_eq!(
+        named(3, &time)
+            .divide(&scalar, &mut meter())
+            .unwrap()
+            .value_type(),
+        &NumericType::Named(time.clone())
+    );
+    assert_eq!(
+        scalar
+            .divide(&named(3, &time), &mut meter())
+            .unwrap()
+            .value_type(),
+        &NumericType::Anonymous(dim([0, 0, -1, 0, 0, 0, 0]))
+    );
+}
+
+#[test]
+fn nominal_kinds_survive_comparison_but_explicit_quotients_can_erase_dimension() {
+    let energy = linear("energy", dim([2, 1, -2, 0, 0, 0, 0]));
+    let torque = linear("torque", energy.dimension());
+    let left = named(7, &energy);
+    let right = named(7, &torque);
+    assert!(left.add(&right, &mut meter()).is_err());
+    assert!(left.compare(&right, &mut meter()).is_err());
+    let ratio = left.divide(&right, &mut meter()).unwrap();
+    assert_eq!(ratio.value_type(), &NumericType::Number);
+    assert_fraction(ratio.coordinate(), 1, 1);
+    let named_ratio = linear("chosen-ratio", Dimension::ZERO);
+    let asserted = ratio.as_kind(&named_ratio, &mut meter()).unwrap();
+    assert_eq!(
+        asserted.value_type(),
+        &NumericType::Named(named_ratio.clone())
+    );
+    assert!(asserted.add(&ratio, &mut meter()).is_err());
+    assert_eq!(
+        NumericValue::<String>::new(NumericType::Anonymous(Dimension::ZERO), source("1")),
+        NumericValue::number(source("1"))
+    );
+}
+
+#[test]
+fn numerical_power_types_and_dimension_overflow_are_checked() {
+    let length = linear("length", dim([1, 0, 0, 0, 0, 0, 0]));
+    let value = named(2, &length);
+    assert_eq!(
+        value.power(0, &mut meter()).unwrap().value_type(),
+        &NumericType::Number
+    );
+    assert_eq!(
+        value.power(1, &mut meter()).unwrap().value_type(),
+        value.value_type()
+    );
+    assert_eq!(
+        value.power(-2, &mut meter()).unwrap().value_type(),
+        &NumericType::Anonymous(dim([-2, 0, 0, 0, 0, 0, 0]))
+    );
+    let large_dimension = linear("large-dimension", dim([32, 0, 0, 0, 0, 0, 0]));
+    assert!(
+        named(1, &large_dimension)
+            .multiply(&value, &mut meter())
+            .is_err()
+    );
+    assert!(named(1, &large_dimension).power(2, &mut meter()).is_err());
+}

crates/oa-core/src/lib.rs

@@ -1,4 +1,5 @@
 //! Framework-independent OA/SA model, transactional commands and editing services.
+pub mod analysis_numeric;
 pub mod data;
 pub mod language;
 pub mod model;

crates/oa-desktop/src/allocation_drag.rs

@@ -0,0 +1,864 @@
+//! Pure, bounded allocation-drag composition. See the v2 interaction contract.
+//!
+//! These values are not input capabilities. The App must independently admit a
+//! clean press and retire its token on every document/input/camera lifetime
+//! change. Cache a SemanticPlan per token and destination; only `place` belongs
+//! on pointer motion. `finish` rechecks the live accepted Project and commands,
+//! but Document::execute still owns source admission and atomic history.
+use oa_core::{
+    projection::{self, ProjectedNode, ProjectedView},
+    validation::{self, Issue, Severity},
+    view_options::ViewIndex,
+    *,
+};
+use std::collections::{BTreeMap, BTreeSet};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Destination {
+    LayoutOnly,
+    Performer(Id),
+    OutsidePerformers,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Uniform {
+    Assigned(Id),
+    Unassigned,
+    MixedOrUnresolved,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct Leaf {
+    pub direct: Option<Relation>,
+    pub role_assignments: Vec<Relation>,
+    pub role_realizations: Vec<Relation>,
+    pub effective_performer: Option<Id>,
+}
+
+/// Exact semantic scope S, leaf scope L and active placement scope Q, including
+/// folded/unplaced leaves. Retaining records detects first-child responsibility
+/// transfer. Revision and input-epoch guards remain the caller's responsibility.
+#[derive(Debug, Clone, PartialEq)]
+pub struct Scope {
+    pub project: Id,
+    pub work: Id,
+    pub placement: Id,
+    pub work_records: BTreeMap<Id, Element>,
+    pub leaves: BTreeMap<Id, Leaf>,
+    pub placements: BTreeMap<Id, NodePlacement>,
+    pub diagram: Diagram,
+    pub uniform: Uniform,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ChangedRecord {
+    pub id: Id,
+    pub name: String,
+    pub category: &'static str,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum Refusal {
+    Ineligible(String),
+    StaleScope,
+    MixedLayoutRequired,
+    RoleExitRequired {
+        work: Id,
+        roles: Vec<Id>,
+        performers: Vec<Id>,
+        message: String,
+    },
+    MissingAllocationId(Id),
+    InvalidCandidate(String),
+    CollateralChangeRequired(Vec<ChangedRecord>),
+    LayoutRequired(String),
+}
+
+pub fn capture(p: &Project, diagram: Id, work: Id, placement: Id) -> Result<Scope, Refusal> {
+    validate_candidate(p).map_err(|e| Refusal::InvalidCandidate(e.to_string()))?;
+    let d = p.diagrams.get(&diagram).ok_or(Refusal::StaleScope)?;
+    let root = p.elements.get(&work).ok_or(Refusal::StaleScope)?;
+    if !root.kind().is_work()
+        || d.projection != ProjectionKind::Allocation
+        || d.layer != root.layer()
+    {
+        return Err(Refusal::Ineligible(
+            "Select an activity or function in an Allocation view.".into(),
+        ));
+    }
+    if d.nodes.get(&placement).is_none_or(|n| n.element != work) {
+        return Err(Refusal::StaleScope);
+    }
+    let mut work_records = BTreeMap::new();
+    let mut leaves = BTreeMap::new();
+    let mut pending = vec![work];
+    while let Some(id) = pending.pop() {
+        let element = p.elements.get(&id).ok_or(Refusal::StaleScope)?;
+        if element.kind() != root.kind() || work_records.insert(id, element.clone()).is_some() {
+            return Err(Refusal::StaleScope);
+        }
+        let children: Vec<_> = p
+            .children(id)
+            .filter(|e| e.kind() == root.kind())
+            .map(|e| e.id)
+            .collect();
+        if !children.is_empty() {
+            pending.extend(children);
+            continue;
+        }
+        let direct: Vec<_> = p
+            .relations
+            .values()
+            .filter(|r| r.kind() == RelationKind::Allocation && r.target() == id)
+            .cloned()
+            .collect();
+        if direct.len() > 1 {
+            return Err(Refusal::StaleScope);
+        }
+        let role_assignments: Vec<_> = p
+            .relations
+            .values()
+            .filter(|r| r.kind() == RelationKind::RoleAssignment && r.target() == id)
+            .cloned()
+            .collect();
+        let roles: BTreeSet<_> = role_assignments.iter().map(Relation::source).collect();
+        let role_realizations = p
+            .relations
+            .values()
+            .filter(|r| r.kind() == RelationKind::RoleRealization && roles.contains(&r.target()))
+            .cloned()
+            .collect();
+        leaves.insert(
+            id,
+            Leaf {
+                direct: direct.into_iter().next(),
+                role_assignments,
+                role_realizations,
+                effective_performer: validation::effective_performer(p, id),
+            },
+        );
+    }
+    if leaves.is_empty() {
+        return Err(Refusal::StaleScope);
+    }
+    let uniform = if leaves
+        .values()
+        .all(|l| l.direct.is_none() && l.role_assignments.is_empty())
+    {
+        Uniform::Unassigned
+    } else if let Some(performer) = leaves.values().next().and_then(|l| l.effective_performer)
+        && leaves
+            .values()
+            .all(|l| l.effective_performer == Some(performer))
+    {
+        Uniform::Assigned(performer)
+    } else {
+        Uniform::MixedOrUnresolved
+    };
+    let placements = d
+        .nodes
+        .iter()
+        .filter(|(_, n)| work_records.contains_key(&n.element))
+        .map(|(id, n)| (*id, n.clone()))
+        .collect();
+    Ok(Scope {
+        project: p.id,
+        work,
+        placement,
+        work_records,
+        leaves,
+        placements,
+        diagram: d.clone(),
+        uniform,
+    })
+}
+
+#[derive(Debug)]
+pub struct SemanticPlan {
+    pub scope: Scope,
+    pub destination: Destination,
+    pub label: String,
+    pub warnings: Vec<Issue>,
+    accepted: Project,
+    candidate: Project,
+    index: ViewIndex,
+    commands: Vec<Command>,
+    before_visible: ProjectedView,
+    before_expanded: ProjectedView,
+}
+
+impl SemanticPlan {
+    /// All preview drawing, ports and routing must use this candidate and index.
+    pub fn project(&self) -> &Project {
+        &self.candidate
+    }
+    pub fn index(&self) -> &ViewIndex {
+        &self.index
+    }
+}
+
+/// Allocation identities are allocated once by the gesture owner, keyed by leaf,
+/// and reused on target revisits and release. No random identity generation here.
+pub fn plan_semantics(
+    p: &Project,
+    scope: &Scope,
+    destination: Destination,
+    allocation_ids: &BTreeMap<Id, Id>,
+) -> Result<SemanticPlan, Refusal> {
+    if &capture(p, scope.diagram.id, scope.work, scope.placement)? != scope {
+        return Err(Refusal::StaleScope);
+    }
+    if scope.work_records.len() > 1 && scope.uniform == Uniform::MixedOrUnresolved {
+        return Err(Refusal::MixedLayoutRequired);
+    }
+    if let Destination::Performer(id) = destination {
+        let valid = p
+            .elements
+            .get(&id)
+            .is_some_and(|e| e.kind().is_performer() && e.layer() == scope.diagram.layer);
+        if !valid {
+            return Err(Refusal::Ineligible(
+                "Choose a performer in this layer.".into(),
+            ));
+        }
+    }
+    let before_index = ViewIndex::new(p);
+    let before_visible = projection::project_diagram_with_index(p, &scope.diagram, &before_index);
+    let before_expanded = expanded_view(p, &scope.diagram, scope, &before_index);
+    if scope.work_records.len() > 1 && !coherent(scope, &before_expanded) {
+        return Err(Refusal::MixedLayoutRequired);
+    }
+    let same_performer =
+        matches!(destination, Destination::Performer(id) if scope.uniform == Uniform::Assigned(id));
+    let mut expected = p.clone();
+    let mut commands = Vec::new();
+    let mut deleted = BTreeSet::new();
+    if destination != Destination::LayoutOnly && !same_performer {
+        for (work, leaf) in &scope.leaves {
+            match destination {
+                Destination::Performer(performer) => {
+                    if let Some(existing) = &leaf.direct {
+                        if existing.source() != performer {
+                            let mut edited = existing.clone();
+                            edited.body = RelationBody::Allocation {
+                                source: performer,
+                                target: *work,
+                            };
+                            expected.relations.insert(edited.id, edited.clone());
+                            commands.push(Command::EditRelation(edited.id, edited));
+                        }
+                    } else {
+                        let id = *allocation_ids
+                            .get(work)
+                            .ok_or(Refusal::MissingAllocationId(*work))?;
+                        if id.is_nil() || expected.contains(id) {
+                            return Err(Refusal::InvalidCandidate(
+                                "The gesture's allocation identity is already in use.".into(),
+                            ));
+                        }
+                        let name = format!("{} performs {}", p.named(performer), p.named(*work));
+                        let relation = Relation {
+                            id,
+                            alias: expected.fresh_alias(&name, "allocation", id),
+                            name,
+                            description: String::new(),
+                            body: RelationBody::Allocation {
+                                source: performer,
+                                target: *work,
+                            },
+                        };
+                        expected.relations.insert(id, relation.clone());
+                        commands.push(Command::CreateRelation(relation));
+                    }
+                }
+                Destination::OutsidePerformers => {
+                    if !leaf.role_assignments.is_empty() {
+                        let roles: Vec<_> = leaf
+                            .role_assignments
+                            .iter()
+                            .map(Relation::source)
+                            .collect::<BTreeSet<_>>()
+                            .into_iter()
+                            .collect();
+                        let performers: Vec<_> = leaf
+                            .role_realizations
+                            .iter()
+                            .map(Relation::source)
+                            .collect::<BTreeSet<_>>()
+                            .into_iter()
+                            .collect();
+                        let message = if leaf.direct.is_some() && performers.len() == 1 {
+                            format!(
+                                "Removing direct assignment would place {} in {} through its role.",
+                                p.named(*work),
+                                p.named(performers[0])
+                            )
+                        } else {
+                            format!(
+                                "{} retains role responsibility through {}{}; edit that responsibility before moving outside performers.",
+                                p.named(*work),
+                                roles
+                                    .iter()
+                                    .map(|id| p.named(*id))
+                                    .collect::<Vec<_>>()
+                                    .join(", "),
+                                if performers.is_empty() {
+                                    String::new()
+                                } else {
+                                    format!(
+                                        " ({})",
+                                        performers
+                                            .iter()
+                                            .map(|id| p.named(*id))
+                                            .collect::<Vec<_>>()
+                                            .join(", ")
+                                    )
+                                }
+                            )
+                        };
+                        return Err(Refusal::RoleExitRequired {
+                            work: *work,
+                            roles,
+                            performers,
+                            message,
+                        });
+                    }
+                    if let Some(existing) = &leaf.direct {
+                        expected.relations.remove(&existing.id);
+                        deleted.insert(existing.id);
+                        commands.push(Command::Delete(existing.id));
+                    }
+                }
+                Destination::LayoutOnly => unreachable!(),
+            }
+        }
+    }
+    // A route cannot survive the intentional deletion of its own edge, even in
+    // another diagram. No other saved-view cleanup is authorized by this drag.
+    for diagram in expected.diagrams.values_mut() {
+        diagram.routes.retain(|r| !deleted.contains(&r.edge));
+    }
+    let actual = prepare_command(p, &Command::Batch(commands.clone()))
+        .map_err(|e| Refusal::InvalidCandidate(e.to_string()))?
+        .project;
+    exact_project(&expected, &actual)?;
+    let retained_roles = scope
+        .leaves
+        .values()
+        .any(|l| !l.role_assignments.is_empty());
+    let label = match destination {
+        Destination::LayoutOnly => "Arrange only".into(),
+        Destination::Performer(id) if same_performer => format!("Arrange within {}", p.named(id)),
+        Destination::Performer(id) => format!(
+            "Assign {} leaf {} to {}{}",
+            scope.leaves.len(),
+            match (scope.diagram.layer, scope.leaves.len()) {
+                (Layer::Oa, 1) => "activity",
+                (Layer::Oa, _) => "activities",
+                (Layer::Sa, 1) => "function",
+                (Layer::Sa, _) => "functions",
+            },
+            p.named(id),
+            if retained_roles {
+                " — explicit assignment; role responsibility retained"
+            } else {
+                ""
+            }
+        ),
+        Destination::OutsidePerformers if commands.is_empty() => {
+            "Arrange unassigned work — decomposition retained".into()
+        }
+        Destination::OutsidePerformers => "Remove assignment — decomposition retained".into(),
+    };
+    let warnings = validation::validate(&actual)
+        .into_iter()
+        .filter(|i| i.severity == Severity::Warning)
+        .collect();
+    let index = ViewIndex::new(&actual);
+    Ok(SemanticPlan {
+        scope: scope.clone(),
+        destination,
+        label,
+        warnings,
+        accepted: p.clone(),
+        candidate: actual,
+        index,
+        commands,
+        before_visible,
+        before_expanded,
+    })
+}
+
+/// World-space rectangle in the gesture's frozen transform. The UI resolver
+/// owns half-open pointer hits, semantic target precedence and occlusion.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Rect {
+    pub position: Position,
+    pub size: Size,
+}
+
+impl Rect {
+    fn valid(self) -> bool {
+        [
+            self.position.x,
+            self.position.y,
+            self.size.width,
+            self.size.height,
+        ]
+        .iter()
+        .all(|n| n.is_finite() && n.abs() <= MAX_COORDINATE)
+            && self.size.width > 0.
+            && self.size.height > 0.
+    }
+    fn contains(self, other: Self) -> bool {
+        other.position.x >= self.position.x
+            && other.position.y >= self.position.y
+            && other.position.x + other.size.width <= self.position.x + self.size.width
+            && other.position.y + other.size.height <= self.position.y + self.size.height
+    }
+    fn overlaps(self, other: Self) -> bool {
+        self.position.x < other.position.x + other.size.width
+            && other.position.x < self.position.x + self.size.width
+            && self.position.y < other.position.y + other.size.height
+            && other.position.y < self.position.y + self.size.height
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct TargetPresentation {
+    pub placement: Id,
+    /// Exact frozen painted label bounds, supplied by the renderer/resolver.
+    pub label: Rect,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct PresentationContext {
+    /// Visible world rectangle derived from the actual captured pan/zoom/bounds.
+    pub viewport: Rect,
+    pub zoom: f32,
+    pub target: Option<TargetPresentation>,
+}
+
+#[derive(Debug)]
+pub struct PlacementPlan {
+    pub diagram: Diagram,
+    pub view: ProjectedView,
+    pub delta: Position,
+    pub unfolded: Option<Id>,
+    requested: Position,
+    presentation: PresentationContext,
+    commands: Vec<Command>,
+}
+
+/// `requested` is the original selected placement position plus pointer motion
+/// in the frozen transform (therefore preserving the press offset). Snap only
+/// this root; apply the resulting identical delta to captured Q and its routes.
+/// No whole Project clone, validator or semantic ViewIndex rebuild occurs here.
+pub fn place(
+    plan: &SemanticPlan,
+    requested: Position,
+    presentation: PresentationContext,
+) -> Result<PlacementPlan, Refusal> {
+    if !requested.x.is_finite()
+        || !requested.y.is_finite()
+        || !presentation.viewport.valid()
+        || !presentation.zoom.is_finite()
+        || presentation.zoom <= 0.
+    {
+        return Err(Refusal::LayoutRequired(
+            "Make room or adjust the view, then drag again.".into(),
+        ));
+    }
+    let root = &plan.scope.placements[&plan.scope.placement];
+    let delta = Position {
+        x: (requested.x / 10.).round() * 10. - root.position.x,
+        y: (requested.y / 10.).round() * 10. - root.position.y,
+    };
+    let mut diagram = plan.candidate.diagrams[&plan.scope.diagram.id].clone();
+    let mut commands = Vec::new();
+    let mut deltas = BTreeMap::new();
+    for (id, original) in &plan.scope.placements {
+        let node = diagram.nodes.get_mut(id).ok_or(Refusal::StaleScope)?;
+        node.position = Position {
+            x: original.position.x + delta.x,
+            y: original.position.y + delta.y,
+        };
+        if !(Rect {
+            position: node.position,
+            size: node.size,
+        })
+        .valid()
+        {
+            return Err(Refusal::InvalidCandidate(
+                "Moved coordinates exceed the model bounds.".into(),
+            ));
+        }
+        deltas.insert(*id, delta);
+        if node != original {
+            commands.push(Command::EditNode {
+                diagram: diagram.id,
+                original: *id,
+                node: node.clone(),
+            });
+        }
+    }
+    // Resolve endpoints using the captured accepted semantics, not a newly
+    // regrouped descendant walk. Own-edge deletions were removed above already.
+    for route in projection::translated_routes(&plan.accepted, &plan.scope.diagram, &deltas) {
+        if let Some(existing) = diagram.routes.iter_mut().find(|r| r.edge == route.edge) {
+            if route.waypoints.iter().any(|p| {
+                !p.x.is_finite()
+                    || !p.y.is_finite()
+                    || p.x.abs() > MAX_COORDINATE
+                    || p.y.abs() > MAX_COORDINATE
+            }) {
+                return Err(Refusal::InvalidCandidate(
+                    "Moved route exceeds the model bounds.".into(),
+                ));
+            }
+            *existing = route.clone();
+            commands.push(Command::SetEdgeRoute {
+                diagram: diagram.id,
+                route,
+            });
+        }
+    }
+    let mut unfolded = None;
+    if let Destination::Performer(performer) = plan.destination {
+        let target = presentation.target.ok_or_else(|| {
+            Refusal::LayoutRequired("The frozen performer label must be visible.".into())
+        })?;
+        let node = diagram
+            .nodes
+            .get_mut(&target.placement)
+            .ok_or(Refusal::StaleScope)?;
+        let frozen_header = plan
+            .before_visible
+            .nodes
+            .iter()
+            .find(|n| n.id == target.placement)
+            .map(|n| Rect {
+                position: n.position,
+                size: Size {
+                    width: n.size.width,
+                    height: n.size.height.min(62.),
+                },
+            });
+        if node.element != performer
+            || frozen_header.is_none_or(|header| !header.contains(target.label))
+            || !target.label.valid()
+            || !presentation.viewport.contains(target.label)
+        {
+            return Err(Refusal::LayoutRequired(
+                "Make room or adjust the view, then drag again.".into(),
+            ));
+        }
+        if node.collapsed && !plan.commands.is_empty() {
+            node.collapsed = false;
+            unfolded = Some(node.id);
+            commands.push(Command::EditNode {
+                diagram: diagram.id,
+                original: node.id,
+                node: node.clone(),
+            });
+        }
+    } else if presentation.target.is_some() {
+        return Err(Refusal::Ineligible(
+            "This layout/outside destination has no performer target.".into(),
+        ));
+    }
+    let view = projection::project_diagram_with_index(&plan.candidate, &diagram, &plan.index);
+    let expanded = expanded_view(&plan.candidate, &diagram, &plan.scope, &plan.index);
+    check_geometry(plan, &view, &expanded, delta)?;
+    let selected = view
+        .nodes
+        .iter()
+        .find(|n| n.id == plan.scope.placement)
+        .ok_or_else(|| {
+            Refusal::LayoutRequired("The selected work header would be hidden.".into())
+        })?;
+    let header = Rect {
+        position: selected.position,
+        size: Size {
+            width: selected.size.width,
+            height: selected.size.height.min(62.),
+        },
+    };
+    if !presentation.viewport.contains(header) {
+        return Err(Refusal::LayoutRequired(
+            "Make room or adjust the view, then drag again.".into(),
+        ));
+    }
+    // A performer may legitimately enclose the work, but its frozen feedback
+    // label is painted above the candidate. Check their joint readability after
+    // projection, including same-performer moves; never shift either rectangle.
+    if presentation
+        .target
+        .is_some_and(|target| header.overlaps(target.label))
+    {
+        return Err(Refusal::LayoutRequired(
+            "The work header overlaps the performer label. Aim below or beside the label, then drag again."
+                .into(),
+        ));
+    }
+    Ok(PlacementPlan {
+        diagram,
+        view,
+        delta,
+        unfolded,
+        requested,
+        presentation,
+        commands,
+    })
+}
+
+/// Final semantic/presentation equality gate, after the App has checked its
+/// current token, owner, revision, clean drafts, frozen target and transform.
+/// Recompute geometry to avoid accepting a modified/stale placement result.
+/// None means a snapped no-op: the caller must not execute or add history.
+pub fn finish(
+    plan: &SemanticPlan,
+    live: &Project,
+    placement: &PlacementPlan,
+) -> Result<Option<Command>, Refusal> {
+    if live != &plan.accepted {
+        return Err(Refusal::StaleScope);
+    }
+    let checked = place(plan, placement.requested, placement.presentation)?;
+    if checked.diagram != placement.diagram
+        || checked.view != placement.view
+        || checked.delta != placement.delta
+        || checked.unfolded != placement.unfolded
+        || checked.commands != placement.commands
+    {
+        return Err(Refusal::StaleScope);
+    }
+    let mut expected = plan.candidate.clone();
+    expected
+        .diagrams
+        .insert(checked.diagram.id, checked.diagram);
+    let mut commands = plan.commands.clone();
+    commands.extend(checked.commands);
+    let command = Command::Batch(commands);
+    let actual = prepare_command(live, &command)
+        .map_err(|e| Refusal::InvalidCandidate(e.to_string()))?
+        .project;
+    exact_project(&expected, &actual)?;
+    Ok((actual != *live).then_some(command))
+}
+
+fn expanded_view(
+    p: &Project,
+    diagram: &Diagram,
+    scope: &Scope,
+    index: &ViewIndex,
+) -> ProjectedView {
+    let mut expanded = diagram.clone();
+    for id in scope.placements.keys() {
+        if let Some(node) = expanded.nodes.get_mut(id) {
+            node.collapsed = false;
+        }
+    }
+    projection::project_diagram_with_index(p, &expanded, index)
+}
+
+fn ancestors(view: &ProjectedView) -> BTreeMap<Id, BTreeSet<Id>> {
+    let parents: BTreeMap<_, _> = view.nodes.iter().map(|n| (n.id, n.visual_parent)).collect();
+    parents
+        .keys()
+        .map(|node| {
+            let mut current = parents[node];
+            let mut seen = BTreeSet::new();
+            while let Some(id) = current {
+                if !seen.insert(id) {
+                    break;
+                }
+                current = parents.get(&id).copied().flatten();
+            }
+            (*node, seen)
+        })
+        .collect()
+}
+
+fn coherent(scope: &Scope, view: &ProjectedView) -> bool {
+    let ancestors = ancestors(view);
+    scope.placements.keys().all(|id| {
+        ancestors
+            .get(id)
+            .is_some_and(|parents| *id == scope.placement || parents.contains(&scope.placement))
+    })
+}
+
+fn overlap(a: &ProjectedNode, b: &ProjectedNode) -> f32 {
+    let width = (a.position.x + a.size.width).min(b.position.x + b.size.width)
+        - a.position.x.max(b.position.x);
+    let height = (a.position.y + a.size.height).min(b.position.y + b.size.height)
+        - a.position.y.max(b.position.y);
+    width.max(0.) * height.max(0.)
+}
+
+fn overlaps(before: &ProjectedView, after: &ProjectedView) -> bool {
+    // Build geometry ancestry once, avoiding a repeated descendant walk for
+    // every pair during pointer motion. Pairwise collision checking is bounded
+    // to these two projected scenes and does not traverse/clone model semantics.
+    let before_ancestors = ancestors(before);
+    let after_ancestors = ancestors(after);
+    let prior_nodes: BTreeMap<_, _> = before.nodes.iter().map(|n| (n.id, n)).collect();
+    for (i, a) in after.nodes.iter().enumerate() {
+        for b in &after.nodes[i + 1..] {
+            if after_ancestors[&a.id].contains(&b.id) || after_ancestors[&b.id].contains(&a.id) {
+                continue;
+            }
+            let prior = match (prior_nodes.get(&a.id), prior_nodes.get(&b.id)) {
+                (Some(x), Some(y))
+                    if !before_ancestors[&x.id].contains(&y.id)
+                        && !before_ancestors[&y.id].contains(&x.id) =>
+                {
+                    overlap(x, y)
+                }
+                _ => 0.,
+            };
+            if overlap(a, b) > prior + 0.01 {
+                return true;
+            }
+        }
+    }
+    false
+}
+
+fn check_geometry(
+    plan: &SemanticPlan,
+    visible: &ProjectedView,
+    expanded: &ProjectedView,
+    delta: Position,
+) -> Result<(), Refusal> {
+    if visible.nodes.iter().chain(&expanded.nodes).any(|n| {
+        !(Rect {
+            position: n.position,
+            size: n.size,
+        })
+        .valid()
+    }) {
+        return Err(Refusal::InvalidCandidate(
+            "The projected enclosure exceeds the model bounds.".into(),
+        ));
+    }
+    if plan.scope.work_records.len() > 1 {
+        if !coherent(&plan.scope, expanded) {
+            return Err(Refusal::MixedLayoutRequired);
+        }
+        for id in plan.scope.placements.keys() {
+            let old = plan
+                .before_expanded
+                .nodes
+                .iter()
+                .find(|n| n.id == *id)
+                .ok_or(Refusal::MixedLayoutRequired)?;
+            let new = expanded
+                .nodes
+                .iter()
+                .find(|n| n.id == *id)
+                .ok_or(Refusal::MixedLayoutRequired)?;
+            if (new.position.x - old.position.x - delta.x).abs() > 0.01
+                || (new.position.y - old.position.y - delta.y).abs() > 0.01
+                || (new.size.width - old.size.width).abs() > 0.01
+                || (new.size.height - old.size.height).abs() > 0.01
+            {
+                return Err(Refusal::LayoutRequired("This work subtree requires an explicit layout; its footprint cannot be translated unchanged.".into()));
+            }
+        }
+    }
+    if overlaps(&plan.before_visible, visible) || overlaps(&plan.before_expanded, expanded) {
+        return Err(Refusal::LayoutRequired("Make room before moving work: the candidate would introduce or enlarge overlapping cards.".into()));
+    }
+    Ok(())
+}
+
+/// Compare complete records, not just removed IDs. Deleting an Allocation can
+/// rewrite a surviving Constraint, remove artifacts/traces or prune view options.
+fn exact_project(expected: &Project, actual: &Project) -> Result<(), Refusal> {
+    if expected == actual {
+        return Ok(());
+    }
+    let mut records = Vec::new();
+    fn changes<T: PartialEq>(
+        expected: &BTreeMap<Id, T>,
+        actual: &BTreeMap<Id, T>,
+        category: &'static str,
+        project: &Project,
+        other: &Project,
+        records: &mut Vec<ChangedRecord>,
+    ) {
+        let ids: BTreeSet<_> = expected.keys().chain(actual.keys()).copied().collect();
+        for id in ids {
+            if expected.get(&id) != actual.get(&id) {
+                records.push(ChangedRecord {
+                    id,
+                    name: if project.contains(id) {
+                        project.named(id)
+                    } else {
+                        other.named(id)
+                    }
+                    .into(),
+                    category,
+                });
+            }
+        }
+    }
+    changes(
+        &expected.elements,
+        &actual.elements,
+        "element",
+        expected,
+        actual,
+        &mut records,
+    );
+    changes(
+        &expected.relations,
+        &actual.relations,
+        "relation",
+        expected,
+        actual,
+        &mut records,
+    );
+    changes(
+        &expected.diagrams,
+        &actual.diagrams,
+        "diagram",
+        expected,
+        actual,
+        &mut records,
+    );
+    changes(
+        &expected.artifact_links,
+        &actual.artifact_links,
+        "artifact",
+        expected,
+        actual,
+        &mut records,
+    );
+    changes(
+        &expected.traces,
+        &actual.traces,
+        "trace",
+        expected,
+        actual,
+        &mut records,
+    );
+    if expected.schema_version != actual.schema_version
+        || expected.id != actual.id
+        || expected.alias != actual.alias
+        || expected.name != actual.name
+        || expected.description != actual.description
+    {
+        records.push(ChangedRecord {
+            id: expected.id,
+            name: expected.name.clone(),
+            category: "project",
+        });
+    }
+    Err(Refusal::CollateralChangeRequired(records))
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/allocation_input.rs

@@ -0,0 +1,266 @@
+//! A narrow dispatch boundary for Allocation work gestures. Iced rows visit
+//! siblings after capture; refusing inside Canvas alone still blurs an inspector
+//! field. Refuse before dispatching that press to any ordinary child instead.
+use crate::{
+    app::{
+        App, Message,
+        allocation_drag::{self, Event as WorkEvent},
+    },
+    diagram::DiagramCanvas,
+};
+use iced::advanced::{
+    Clipboard, Layout, Shell, Widget, layout, overlay, renderer,
+    widget::{Id, Operation, Tree, tree},
+};
+use iced::{
+    Element, Event, Length, Point, Rectangle, Renderer, Size, Theme, Vector, keyboard, mouse,
+};
+
+pub const CANVAS_ID: &str = "allocation-work-canvas";
+pub const ARRANGE_SHORTCUT: &str = "Alt+A";
+
+struct Root<'a> {
+    app: &'a App,
+    content: Element<'a, Message>,
+}
+#[derive(Default)]
+struct State {
+    pointer: Option<Point>,
+    refused_left: bool,
+}
+#[derive(Default)]
+struct CanvasBounds(Option<Rectangle>);
+impl Operation for CanvasBounds {
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        visit(self);
+    }
+    fn container(&mut self, id: Option<&Id>, bounds: Rectangle) {
+        if id == Some(&Id::new(CANVAS_ID)) {
+            self.0 = Some(bounds);
+        }
+    }
+}
+pub fn root<'a>(app: &'a App, content: impl Into<Element<'a, Message>>) -> Element<'a, Message> {
+    Element::new(Root {
+        app,
+        content: content.into(),
+    })
+}
+fn arrange_key(event: &Event) -> bool {
+    matches!(event, Event::Keyboard(keyboard::Event::KeyPressed {
+        key: keyboard::Key::Character(key), modifiers, repeat: false, ..
+    }) if key.eq_ignore_ascii_case("a") && *modifiers == keyboard::Modifiers::ALT)
+}
+impl Root<'_> {
+    fn dirty_object(&self, bounds: Rectangle, screen: Point) -> bool {
+        let Some(diagram) = self.app.active_diagram else {
+            return false;
+        };
+        if !allocation_drag::contains(bounds, screen) {
+            return false;
+        }
+        let canvas = DiagramCanvas {
+            allocation: Some(self.app.allocation_capability()),
+            project: self.app.project(),
+            view_index: Some(self.app.document.view_index()),
+            diagram,
+            selected: self.app.selected,
+            zoom: self.app.zoom,
+            pan: self.app.pan,
+            context: self.app.route_context().unwrap(),
+            selected_bend: None,
+            editable: false,
+            placing: false,
+            connection: None,
+        };
+        canvas.work_dirty_point(bounds, screen)
+    }
+}
+impl Widget<Message, Theme, Renderer> for Root<'_> {
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<State>()
+    }
+    fn state(&self) -> tree::State {
+        tree::State::new(State::default())
+    }
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+    fn diff(&self, tree: &mut Tree) {
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+    fn layout(
+        &mut self,
+        tree: &mut Tree,
+        renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &Renderer,
+        operation: &mut dyn Operation,
+    ) {
+        self.content
+            .as_widget_mut()
+            .operate(&mut tree.children[0], layout, renderer, operation);
+    }
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &Renderer,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        let state = tree.state.downcast_mut::<State>();
+        match event {
+            Event::Mouse(mouse::Event::CursorMoved { position }) => state.pointer = Some(*position),
+            Event::Mouse(mouse::Event::CursorLeft) => state.pointer = None,
+            Event::Window(iced::window::Event::RedrawRequested(_)) => {
+                state.pointer = cursor.position()
+            }
+            Event::Window(iced::window::Event::Unfocused) => {
+                state.pointer = None;
+                state.refused_left = false;
+            }
+            _ => {}
+        }
+        if state.refused_left {
+            if matches!(
+                event,
+                Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
+            ) {
+                state.refused_left = false;
+                shell.capture_event();
+                return;
+            }
+            if matches!(event, Event::Mouse(mouse::Event::CursorMoved { .. })) {
+                shell.capture_event();
+                return;
+            }
+        }
+        if self.app.allocation_input_owner() && !shell.is_event_captured() {
+            if arrange_key(event) {
+                // App rechecks clean ownership before arming. A dirty field
+                // retains its actual widget focus and selection on refusal.
+                shell.publish(Message::WorkDrag(WorkEvent::ArrangeNext));
+                shell.capture_event();
+                return;
+            }
+            if self.app.allocation_drag.arrange_next
+                && matches!(
+                    event,
+                    Event::Keyboard(keyboard::Event::KeyPressed {
+                        key: keyboard::Key::Named(keyboard::key::Named::Escape),
+                        ..
+                    })
+                )
+            {
+                shell.publish(Message::Escape);
+                shell.capture_event();
+                return;
+            }
+            if !self.app.allocation_drag_clean()
+                && matches!(
+                    event,
+                    Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+                )
+                && let Some(screen) = state.pointer.or_else(|| cursor.position())
+            {
+                let mut canvas = CanvasBounds::default();
+                self.content.as_widget_mut().operate(
+                    &mut tree.children[0],
+                    layout,
+                    renderer,
+                    &mut canvas,
+                );
+                if canvas
+                    .0
+                    .is_some_and(|bounds| self.dirty_object(bounds, screen))
+                {
+                    state.refused_left = true;
+                    shell.publish(Message::WorkDrag(WorkEvent::Refused(
+                        self.app.allocation_drag.epoch,
+                        allocation_drag::FINISH_EDIT.into(),
+                    )));
+                    shell.capture_event();
+                    return;
+                }
+            }
+        }
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut Renderer,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            style,
+            layout,
+            cursor,
+            viewport,
+        );
+    }
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &Renderer,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout,
+            cursor,
+            viewport,
+            renderer,
+        )
+    }
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'b>,
+        renderer: &Renderer,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}

crates/oa-desktop/src/app.rs

@@ -1,10 +1,15 @@
+pub(crate) mod allocation_drag;
 pub(crate) mod architecture_authoring;
 #[cfg(test)]
 mod architecture_authoring_tests;
 mod checkpoints;
+pub(crate) mod diagram_removal;
+#[cfg(test)]
+mod diagram_removal_tests;
 #[cfg(test)]
 mod diagram_selection_tests;
 mod hosted;
+mod reference_authoring;
 #[cfg(test)]
 mod review_navigation_tests;
 #[cfg(test)]
@@ -57,7 +62,7 @@ mod direct_scenario_tests {
         }
     }
     #[test]
-    fn direct_scenario_scroll_and_real_resize_invalidate_only_pointer_context() {
+    fn direct_scenario_camera_details_and_real_resize_invalidate_only_pointer_context() {
         let (mut app, f) = setup();
         let original = app.document.bundle().clone();
         let event = begin(&app, &f);
@@ -73,18 +78,26 @@ mod direct_scenario_tests {
         let _ = app.update(Message::ScenarioCanvas(event));
         assert!(!app.behavior.has_pending());
         let context = app.scenario_context().unwrap();
-        for (area, offset) in [
-            (scenario::ScrollArea::Canvas, iced::Vector::new(30., 150.)),
-            (scenario::ScrollArea::Page, iced::Vector::new(0., 90.)),
-        ] {
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Camera(
+            context,
+            app.camera_epoch,
+            behavior::canvas_workspace::Event::Pan(iced::Vector::new(30., 150.)),
+        )));
+        assert_ne!(app.scenario_context(), Some(context));
+        let context = app.scenario_context().unwrap();
+        for offset in [iced::Vector::new(0., 90.), iced::Vector::new(0., 150.)] {
             let before = app.scenario_context().unwrap();
             let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Scrolled(
-                context, area, offset,
+                context,
+                scenario::ScrollArea::Page,
+                offset,
             )));
             assert_ne!(app.scenario_context(), Some(before));
             let current = app.scenario_context().unwrap();
             let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Scrolled(
-                context, area, offset,
+                context,
+                scenario::ScrollArea::Page,
+                offset,
             )));
             assert_eq!(
                 app.scenario_context(),
@@ -113,7 +126,7 @@ mod direct_scenario_tests {
             }
             let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Scrolled(
                 stale,
-                scenario::ScrollArea::Canvas,
+                scenario::ScrollArea::Page,
                 iced::Vector::new(0., 900.),
             )));
             assert_eq!(app.scenario_context(), Some(current));
@@ -318,6 +331,8 @@ pub struct FilePrompt {
 
 #[derive(Debug, Clone)]
 pub enum Message {
+    WorkDrag(allocation_drag::Event),
+    BehaviorControl(behavior::canvas_workspace::Intent),
     Architecture(architecture_authoring::Event),
     Home(crate::home::Event),
     CheckpointTick,
@@ -371,6 +386,8 @@ pub enum Message {
     FieldValuePath(String, crate::data_values::FieldPathKey),
     FieldValueBrowse(String, Option<crate::data_values::FieldPathKey>, usize),
     FieldReferenceBrowse(String, String, usize),
+    FieldReferenceOpen(crate::forms::reference_chooser::adapter::Open),
+    FieldReferenceEvent(crate::forms::reference_chooser::Event),
     FieldVariant(String, Value),
     FieldArray(String, Option<usize>, i32),
     Apply,
@@ -379,7 +396,9 @@ pub enum Message {
     RelationKind(RelationKind),
     Command(Command),
     Delete,
-    ConfirmDelete,
+    ConfirmDelete(u64),
+    DiagramRemove(diagram_removal::Intent),
+    DiagramTraverse(bool),
     CancelDelete,
     Undo,
     Redo,
@@ -438,6 +457,7 @@ pub enum Message {
 }
 
 pub struct App {
+    pub allocation_drag: allocation_drag::State,
     pub home: crate::home::State,
     pub recovery: crate::recovery::State,
     recent_target: Option<PathBuf>,
@@ -445,10 +465,14 @@ pub struct App {
     pub hosted: crate::hosted::State,
     pub connection: Option<crate::connection_edit::Session>,
     pub model_menu: Option<crate::model_menu::Opened>,
+    reference_authoring: reference_authoring::State,
     pub source_tree: crate::source_tree::State,
     menu_sequence: u64,
     pub canvas_document: Id,
     pub canvas_epoch: u64,
+    /// Camera batches survive their own updates, never external presentation changes.
+    pub camera_epoch: u64,
+    camera_boundary_epoch: u64,
     pub selected_bend: Option<(Id, usize)>,
     pub exact_strings: bool,
     pub document: Document,
@@ -473,6 +497,7 @@ pub struct App {
     pub busy: bool,
     pub pending: Option<Pending>,
     pub delete_pending: bool,
+    pub delete_target: Option<diagram_removal::Confirmation>,
     pub path: Option<PathBuf>,
     /// A disk transaction requiring an explicit action, independent of lint.
     pub pending_recovery: Option<PathBuf>,
@@ -541,16 +566,20 @@ impl App {
         let explorer_index = crate::explorer::Index::new(&project, layer);
         let explorer_collapsed = project.elements.values().filter_map(|e| e.parent).collect();
         let mut app = Self {
+            allocation_drag: Default::default(),
             home: Default::default(),
             recovery: Default::default(),
             recent_target: None,
             checkpoint_close: None,
             connection: None,
             model_menu: None,
+            reference_authoring: Default::default(),
             source_tree: Default::default(),
             menu_sequence: 0,
             canvas_document: Id::new_v4(),
             canvas_epoch: 0,
+            camera_epoch: 0,
+            camera_boundary_epoch: 0,
             selected_bend: None,
             exact_strings: false,
             document,
@@ -579,6 +608,7 @@ impl App {
             busy: false,
             pending: None,
             delete_pending: false,
+            delete_target: None,
             path: None,
             pending_recovery: None,
             disk_project: None,
@@ -854,8 +884,12 @@ impl App {
         let scenario_selection = self
             .behavior
             .scenario
-            .created_selection(&command)
-            .or_else(|| self.behavior.topology.created_selection(&command));
+            .created_selection(self.project(), &command)
+            .or_else(|| {
+                self.behavior
+                    .topology
+                    .created_selection(self.project(), &command)
+            });
         match self.document.execute(command) {
             Ok(selected) => {
                 if let Some(created) = created {
@@ -1023,7 +1057,13 @@ impl App {
             crate::model_menu::popup(self),
         )
         .into();
-        crate::hosted::view::overlay(self, base)
+        crate::behavior::scenario::focus::root(
+            behavior::canvas_workspace::focus_root(
+                crate::hosted::view::overlay(self, self.reference_overlay(base)),
+                behavior::canvas_workspace::Scope::input_owner(self),
+            ),
+            self.scenario_focus_owner(),
+        )
     }
     pub fn subscription(&self) -> Subscription<Message> {
         Subscription::batch([
@@ -1031,9 +1071,21 @@ impl App {
             window::close_requests().map(|id| Message::Request(Pending::Close(id))),
             window::resize_events().map(|(_, size)| Message::WindowResized(size)),
             architecture_authoring::subscription(self),
-            behavior::creation::subscription(self.behavior.creation.has_pending())
-                .map(|()| Message::Escape),
+            iced::event::listen_with(|event, _, _| {
+                matches!(
+                    event,
+                    iced::Event::Keyboard(keyboard::Event::KeyPressed { .. })
+                )
+                .then_some(Message::WorkDrag(allocation_drag::Event::KeyboardBoundary))
+            }),
+            behavior::creation::subscription(
+                self.behavior.creation.has_pending() || self.behavior.source_active(),
+            )
+            .map(|()| Message::Escape),
             iced::event::listen_with(|event, status, _| {
+                if matches!(event, iced::Event::Window(window::Event::Unfocused)) {
+                    return Some(Message::WorkDrag(allocation_drag::Event::Unfocused));
+                }
                 let iced::Event::Keyboard(keyboard::Event::KeyPressed {
                     key,
                     modifiers: mods,
@@ -1077,6 +1129,116 @@ impl App {
         ])
     }
     pub fn update(&mut self, message: Message) -> Task<Message> {
+        self.allocation_before(&message);
+        if let Message::WorkDrag(event) = message {
+            return self.allocation_event(event);
+        }
+        let allocation_before = self.allocation_boundary();
+        if let Message::BehaviorControl(intent) = message {
+            return self.behavior_control(intent);
+        }
+        let camera = matches!(
+            &message,
+            Message::ScenarioCanvas(crate::behavior::scenario::CanvasEvent::Camera(..))
+                | Message::TopologyCanvas(crate::behavior::topology::CanvasEvent::Camera(..))
+        );
+        let before = self.camera_boundary();
+        let task = self.update_inner(message);
+        if self.allocation_boundary() != allocation_before {
+            self.allocation_retire();
+        }
+        if !camera && self.camera_boundary() != before {
+            self.camera_epoch = self.camera_epoch.wrapping_add(1);
+            self.camera_boundary_epoch = self.canvas_epoch;
+        }
+        task
+    }
+    fn behavior_control(&mut self, intent: behavior::canvas_workspace::Intent) -> Task<Message> {
+        use behavior::canvas_workspace::{self, Event as Camera, Scope};
+        use behavior::scenario::CanvasEvent as Scenario;
+        use behavior::topology::CanvasEvent as Process;
+        if Scope::input_owner(self) != Some(intent.scope) {
+            return Task::none();
+        }
+        let mut message = *intent.message;
+        let scope = intent.scope;
+        let valid_scenario = |c: behavior::scenario::Context| {
+            c.document == scope.document
+                && c.scenario == scope.owner
+                && c.revision == scope.revision
+                && self.camera_toolbar_epoch(c.epoch)
+        };
+        let valid_process = |c: behavior::topology::Context| {
+            c.document == scope.document
+                && c.owner == scope.owner
+                && c.revision == scope.revision
+                && self.camera_toolbar_epoch(c.epoch)
+        };
+        // This whitelist contains only the production presentation controls.
+        // A stamped toolbar cannot smuggle an arbitrary authoring command.
+        match &mut message {
+            Message::ScenarioCanvas(Scenario::Camera(c, lifetime, Camera::Focus))
+                if valid_scenario(*c) && *lifetime == scope.epoch =>
+            {
+                return canvas_workspace::focus_task(scope, Camera::Focus);
+            }
+            Message::TopologyCanvas(Process::Camera(c, lifetime, Camera::Focus))
+                if valid_process(*c) && *lifetime == scope.epoch =>
+            {
+                return canvas_workspace::focus_task(scope, Camera::Focus);
+            }
+            Message::ScenarioCanvas(
+                Scenario::Zoom(c, _)
+                | Scenario::Choose(c, _)
+                | Scenario::Focus(c)
+                | Scenario::Shelf(c, _),
+            ) if valid_scenario(*c) => {
+                c.epoch = self.canvas_epoch;
+            }
+            Message::TopologyCanvas(
+                Process::Zoom(c, _) | Process::Choose(c, _) | Process::Focus(c),
+            ) if valid_process(*c) => {
+                c.epoch = self.canvas_epoch;
+            }
+            Message::Behavior(behavior::Event::Topology(behavior::topology::Event::Shelf(_)))
+                if self.topology_context().is_some() => {}
+            _ => return Task::none(),
+        }
+        let task = self.update(message);
+        // Reapplying Fit or a tool also ends a held gesture. Focus is stamped
+        // after the action, for Iced's final-view ordering.
+        if self.camera_epoch == scope.epoch {
+            self.camera_epoch = self.camera_epoch.wrapping_add(1);
+            self.camera_boundary_epoch = self.canvas_epoch;
+        }
+        let focus = Scope::input_owner(self).map_or_else(Task::none, |scope| {
+            canvas_workspace::focus_task(scope, Camera::ControlFocus(intent.name))
+        });
+        Task::batch([task, focus])
+    }
+    fn camera_toolbar_epoch(&self, epoch: u64) -> bool {
+        epoch >= self.camera_boundary_epoch && epoch <= self.canvas_epoch
+    }
+    fn camera_boundary(&self) -> impl PartialEq + use<> {
+        (
+            self.canvas_epoch,
+            self.canvas_document,
+            self.document.revision(),
+            crate::behavior::selected_owner(self),
+            self.page,
+            self.window_size,
+            crate::behavior::canvas_workspace::keyboard_enabled(self),
+            self.behavior.has_pending(),
+            self.draft_dirty(),
+            self.source_dirty(),
+            self.behavior.topology.camera_boundary(),
+            self.behavior.scenario.camera_boundary(),
+        )
+    }
+    fn update_inner(&mut self, message: Message) -> Task<Message> {
+        if let Some(task) = self.reference_message(&message) {
+            return task;
+        }
         if matches!(&message, Message::Connection(_))
             && self
                 .architecture
@@ -1211,6 +1373,8 @@ impl App {
             }
             if self.delete_pending {
                 self.delete_pending = false;
+                self.delete_target = None;
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
                 return Task::none();
             }
             if self.pending.take().is_some() {
@@ -1245,7 +1409,7 @@ impl App {
                         Message::FilePath(_) | Message::SubmitFile | Message::CancelFile
                     ))
                 || (self.delete_pending
-                    && !matches!(message, Message::ConfirmDelete | Message::CancelDelete))
+                    && !matches!(message, Message::ConfirmDelete(_) | Message::CancelDelete))
                 || (self.pending.is_some()
                     && self.file_prompt.is_none()
                     && !matches!(
@@ -1299,6 +1463,7 @@ impl App {
             self.last_workspace_page = self.page;
         }
         let mut task = self.handle(message);
+        self.reconcile_reference_chooser();
         self.route_state_diagram_workspace();
         if self.page != Page::Home {
             self.last_workspace_page = self.page;
@@ -1366,8 +1531,24 @@ impl App {
                 epoch: self.canvas_epoch,
             })
     }
+    pub(crate) fn scenario_focus_owner(&self) -> Option<crate::behavior::scenario::focus::Stamp> {
+        if self.busy
+            || self.hosted.visible
+            || self.workflow.is_some()
+            || self.architecture.is_some()
+            || self.model_menu.is_some()
+            || self.file_prompt.is_some()
+            || self.delete_pending
+            || self.pending.is_some()
+        {
+            return None;
+        }
+        self.behavior.scenario.focus_stamp(self.scenario_context()?)
+    }
     fn handle(&mut self, message: Message) -> Task<Message> {
         match message {
+            Message::WorkDrag(event) => return self.allocation_event(event),
+            Message::BehaviorControl(intent) => return self.behavior_control(intent),
             Message::Architecture(event) => return self.architecture_event(event),
             Message::Home(event) => return self.home_event(event),
             Message::CheckpointTick => return self.checkpoint_tick(),
@@ -1383,6 +1564,18 @@ impl App {
             Message::ScenarioCanvas(event) => {
                 use crate::behavior::scenario::{self, CanvasEvent};
                 let context = event.context();
+                if let CanvasEvent::FormShown(_, mount) = event {
+                    if self.scenario_context().is_some_and(|current| {
+                        current.document == context.document
+                            && current.scenario == context.scenario
+                            && current.revision == context.revision
+                    }) && self.scenario_focus_owner().is_some()
+                        && self.behavior.scenario.take_form_focus(mount)
+                    {
+                        return scenario::focus::task(self.scenario_focus_owner().unwrap());
+                    }
+                    return Task::none();
+                }
                 if let CanvasEvent::Viewport(_, size) = event {
                     if self.scenario_context().is_some_and(|current| {
                         current.document == context.document
@@ -1407,9 +1600,9 @@ impl App {
                     return Task::none();
                 }
                 if let CanvasEvent::Scrolled(_, area, offset) = event {
-                    // Canvas and outline notifications may come from the
-                    // same frame. Accept both across the first epoch bump,
-                    // while still rejecting another owner/document/revision.
+                    // Details may report more than once in a frame. Accept the
+                    // current owner's passive clamps across an epoch bump while
+                    // still rejecting another document, owner or revision.
                     if self.scenario_context().is_some_and(|current| {
                         current.document == context.document
                             && current.scenario == context.scenario
@@ -1420,6 +1613,49 @@ impl App {
                     }
                     return Task::none();
                 }
+                if let CanvasEvent::Camera(_, lifetime, input) = event {
+                    use crate::behavior::canvas_workspace::{self, Event};
+                    if lifetime != self.camera_epoch
+                        || !self.scenario_context().is_some_and(|c| {
+                            c.document == context.document
+                                && c.scenario == context.scenario
+                                && c.revision == context.revision
+                        })
+                    {
+                        return Task::none();
+                    }
+                    let scope = canvas_workspace::Scope {
+                        document: context.document,
+                        owner: context.scenario,
+                        revision: context.revision,
+                        epoch: lifetime,
+                    };
+                    if self.behavior.has_pending()
+                        || self.draft_dirty()
+                        || self.source_dirty()
+                        || !canvas_workspace::keyboard_enabled(self)
+                    {
+                        return Task::none();
+                    }
+                    match input {
+                        Event::Focus
+                        | Event::Traverse(_)
+                        | Event::ControlFocus(_)
+                        | Event::ToggleFocus
+                        | Event::Leave => {
+                            return canvas_workspace::focus_task(scope, input);
+                        }
+                        Event::CancelGesture => {
+                            self.canvas_epoch = self.canvas_epoch.wrapping_add(1)
+                        }
+                        input => {
+                            if self.behavior.scenario.camera(input) {
+                                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                            }
+                        }
+                    }
+                    return Task::none();
+                }
                 if self.scenario_context() != Some(context) {
                     return Task::none();
                 }
@@ -1433,9 +1669,11 @@ impl App {
                         self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
                     }
                     CanvasEvent::Zoom(_, scale) => {
-                        if self.behavior.scenario.zoom(scale) {
+                        let mut state = std::mem::take(&mut self.behavior.scenario);
+                        if state.camera_zoom(self.project(), context.scenario, scale) {
                             self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
                         }
+                        self.behavior.scenario = state;
                     }
                     CanvasEvent::OpenUse(_, occurrence) => {
                         if self.behavior.has_pending() || self.draft_dirty() || self.source_dirty()
@@ -1526,13 +1764,22 @@ impl App {
                                 ..
                             } => {
                                 let mut state = std::mem::take(&mut self.behavior.scenario);
-                                let result = state.begin_occurrence(
-                                    self.project(),
-                                    context,
-                                    tool,
-                                    slot,
-                                    lifeline,
-                                );
+                                let result = if tool == scenario::Tool::Lifeline {
+                                    state
+                                        .update(
+                                            self.project(),
+                                            scenario::Event::Start(context.scenario, tool),
+                                        )
+                                        .map(|_| ())
+                                } else {
+                                    state.begin_occurrence(
+                                        self.project(),
+                                        context,
+                                        tool,
+                                        slot,
+                                        lifeline,
+                                    )
+                                };
                                 self.behavior.scenario = state;
                                 match result {
                                     Ok(()) => {
@@ -1754,7 +2001,15 @@ impl App {
                 return self.update(Message::Add(child));
             }
             Message::Escape => {
-                if self.behavior.creation.has_pending() {
+                if self.behavior.source_back() {
+                    self.status =
+                        "Returned to the unchanged parent form; no source was created.".into();
+                    return Task::none();
+                }
+                if self.behavior.source_active() {
+                    self.behavior.acknowledge_commit();
+                    self.status = "Behavior form cancelled; no staged source was created.".into();
+                } else if self.behavior.creation.has_pending() {
                     self.behavior.creation.acknowledge_commit();
                     self.status = "Behavior creation cancelled".into();
                 }
@@ -1817,6 +2072,9 @@ impl App {
                         .insert(path, crate::forms::ValueBrowser { scope, page });
                 }
             }
+            Message::FieldReferenceOpen(_) | Message::FieldReferenceEvent(_) => {
+                return Task::none();
+            }
             Message::FieldReferenceBrowse(path, query, page) => {
                 if let Some(draft) = &mut self.draft {
                     let page = if draft
@@ -2057,7 +2315,7 @@ impl App {
                     if let crate::workflow::Workflow::Semantic(state) = &mut workflow {
                         match event {
                             crate::workflow::Event::Semantic(event) => {
-                                state.update(self.project(), event)
+                                state.update(self.project(), *event)
                             }
                             crate::workflow::Event::Apply => {
                                 let focus = state.target(self.project());
@@ -2321,10 +2579,13 @@ impl App {
                     self.status = "Apply or cancel the current draft before starting a new behavior. Your inputs are retained.".into();
                     return Task::none();
                 }
-                if !creating && event.starts_form() && !self.behavior.has_pending() && !self.apply()
+                if (event.starts_form() || (event.is_source() && !event.is_source_back()))
+                    && (self.source_dirty() || self.draft_dirty())
                 {
+                    self.status="Apply or cancel the other editors before starting this form. Your inputs are retained.".into();
                     return Task::none();
                 }
+                let source_was_open = self.behavior.source_open();
                 if event.is_submit() && (self.source_dirty() || self.draft_dirty()) {
                     self.status = "Revert the other drafts before applying the behavior form. Your inputs are retained.".into();
                     return Task::none();
@@ -2342,6 +2603,11 @@ impl App {
                         }
                     }
                     Ok(None) => {
+                        if !source_was_open && self.behavior.source_open() {
+                            return iced::widget::operation::focus(
+                                behavior::source_draft::NAME_INPUT,
+                            );
+                        }
                         if focus_name {
                             return iced::widget::operation::focus(behavior::creation::NAME_INPUT);
                         }
@@ -2521,29 +2787,41 @@ impl App {
                     }
                 }
             }
+            Message::DiagramRemove(intent) => self.remove_from_diagram(intent),
+            Message::DiagramTraverse(back) => {
+                return if back {
+                    iced::widget::operation::focus_previous()
+                } else {
+                    iced::widget::operation::focus_next()
+                };
+            }
             Message::Delete => {
                 if self.selected != self.project().id && self.apply() {
-                    self.delete_pending = true;
+                    self.begin_model_delete(None);
                 }
             }
-            Message::ConfirmDelete => {
-                if !self.delete_pending || self.behavior.has_pending() {
-                    return Task::none();
-                }
+            Message::ConfirmDelete(token) => self.confirm_model_delete(token),
+            Message::CancelDelete => {
                 self.delete_pending = false;
-                self.execute(Command::Delete(self.selected));
+                self.delete_target = None;
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
             }
-            Message::CancelDelete => self.delete_pending = false,
             Message::Undo | Message::Redo => {
                 let redo = matches!(message, Message::Redo);
                 if self.apply() {
-                    if redo {
-                        self.document.redo();
+                    let changed = if redo {
+                        self.document.redo()
                     } else {
-                        self.document.undo();
+                        self.document.undo()
+                    };
+                    if changed {
+                        self.sync();
                     }
-                    self.sync();
-                    self.status = if redo {
+                    self.status = if !changed && redo {
+                        "Nothing to redo"
+                    } else if !changed {
+                        "Nothing to undo"
+                    } else if redo {
                         "Model change redone"
                     } else {
                         "Model change undone"
@@ -2797,11 +3075,17 @@ impl App {
                                     || self.path.as_ref() == Some(&receipt.target)
                                 {
                                     self.path = Some(receipt.target);
+                                    self.document.bind_repair_baseline(disk.reachable_bundle());
                                     self.disk_project = Some(disk);
                                 }
                                 self.status = "Interrupted disk save recovered. Current model and drafts are retained; Save all can be retried.".into();
                             }
                             Err(error) => {
+                                if self.path.is_none()
+                                    || self.path.as_ref() == Some(&receipt.target)
+                                {
+                                    self.document.invalidate_saved_baseline();
+                                }
                                 self.status = format!(
                                     "Disk recovery completed; files could not be reloaded: {error}"
                                 )
@@ -3578,6 +3862,7 @@ impl App {
                 self.canvas_document = Id::new_v4();
                 self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
                 self.path = Some(path);
+                self.document.bind_repair_baseline(disk.reachable_bundle());
                 self.source_workspace = Workspace::new(&disk.bundle, false);
                 self.source_workspace.reachable = disk.reachable.clone();
                 self.show_source_file(false);
@@ -4245,6 +4530,10 @@ fn read_snapshot(path: PathBuf) -> Result<LoadedSnapshot, String> {
 #[path = "app/save_as_tests.rs"]
 mod save_as_tests;
 
+#[cfg(test)]
+#[path = "app/repair_save_state_tests.rs"]
+mod repair_save_state_tests;
+
 #[cfg(test)]
 mod source_project_tests {
     use super::*;

crates/oa-desktop/src/app/allocation_drag.rs

@@ -0,0 +1,601 @@
+//! Allocation work-body input admission. Gesture authority lives here, while
+//! the canvas retains ordered native pointer positions and frozen hit geometry.
+use super::{App, Message, Page};
+use crate::{allocation_drag as plan, route_edit::Context};
+use iced::{Point, Rectangle, Task, Vector};
+use oa_core::{projection::ProjectedView, routing::RoutedView, *};
+use std::{collections::BTreeMap, sync::Arc};
+
+pub const FINISH_EDIT: &str = "Finish or cancel the current edit before selecting or moving work.";
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Stamp {
+    pub context: Context,
+    pub epoch: u64,
+    pub snapshot: usize,
+    pub bounds: Rectangle,
+    pub pan: Vector,
+    pub zoom: f32,
+}
+impl Stamp {
+    pub fn world(self, screen: Point) -> Point {
+        Point::new(
+            (screen.x - self.bounds.x - self.pan.x) / self.zoom,
+            (screen.y - self.bounds.y - self.pan.y) / self.zoom,
+        )
+    }
+    pub fn viewport(self) -> plan::Rect {
+        let p = self.world(Point::new(self.bounds.x, self.bounds.y));
+        plan::Rect {
+            position: Position { x: p.x, y: p.y },
+            size: Size {
+                width: self.bounds.width / self.zoom,
+                height: self.bounds.height / self.zoom,
+            },
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct Target {
+    pub element: Id,
+    pub placement: Id,
+    pub region: Rectangle,
+    pub label: plan::Rect,
+    pub name: String,
+    pub ancestors: Vec<Id>,
+}
+#[derive(Debug, Clone)]
+pub struct Frozen {
+    pub targets: Vec<Target>,
+    cards: Vec<Rectangle>,
+    controls: Vec<Rectangle>,
+    edges: Vec<(Point, Point)>,
+    radius: f32,
+}
+#[derive(Debug, Clone, PartialEq)]
+pub enum Hit {
+    Destination(plan::Destination, Option<usize>),
+    OutsideViewport,
+    Occluded,
+    Ambiguous(Vec<usize>),
+}
+pub fn contains(r: Rectangle, p: Point) -> bool {
+    p.x >= r.x && p.y >= r.y && p.x < r.x + r.width && p.y < r.y + r.height
+}
+impl Frozen {
+    pub fn capture(
+        project: &Project,
+        scope: &plan::Scope,
+        view: &ProjectedView,
+        routed: &RoutedView,
+        zoom: f32,
+    ) -> Self {
+        let mut targets = Vec::new();
+        let mut cards = Vec::new();
+        for n in &view.nodes {
+            if scope.placements.contains_key(&n.id) {
+                continue;
+            }
+            let region = Rectangle::new(
+                Point::new(n.position.x, n.position.y),
+                iced::Size::new(n.size.width, n.size.height),
+            );
+            let Some(e) = project.elements.get(&n.element) else {
+                cards.push(region);
+                continue;
+            };
+            if e.kind().is_performer() && e.layer() == scope.diagram.layer {
+                let mut ancestors = Vec::new();
+                let mut parent = e.parent;
+                while let Some(id) = parent {
+                    if ancestors.contains(&id) {
+                        break;
+                    }
+                    ancestors.push(id);
+                    parent = project.elements.get(&id).and_then(|e| e.parent);
+                }
+                // This is also the exact frozen label painted above the ghost.
+                let name = crate::views::short(
+                    project.named(e.id),
+                    (((region.width - 28.).max(10.) / 10.) as usize).min(34),
+                );
+                let label = plan::Rect {
+                    position: Position {
+                        x: region.x + 10.,
+                        y: region.y + 31.,
+                    },
+                    size: Size {
+                        width: (name.chars().count() as f32 * 10. + 8.)
+                            .min((region.width - 20.).max(1.)),
+                        height: 22.,
+                    },
+                };
+                let collapsed = scope.diagram.nodes[&n.id].collapsed;
+                targets.push(Target {
+                    element: e.id,
+                    placement: n.id,
+                    region: if collapsed {
+                        Rectangle {
+                            height: region.height.min(62.),
+                            ..region
+                        }
+                    } else {
+                        region
+                    },
+                    label,
+                    name,
+                    ancestors,
+                });
+            } else {
+                cards.push(region);
+            }
+        }
+        let radius = (10. / zoom).max(10.);
+        let mut controls: Vec<_> = view
+            .ports
+            .iter()
+            .filter(|port| !scope.placements.contains_key(&port.owner))
+            .map(|port| {
+                Rectangle::new(
+                    Point::new(port.position.x - radius, port.position.y - radius),
+                    iced::Size::new(radius * 2., radius * 2.),
+                )
+            })
+            .collect();
+        let mut edges = Vec::new();
+        for edge in routed.edges.values() {
+            if let Some(relation) = project.relations.get(&edge.id) {
+                for end in routing::association_end_geometry(relation, edge) {
+                    if !end.label.text.is_empty() {
+                        controls.push(Rectangle::new(
+                            Point::new(end.label.bounds.position.x, end.label.bounds.position.y),
+                            iced::Size::new(
+                                end.label.bounds.size.width,
+                                end.label.bounds.size.height,
+                            ),
+                        ));
+                    }
+                }
+            }
+            if !edge.label.text.is_empty() {
+                controls.push(Rectangle::new(
+                    Point::new(edge.label.bounds.position.x, edge.label.bounds.position.y),
+                    iced::Size::new(edge.label.bounds.size.width, edge.label.bounds.size.height),
+                ));
+            }
+            for pin in &edge.pins {
+                controls.push(Rectangle::new(
+                    Point::new(pin.x - 8. / zoom, pin.y - 8. / zoom),
+                    iced::Size::new(16. / zoom, 16. / zoom),
+                ));
+            }
+            for points in edge.points.windows(2) {
+                edges.push((
+                    Point::new(points[0].x, points[0].y),
+                    Point::new(points[1].x, points[1].y),
+                ));
+            }
+        }
+        Self {
+            targets,
+            cards,
+            controls,
+            edges,
+            radius: 6. / zoom,
+        }
+    }
+    pub fn resolve(&self, stamp: Stamp, screen: Option<Point>, arrange: bool) -> Hit {
+        let Some(screen) = screen.filter(|p| contains(stamp.bounds, *p)) else {
+            return Hit::OutsideViewport;
+        };
+        let p = stamp.world(screen);
+        // Drag status lives in the toolbar, outside this actual canvas viewport.
+        if self
+            .controls
+            .iter()
+            .chain(&self.cards)
+            .any(|r| contains(*r, p))
+            || self.edges.iter().any(|(a, b)| {
+                let d = *b - *a;
+                let length = d.x * d.x + d.y * d.y;
+                let t = if length == 0. {
+                    0.
+                } else {
+                    (((p.x - a.x) * d.x + (p.y - a.y) * d.y) / length).clamp(0., 1.)
+                };
+                p.distance(*a + d * t) <= self.radius
+            })
+        {
+            return Hit::Occluded;
+        }
+        if arrange {
+            return Hit::Destination(plan::Destination::LayoutOnly, None);
+        }
+        let hits: Vec<_> = self
+            .targets
+            .iter()
+            .enumerate()
+            .filter(|(_, t)| contains(t.region, p))
+            .map(|(i, _)| i)
+            .collect();
+        for (i, a) in hits.iter().enumerate() {
+            for b in &hits[i + 1..] {
+                let a = &self.targets[*a];
+                let b = &self.targets[*b];
+                if !a.ancestors.contains(&b.element) && !b.ancestors.contains(&a.element) {
+                    return Hit::Ambiguous(hits);
+                }
+            }
+        }
+        match hits
+            .into_iter()
+            .max_by_key(|i| self.targets[*i].ancestors.len())
+        {
+            Some(i) => Hit::Destination(
+                plan::Destination::Performer(self.targets[i].element),
+                Some(i),
+            ),
+            None => Hit::Destination(plan::Destination::OutsidePerformers, None),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct Press {
+    pub stamp: Stamp,
+    pub token: Id,
+    pub start: Point,
+    pub scope: plan::Scope,
+    pub frozen: Frozen,
+    pub arrange: bool,
+}
+#[derive(Debug, Clone)]
+pub enum Event {
+    Press(Arc<Press>),
+    Preview(Stamp, Id, Option<Point>),
+    Release(Stamp, Id, Option<Point>),
+    Refused(u64, String),
+    Cancel(Id),
+    ArrangeNext,
+    Unfocused,
+    KeyboardBoundary,
+}
+pub struct Preview {
+    pub token: Id,
+    pub semantic: Arc<plan::SemanticPlan>,
+    pub placement: plan::PlacementPlan,
+    pub routed: Arc<RoutedView>,
+}
+struct Active {
+    press: Arc<Press>,
+    ids: BTreeMap<Id, Id>,
+    cache: Vec<(
+        plan::Destination,
+        Result<Arc<plan::SemanticPlan>, plan::Refusal>,
+    )>,
+}
+pub struct Feedback {
+    pub press: Arc<Press>,
+    pub targets: Vec<usize>,
+    pub text: String,
+    pub refused: bool,
+}
+#[derive(Default)]
+pub struct State {
+    pub epoch: u64,
+    pub arrange_next: bool,
+    active: Option<Active>,
+    pub preview: Option<Arc<Preview>>,
+    pub feedback: Option<Feedback>,
+}
+#[derive(Clone, Copy)]
+pub struct Capability<'a> {
+    pub state: &'a State,
+    pub clean: bool,
+    pub snapshot: usize,
+}
+impl State {
+    fn retire(&mut self) {
+        self.epoch = self.epoch.wrapping_add(1);
+        self.active = None;
+        self.preview = None;
+        self.feedback = None;
+        self.arrange_next = false;
+    }
+}
+pub fn refusal(r: &plan::Refusal) -> String {
+    match r {
+        plan::Refusal::Ineligible(s) | plan::Refusal::InvalidCandidate(s) | plan::Refusal::LayoutRequired(s) => s.clone(),
+        plan::Refusal::StaleScope => "The view changed. Start this drag again.".into(),
+        plan::Refusal::MixedLayoutRequired => "This work has a distributed or mixed assignment. Drag a specific leaf; arranging this group needs a layout step.".into(),
+        plan::Refusal::RoleExitRequired { message, .. } => message.clone(),
+        plan::Refusal::MissingAllocationId(_) => "Assignment identity expired. Start this drag again.".into(),
+        plan::Refusal::CollateralChangeRequired(records) => format!(
+            "Assignment needs dependent edits to {}. Resolve these before dragging again.",
+            records.iter().map(|r| r.name.as_str()).collect::<Vec<_>>().join(", ")
+        ),
+    }
+}
+impl App {
+    pub fn allocation_drag_clean(&self) -> bool {
+        self.allocation_input_owner()
+            && !self.draft_dirty()
+            && !self.source_dirty()
+            && !self.behavior.has_pending()
+    }
+    pub(crate) fn allocation_input_owner(&self) -> bool {
+        self.page == Page::Diagram
+            && self
+                .active_diagram
+                .and_then(|id| self.project().diagrams.get(&id))
+                .is_some_and(|d| d.projection == ProjectionKind::Allocation)
+            && self.architecture.is_none()
+            && self.connection.is_none()
+            && self.model_menu.is_none()
+            && !self.reference_input_active()
+            && !self.busy
+            && !self.hosted.visible
+            && self.workflow.is_none()
+            && self.pending.is_none()
+            && self.file_prompt.is_none()
+            && !self.delete_pending
+    }
+    pub fn allocation_capability(&self) -> Capability<'_> {
+        Capability {
+            state: &self.allocation_drag,
+            clean: self.allocation_drag_clean(),
+            snapshot: Arc::as_ptr(&self.document.snapshot()) as usize,
+        }
+    }
+    fn allocation_stamp_valid(&self, stamp: Stamp) -> bool {
+        self.allocation_drag_clean()
+            && self.route_context() == Some(stamp.context)
+            && self.allocation_drag.epoch == stamp.epoch
+            && Arc::as_ptr(&self.document.snapshot()) as usize == stamp.snapshot
+            && self.pan == stamp.pan
+            && self.zoom == stamp.zoom
+            && self.canvas_size.is_none_or(|s| s == stamp.bounds.size())
+            && stamp.bounds.width > 0.
+            && stamp.bounds.height > 0.
+    }
+    /// Called before general input dispatch. Even equal-valued actions (Fit,
+    /// Undo/Redo, tool/modal round trips) retire old render-time capabilities.
+    pub(super) fn allocation_before(&mut self, message: &Message) {
+        if !matches!(
+            message,
+            Message::WorkDrag(_)
+                | Message::CheckpointTick
+                | Message::CheckpointWritten(..)
+                | Message::Lint(_)
+                | Message::Linted(..)
+                | Message::CanvasResized(_)
+                | Message::WindowResized(_)
+                | Message::SourceViewport
+        ) {
+            self.allocation_drag.retire();
+        }
+    }
+    pub(super) fn allocation_boundary(&self) -> impl PartialEq + use<> {
+        (
+            self.route_context(),
+            self.pan,
+            self.zoom,
+            self.canvas_size,
+            self.window_size,
+            self.allocation_drag_clean(),
+            Arc::as_ptr(&self.document.snapshot()) as usize,
+        )
+    }
+    pub(super) fn allocation_retire(&mut self) {
+        self.allocation_drag.retire();
+    }
+    fn select_work_clean(&mut self, press: &Press) -> bool {
+        if !self.allocation_stamp_valid(press.stamp) {
+            return false;
+        }
+        self.selected = press.scope.work;
+        self.selected_node = Some(press.scope.placement);
+        self.selected_bend = None;
+        self.refresh_draft();
+        true
+    }
+    pub(super) fn allocation_event(&mut self, event: Event) -> Task<Message> {
+        match event {
+            Event::ArrangeNext => {
+                self.allocation_drag.retire();
+                if self.allocation_drag_clean() {
+                    self.allocation_drag.arrange_next = true;
+                    self.status = "Arrange next drag armed · moves work only · Esc cancels".into();
+                } else {
+                    self.status = FINISH_EDIT.into();
+                }
+            }
+            Event::Unfocused => self.allocation_drag.retire(),
+            Event::KeyboardBoundary => {
+                if self.allocation_drag.active.is_some() {
+                    self.allocation_drag.retire();
+                }
+            }
+            Event::Cancel(token) => {
+                if self
+                    .allocation_drag
+                    .active
+                    .as_ref()
+                    .is_some_and(|a| a.press.token == token)
+                {
+                    self.allocation_drag.retire();
+                    self.status = "Work drag canceled".into();
+                }
+            }
+            Event::Refused(epoch, text) => {
+                if epoch == self.allocation_drag.epoch {
+                    self.allocation_drag.retire();
+                    self.status = text;
+                }
+            }
+            Event::Press(press) => {
+                if self.allocation_drag.active.is_some() {
+                    return Task::none();
+                }
+                if !self.allocation_stamp_valid(press.stamp)
+                    || press.arrange != self.allocation_drag.arrange_next
+                {
+                    self.status = if self.allocation_drag_clean() {
+                        "The view changed. Start this drag again.".into()
+                    } else {
+                        FINISH_EDIT.into()
+                    };
+                    return Task::none();
+                }
+                let checked = plan::capture(
+                    self.project(),
+                    press.scope.diagram.id,
+                    press.scope.work,
+                    press.scope.placement,
+                );
+                if checked.as_ref() != Ok(&press.scope) || !self.select_work_clean(&press) {
+                    self.status = checked
+                        .err()
+                        .as_ref()
+                        .map(refusal)
+                        .unwrap_or_else(|| "The view changed. Start this drag again.".into());
+                    self.allocation_drag.retire();
+                    return Task::none();
+                }
+                let ids = press
+                    .scope
+                    .leaves
+                    .keys()
+                    .map(|id| (*id, Id::new_v4()))
+                    .collect();
+                self.allocation_drag.arrange_next = false;
+                self.allocation_drag.preview = None;
+                self.allocation_drag.feedback = None;
+                self.allocation_drag.active = Some(Active {
+                    press,
+                    ids,
+                    cache: Vec::new(),
+                });
+            }
+            Event::Preview(stamp, token, pointer) => {
+                self.allocation_motion(stamp, token, pointer, false)
+            }
+            Event::Release(stamp, token, pointer) => {
+                self.allocation_motion(stamp, token, pointer, true)
+            }
+        }
+        Task::none()
+    }
+    fn allocation_motion(
+        &mut self,
+        stamp: Stamp,
+        token: Id,
+        pointer: Option<Point>,
+        release: bool,
+    ) {
+        if self
+            .allocation_drag
+            .active
+            .as_ref()
+            .is_none_or(|a| a.press.token != token)
+        {
+            return; // An old packet cannot cancel a newer gesture.
+        }
+        if !self.allocation_stamp_valid(stamp) {
+            self.allocation_drag.retire();
+            self.status = if self.allocation_drag_clean() {
+                "The view changed. Start this drag again.".into()
+            } else {
+                FINISH_EDIT.into()
+            };
+            return;
+        }
+        let Some(mut active) = self.allocation_drag.active.take() else {
+            return;
+        };
+        if active.press.token != token || active.press.stamp != stamp {
+            self.allocation_drag.active = Some(active);
+            return;
+        }
+        let press = active.press.clone();
+        let moved = pointer.is_some_and(|p| p.distance(press.start) > 3.);
+        let hit = press.frozen.resolve(stamp, pointer, press.arrange);
+        let mut targets = Vec::new();
+        let mut preview = None;
+        let result: Result<String, String> = match hit {
+            Hit::OutsideViewport => Err("Work drag canceled outside the canvas.".into()),
+            _ if !moved => Ok("Work selected".into()),
+            Hit::Occluded => Err("Aim at exposed performer space or empty canvas; this card, port, connection or control blocks the drop.".into()),
+            Hit::Ambiguous(indices) => {
+                targets = indices;
+                Err("Two unrelated performers overlap here. Use an exposed region.".into())
+            }
+            Hit::Destination(destination, target) => {
+                targets.extend(target);
+                let semantic = if let Some((_, result)) = active.cache.iter().find(|(d, _)| *d == destination) {
+                    result.clone()
+                } else {
+                    let result = plan::plan_semantics(self.project(), &press.scope, destination, &active.ids).map(Arc::new);
+                    active.cache.push((destination, result.clone()));
+                    result
+                };
+                semantic.map_err(|r| refusal(&r)).and_then(|semantic| {
+                    if stamp.zoom * 16. < 9. {
+                        return Err("Make room or adjust the view, then drag again. Zoom in to read the work and destination.".into());
+                    }
+                    let pointer = pointer.unwrap();
+                    let delta = pointer - press.start;
+                    let original = press.scope.placements[&press.scope.placement].position;
+                    let requested = Position { x: original.x + delta.x / stamp.zoom, y: original.y + delta.y / stamp.zoom };
+                    let presentation = plan::PresentationContext {
+                        viewport: stamp.viewport(), zoom: stamp.zoom,
+                        target: target.map(|i| {
+                            let t = &press.frozen.targets[i];
+                            plan::TargetPresentation { placement: t.placement, label: t.label }
+                        }),
+                    };
+                    let placement = plan::place(&semantic, requested, presentation).map_err(|r| refusal(&r))?;
+                    let label = if semantic.warnings.is_empty() { semantic.label.clone() } else {
+                        format!("{} · {} model warning(s) retained", semantic.label, semantic.warnings.len())
+                    };
+                    if release {
+                        let command = plan::finish(&semantic, self.project(), &placement).map_err(|r| refusal(&r))?;
+                        if let Some(command) = command {
+                            // Bypass applying selectors and unrelated repair helpers. The
+                            // planner's exact Batch enters the authoritative source pipeline.
+                            self.document.execute(command).map_err(|e| format!("{} · retry this drag after correcting the source issue", e))?;
+                            self.sync();
+                            self.selected = press.scope.work;
+                            self.selected_node = Some(press.scope.placement);
+                            self.refresh_draft();
+                        }
+                    } else {
+                        let routed = Arc::new(routing::route_diagram(semantic.project(), &placement.diagram, &placement.view));
+                        preview = Some(Arc::new(Preview { token, semantic, placement, routed }));
+                    }
+                    Ok(label)
+                })
+            }
+        };
+        let refused = result.is_err();
+        let text = result.unwrap_or_else(|text| text);
+        self.status = text.clone();
+        if release {
+            self.allocation_drag.retire();
+        } else {
+            self.allocation_drag.active = Some(active);
+            self.allocation_drag.preview = preview;
+            self.allocation_drag.feedback = Some(Feedback {
+                press,
+                targets,
+                text,
+                refused,
+            });
+        }
+    }
+}
+
+#[cfg(test)]
+#[path = "allocation_drag_tests.rs"]
+mod tests;

crates/oa-desktop/src/app/allocation_drag_full_tree_tests.rs

@@ -0,0 +1,290 @@
+//! Actual App root, retained Iced tree, property widgets and production renderer.
+//! Unlike packet-only tests, these prove the next key still reaches the field.
+use super::*;
+use crate::behavior::canvas_workspace::tests::{Mounted, key};
+use iced::{Event as Input, keyboard};
+
+fn character(text: &str, modifiers: keyboard::Modifiers) -> Input {
+    Input::Keyboard(keyboard::Event::KeyPressed {
+        key: keyboard::Key::Character(text.into()),
+        modified_key: keyboard::Key::Character(text.into()),
+        physical_key: keyboard::key::Physical::Code(keyboard::key::Code::KeyA),
+        location: keyboard::Location::Standard,
+        modifiers,
+        text: Some(text.into()),
+        repeat: false,
+    })
+}
+async fn mount() -> (Fixture, Mounted) {
+    let mut f = fixture(Layer::Oa);
+    f.app.window_size = iced::Size::new(2000., 1400.);
+    let _ = f.app.update(Message::Select(f.work));
+    let mut mounted = Mounted::new(&mut f.app).await;
+    // First sensor measurement intentionally Fits; now use a fixed known camera.
+    f.app.zoom = 1.;
+    f.app.pan = Vector::ZERO;
+    f.app.fit_to_view = false;
+    mounted.settle(&mut f.app).await;
+    (f, mounted)
+}
+fn canvas_bounds(mounted: &mut Mounted, app: &App) -> Rectangle {
+    mounted
+        .geometry(app)
+        .bounds(crate::allocation_input::CANVAS_ID)
+}
+fn at(mounted: &mut Mounted, f: &Fixture, world: Position) -> Point {
+    let bounds = canvas_bounds(mounted, &f.app);
+    Point::new(
+        bounds.x + world.x * f.app.zoom + f.app.pan.x,
+        bounds.y + world.y * f.app.zoom + f.app.pan.y,
+    )
+}
+fn name_field(mounted: &mut Mounted, app: &App) -> Rectangle {
+    mounted
+        .geometry(app)
+        .text_inputs
+        .into_iter()
+        .filter(|b| b.x > app.window_size.width - 320.)
+        .min_by(|a, b| a.y.total_cmp(&b.y))
+        .expect("actual inspector Name TextInput")
+}
+fn description_field(mounted: &mut Mounted, app: &App) -> Rectangle {
+    mounted
+        .geometry(app)
+        .focused
+        .into_iter()
+        .map(|(_, bounds, _)| bounds)
+        .filter(|b| b.x > app.window_size.width - 320. && b.height >= 90.)
+        .min_by(|a, b| a.y.total_cmp(&b.y))
+        .expect("actual inspector Description TextEditor")
+}
+fn is_focused(mounted: &mut Mounted, app: &App, field: Rectangle) -> bool {
+    mounted
+        .geometry(app)
+        .focused
+        .iter()
+        .any(|(_, bounds, focused)| *bounds == field && *focused)
+}
+async fn type_key(mounted: &mut Mounted, app: &mut App, text: &str) -> Vec<Message> {
+    mounted
+        .batch(
+            app,
+            &[character(text, keyboard::Modifiers::empty())],
+            mouse::Cursor::Unavailable,
+        )
+        .await
+}
+async fn refused_click_keeps_field(mounted: &mut Mounted, f: &mut Fixture, field: Rectangle) {
+    let before = f.app.document.bundle().clone();
+    let selected = (f.app.selected, f.app.selected_node);
+    let point = at(mounted, f, xy(140., 535.));
+    let messages = mounted.click(&mut f.app, point).await;
+    assert!(
+        messages
+            .iter()
+            .any(|m| matches!(m, Message::WorkDrag(Event::Refused(..))))
+    );
+    assert!(!messages.iter().any(|m| matches!(
+        m,
+        Message::Select(_) | Message::SelectNode(_) | Message::MoveNode(..)
+    )));
+    assert_eq!(f.app.document.bundle(), &before);
+    assert_eq!((f.app.selected, f.app.selected_node), selected);
+    assert!(
+        is_focused(mounted, &f.app, field),
+        "refused press must not reach the outside-press unfocus handler"
+    );
+}
+
+#[tokio::test]
+async fn actual_app_tree_dirty_name_retains_focus_and_middle_caret_for_next_key() {
+    let (mut f, mut mounted) = mount().await;
+    let field = name_field(&mut mounted, &f.app);
+    mounted.click(&mut f.app, field.center()).await;
+    mounted
+        .batch(
+            &mut f.app,
+            &[key(keyboard::key::Named::Home)],
+            mouse::Cursor::Unavailable,
+        )
+        .await;
+    type_key(&mut mounted, &mut f.app, "X").await;
+    mounted
+        .batch(
+            &mut f.app,
+            &[key(keyboard::key::Named::ArrowLeft)],
+            mouse::Cursor::Unavailable,
+        )
+        .await;
+    assert_eq!(f.app.draft.as_ref().unwrap().inputs["/name"].raw, "XWork");
+    refused_click_keeps_field(&mut mounted, &mut f, field).await;
+    let messages = type_key(&mut mounted, &mut f.app, "Y").await;
+    assert!(
+        messages
+            .iter()
+            .any(|m| matches!(m, Message::Field(path, _) if path == "/name"))
+    );
+    assert_eq!(f.app.draft.as_ref().unwrap().inputs["/name"].raw, "YXWork");
+    assert!(!f.app.document.can_undo());
+}
+
+#[tokio::test]
+async fn actual_app_tree_dirty_description_retains_focus_and_middle_caret_for_next_key() {
+    let (mut f, mut mounted) = mount().await;
+    let field = description_field(&mut mounted, &f.app);
+    mounted
+        .click(&mut f.app, Point::new(field.x + 16., field.y + 16.))
+        .await;
+    type_key(&mut mounted, &mut f.app, "A").await;
+    type_key(&mut mounted, &mut f.app, "B").await;
+    mounted
+        .batch(
+            &mut f.app,
+            &[key(keyboard::key::Named::ArrowLeft)],
+            mouse::Cursor::Unavailable,
+        )
+        .await;
+    assert_eq!(
+        f.app.draft.as_ref().unwrap().inputs["/description"].raw,
+        "AB"
+    );
+    refused_click_keeps_field(&mut mounted, &mut f, field).await;
+    let messages = type_key(&mut mounted, &mut f.app, "X").await;
+    assert!(
+        messages
+            .iter()
+            .any(|m| matches!(m, Message::FieldText(path, _) if path == "/description"))
+    );
+    assert_eq!(
+        f.app.draft.as_ref().unwrap().inputs["/description"].raw,
+        "AXB"
+    );
+    assert!(!f.app.document.can_undo());
+}
+
+#[tokio::test]
+async fn actual_keyboard_arrange_shortcut_consumes_once_escape_cancels_and_dirty_owner_refuses() {
+    let (mut f, mut mounted) = mount().await;
+    let shortcut = character("a", keyboard::Modifiers::ALT);
+    let messages = mounted
+        .batch(&mut f.app, &[shortcut.clone()], mouse::Cursor::Unavailable)
+        .await;
+    assert!(
+        messages
+            .iter()
+            .any(|m| matches!(m, Message::WorkDrag(Event::ArrangeNext)))
+    );
+    assert!(f.app.allocation_drag.arrange_next);
+    mounted
+        .batch(
+            &mut f.app,
+            &[key(keyboard::key::Named::Escape)],
+            mouse::Cursor::Unavailable,
+        )
+        .await;
+    assert!(!f.app.allocation_drag.arrange_next);
+    mounted
+        .batch(&mut f.app, &[shortcut.clone()], mouse::Cursor::Unavailable)
+        .await;
+    let from = at(&mut mounted, &f, xy(140., 535.));
+    let to = from + Vector::new(30., 0.);
+    let messages = mounted
+        .batch(
+            &mut f.app,
+            &[
+                Input::Mouse(mouse::Event::CursorMoved { position: from }),
+                Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                Input::Mouse(mouse::Event::CursorMoved { position: to }),
+                Input::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)),
+            ],
+            mouse::Cursor::Available(to),
+        )
+        .await;
+    assert!(
+        messages
+            .iter()
+            .any(|m| matches!(m, Message::WorkDrag(Event::Press(p)) if p.arrange))
+    );
+    assert!(!f.app.allocation_drag.arrange_next);
+    assert_eq!(f.app.document.revision(), 1, "{}", f.app.status);
+    assert!(f.app.project().relations.is_empty());
+    let field = name_field(&mut mounted, &f.app);
+    mounted.click(&mut f.app, field.center()).await;
+    type_key(&mut mounted, &mut f.app, "X").await;
+    let raw = f.app.draft.as_ref().unwrap().inputs["/name"].raw.clone();
+    let before = f.app.document.bundle().clone();
+    mounted
+        .batch(&mut f.app, &[shortcut], mouse::Cursor::Unavailable)
+        .await;
+    assert!(!f.app.allocation_drag.arrange_next);
+    assert_eq!(f.app.status, FINISH_EDIT);
+    assert!(is_focused(&mut mounted, &f.app, field));
+    assert_eq!(f.app.draft.as_ref().unwrap().inputs["/name"].raw, raw);
+    assert_eq!(f.app.document.bundle(), &before);
+}
+
+fn canvas_pixels(pixels: &[u8], width: usize, canvas: Rectangle) -> Vec<u8> {
+    let x = canvas.x.ceil() as usize;
+    let y = canvas.y.ceil() as usize;
+    let right = (canvas.x + canvas.width).floor() as usize;
+    let bottom = (canvas.y + canvas.height).floor() as usize;
+    (y..bottom)
+        .flat_map(|row| {
+            pixels[(row * width + x) * 4..(row * width + right) * 4]
+                .iter()
+                .copied()
+        })
+        .collect()
+}
+
+#[tokio::test]
+async fn actual_rendered_canvas_pixels_do_not_change_when_toolbar_feedback_text_changes() {
+    let (mut f, mut mounted) = mount().await;
+    let mut project = f.app.project().clone();
+    let target = project
+        .diagrams
+        .get_mut(&f.diagram)
+        .unwrap()
+        .nodes
+        .values_mut()
+        .find(|n| n.element == f.a)
+        .unwrap();
+    target.position.y = -41.;
+    target.size.height = 300.;
+    replace(&mut f, project);
+    f.app.zoom = 0.75;
+    f.app.pan = Vector::new(15., 15.);
+    let from = at(&mut mounted, &f, xy(140., 535.));
+    let to = at(&mut mounted, &f, xy(200., 80.));
+    mounted
+        .batch(
+            &mut f.app,
+            &[
+                Input::Mouse(mouse::Event::CursorMoved { position: from }),
+                Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                Input::Mouse(mouse::Event::CursorMoved { position: to }),
+            ],
+            mouse::Cursor::Available(to),
+        )
+        .await;
+    let feedback = f
+        .app
+        .allocation_drag
+        .feedback
+        .as_ref()
+        .expect("active frozen destination");
+    assert!(!feedback.refused, "{}", feedback.text);
+    let target = &feedback.press.frozen.targets[feedback.targets[0]];
+    assert!(target.label.position.y * f.app.zoom + f.app.pan.y < 14.);
+    let canvas = canvas_bounds(&mut mounted, &f.app);
+    let first = mounted.pixels(&f.app);
+    f.app.allocation_drag.feedback.as_mut().unwrap().text =
+        "Very different drag status, retained outside the readable canvas. ".repeat(10);
+    let second = mounted.pixels(&f.app);
+    assert_ne!(first, second, "the actual toolbar status changes");
+    assert_eq!(
+        canvas_pixels(&first, f.app.window_size.width as usize, canvas),
+        canvas_pixels(&second, f.app.window_size.width as usize, canvas),
+        "status must not obscure any candidate header or frozen target label"
+    );
+}

crates/oa-desktop/src/app/architecture_authoring/tests.rs

@@ -77,6 +77,7 @@ fn architecture_f2_routes_selected_node_to_inline_rename_and_exact_undo() {
         editable: true,
         placing: false,
         connection: None,
+        allocation: None,
     };
     let mut state = crate::diagram::State::default();
     let key = CanvasEvent::Keyboard(keyboard::Event::KeyPressed {

crates/oa-desktop/src/app/architecture_authoring_tests.rs

@@ -232,6 +232,7 @@ fn architecture_canvas_left_click_uses_world_coordinate_once_at_zoom_and_pan() {
         editable: true,
         placing: true,
         connection: None,
+        allocation: None,
     };
     let mut state = crate::diagram::State::default();
     let action = canvas
@@ -306,6 +307,7 @@ fn architecture_f2_rename_preserves_identity_placement_and_atomic_history() {
         editable: true,
         placing: false,
         connection: None,
+        allocation: None,
     };
     let bounds = iced::Rectangle::with_size(iced::Size::new(800., 600.));
     let cursor = mouse::Cursor::Available(iced::Point::new(500., 400.));

crates/oa-desktop/src/app/behavior_lifecycle_tests.rs

@@ -291,7 +291,7 @@ fn pending_behavior_blocks_navigation_property_edits_and_model_history() {
         Message::BrowseGroup(crate::explorer::Group::Work),
         Message::Field("/name".into(), "Overwrite properties".into()),
         Message::Command(Command::Rename(fixture.source, "Overwrite model".into())),
-        Message::ConfirmDelete,
+        Message::ConfirmDelete(0),
         Message::Undo,
         Message::Redo,
         Message::ShortcutUndo(false),

crates/oa-desktop/src/app/checkpoints.rs

@@ -214,6 +214,11 @@ impl App {
             .is_some_and(architecture_authoring::State::inline)
         {
             Task::batch([lint, iced::widget::operation::focus("architecture-name")])
+        } else if self.page == Page::Behavior && self.behavior.source_open() {
+            Task::batch([
+                lint,
+                iced::widget::operation::focus(behavior::source_draft::NAME_INPUT),
+            ])
         } else if self.page == Page::Behavior && self.behavior.creation.created().is_some() {
             Task::batch([
                 lint,

crates/oa-desktop/src/app/diagram_removal.rs

@@ -0,0 +1,152 @@
+//! Captured diagram removal and model-confirmation lifetimes.
+use super::*;
+use crate::{model_menu, route_edit::Context};
+
+#[derive(Debug, Clone)]
+pub struct Intent {
+    pub context: Context,
+    pub object: Id,
+    pub placement: Option<Id>,
+    pub model: bool,
+}
+
+pub struct Confirmation {
+    pub snapshot: model_menu::Opened,
+    pub selection: Id,
+    pub placement: Option<Id>,
+}
+
+pub fn enabled(app: &App) -> bool {
+    crate::behavior::canvas_workspace::keyboard_enabled(app)
+        && !app.draft_dirty()
+        && !app.source_dirty()
+        && !app.behavior.has_pending()
+        && app
+            .architecture
+            .as_ref()
+            .is_none_or(|state| !state.inline())
+}
+
+impl App {
+    pub(super) fn remove_from_diagram(&mut self, intent: Intent) {
+        if !enabled(self) || self.connection.is_some() || self.selected_bend.is_some() {
+            return;
+        }
+        let current = match self.page {
+            Page::Diagram if self.architecture.as_ref().is_none_or(|s| !s.saved.placing) => {
+                self.route_context()
+            }
+            Page::Behavior
+                if self.behavior.diagram.tool == crate::behavior::state_edit::Tool::Select =>
+            {
+                self.state_context()
+            }
+            _ => None,
+        };
+        if current != Some(intent.context) || self.selected != intent.object {
+            return;
+        }
+        let view = projection::project_view(self.project(), intent.context.diagram);
+        let placement = if self.page == Page::Behavior {
+            self.behavior.diagram.placement
+        } else {
+            self.selected_node
+        };
+        if intent.placement != placement || intent.object == intent.context.diagram {
+            return;
+        }
+        let visible = if let Some(id) = intent.placement {
+            self.project().diagrams[&intent.context.diagram]
+                .nodes
+                .get(&id)
+                .is_some_and(|node| node.element == intent.object)
+                && view
+                    .nodes
+                    .iter()
+                    .any(|node| node.id == id && node.element == intent.object)
+        } else {
+            view.edges.iter().any(|edge| edge.id == intent.object)
+                || view.ports.iter().any(|port| port.element == intent.object)
+        };
+        if !visible {
+            return;
+        }
+        if !intent.model
+            && let Some(placement) = intent.placement
+        {
+            if self.execute(Command::Delete(placement)) {
+                self.selected_node = None;
+                self.behavior.diagram.placement = None;
+                self.selected_bend = None;
+                self.status = "Hidden from this diagram · Model element preserved · Undo restores the placement".into();
+            }
+        } else {
+            self.begin_model_delete(Some(intent.context));
+        }
+    }
+
+    pub(super) fn begin_model_delete(&mut self, canvas: Option<Context>) {
+        if self.selected == self.project().id || self.behavior.has_pending() {
+            return;
+        }
+        let mut request = model_menu::Request::object(self.selected, iced::Point::ORIGIN);
+        request.canvas = canvas;
+        request.placement = if self.page == Page::Behavior {
+            self.behavior.diagram.placement
+        } else {
+            self.selected_node
+        };
+        // Opening a modal retires any pending canvas intent before capturing
+        // the confirmation; every new dialog receives its own replay token.
+        self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        if canvas.is_some() {
+            request.canvas = if self.page == Page::Behavior {
+                self.state_context()
+            } else {
+                self.route_context()
+            };
+        }
+        self.menu_sequence = self.menu_sequence.wrapping_add(1);
+        self.delete_target =
+            model_menu::Opened::new(self, request, self.menu_sequence).map(|snapshot| {
+                Confirmation {
+                    snapshot,
+                    selection: self.selected,
+                    placement: if self.page == Page::Behavior {
+                        self.behavior.diagram.placement
+                    } else {
+                        self.selected_node
+                    },
+                }
+            });
+        self.delete_pending = self.delete_target.is_some();
+    }
+
+    pub(super) fn confirm_model_delete(&mut self, token: u64) {
+        let Some(target) = self.delete_target.as_ref() else {
+            return;
+        };
+        if target.snapshot.token != token {
+            return;
+        }
+        let valid = self.delete_pending
+            && target.snapshot.valid(self)
+            && target.selection == self.selected
+            && target.placement
+                == if self.page == Page::Behavior {
+                    self.behavior.diagram.placement
+                } else {
+                    self.selected_node
+                }
+            && !self.behavior.has_pending()
+            && !self.source_dirty()
+            && !self.draft_dirty();
+        let id = target.snapshot.request.object;
+        self.delete_pending = false;
+        self.delete_target = None;
+        self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+        if valid {
+            self.execute(Command::Delete(id));
+        }
+    }
+}

crates/oa-desktop/src/app/diagram_removal_tests.rs

@@ -0,0 +1,681 @@
+//! Real App tree regression tests; no private canvas focus or gesture seeding.
+use super::*;
+use crate::behavior::canvas_workspace::tests::{Mounted, key};
+use iced::advanced::widget::{Operation, operation};
+use iced::{Event as Input, Point, Rectangle, Size, Vector, keyboard, mouse};
+
+struct Fixture {
+    app: App,
+    object: Id,
+    node: Id,
+    other: Id,
+    diagram: Id,
+    copy: Id,
+}
+fn fixture(layer: Layer) -> Fixture {
+    let mut p = Project::empty();
+    let kind = if layer == Layer::Oa {
+        Kind::Entity
+    } else {
+        Kind::System
+    };
+    let object = p.add_element(kind, layer, "Target", None).unwrap();
+    let other = p
+        .add_element(
+            if layer == Layer::Oa {
+                Kind::Actor
+            } else {
+                Kind::SystemActor
+            },
+            layer,
+            "Other",
+            None,
+        )
+        .unwrap();
+    let diagram = p.ensure_diagram(layer);
+    p.diagrams.get_mut(&diagram).unwrap().projection = ProjectionKind::Overview;
+    let node = p.place(diagram, object, Position { x: 80., y: 80. });
+    p.place(diagram, other, Position { x: 500., y: 80. });
+    let mut second = p.diagrams[&diagram].clone();
+    second.id = Id::new_v4();
+    second.name = "Other diagram".into();
+    second.alias = "other_diagram".into();
+    second.nodes.clear();
+    second.routes.clear();
+    let copy = second.id;
+    p.diagrams.insert(copy, second);
+    p.place(copy, object, Position { x: 70., y: 70. });
+    let mut app = App::with_project(p);
+    app.page = Page::Diagram;
+    app.layer = layer;
+    app.active_diagram = Some(diagram);
+    app.window_size = Size::new(2000., 1400.);
+    Fixture {
+        app,
+        object,
+        node,
+        other,
+        diagram,
+        copy,
+    }
+}
+async fn mount(layer: Layer) -> (Fixture, Mounted) {
+    let mut f = fixture(layer);
+    let mut mounted = Mounted::new(&mut f.app).await;
+    f.app.zoom = 1.;
+    f.app.pan = Vector::ZERO;
+    f.app.fit_to_view = false;
+    mounted.settle(&mut f.app).await;
+    select(&mut mounted, &mut f).await;
+    (f, mounted)
+}
+async fn select(mounted: &mut Mounted, f: &mut Fixture) {
+    let bounds = mounted
+        .geometry(&f.app)
+        .bounds(crate::allocation_input::CANVAS_ID);
+    let node = projection::project_view(f.app.project(), f.diagram)
+        .nodes
+        .into_iter()
+        .find(|node| node.id == f.node)
+        .unwrap();
+    let point = Point::new(
+        bounds.x + (node.position.x + 40.) * f.app.zoom + f.app.pan.x,
+        bounds.y + (node.position.y + 35.) * f.app.zoom + f.app.pan.y,
+    );
+    mounted.click(&mut f.app, point).await;
+    assert_eq!(f.app.selected, f.object);
+    assert_eq!(f.app.selected_node, Some(f.node));
+}
+fn modified(named: keyboard::key::Named, modifiers: keyboard::Modifiers) -> Input {
+    let mut input = key(named);
+    if let Input::Keyboard(keyboard::Event::KeyPressed {
+        modifiers: value, ..
+    }) = &mut input
+    {
+        *value = modifiers;
+    }
+    input
+}
+async fn delete(mounted: &mut Mounted, app: &mut App, shift: bool) -> Vec<Message> {
+    mounted
+        .batch(
+            app,
+            &[modified(
+                keyboard::key::Named::Delete,
+                if shift {
+                    keyboard::Modifiers::SHIFT
+                } else {
+                    keyboard::Modifiers::empty()
+                },
+            )],
+            mouse::Cursor::Unavailable,
+        )
+        .await
+}
+fn consistent(app: &App) {
+    assert_eq!(
+        source_project::compile_bundle(app.document.bundle(), LIMITS)
+            .unwrap()
+            .decoded
+            .project,
+        *app.project()
+    );
+    assert_eq!(
+        source_workspace::reachable(&app.source_workspace.bundle()).unwrap(),
+        *app.document.bundle()
+    );
+}
+
+#[tokio::test]
+async fn mounted_oa_sa_delete_hides_exact_placement_and_round_trips_source_and_model() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let (mut f, mut mounted) = mount(layer).await;
+        let before = f.app.document.snapshot();
+        let messages = delete(&mut mounted, &mut f.app, false).await;
+        assert!(
+            messages
+                .iter()
+                .any(|message| matches!(message, Message::DiagramRemove(_)))
+        );
+        assert!(f.app.project().contains(f.object));
+        assert!(
+            !f.app.project().diagrams[&f.diagram]
+                .nodes
+                .contains_key(&f.node)
+        );
+        assert!(
+            f.app.project().diagrams[&f.copy]
+                .nodes
+                .values()
+                .any(|node| node.element == f.object)
+        );
+        assert!(!f.app.delete_pending);
+        consistent(&f.app);
+        let after = f.app.document.snapshot();
+        let task = f.app.update(Message::Undo);
+        mounted.perform(&mut f.app, task).await;
+        assert_eq!(f.app.project(), &before.decoded.project);
+        assert_eq!(f.app.document.bundle(), &before.bundle);
+        assert!(!f.app.document.can_undo(), "one removal, one undo unit");
+        let task = f.app.update(Message::Redo);
+        mounted.perform(&mut f.app, task).await;
+        assert_eq!(f.app.project(), &after.decoded.project);
+        assert_eq!(f.app.document.bundle(), &after.bundle);
+        consistent(&f.app);
+    }
+}
+
+#[tokio::test]
+async fn mounted_shift_delete_captures_target_cancel_escape_and_confirmation_replay() {
+    let (mut f, mut mounted) = mount(Layer::Oa).await;
+    let before = f.app.document.snapshot();
+    delete(&mut mounted, &mut f.app, true).await;
+    let target = f.app.delete_target.as_ref().unwrap();
+    assert_eq!(target.snapshot.request.object, f.object);
+    let stale_token = target.snapshot.token;
+    let task = f.app.update(Message::CancelDelete);
+    mounted.perform(&mut f.app, task).await;
+    let task = f.app.update(Message::ConfirmDelete(stale_token));
+    mounted.perform(&mut f.app, task).await;
+    assert_eq!(f.app.document.bundle(), &before.bundle);
+    select(&mut mounted, &mut f).await;
+    delete(&mut mounted, &mut f.app, true).await;
+    let token = f.app.delete_target.as_ref().unwrap().snapshot.token;
+    let task = f.app.update(Message::ConfirmDelete(stale_token));
+    mounted.perform(&mut f.app, task).await;
+    assert!(
+        f.app.delete_pending,
+        "old dialog must not accept a new confirmation"
+    );
+    let task = f.app.update(Message::ConfirmDelete(token));
+    mounted.perform(&mut f.app, task).await;
+    assert!(!f.app.project().contains(f.object));
+    assert!(f.app.project().contains(f.other));
+    consistent(&f.app);
+    let task = f.app.update(Message::Undo);
+    mounted.perform(&mut f.app, task).await;
+    assert_eq!(f.app.document.bundle(), &before.bundle);
+    select(&mut mounted, &mut f).await;
+    delete(&mut mounted, &mut f.app, true).await;
+    let task = f.app.update(Message::Escape);
+    mounted.perform(&mut f.app, task).await;
+    assert!(!f.app.delete_pending);
+    assert!(f.app.delete_target.is_none());
+    assert_eq!(f.app.document.bundle(), &before.bundle);
+}
+
+struct FocusField(Rectangle);
+impl Operation for FocusField {
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        visit(self);
+    }
+    fn focusable(
+        &mut self,
+        _: Option<&iced::advanced::widget::Id>,
+        bounds: Rectangle,
+        state: &mut dyn operation::Focusable,
+    ) {
+        if bounds == self.0 {
+            state.focus();
+        } else {
+            state.unfocus();
+        }
+    }
+}
+fn name_field(mounted: &mut Mounted, app: &App) -> Rectangle {
+    mounted
+        .geometry(app)
+        .text_inputs
+        .into_iter()
+        .filter(|bounds| bounds.x > app.window_size.width - 320.)
+        .min_by(|a, b| a.y.total_cmp(&b.y))
+        .unwrap()
+}
+
+#[tokio::test]
+async fn mounted_clean_text_programmatic_focus_and_tab_remove_canvas_keyboard_ownership() {
+    for programmatic in [true, false] {
+        let (mut f, mut mounted) = mount(Layer::Oa).await;
+        let before = f.app.document.snapshot();
+        let field = name_field(&mut mounted, &f.app);
+        if programmatic {
+            mounted.operate(&f.app, &mut FocusField(field));
+        } else {
+            let messages = mounted
+                .batch(
+                    &mut f.app,
+                    &[
+                        key(keyboard::key::Named::Tab),
+                        key(keyboard::key::Named::Delete),
+                    ],
+                    mouse::Cursor::Unavailable,
+                )
+                .await;
+            assert!(
+                !messages
+                    .iter()
+                    .any(|message| matches!(message, Message::DiagramRemove(_))),
+                "Tab retires canvas admission before its queued focus operation runs"
+            );
+        }
+        let geometry = mounted.geometry(&f.app);
+        assert!(
+            geometry
+                .focused
+                .iter()
+                .any(|(_, bounds, focused)| *bounds == field && *focused),
+            "clean Inspector receives real focus"
+        );
+        assert!(!f.app.draft_dirty());
+        assert!(
+            delete(&mut mounted, &mut f.app, true)
+                .await
+                .iter()
+                .all(|message| !matches!(message, Message::DiagramRemove(_)))
+        );
+        assert!(!f.app.delete_pending);
+        mounted
+            .batch(
+                &mut f.app,
+                &[key(keyboard::key::Named::Home)],
+                mouse::Cursor::Unavailable,
+            )
+            .await;
+        let messages = delete(&mut mounted, &mut f.app, false).await;
+        assert!(
+            messages
+                .iter()
+                .any(|message| matches!(message, Message::Field(path, _) if path == "/name"))
+        );
+        assert_eq!(f.app.draft.as_ref().unwrap().inputs["/name"].raw, "arget");
+        assert_eq!(f.app.document.bundle(), &before.bundle);
+        assert!(f.app.project().contains(f.node));
+        assert!(!f.app.delete_pending);
+    }
+}
+
+#[tokio::test]
+async fn mounted_removal_intents_reject_stale_selection_revision_owner_and_document() {
+    for boundary in 0..5 {
+        let (mut f, mut mounted) = mount(Layer::Oa).await;
+        let messages = mounted.input(
+            &f.app,
+            &[key(keyboard::key::Named::Delete)],
+            mouse::Cursor::Unavailable,
+        );
+        let intent = messages
+            .into_iter()
+            .find(|message| matches!(message, Message::DiagramRemove(_)))
+            .unwrap();
+        match boundary {
+            0 => {
+                let _ = f.app.update(Message::Select(f.other));
+            }
+            1 => {
+                f.app.canvas_epoch = f.app.canvas_epoch.wrapping_add(1);
+            }
+            2 => {
+                f.app.active_diagram = Some(f.copy);
+            }
+            3 => {
+                f.app.canvas_document = Id::new_v4();
+            }
+            _ => {
+                let _ = f
+                    .app
+                    .update(Message::Command(Command::Rename(f.other, "Renamed".into())));
+            }
+        }
+        let before = f.app.document.snapshot();
+        let task = f.app.update(intent);
+        mounted.perform(&mut f.app, task).await;
+        assert_eq!(f.app.document.bundle(), &before.bundle);
+        assert!(f.app.project().contains(f.node));
+        assert!(!f.app.delete_pending);
+    }
+}
+
+#[tokio::test]
+async fn mounted_window_modal_dirty_and_modifier_boundaries_retire_delete_focus() {
+    for boundary in 0..5 {
+        let (mut f, mut mounted) = mount(Layer::Oa).await;
+        let before = f.app.document.snapshot();
+        match boundary {
+            0 => {
+                mounted
+                    .batch(
+                        &mut f.app,
+                        &[Input::Window(iced::window::Event::Unfocused)],
+                        mouse::Cursor::Unavailable,
+                    )
+                    .await;
+            }
+            1 => {
+                let _ = f.app.update(Message::Menu(crate::model_menu::Event::Open(
+                    crate::model_menu::Request::object(f.object, Point::ORIGIN),
+                )));
+                mounted.settle(&mut f.app).await;
+                let _ = f.app.update(Message::Menu(crate::model_menu::Event::Close));
+            }
+            2 => {
+                let _ = f.app.update(Message::Field("/name".into(), "Dirty".into()));
+            }
+            3 => {
+                let _ = f.app.update(Message::Delete);
+            }
+            _ => {
+                f.app.canvas_epoch = f.app.canvas_epoch.wrapping_add(1);
+            }
+        }
+        delete(&mut mounted, &mut f.app, false).await;
+        assert_eq!(f.app.document.bundle(), &before.bundle);
+        assert!(f.app.project().contains(f.node));
+    }
+    let (mut f, mut mounted) = mount(Layer::Oa).await;
+    let before = f.app.document.snapshot();
+    mounted
+        .batch(
+            &mut f.app,
+            &[modified(
+                keyboard::key::Named::Delete,
+                keyboard::Modifiers::CTRL,
+            )],
+            mouse::Cursor::Unavailable,
+        )
+        .await;
+    assert_eq!(f.app.document.bundle(), &before.bundle);
+    assert!(!f.app.delete_pending);
+    // Refusal is temporary: a fresh live canvas click owns Delete again.
+    select(&mut mounted, &mut f).await;
+    delete(&mut mounted, &mut f.app, false).await;
+    assert!(!f.app.project().contains(f.node));
+}
+
+#[tokio::test]
+async fn mounted_bend_delete_has_priority_and_semantic_edge_delete_is_confirmed() {
+    let mut p = Project::empty();
+    let a = p.add(Kind::Activity, "Send", 0., 0.);
+    let b = p.add(Kind::Activity, "Receive", 650., 0.);
+    let edge = p.relate(RelationKind::Interaction, "Report", a, b);
+    let diagram = p.ensure_diagram(Layer::Oa);
+    let p = execute_batch(
+        &p,
+        &[Command::SetEdgeRoute {
+            diagram,
+            route: EdgeRoute {
+                edge,
+                waypoints: vec![Position { x: 400., y: -100. }],
+                label: None,
+            },
+        }],
+    )
+    .unwrap();
+    let mut app = App::with_project(p);
+    app.page = Page::Diagram;
+    app.active_diagram = Some(diagram);
+    app.window_size = Size::new(2000., 1400.);
+    let _ = app.update(Message::Select(edge));
+    let mut mounted = Mounted::new(&mut app).await;
+    app.zoom = 1.;
+    app.pan = Vector::new(100., 250.);
+    app.fit_to_view = false;
+    mounted.settle(&mut app).await;
+    let bounds = mounted
+        .geometry(&app)
+        .bounds(crate::allocation_input::CANVAS_ID);
+    let pin = Point::new(bounds.x + 500., bounds.y + 150.);
+    mounted.click(&mut app, pin).await;
+    assert_eq!(
+        app.selected_bend,
+        Some((edge, 0)),
+        "real pointer selects route pin"
+    );
+    let before = app.document.snapshot();
+    let messages = delete(&mut mounted, &mut app, false).await;
+    assert!(messages.iter().any(|message| matches!(
+        message,
+        Message::Route(crate::route_edit::Event::RemoveBend)
+    )));
+    assert!(
+        !messages
+            .iter()
+            .any(|message| matches!(message, Message::DiagramRemove(_)))
+    );
+    assert!(app.project().contains(edge) && app.project().contains(a) && app.project().contains(b));
+    assert!(
+        crate::route_edit::stored_route(&app.project().diagrams[&diagram], edge)
+            .waypoints
+            .is_empty()
+    );
+    assert!(!app.delete_pending);
+    consistent(&app);
+    let task = app.update(Message::Undo);
+    mounted.perform(&mut app, task).await;
+    assert_eq!(app.document.bundle(), &before.bundle);
+    // Select a real edge segment away from its handle, then Delete opens the
+    // same semantic confirmation instead of inventing an edge hide operation.
+    let view = projection::project_view(app.project(), diagram);
+    let routed = routing::route_diagram(app.project(), &app.project().diagrams[&diagram], &view);
+    let route = &routed.edges[&edge];
+    let segment = route
+        .points
+        .windows(2)
+        .max_by(|a, b| {
+            let len = |s: &[Position]| (s[1].x - s[0].x).abs() + (s[1].y - s[0].y).abs();
+            len(a).total_cmp(&len(b))
+        })
+        .unwrap();
+    let at = Point::new(
+        bounds.x + (segment[0].x + segment[1].x) / 2. + app.pan.x,
+        bounds.y + (segment[0].y + segment[1].y) / 2. + app.pan.y,
+    );
+    mounted.click(&mut app, at).await;
+    assert_eq!(app.selected, edge);
+    assert!(app.selected_bend.is_none());
+    delete(&mut mounted, &mut app, false).await;
+    assert_eq!(
+        app.delete_target.as_ref().unwrap().snapshot.request.object,
+        edge
+    );
+    assert_eq!(app.document.bundle(), &before.bundle);
+}
+
+#[tokio::test]
+async fn mounted_state_delete_uses_state_placement_and_preserves_architecture_placement() {
+    let mut p = Project::empty();
+    let machine = p
+        .add_element(Kind::StateMachine, Layer::Sa, "Machine", None)
+        .unwrap();
+    let region = p
+        .add_element(Kind::Region, Layer::Sa, "Main", Some(machine))
+        .unwrap();
+    let state = p
+        .add_element(Kind::State, Layer::Sa, "Ready", Some(region))
+        .unwrap();
+    let architecture = p.ensure_diagram(Layer::Sa);
+    let architecture_node = p.place(architecture, state, Position { x: 50., y: 50. });
+    let plan = crate::behavior::state_edit::create_view(&p, machine).unwrap();
+    let diagram = plan.diagram;
+    let p = execute_batch(&p, &[plan.command]).unwrap();
+    let node = p.diagrams[&diagram]
+        .nodes
+        .values()
+        .find(|node| node.element == state)
+        .unwrap()
+        .id;
+    let mut app = App::with_project(p);
+    app.layer = Layer::Sa;
+    app.page = Page::Behavior;
+    app.active_diagram = Some(architecture);
+    app.behavior.active_owner = Some(machine);
+    app.behavior.diagram.diagram = Some(diagram);
+    app.window_size = Size::new(2000., 1400.);
+    let _ = app.update(Message::Select(state));
+    let mut mounted = Mounted::new(&mut app).await;
+    let bounds = mounted
+        .geometry(&app)
+        .focused
+        .into_iter()
+        .find(|(id, _, _)| {
+            id.as_ref() == Some(&iced::advanced::widget::Id::from("diagram-keyboard-owner"))
+        })
+        .unwrap()
+        .1;
+    let projected = projection::project_view(app.project(), diagram)
+        .nodes
+        .into_iter()
+        .find(|n| n.id == node)
+        .unwrap();
+    let at = Point::new(
+        bounds.x
+            + (projected.position.x + 35.) * app.behavior.diagram.zoom
+            + app.behavior.diagram.pan.x,
+        bounds.y
+            + (projected.position.y + 35.) * app.behavior.diagram.zoom
+            + app.behavior.diagram.pan.y,
+    );
+    mounted.click(&mut app, at).await;
+    assert_eq!(app.selected, state);
+    assert_eq!(app.behavior.diagram.placement, Some(node));
+    let before = app.document.snapshot();
+    let messages = delete(&mut mounted, &mut app, false).await;
+    assert!(messages.iter().any(|message| matches!(
+        message,
+        Message::StateDiagram(crate::behavior::state_edit::Event::Remove(_))
+    )));
+    assert!(!app.project().contains(node));
+    assert!(app.project().contains(architecture_node) && app.project().contains(state));
+    consistent(&app);
+    let task = app.update(Message::Undo);
+    mounted.perform(&mut app, task).await;
+    assert_eq!(app.document.bundle(), &before.bundle);
+}
+
+#[tokio::test]
+async fn captured_confirmation_rejects_selection_document_revision_and_placement_changes() {
+    for boundary in 0..5 {
+        let (mut f, mut mounted) = mount(Layer::Oa).await;
+        delete(&mut mounted, &mut f.app, true).await;
+        let token = f.app.delete_target.as_ref().unwrap().snapshot.token;
+        // Model asynchronous adoption / retained stale UI using a changed App
+        // state while preserving the old confirmation payload deliberately.
+        match boundary {
+            0 => {
+                f.app.selected = f.other;
+            }
+            1 => {
+                f.app.canvas_document = Id::new_v4();
+            }
+            2 => {
+                f.app.canvas_epoch = f.app.canvas_epoch.wrapping_add(1);
+            }
+            3 => {
+                f.app.selected_node = None;
+            }
+            _ => {
+                assert!(
+                    f.app
+                        .document
+                        .execute(Command::Rename(f.other, "New revision".into()))
+                        .is_ok()
+                );
+            }
+        }
+        let before = f.app.document.snapshot();
+        let task = f.app.update(Message::ConfirmDelete(token));
+        mounted.perform(&mut f.app, task).await;
+        assert_eq!(f.app.document.bundle(), &before.bundle);
+        assert!(f.app.project().contains(f.object));
+        assert!(!f.app.delete_pending);
+    }
+}
+
+#[tokio::test]
+async fn mounted_programmatic_canvas_entry_needs_no_mouse_focus_boolean() {
+    let mut f = fixture(Layer::Oa);
+    let _ = f.app.update(Message::Select(f.object));
+    let mut mounted = Mounted::new(&mut f.app).await;
+    let task =
+        iced::widget::operation::focus(iced::advanced::widget::Id::from("diagram-keyboard-owner"));
+    mounted.perform(&mut f.app, task).await;
+    let messages = delete(&mut mounted, &mut f.app, false).await;
+    assert!(
+        messages
+            .iter()
+            .any(|message| matches!(message, Message::DiagramRemove(_)))
+    );
+    assert!(!f.app.project().contains(f.node));
+    assert!(f.app.project().contains(f.object));
+}
+
+#[tokio::test]
+async fn mounted_allocation_work_click_then_delete_without_redraw_removes_placement_once() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let mut p = Project::empty();
+        let performer = p
+            .add_element(
+                if layer == Layer::Oa {
+                    Kind::Entity
+                } else {
+                    Kind::System
+                },
+                layer,
+                "Performer",
+                None,
+            )
+            .unwrap();
+        let work = p
+            .add_element(
+                if layer == Layer::Oa {
+                    Kind::Activity
+                } else {
+                    Kind::Function
+                },
+                layer,
+                "Work",
+                None,
+            )
+            .unwrap();
+        let diagram = p.ensure_diagram(layer);
+        p.diagrams.get_mut(&diagram).unwrap().projection = ProjectionKind::Allocation;
+        p.place(diagram, performer, Position { x: 100., y: 100. });
+        let node = p.place(diagram, work, Position { x: 100., y: 500. });
+        let mut app = App::with_project(p);
+        app.page = Page::Diagram;
+        app.layer = layer;
+        app.active_diagram = Some(diagram);
+        app.window_size = Size::new(2000., 1400.);
+        let mut mounted = Mounted::new(&mut app).await;
+        app.zoom = 1.;
+        app.pan = Vector::ZERO;
+        app.fit_to_view = false;
+        mounted.settle(&mut app).await;
+        let bounds = mounted
+            .geometry(&app)
+            .bounds(crate::allocation_input::CANVAS_ID);
+        let point = Point::new(bounds.x + 140., bounds.y + 535.);
+        let messages = mounted.click(&mut app, point).await;
+        assert!(messages.iter().any(|message| matches!(
+            message,
+            Message::WorkDrag(crate::app::allocation_drag::Event::Press(_))
+        )));
+        assert_eq!(app.selected, work);
+        assert_eq!(app.selected_node, Some(node));
+        let before = app.document.snapshot();
+        // Deliberately do not settle/redraw between completed click and key.
+        let messages = delete(&mut mounted, &mut app, false).await;
+        assert!(
+            messages
+                .iter()
+                .any(|message| matches!(message, Message::DiagramRemove(_))),
+            "retired allocation press cannot consume first Delete"
+        );
+        assert!(!app.project().contains(node));
+        assert!(app.project().contains(work) && app.project().contains(performer));
+        consistent(&app);
+        let task = app.update(Message::Undo);
+        mounted.perform(&mut app, task).await;
+        assert_eq!(app.document.bundle(), &before.bundle);
+        assert!(!app.document.can_undo());
+    }
+}

crates/oa-desktop/src/app/process_canvas.rs

@@ -15,18 +15,15 @@ impl App {
             epoch: self.canvas_epoch,
         })
     }
-    pub(super) fn reveal_process_selection(&self) -> Task<Message> {
-        let Some(context) = self.topology_context() else {
-            return Task::none();
-        };
-        let Some(offset) =
-            self.behavior
-                .topology
-                .selection_offset(self.project(), context.owner, self.selected)
-        else {
-            return Task::none();
-        };
-        iced::widget::operation::scroll_to("process-canvas", offset)
+    pub(super) fn reveal_process_selection(&mut self) -> Task<Message> {
+        if let Some(context) = self.topology_context() {
+            let mut state = std::mem::take(&mut self.behavior.topology);
+            if state.reveal_selection(self.project(), context.owner, self.selected) {
+                self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+            }
+            self.behavior.topology = state;
+        }
+        Task::none()
     }
     pub(super) fn edit_process_canvas(&mut self, event: CanvasEvent) -> Task<Message> {
         let context = event.context();
@@ -52,6 +49,47 @@ impl App {
             }
             return Task::none();
         }
+        if let CanvasEvent::Camera(_, lifetime, input) = event {
+            use crate::behavior::canvas_workspace::{self, Event};
+            if lifetime != self.camera_epoch
+                || !self.topology_context().is_some_and(|c| {
+                    c.document == context.document
+                        && c.owner == context.owner
+                        && c.revision == context.revision
+                })
+            {
+                return Task::none();
+            }
+            let scope = canvas_workspace::Scope {
+                document: context.document,
+                owner: context.owner,
+                revision: context.revision,
+                epoch: lifetime,
+            };
+            if self.behavior.has_pending()
+                || self.draft_dirty()
+                || self.source_dirty()
+                || !canvas_workspace::keyboard_enabled(self)
+            {
+                return Task::none();
+            }
+            match input {
+                Event::Focus
+                | Event::Traverse(_)
+                | Event::ControlFocus(_)
+                | Event::ToggleFocus
+                | Event::Leave => {
+                    return canvas_workspace::focus_task(scope, input);
+                }
+                Event::CancelGesture => self.canvas_epoch = self.canvas_epoch.wrapping_add(1),
+                input => {
+                    if self.behavior.topology.camera(input) {
+                        self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
+                    }
+                }
+            }
+            return Task::none();
+        }
         if self.topology_context() != Some(context) {
             return Task::none();
         }
@@ -81,6 +119,7 @@ impl App {
                             .first()
                             .copied()
                             .unwrap_or(endpoint.occurrence),
+                        resolved.defining_sequence,
                     );
                     self.behavior.active_owner = Some(resolved.defining_sequence);
                     self.select(endpoint.occurrence);
@@ -118,14 +157,18 @@ impl App {
                 }
             }
             CanvasEvent::Choose(_, tool) => {
-                if self.behavior.has_pending() || !self.apply() {
+                if self.behavior.has_pending() || self.draft_dirty() || self.source_dirty() {
+                    self.status =
+                        "Apply or cancel pending edits before choosing a process tool.".into();
                     return Task::none();
                 }
                 self.behavior.topology.choose(tool);
                 self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
             }
             CanvasEvent::Zoom(_, zoom) => {
-                self.behavior.topology.zoom(zoom);
+                let mut state = std::mem::take(&mut self.behavior.topology);
+                state.camera_zoom(self.project(), context.owner, zoom);
+                self.behavior.topology = state;
                 self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
             }
             CanvasEvent::Expand(_, id) => {
@@ -149,7 +192,9 @@ impl App {
                         .get(&target)
                         .is_some_and(|e| matches!(e.kind(), Kind::Process | Kind::FunctionalChain))
                     {
-                        self.behavior.topology.remember(context.owner, occurrence);
+                        self.behavior
+                            .topology
+                            .remember(context.owner, occurrence, target);
                         self.behavior.active_owner = Some(target);
                     }
                     self.canvas_epoch = self.canvas_epoch.wrapping_add(1);
@@ -524,32 +569,30 @@ mod tests {
         assert!(!app.behavior.has_pending());
     }
     #[test]
-    fn direct_process_app_save_scroll_resize_and_passive_geometry_keep_drafts_and_current_origin() {
+    fn direct_process_app_save_details_resize_and_passive_geometry_keep_drafts_and_camera() {
         let (mut app, f) = setup();
         let context = app.topology_context().unwrap();
+        let _ = app.update(Message::TopologyCanvas(CanvasEvent::Camera(
+            context,
+            app.camera_epoch,
+            behavior::canvas_workspace::Event::Pan(iced::Vector::new(25., 100.)),
+        )));
+        let context = app.topology_context().unwrap();
         let original = app.document.snapshot();
         app.busy = true;
-        for (area, offset) in [
-            (
-                behavior::scenario::ScrollArea::Canvas,
-                iced::Vector::new(25., 100.),
-            ),
-            (
-                behavior::scenario::ScrollArea::Page,
-                iced::Vector::new(0., 40.),
-            ),
-        ] {
-            let _ = app.update(Message::TopologyCanvas(CanvasEvent::Scrolled(
-                context, area, offset,
-            )));
-        }
+        let _ = app.update(Message::TopologyCanvas(CanvasEvent::Scrolled(
+            context,
+            behavior::scenario::ScrollArea::Page,
+            iced::Vector::new(0., 40.),
+        )));
         let _ = app.update(Message::TopologyCanvas(CanvasEvent::Viewport(
             context,
             iced::Size::new(500., 300.),
         )));
+        let camera = app.behavior.topology.camera_boundary();
         assert_eq!(
-            app.behavior.topology.scroll_offset(),
-            iced::Vector::new(25., 140.)
+            app.behavior.topology.details_offset(),
+            iced::Vector::new(0., 40.)
         );
         assert_ne!(app.topology_context(), Some(context));
         assert!(app.busy);
@@ -557,12 +600,12 @@ mod tests {
         stale.document = Id::new_v4();
         let _ = app.update(Message::TopologyCanvas(CanvasEvent::Scrolled(
             stale,
-            behavior::scenario::ScrollArea::Canvas,
+            behavior::scenario::ScrollArea::Page,
             iced::Vector::new(0., 900.),
         )));
         assert_eq!(
-            app.behavior.topology.scroll_offset(),
-            iced::Vector::new(25., 140.)
+            app.behavior.topology.details_offset(),
+            iced::Vector::new(0., 40.)
         );
         let root = PathBuf::from("process-scroll-save-fixture");
         let receipt = FileSnapshot {
@@ -582,6 +625,7 @@ mod tests {
         assert!(!app.busy);
         assert!(!app.document.can_undo());
         assert_eq!(app.project(), &f.p);
+        assert!(app.behavior.topology.camera_boundary() == camera);
         let context = app.topology_context().unwrap();
         let size = app.window_size;
         let _ = app.update(Message::WindowResized(size));

crates/oa-desktop/src/app/reference_authoring.rs

@@ -0,0 +1,304 @@
+//! One transient chooser for the currently mounted Inspector or review field.
+//! Browsing never calls a draft setter or semantic planner.
+use super::{App, Message, Page, Pending};
+use crate::{
+    forms::{
+        Draft,
+        reference_chooser::{self as chooser, Action, Close, Outcome, adapter, trigger},
+    },
+    navigation::InspectorTab,
+    semantic_review::{self, RowAddress, RowEvent},
+    workflow,
+};
+use iced::{Element, Rectangle, Task};
+use oa_core::{FacetSelector, Id, Layer};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+enum Host {
+    Inspector,
+    Review {
+        address: Option<RowAddress>,
+        facet: FacetSelector,
+    },
+}
+impl Host {
+    fn message(&self, event: chooser::Event) -> Message {
+        match self {
+            Self::Inspector => Message::FieldReferenceEvent(event),
+            Self::Review { address, facet } => {
+                Message::Workflow(workflow::Event::semantic(semantic_review::Event::Row {
+                    address: *address,
+                    facet: Some(facet.clone()),
+                    event: RowEvent::ReferenceEvent(event),
+                }))
+            }
+        }
+    }
+}
+struct Opened {
+    host: Host,
+    request: adapter::Open,
+    document_session: Id,
+    page: Page,
+    layer: Layer,
+    chooser: chooser::State,
+}
+#[derive(Default)]
+pub(super) struct State {
+    opened: Option<Opened>,
+}
+
+impl App {
+    pub(crate) fn reference_input_active(&self) -> bool {
+        self.reference_authoring.opened.is_some()
+    }
+
+    fn reference_draft(&self, host: &Host, path: &str) -> Option<&Draft> {
+        match host {
+            Host::Inspector
+                if self.workflow.is_none() && self.inspector_tab == InspectorTab::Properties =>
+            {
+                self.draft.as_ref()
+            }
+            Host::Review { address, facet } => match self.workflow.as_ref()? {
+                workflow::Workflow::Semantic(state) => {
+                    state.reference_draft(self.project(), *address, facet, path)
+                }
+                _ => None,
+            },
+            _ => None,
+        }
+    }
+    fn reference_available(&self) -> bool {
+        !self.busy
+            && !self.hosted.visible
+            && self.architecture.is_none()
+            && self.model_menu.is_none()
+            && self.file_prompt.is_none()
+            && !self.delete_pending
+            && self.pending.is_none()
+            && !self.source_dirty()
+            && !self.behavior.has_pending()
+            && !matches!(self.page, Page::Home | Page::Guide | Page::Text)
+    }
+    fn reference_valid(&self, opened: &Opened) -> bool {
+        self.reference_available()
+            && self.canvas_document == opened.document_session
+            && self.page == opened.page
+            && self.layer == opened.layer
+            && self.document.revision() == opened.chooser.stamp().context.revision
+            && self.project().id == opened.request.document
+            && self
+                .reference_draft(&opened.host, &opened.request.path)
+                .is_some_and(|draft| draft.reference_matches(&opened.request))
+    }
+    pub(super) fn reconcile_reference_chooser(&mut self) {
+        if self
+            .reference_authoring
+            .opened
+            .as_ref()
+            .is_some_and(|opened| !self.reference_valid(opened))
+        {
+            self.reference_authoring
+                .opened
+                .as_mut()
+                .unwrap()
+                .chooser
+                .invalidate();
+            self.reference_authoring.opened = None;
+        }
+    }
+    fn open_reference(&mut self, host: Host, request: adapter::Open) -> Task<Message> {
+        if !self.reference_available() {
+            return Task::none();
+        }
+        let Some(draft) = self.reference_draft(&host, &request.path) else {
+            return Task::none();
+        };
+        let Ok(chooser) =
+            draft.reference_catalog(self.project(), &request, self.document.revision())
+        else {
+            return Task::none();
+        };
+        self.reference_authoring.opened = Some(Opened {
+            host,
+            request,
+            document_session: self.canvas_document,
+            page: self.page,
+            layer: self.layer,
+            chooser,
+        });
+        Task::none()
+    }
+    fn reference_event(&mut self, host: Host, event: chooser::Event) -> Task<Message> {
+        let Some(mut opened) = self.reference_authoring.opened.take() else {
+            return Task::none();
+        };
+        if !self.reference_valid(&opened) {
+            return Task::none();
+        }
+        if opened.host != host {
+            self.reference_authoring.opened = Some(opened);
+            return Task::none();
+        }
+        match opened.chooser.update(event) {
+            Outcome::Ignored | Outcome::Browsed => {
+                self.reference_authoring.opened = Some(opened);
+                Task::none()
+            }
+            Outcome::Closed(reason) => self.reference_focus(
+                &opened,
+                match reason {
+                    Close::Escape => Some(0),
+                    Close::Tab { backwards } => Some(if backwards { -1 } else { 1 }),
+                    Close::Outside | Close::WindowChanged => None,
+                },
+            ),
+            Outcome::Write { context, value } => {
+                let intent = adapter::Set {
+                    context,
+                    generation: opened.request.generation,
+                    value,
+                };
+                let result = match &opened.host {
+                    Host::Inspector => self
+                        .draft
+                        .as_mut()
+                        .ok_or_else(|| "The property editor closed.".to_owned())
+                        .and_then(|draft| draft.reference_set(self.document.project(), &intent)),
+                    Host::Review { address, facet } => match self.workflow.as_mut() {
+                        Some(workflow::Workflow::Semantic(state)) => {
+                            state.set_reference(self.document.project(), *address, facet, intent)
+                        }
+                        _ => Err("The review editor closed.".into()),
+                    },
+                };
+                if let Err(error) = result {
+                    self.status = error;
+                }
+                // A scoped write rotates field generation. The task targets the
+                // newly rendered field, while a later structural edit makes it inert.
+                self.reference_focus(&opened, Some(0))
+            }
+        }
+    }
+    fn reference_focus(&self, opened: &Opened, step: Option<i32>) -> Task<Message> {
+        let Some(step) = step else {
+            return Task::none();
+        };
+        let Some(draft) = self.reference_draft(&opened.host, &opened.request.path) else {
+            return Task::none();
+        };
+        if draft.reference_session() != opened.request.session {
+            return Task::none();
+        }
+        trigger::focus(
+            draft.reference_session(),
+            draft.reference_generation(),
+            &opened.request.path,
+            step,
+        )
+    }
+    /// Called before generic modal dispatch: the review owns a modal, and this
+    /// chooser owns only its active field. All browser events stop here.
+    pub(super) fn reference_message(&mut self, message: &Message) -> Option<Task<Message>> {
+        self.reconcile_reference_chooser();
+        match message {
+            Message::FieldReferenceOpen(request) => {
+                Some(self.open_reference(Host::Inspector, request.clone()))
+            }
+            Message::FieldReferenceEvent(event) => {
+                Some(self.reference_event(Host::Inspector, event.clone()))
+            }
+            Message::Workflow(workflow::Event::Semantic(review_event)) => {
+                let semantic_review::Event::Row {
+                    address,
+                    facet: Some(facet),
+                    event,
+                } = review_event.as_ref()
+                else {
+                    return None;
+                };
+                let host = Host::Review {
+                    address: *address,
+                    facet: facet.clone(),
+                };
+                match event {
+                    RowEvent::ReferenceOpen(request) => {
+                        Some(self.open_reference(host, request.clone()))
+                    }
+                    RowEvent::ReferenceEvent(event) => {
+                        Some(self.reference_event(host, event.clone()))
+                    }
+                    _ => None,
+                }
+            }
+            Message::Escape | Message::Request(Pending::Close(_))
+                if self.reference_authoring.opened.is_some() =>
+            {
+                let opened = self.reference_authoring.opened.as_ref().unwrap();
+                let host = opened.host.clone();
+                let event = opened.chooser.event(Action::Close(Close::Escape));
+                Some(self.reference_event(host, event))
+            }
+            // Global shortcuts are also emitted for keys captured by the search
+            // input. They must not apply drafts, navigate, or undo the model.
+            Message::Save(_)
+            | Message::ShortcutUndo(_)
+            | Message::Request(Pending::Open | Pending::New)
+            | Message::SourceNavigation(_)
+            | Message::Page(Page::Guide)
+                if self.reference_authoring.opened.is_some() =>
+            {
+                Some(Task::none())
+            }
+            _ => None,
+        }
+    }
+    pub(super) fn reference_overlay<
+        'a,
+        R: iced::advanced::text::Renderer<Font = iced::Font> + 'a,
+    >(
+        &'a self,
+        content: Element<'a, Message, iced::Theme, R>,
+    ) -> Element<'a, Message, iced::Theme, R> {
+        let opened = self
+            .reference_authoring
+            .opened
+            .as_ref()
+            .filter(|opened| self.reference_valid(opened));
+        let host = opened
+            .map(|opened| opened.host.clone())
+            .unwrap_or(Host::Inspector);
+        let focus_scope = if self.reference_available() {
+            match self.workflow.as_ref() {
+                None if self.inspector_tab == InspectorTab::Properties => {
+                    self.draft.as_ref().map(|draft| trigger::FormScope {
+                        session: draft.reference_session(),
+                        modal: false,
+                    })
+                }
+                Some(workflow::Workflow::Semantic(state)) => state
+                    .reference_form(self.project())
+                    .map(|draft| trigger::FormScope {
+                        session: draft.reference_session(),
+                        modal: true,
+                    }),
+                _ => None,
+            }
+        } else {
+            None
+        };
+        chooser::widget::Popup::new(
+            content,
+            opened.map(|opened| &opened.chooser),
+            opened.map_or(Rectangle::default(), |opened| opened.request.anchor),
+            move |event| host.message(event),
+        )
+        .focus_scope(focus_scope)
+        .into()
+    }
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/app/reference_authoring/tests.rs

@@ -0,0 +1,586 @@
+use super::*;
+use crate::forms::Draft;
+use oa_core::*;
+use serde_json::{Value, json};
+
+const OWNER: Id = Id::from_u128(100);
+const BASE: u128 = 10_000;
+const PATH: &str = "/body/Oa/Shared/DataType/definition/Record/supertype";
+
+fn element(p: &mut Project, id: Id, kind: Kind, layer: Layer, name: &str, parent: Option<Id>) {
+    let generated = p.add_element(kind, layer, name, parent).unwrap();
+    let mut element = p.elements.remove(&generated).unwrap();
+    element.id = id;
+    element.alias = format!("object_{}", id.as_u128());
+    if let Some(SharedBody::DataType { definition, .. }) = element.shared_mut() {
+        *definition = DataTypeDefinition::Record { supertype: None };
+    }
+    p.elements.insert(id, element);
+}
+fn catalog() -> Project {
+    let mut p = Project::empty();
+    p.id = Id::from_u128(1);
+    p.name = "Reference catalog".into();
+    element(
+        &mut p,
+        OWNER,
+        Kind::DataType,
+        Layer::Oa,
+        "Edited record",
+        None,
+    );
+    for n in (0..1_000).rev() {
+        let id = Id::from_u128(BASE + n);
+        element(&mut p, id, Kind::DataType, Layer::Oa, "Controller", None);
+        p.elements.get_mut(&id).unwrap().alias = format!("controller_{n:04}");
+    }
+    element(
+        &mut p,
+        Id::from_u128(200),
+        Kind::DataType,
+        Layer::Sa,
+        "Controller",
+        None,
+    );
+    element(
+        &mut p,
+        Id::from_u128(201),
+        Kind::Activity,
+        Layer::Oa,
+        "Controller",
+        None,
+    );
+    p
+}
+fn inspector(p: Project, selected: Id) -> App {
+    let mut app = App::with_project(p);
+    let _ = app.update(Message::Select(selected));
+    app
+}
+fn request(app: &App, host: &Host, path: &str) -> adapter::Open {
+    app.reference_draft(host, path).unwrap().reference_open(
+        app.project(),
+        path,
+        Rectangle {
+            x: 790.,
+            y: 640.,
+            width: 278.,
+            height: 32.,
+        },
+    )
+}
+fn open(app: &mut App, host: &Host, path: &str) {
+    let request = request(app, host, path);
+    let message = match host {
+        Host::Inspector => Message::FieldReferenceOpen(request),
+        Host::Review { address, facet } => {
+            Message::Workflow(workflow::Event::semantic(semantic_review::Event::Row {
+                address: *address,
+                facet: Some(facet.clone()),
+                event: RowEvent::ReferenceOpen(request),
+            }))
+        }
+    };
+    let _ = app.update(message);
+    assert!(
+        app.reference_authoring.opened.is_some(),
+        "field must open: {}",
+        app.status
+    );
+}
+fn event(app: &App, action: Action) -> Message {
+    let opened = app.reference_authoring.opened.as_ref().unwrap();
+    opened.host.message(opened.chooser.event(action))
+}
+fn search(app: &mut App, query: &str) {
+    let serial = app
+        .reference_authoring
+        .opened
+        .as_ref()
+        .unwrap()
+        .chooser
+        .query_serial()
+        + 1;
+    let event = event(
+        app,
+        Action::Query {
+            text: query.into(),
+            serial,
+        },
+    );
+    let _ = app.update(event);
+}
+fn choose(app: &mut App, id: Id) {
+    let event = event(app, Action::Choose(id));
+    let _ = app.update(event);
+}
+fn raw(app: &App) -> Value {
+    serde_json::to_value(app.draft.as_ref().unwrap().recovery_snapshot()).unwrap()
+}
+fn review(app: &App) -> &semantic_review::State {
+    let Some(workflow::Workflow::Semantic(state)) = app.workflow.as_ref() else {
+        panic!("Review is open")
+    };
+    state
+}
+fn send_review(app: &mut App, event: RowEvent) {
+    let addressed = review(app).address_event(event);
+    let _ = app.update(Message::Workflow(workflow::Event::semantic(addressed)));
+}
+fn review_host(app: &App) -> Host {
+    let semantic_review::Event::Row {
+        address,
+        facet: Some(facet),
+        ..
+    } = review(app).address_event(RowEvent::Preview)
+    else {
+        panic!("Active facet")
+    };
+    Host::Review { address, facet }
+}
+fn trace(p: &mut Project, id: Id, oa: Id, sa: Id) {
+    p.traces.insert(
+        id,
+        Trace {
+            id,
+            alias: format!("trace_{}", id.as_u128()),
+            name: "Rationale".into(),
+            description: String::new(),
+            oa,
+            sa,
+            kind: TraceKind::Manual,
+            baseline: None,
+        },
+    );
+}
+
+#[test]
+fn inspector_reference_browse_is_read_only_then_one_scoped_value_applies_with_exact_undo_redo() {
+    let p = catalog();
+    let mut app = inspector(p.clone(), OWNER);
+    let before = app.document.bundle().clone();
+    let revision = app.document.revision();
+    // Malformed escaped text is unrelated to the selected reference. Browsing
+    // and the scoped write must keep its exact spelling and inactive payload.
+    app.draft.as_mut().unwrap().set_exact(true).unwrap();
+    let _ = app.update(Message::Field("/name".into(), "\"unfinished".into()));
+    let raw_before = raw(&app);
+    open(&mut app, &Host::Inspector, PATH);
+    assert_eq!(
+        app.reference_authoring
+            .opened
+            .as_ref()
+            .unwrap()
+            .chooser
+            .count(),
+        1_000
+    );
+    search(&mut app, "controller @controller_0720 OA");
+    let picker = &app.reference_authoring.opened.as_ref().unwrap().chooser;
+    assert_eq!(picker.count(), 1);
+    assert_eq!(picker.highlighted().unwrap().id, Id::from_u128(BASE + 720));
+    assert_eq!(raw(&app), raw_before);
+    assert_eq!(app.document.bundle(), &before);
+    assert_eq!(app.document.revision(), revision);
+    assert!(!app.document.can_undo());
+    // Captured search shortcuts cannot accidentally save/apply or undo a model.
+    let _ = app.update(Message::Save(false));
+    let _ = app.update(Message::ShortcutUndo(false));
+    assert_eq!(raw(&app), raw_before);
+    assert_eq!(app.document.bundle(), &before);
+    choose(&mut app, Id::from_u128(BASE + 720));
+    let mut expected_raw = raw_before;
+    *expected_raw["value"].pointer_mut(PATH).unwrap() = json!(Id::from_u128(BASE + 720));
+    expected_raw["inputs"][PATH] = json!(Id::from_u128(BASE + 720).to_string());
+    assert_eq!(raw(&app), expected_raw);
+    assert_eq!(app.document.bundle(), &before);
+    assert!(!app.document.can_undo());
+    let _ = app.update(Message::Apply);
+    assert_eq!(
+        app.document.bundle(),
+        &before,
+        "Unrelated invalid text remains an Apply error"
+    );
+    let _ = app.update(Message::Field("/name".into(), "\"Edited record\"".into()));
+    let _ = app.update(Message::Apply);
+    let mut expected = p;
+    if let Some(SharedBody::DataType { definition, .. }) =
+        expected.elements.get_mut(&OWNER).unwrap().shared_mut()
+    {
+        *definition = DataTypeDefinition::Record {
+            supertype: Some(Id::from_u128(BASE + 720)),
+        };
+    }
+    assert_eq!(app.project(), &expected);
+    let accepted = app.document.bundle().clone();
+    assert_ne!(accepted, before);
+    let _ = app.update(Message::Undo);
+    assert_eq!(app.document.bundle(), &before);
+    let _ = app.update(Message::Redo);
+    assert_eq!(app.document.bundle(), &accepted);
+    assert_eq!(app.project(), &expected);
+}
+
+#[test]
+fn inspector_reference_retains_invalid_missing_and_incompatible_current_until_explicit_clear() {
+    for (raw_id, expected) in [
+        ("-".into(), "invalid"),
+        (Id::from_u128(999).to_string(), "missing"),
+        (Id::from_u128(200).to_string(), "incompatible"),
+    ] {
+        let mut app = inspector(catalog(), OWNER);
+        app.draft
+            .as_mut()
+            .unwrap()
+            .shape_scoped(PATH, json!(raw_id))
+            .unwrap();
+        let original = raw(&app);
+        let accepted = app.document.bundle().clone();
+        open(&mut app, &Host::Inspector, PATH);
+        let current = &app
+            .reference_authoring
+            .opened
+            .as_ref()
+            .unwrap()
+            .chooser
+            .current;
+        assert!(matches!(
+            (expected, current),
+            ("invalid", chooser::Current::InvalidRaw(_))
+                | ("missing", chooser::Current::Missing(_))
+                | ("incompatible", chooser::Current::Incompatible(_))
+        ));
+        let _ = app.update(Message::Escape);
+        assert_eq!(raw(&app), original);
+        open(&mut app, &Host::Inspector, PATH);
+        let clear = event(&app, Action::Clear);
+        let _ = app.update(clear);
+        assert!(
+            app.draft
+                .as_ref()
+                .unwrap()
+                .value
+                .pointer(PATH)
+                .unwrap()
+                .is_null()
+        );
+        assert_eq!(app.document.bundle(), &accepted);
+        assert!(!app.document.can_undo());
+    }
+}
+
+#[test]
+fn chooser_rejects_old_results_after_context_recovery_reload_or_modal_and_keeps_history_text_out() {
+    for change in 0..7 {
+        let mut app = inspector(catalog(), OWNER);
+        open(&mut app, &Host::Inspector, PATH);
+        let delayed = event(&app, Action::Choose(Id::from_u128(BASE + 1)));
+        match change {
+            0 => {
+                app.draft
+                    .as_mut()
+                    .unwrap()
+                    .shape_scoped(PATH, json!(Id::from_u128(BASE + 2)))
+                    .unwrap();
+            }
+            1 => {
+                let saved = app.draft.as_ref().unwrap().recovery_snapshot();
+                app.draft = Some(Draft::from_recovery(app.project(), saved).unwrap());
+            }
+            2 => {
+                app.canvas_document = Id::new_v4();
+            }
+            3 => {
+                app.hosted.visible = true;
+            }
+            4 => {
+                app.draft
+                    .as_mut()
+                    .unwrap()
+                    .set_context(Some(json!({"different":"scope"})));
+            }
+            5 => {
+                let _ = app.update(Message::Command(Command::Rename(
+                    Id::from_u128(BASE + 3),
+                    "Changed model".into(),
+                )));
+            }
+            _ => {
+                app.source_workspace.edit(
+                    "unfinished source".into(),
+                    iced::widget::text_editor::Cursor {
+                        position: iced::widget::text_editor::Position { line: 0, column: 0 },
+                        selection: None,
+                    },
+                );
+            }
+        }
+        let expected = raw(&app);
+        let source = app.document.bundle().clone();
+        let _ = app.update(delayed);
+        assert!(app.reference_authoring.opened.is_none());
+        assert_eq!(raw(&app), expected);
+        assert_eq!(app.document.bundle(), &source);
+    }
+    let mut p = catalog();
+    trace(&mut p, Id::from_u128(300), OWNER, Id::from_u128(200));
+    let app = inspector(p, Id::from_u128(300));
+    let draft = app.draft.as_ref().unwrap();
+    let request = draft.reference_open(
+        app.project(),
+        "/baseline/semantic/facets/0/references/0/target",
+        Rectangle::default(),
+    );
+    assert!(draft.reference_catalog(app.project(), &request, 0).is_err());
+}
+
+#[test]
+fn reference_array_row_reorder_and_constructor_switch_invalidate_exact_old_field() {
+    let mut p = Project::empty();
+    for n in 0..3 {
+        element(
+            &mut p,
+            Id::from_u128(BASE + n),
+            Kind::ExchangeItem,
+            Layer::Oa,
+            "Signal item",
+            None,
+        );
+    }
+    element(&mut p, OWNER, Kind::Event, Layer::Oa, "Signal", None);
+    *p.elements.get_mut(&OWNER).unwrap().shared_mut().unwrap() = SharedBody::Event {
+        body: EventBody::Signal {
+            items: vec![Id::from_u128(BASE), Id::from_u128(BASE + 1)],
+        },
+    };
+    let mut app = inspector(p, OWNER);
+    let list = "/body/Oa/Shared/Event/body/Signal/items";
+    let path = format!("{list}/0");
+    open(&mut app, &Host::Inspector, &path);
+    let delayed = event(&app, Action::Choose(Id::from_u128(BASE + 2)));
+    let _ = app.update(Message::FieldArray(list.into(), Some(0), 1));
+    let expected = raw(&app);
+    assert_eq!(
+        app.draft.as_ref().unwrap().value.pointer(list),
+        Some(&json!([Id::from_u128(BASE + 1), Id::from_u128(BASE)]))
+    );
+    let _ = app.update(delayed);
+    assert_eq!(raw(&app), expected);
+    open(&mut app, &Host::Inspector, &path);
+    let delayed = event(&app, Action::Choose(Id::from_u128(BASE + 2)));
+    let _ = app.update(Message::FieldVariant(
+        "/body/Oa/Shared/Event/body".into(),
+        json!({"Change":{"expression":"unfinished"}}),
+    ));
+    let expected = raw(&app);
+    let _ = app.update(delayed);
+    assert_eq!(raw(&app), expected);
+    assert!(!app.document.can_undo());
+}
+
+#[test]
+fn review_reference_facets_groups_and_attachment_hosts_browse_without_replanning_and_reject_old_facet()
+ {
+    for mode in 0..3 {
+        let mut p = Project::empty();
+        p.id = Id::from_u128(1);
+        for (id, layer, parent) in [
+            (100, Layer::Oa, None),
+            (101, Layer::Sa, None),
+            (102, Layer::Sa, None),
+            (103, Layer::Oa, Some(Id::from_u128(100))),
+            (104, Layer::Sa, Some(Id::from_u128(101))),
+        ] {
+            element(
+                &mut p,
+                Id::from_u128(id),
+                if parent.is_some() {
+                    Kind::DataField
+                } else {
+                    Kind::DataType
+                },
+                layer,
+                "Record",
+                parent,
+            );
+        }
+        trace(
+            &mut p,
+            Id::from_u128(300),
+            Id::from_u128(100),
+            Id::from_u128(101),
+        );
+        let facet = match mode {
+            0 => FacetSelector::Data(DataFacet::RecordSupertype),
+            1 => FacetSelector::Data(DataFacet::Constructor),
+            _ => FacetSelector::Child(KeyPair {
+                oa: Some(Id::from_u128(103)),
+                sa: Some(Id::from_u128(104)),
+            }),
+        };
+        let path = if mode == 2 {
+            "/parent"
+        } else {
+            "/body/Sa/Shared/DataType/definition/Record/supertype"
+        };
+        let mut app = App::with_project(p.clone());
+        let _ = app.update(Message::StartSemanticReview(Id::from_u128(100)));
+        if mode == 2 {
+            // A paired attachment is a real catalog facet only after explicit
+            // correspondence; selecting an unstaged synthetic pair is rejected.
+            for (id, oa) in [(103, true), (104, false)] {
+                let choice = crate::app::Choice {
+                    id: Id::from_u128(id),
+                    label: format!("Record · @object_{id}"),
+                };
+                send_review(
+                    &mut app,
+                    if oa {
+                        RowEvent::ReferenceOa(choice)
+                    } else {
+                        RowEvent::ReferenceSa(choice)
+                    },
+                );
+            }
+            send_review(&mut app, RowEvent::AddReference);
+        }
+        send_review(&mut app, RowEvent::Select(facet.clone()));
+        send_review(
+            &mut app,
+            RowEvent::Decide(facet.clone(), Some(SemanticDecision::Candidate)),
+        );
+        let host = review_host(&app);
+        let record = if mode == 2 {
+            Id::from_u128(104)
+        } else {
+            Id::from_u128(101)
+        };
+        assert_eq!(
+            app.reference_draft(&host, path)
+                .unwrap_or_else(|| {
+                    panic!(
+                        "Reference fixture mode={mode}, facet={facet:?}, selected={:?}, decisions={:?}, error={:?}",
+                        review(&app).selected,
+                        review(&app).decisions,
+                        review(&app).error
+                    )
+                })
+                .original,
+            record
+        );
+        let before = review(&app).recovery_snapshot().unwrap();
+        let plan = serde_json::to_value(&review(&app).plan).unwrap();
+        let proposed = review(&app).proposed.clone();
+        let source = app.document.bundle().clone();
+        open(&mut app, &host, path);
+        search(&mut app, "@object_102 SA");
+        assert_eq!(
+            app.reference_authoring
+                .opened
+                .as_ref()
+                .unwrap()
+                .chooser
+                .count(),
+            1
+        );
+        assert_eq!(review(&app).recovery_snapshot().unwrap(), before);
+        assert_eq!(serde_json::to_value(&review(&app).plan).unwrap(), plan);
+        assert_eq!(review(&app).proposed, proposed);
+        assert_eq!(app.document.bundle(), &source);
+        let old = event(&app, Action::Choose(Id::from_u128(102)));
+        send_review(
+            &mut app,
+            RowEvent::Select(FacetSelector::Header(HeaderFacet::Name)),
+        );
+        let switched = review(&app).recovery_snapshot().unwrap();
+        let _ = app.update(old);
+        assert_eq!(review(&app).recovery_snapshot().unwrap(), switched);
+        send_review(&mut app, RowEvent::Select(facet));
+        open(&mut app, &host, path);
+        choose(&mut app, Id::from_u128(102));
+        let draft = app.reference_draft(&host, path).unwrap();
+        let mut expected_record = serde_json::to_value(&p.elements[&record]).unwrap();
+        *expected_record.pointer_mut(path).unwrap() = json!(Id::from_u128(102));
+        assert_eq!(draft.materialize().unwrap(), expected_record);
+        assert_eq!(app.document.bundle(), &source);
+        assert!(
+            !app.document.can_undo(),
+            "A choice only stages the active review candidate"
+        );
+    }
+}
+
+mod mounted;
+
+#[test]
+fn review_reference_cannot_reopen_or_write_a_banked_row_after_another_row_takes_focus() {
+    let mut p = Project::empty();
+    for (id, layer) in [
+        (100, Layer::Oa),
+        (101, Layer::Sa),
+        (102, Layer::Sa),
+        (110, Layer::Oa),
+        (111, Layer::Sa),
+    ] {
+        element(
+            &mut p,
+            Id::from_u128(id),
+            Kind::DataType,
+            layer,
+            "Record",
+            None,
+        );
+    }
+    trace(
+        &mut p,
+        Id::from_u128(300),
+        Id::from_u128(100),
+        Id::from_u128(101),
+    );
+    trace(
+        &mut p,
+        Id::from_u128(310),
+        Id::from_u128(110),
+        Id::from_u128(111),
+    );
+    let mut app = App::with_project(p);
+    let _ = app.update(Message::StartSemanticReview(Id::from_u128(300)));
+    let facet = FacetSelector::Data(DataFacet::RecordSupertype);
+    send_review(&mut app, RowEvent::Select(facet.clone()));
+    send_review(
+        &mut app,
+        RowEvent::Decide(facet, Some(SemanticDecision::Candidate)),
+    );
+    let host = review_host(&app);
+    let path = "/body/Sa/Shared/DataType/definition/Record/supertype";
+    let old_open = request(&app, &host, path);
+    open(&mut app, &host, path);
+    let old_choice = event(&app, Action::Choose(Id::from_u128(102)));
+    for event in [
+        semantic_review::Event::ChooseTrace(crate::app::Choice {
+            id: Id::from_u128(310),
+            label: "Second exact trace".into(),
+        }),
+        semantic_review::Event::OpenTrace,
+    ] {
+        let _ = app.update(Message::Workflow(workflow::Event::semantic(event)));
+    }
+    assert_eq!(review(&app).target(app.project()), Some(Id::from_u128(111)));
+    let expected = review(&app).recovery_snapshot().unwrap();
+    let source = app.document.bundle().clone();
+    let _ = app.update(old_choice);
+    let Host::Review { address, facet } = host else {
+        unreachable!()
+    };
+    let _ = app.update(Message::Workflow(workflow::Event::semantic(
+        semantic_review::Event::Row {
+            address,
+            facet: Some(facet),
+            event: RowEvent::ReferenceOpen(old_open),
+        },
+    )));
+    assert!(app.reference_authoring.opened.is_none());
+    assert_eq!(review(&app).recovery_snapshot().unwrap(), expected);
+    assert_eq!(app.document.bundle(), &source);
+    assert!(!app.document.can_undo());
+}

crates/oa-desktop/src/app/reference_authoring/tests/mounted.rs

@@ -0,0 +1,910 @@
+//! Real field + app-root overlay interaction. The null text renderer lets the
+//! same retained widget tree exercise focus and geometry without a GPU/window.
+use super::*;
+use iced::futures::StreamExt;
+use iced::{
+    Element, Event as Input, Point, Size, Theme, Vector,
+    advanced::{
+        Layout, Shell, layout,
+        widget::{Id as WidgetId, Operation, Tree, operation},
+    },
+    keyboard, mouse,
+    widget::{Space, column, container, opaque, scrollable, stack, text_input},
+};
+use oa_core::transitions::TransitionDirection;
+
+#[derive(Default)]
+struct Clipboard;
+impl iced::advanced::Clipboard for Clipboard {
+    fn read(&self, _: iced::advanced::clipboard::Kind) -> Option<String> {
+        None
+    }
+    fn write(&mut self, _: iced::advanced::clipboard::Kind, _: String) {}
+}
+#[derive(Default)]
+struct Fields {
+    values: Vec<(WidgetId, Rectangle, bool)>,
+    scrolls: Vec<(Rectangle, Vector)>,
+}
+impl Operation for Fields {
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        visit(self);
+    }
+    fn focusable(
+        &mut self,
+        id: Option<&WidgetId>,
+        bounds: Rectangle,
+        state: &mut dyn operation::Focusable,
+    ) {
+        if let Some(id) = id {
+            self.values.push((id.clone(), bounds, state.is_focused()));
+        }
+    }
+    fn scrollable(
+        &mut self,
+        _: Option<&WidgetId>,
+        bounds: Rectangle,
+        _: Rectangle,
+        translation: Vector,
+        _: &mut dyn operation::Scrollable,
+    ) {
+        self.scrolls.push((bounds, translation));
+    }
+}
+impl Fields {
+    fn field(&self, id: &WidgetId) -> (Rectangle, bool) {
+        self.values
+            .iter()
+            .find(|(actual, _, _)| actual == id)
+            .map(|(_, bounds, focused)| (*bounds, *focused))
+            .expect("Mounted field identity")
+    }
+}
+fn view(
+    app: &App,
+    scrolled: bool,
+    nested: bool,
+    show_review: bool,
+) -> Element<'_, Message, Theme, ()> {
+    let draft = app.draft.as_ref().unwrap();
+    let form = column![
+        text_input("Name", &draft.inputs["/name"].raw)
+            .id("before-reference")
+            .on_input(|raw| Message::Field("/name".into(), raw)),
+        adapter::field(draft, app.project(), PATH),
+        text_input("Description", &draft.inputs["/description"].raw)
+            .id("after-reference")
+            .on_input(|raw| Message::Field("/description".into(), raw)),
+    ]
+    .spacing(9);
+    let form = trigger::scope(form, draft.reference_session());
+    let base: Element<'_, Message, Theme, ()> = if scrolled {
+        container(
+            scrollable(column![Space::new().height(500), form])
+                .id("reference-scroll")
+                .height(180),
+        )
+        .width(300)
+        .into()
+    } else {
+        container(form).width(300).height(iced::Fill).into()
+    };
+    let base: Element<'_, Message, Theme, ()> = if nested {
+        scrollable(column![Space::new().height(400), base])
+            .id("outer-reference-scroll")
+            .height(180)
+            .width(300)
+            .into()
+    } else {
+        base
+    };
+    let base = if show_review {
+        let review: Element<'_, Message, Theme, ()> = match app.workflow.as_ref() {
+            Some(workflow::Workflow::Semantic(state)) => {
+                match state.reference_form(app.project()) {
+                    Some(draft) => {
+                        let mut content = column![];
+                        if let Some(raw) = &state.operation_omission {
+                            content = content.push(
+                                text_input("Required engineering rationale", raw)
+                                    .id("review-rationale")
+                                    .on_input(|raw| {
+                                        Message::Workflow(workflow::Event::semantic(
+                                            state.address_event(RowEvent::OperationRationale(raw)),
+                                        ))
+                                    }),
+                            );
+                        }
+                        content = content.push(trigger::scope(
+                            adapter::field(draft, app.project(), "/parent").map(|message| {
+                                match message {
+                                    Message::FieldReferenceOpen(request) => {
+                                        Message::Workflow(workflow::Event::semantic(
+                                            state.address_event(RowEvent::ReferenceOpen(request)),
+                                        ))
+                                    }
+                                    other => other,
+                                }
+                            }),
+                            draft.reference_session(),
+                        ));
+                        opaque(container(trigger::modal(content)).width(300).height(180))
+                    }
+                    None => Space::new().into(),
+                }
+            }
+            _ => Space::new().into(),
+        };
+        stack![base, review].into()
+    } else {
+        base
+    };
+    app.reference_overlay(base)
+}
+struct Mount {
+    tree: Option<Tree>,
+    size: Size,
+    scrolled: bool,
+    nested: bool,
+    show_review: bool,
+}
+impl Default for Mount {
+    fn default() -> Self {
+        Self {
+            tree: None,
+            size: Size::new(360., 320.),
+            scrolled: false,
+            nested: false,
+            show_review: false,
+        }
+    }
+}
+impl Mount {
+    fn frame(
+        &mut self,
+        app: &App,
+        events: &[(Input, Option<Point>)],
+    ) -> (Vec<Message>, Fields, Option<Rectangle>) {
+        let mut view = view(app, self.scrolled, self.nested, self.show_review);
+        let tree = self.tree.get_or_insert_with(|| Tree::new(view.as_widget()));
+        view.as_widget().diff(tree);
+        let node =
+            view.as_widget_mut()
+                .layout(tree, &(), &layout::Limits::new(Size::ZERO, self.size));
+        let viewport = Rectangle::with_size(self.size);
+        let overlay_node = view
+            .as_widget_mut()
+            .overlay(tree, Layout::new(&node), &(), &viewport, Vector::ZERO)
+            .map(|mut overlay| overlay.as_overlay_mut().layout(&(), self.size));
+        let mut messages = Vec::new();
+        for (input, point) in events {
+            let mut shell = Shell::new(&mut messages);
+            let cursor = point.map_or(mouse::Cursor::Unavailable, mouse::Cursor::Available);
+            if let Some(overlay_node) = &overlay_node {
+                let mut overlay = view
+                    .as_widget_mut()
+                    .overlay(tree, Layout::new(&node), &(), &viewport, Vector::ZERO)
+                    .unwrap();
+                overlay.as_overlay_mut().update(
+                    input,
+                    Layout::new(overlay_node),
+                    cursor,
+                    &(),
+                    &mut Clipboard,
+                    &mut shell,
+                );
+                assert!(shell.is_event_captured());
+            } else {
+                view.as_widget_mut().update(
+                    tree,
+                    input,
+                    Layout::new(&node),
+                    cursor,
+                    &(),
+                    &mut Clipboard,
+                    &mut shell,
+                    &viewport,
+                );
+            }
+        }
+        let mut fields = Fields::default();
+        view.as_widget_mut()
+            .operate(tree, Layout::new(&node), &(), &mut fields);
+        (
+            messages,
+            fields,
+            overlay_node.map(|node| node.children()[0].bounds()),
+        )
+    }
+    fn click(&mut self, app: &App, point: Point) -> Vec<Message> {
+        self.frame(
+            app,
+            &[
+                (
+                    Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                    Some(point),
+                ),
+                (
+                    Input::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)),
+                    Some(point),
+                ),
+            ],
+        )
+        .0
+    }
+    async fn perform(&mut self, app: &App, task: Task<Message>) {
+        let Some(mut stream) = iced_runtime::task::into_stream(task) else {
+            return;
+        };
+        while let Some(action) = stream.next().await {
+            let iced_runtime::Action::Widget(mut operation) = action else {
+                panic!("Chooser only requests scoped widget focus")
+            };
+            let mut view = view(app, self.scrolled, self.nested, self.show_review);
+            let tree = self.tree.get_or_insert_with(|| Tree::new(view.as_widget()));
+            view.as_widget().diff(tree);
+            let node =
+                view.as_widget_mut()
+                    .layout(tree, &(), &layout::Limits::new(Size::ZERO, self.size));
+            loop {
+                view.as_widget_mut()
+                    .operate(tree, Layout::new(&node), &(), operation.as_mut());
+                match operation.finish() {
+                    operation::Outcome::Chain(next) => operation = next,
+                    _ => break,
+                }
+            }
+        }
+    }
+    async fn dispatch(&mut self, app: &mut App, messages: Vec<Message>) {
+        for message in messages {
+            let task = app.update(message);
+            self.perform(app, task).await;
+        }
+    }
+}
+fn key(key: keyboard::key::Named, shift: bool) -> Input {
+    Input::Keyboard(keyboard::Event::KeyPressed {
+        key: keyboard::Key::Named(key),
+        modified_key: keyboard::Key::Named(key),
+        physical_key: keyboard::key::Physical::Code(keyboard::key::Code::Space),
+        location: keyboard::Location::Standard,
+        modifiers: if shift {
+            keyboard::Modifiers::SHIFT
+        } else {
+            keyboard::Modifiers::empty()
+        },
+        text: None,
+        repeat: false,
+    })
+}
+fn typing(raw: &str) -> Vec<(Input, Option<Point>)> {
+    raw.chars()
+        .map(|character| {
+            let raw = character.to_string();
+            (
+                Input::Keyboard(keyboard::Event::KeyPressed {
+                    key: keyboard::Key::Character(raw.clone().into()),
+                    modified_key: keyboard::Key::Character(raw.clone().into()),
+                    physical_key: keyboard::key::Physical::Code(keyboard::key::Code::KeyA),
+                    location: keyboard::Location::Standard,
+                    modifiers: keyboard::Modifiers::empty(),
+                    text: Some(raw.into()),
+                    repeat: false,
+                }),
+                None,
+            )
+        })
+        .collect()
+}
+
+#[tokio::test]
+async fn mounted_reference_trigger_tabs_to_root_popup_search_escape_and_exact_adjacent_fields() {
+    let mut app = inspector(catalog(), OWNER);
+    let accepted = app.document.bundle().clone();
+    let original = raw(&app);
+    let mut mount = Mount::default();
+    let fields = mount.frame(&app, &[]).1;
+    let messages = mount.click(
+        &app,
+        fields.field(&WidgetId::new("before-reference")).0.center(),
+    );
+    mount.dispatch(&mut app, messages).await;
+    let (_, fields, _) = mount.frame(&app, &[(key(keyboard::key::Named::Tab, false), None)]);
+    let id = trigger::field_id(app.draft.as_ref().unwrap().reference_generation(), PATH);
+    assert!(
+        fields.field(&id).1,
+        "Tab reaches the real reference trigger"
+    );
+    let messages = mount
+        .frame(&app, &[(key(keyboard::key::Named::Enter, false), None)])
+        .0;
+    assert_eq!(messages.len(), 1, "One keyboard activation opens one field");
+    mount.dispatch(&mut app, messages).await;
+    let popup = mount
+        .frame(&app, &[])
+        .2
+        .expect("App root overlay is mounted");
+    assert!(
+        popup.x >= 0.
+            && popup.y >= 0.
+            && popup.x + popup.width <= 360.
+            && popup.y + popup.height <= 320.
+    );
+    let mut inputs = typing("@controller_0720");
+    inputs.push((key(keyboard::key::Named::Escape, false), None));
+    let messages = mount.frame(&app, &inputs).0;
+    mount.dispatch(&mut app, messages).await;
+    let (_, fields, popup) = mount.frame(&app, &[]);
+    assert!(popup.is_none());
+    assert!(
+        fields.field(&id).1,
+        "Escape returns to its exact reference field"
+    );
+    assert_eq!(raw(&app), original);
+    assert_eq!(app.document.bundle(), &accepted);
+    for (backwards, expected) in [(false, "after-reference"), (true, "before-reference")] {
+        let messages = mount.click(&app, fields.field(&id).0.center());
+        mount.dispatch(&mut app, messages).await;
+        let messages = mount
+            .frame(&app, &[(key(keyboard::key::Named::Tab, backwards), None)])
+            .0;
+        mount.dispatch(&mut app, messages).await;
+        let (_, fields, popup) = mount.frame(&app, &[]);
+        assert!(popup.is_none());
+        assert!(
+            fields.field(&WidgetId::new(expected)).1,
+            "Chooser Tab stays within the originating form"
+        );
+    }
+    assert_eq!(app.document.bundle(), &accepted);
+}
+
+#[tokio::test]
+async fn mounted_reference_choice_stages_literal_identity_and_delayed_focus_cannot_hit_replacement_field()
+ {
+    let mut app = inspector(catalog(), OWNER);
+    let accepted = app.document.bundle().clone();
+    let mut mount = Mount::default();
+    let id = trigger::field_id(app.draft.as_ref().unwrap().reference_generation(), PATH);
+    let fields = mount.frame(&app, &[]).1;
+    let messages = mount.click(&app, fields.field(&id).0.center());
+    mount.dispatch(&mut app, messages).await;
+    let messages = mount.frame(&app, &typing("@controller_0720")).0;
+    mount.dispatch(&mut app, messages).await;
+    assert_eq!(
+        app.reference_authoring
+            .opened
+            .as_ref()
+            .unwrap()
+            .chooser
+            .count(),
+        1
+    );
+    let messages = mount
+        .frame(&app, &[(key(keyboard::key::Named::Enter, false), None)])
+        .0;
+    assert_eq!(messages.len(), 1);
+    let delayed_focus = app.update(messages.into_iter().next().unwrap());
+    assert_eq!(
+        app.draft.as_ref().unwrap().value.pointer(PATH),
+        Some(&json!(Id::from_u128(BASE + 720)))
+    );
+    assert_eq!(app.document.bundle(), &accepted);
+    // A structural edit occurs after Choose but before its asynchronous focus.
+    app.draft
+        .as_mut()
+        .unwrap()
+        .shape_scoped(PATH, Value::Null)
+        .unwrap();
+    let fields = mount.frame(&app, &[]).1;
+    let messages = mount.click(
+        &app,
+        fields.field(&WidgetId::new("after-reference")).0.center(),
+    );
+    mount.dispatch(&mut app, messages).await;
+    mount.perform(&app, delayed_focus).await;
+    let fields = mount.frame(&app, &[]).1;
+    assert!(
+        fields.field(&WidgetId::new("after-reference")).1,
+        "A missing old field target makes no focus changes"
+    );
+    assert!(
+        !fields
+            .field(&trigger::field_id(
+                app.draft.as_ref().unwrap().reference_generation(),
+                PATH
+            ))
+            .1
+    );
+    assert_eq!(app.document.bundle(), &accepted);
+}
+
+#[tokio::test]
+async fn mounted_scrolled_reference_anchor_uses_window_geometry_for_pointer_and_keyboard() {
+    let mut app = inspector(catalog(), OWNER);
+    let mut mount = Mount {
+        scrolled: true,
+        ..Default::default()
+    };
+    mount.frame(&app, &[]);
+    mount
+        .perform(
+            &app,
+            iced::widget::operation::snap_to("reference-scroll", scrollable::RelativeOffset::END),
+        )
+        .await;
+    let fields = mount.frame(&app, &[]).1;
+    let id = trigger::field_id(app.draft.as_ref().unwrap().reference_generation(), PATH);
+    let content = fields.field(&id).0;
+    let (viewport, offset) = fields.scrolls[0];
+    assert!(offset.y > 400., "Fixture is genuinely scrolled");
+    let expected = Rectangle {
+        x: content.x - offset.x,
+        y: content.y - offset.y,
+        ..content
+    }
+    .intersection(&viewport)
+    .unwrap();
+    let messages = mount.click(&app, expected.center());
+    let [Message::FieldReferenceOpen(request)] = messages.as_slice() else {
+        panic!("Scrolled field should emit one actual Open")
+    };
+    assert_eq!(request.anchor, expected);
+    mount.dispatch(&mut app, messages).await;
+    let close = app.update(Message::Escape);
+    mount.perform(&app, close).await;
+    let messages = mount
+        .frame(&app, &[(key(keyboard::key::Named::Enter, false), None)])
+        .0;
+    let [Message::FieldReferenceOpen(request)] = messages.as_slice() else {
+        panic!("Focused scrolled field opens without a pointer")
+    };
+    assert_eq!(request.anchor, expected);
+}
+
+#[tokio::test]
+async fn mounted_fresh_tab_reveals_offscreen_reference_and_return_reveals_it_again() {
+    for nested in [false, true] {
+        let mut app = inspector(catalog(), OWNER);
+        let original = raw(&app);
+        let source = app.document.bundle().clone();
+        let mut mount = Mount {
+            scrolled: true,
+            nested,
+            ..Default::default()
+        };
+        let fields = mount.frame(&app, &[]).1;
+        assert!(
+            fields
+                .scrolls
+                .iter()
+                .all(|(_, offset)| *offset == Vector::ZERO)
+        );
+        assert!(fields.field(&WidgetId::new("before-reference")).0.y > 180.);
+        let messages = mount
+            .frame(&app, &[(key(keyboard::key::Named::Tab, false), None)])
+            .0;
+        assert!(
+            messages.is_empty(),
+            "Keyboard reveal must not author any input"
+        );
+        let fields = mount.frame(&app, &[]).1;
+        assert!(fields.field(&WidgetId::new("before-reference")).1);
+        assert!(
+            fields.scrolls.iter().all(|(_, offset)| offset.y > 0.),
+            "Every enclosing viewport reveals fresh focus"
+        );
+        let id = trigger::field_id(app.draft.as_ref().unwrap().reference_generation(), PATH);
+        let offset: f32 = fields.scrolls.iter().map(|(_, offset)| offset.y).sum();
+        assert!(
+            fields.field(&id).0.y - offset >= 180.,
+            "The next reference starts below the fold"
+        );
+        let messages = mount
+            .frame(&app, &[(key(keyboard::key::Named::Tab, false), None)])
+            .0;
+        assert!(messages.is_empty());
+        let fields = mount.frame(&app, &[]).1;
+        let offset: f32 = fields.scrolls.iter().map(|(_, offset)| offset.y).sum();
+        let (bounds, focused) = fields.field(&id);
+        assert!(focused);
+        assert!(bounds.y - offset >= -0.01 && bounds.y + bounds.height - offset <= 180.01);
+        let messages = mount
+            .frame(&app, &[(key(keyboard::key::Named::Enter, false), None)])
+            .0;
+        assert_eq!(
+            messages.len(),
+            1,
+            "A newly revealed field opens through Enter"
+        );
+        mount.dispatch(&mut app, messages).await;
+        let return_focus = app.update(Message::Escape);
+        mount
+            .perform(
+                &app,
+                iced::widget::operation::snap_to(
+                    "reference-scroll",
+                    scrollable::RelativeOffset::START,
+                ),
+            )
+            .await;
+        if nested {
+            mount
+                .perform(
+                    &app,
+                    iced::widget::operation::snap_to(
+                        "outer-reference-scroll",
+                        scrollable::RelativeOffset::START,
+                    ),
+                )
+                .await;
+        }
+        assert!(
+            mount
+                .frame(&app, &[])
+                .1
+                .scrolls
+                .iter()
+                .all(|(_, offset)| *offset == Vector::ZERO)
+        );
+        mount.perform(&app, return_focus).await;
+        let fields = mount.frame(&app, &[]).1;
+        let offset: f32 = fields.scrolls.iter().map(|(_, offset)| offset.y).sum();
+        let (bounds, focused) = fields.field(&id);
+        assert!(
+            focused && bounds.y - offset >= -0.01 && bounds.y + bounds.height - offset <= 180.01
+        );
+        assert_eq!(raw(&app), original);
+        assert_eq!(app.document.bundle(), &source);
+    }
+}
+
+#[tokio::test]
+async fn mounted_form_tab_enters_in_both_directions_and_cycles_boundaries_without_losing_focus() {
+    for backwards in [false, true] {
+        let app = inspector(catalog(), OWNER);
+        let original = raw(&app);
+        let mut mount = Mount::default();
+        let reference = trigger::field_id(app.draft.as_ref().unwrap().reference_generation(), PATH);
+        let forward = [
+            WidgetId::new("before-reference"),
+            reference.clone(),
+            WidgetId::new("after-reference"),
+        ];
+        let reverse = [
+            WidgetId::new("after-reference"),
+            reference,
+            WidgetId::new("before-reference"),
+        ];
+        let expected = if backwards { &reverse } else { &forward };
+        for n in 0..7 {
+            let (messages, fields, popup) =
+                mount.frame(&app, &[(key(keyboard::key::Named::Tab, backwards), None)]);
+            assert!(messages.is_empty() && popup.is_none());
+            assert!(fields.field(&expected[n % 3]).1);
+            assert_eq!(
+                fields
+                    .values
+                    .iter()
+                    .filter(|(_, _, focused)| *focused)
+                    .count(),
+                1
+            );
+        }
+        assert_eq!(raw(&app), original);
+        assert!(!app.document.can_undo());
+    }
+}
+
+#[tokio::test]
+async fn mounted_delayed_return_cannot_focus_under_review_and_fresh_modal_tab_owns_its_form() {
+    let mut p = catalog();
+    trace(&mut p, Id::from_u128(300), OWNER, Id::from_u128(200));
+    let mut app = inspector(p, OWNER);
+    let source = app.document.bundle().clone();
+    let original = raw(&app);
+    let mut mount = Mount {
+        show_review: true,
+        ..Default::default()
+    };
+    let id = trigger::field_id(app.draft.as_ref().unwrap().reference_generation(), PATH);
+    let session = app.draft.as_ref().unwrap().reference_session();
+    let fields = mount.frame(&app, &[]).1;
+    let messages = mount.click(&app, fields.field(&id).0.center());
+    mount.dispatch(&mut app, messages).await;
+    let return_focus = app.update(Message::Escape);
+    let fields = mount.frame(&app, &[]).1;
+    let messages = mount.click(
+        &app,
+        fields.field(&WidgetId::new("after-reference")).0.center(),
+    );
+    mount.dispatch(&mut app, messages).await;
+    let _ = app.update(Message::StartSemanticReview(Id::from_u128(300)));
+    let facet = FacetSelector::Header(HeaderFacet::Parent);
+    send_review(&mut app, RowEvent::Select(facet.clone()));
+    send_review(
+        &mut app,
+        RowEvent::Decide(facet, Some(SemanticDecision::Candidate)),
+    );
+    assert_eq!(
+        app.draft.as_ref().unwrap().reference_session(),
+        session,
+        "Old Inspector really remains mounted"
+    );
+    assert_eq!(
+        trigger::field_id(app.draft.as_ref().unwrap().reference_generation(), PATH),
+        id
+    );
+    let review_before = review(&app).recovery_snapshot().unwrap();
+    let review_field = trigger::field_id(
+        review(&app)
+            .reference_form(app.project())
+            .unwrap()
+            .reference_generation(),
+        "/parent",
+    );
+    mount.perform(&app, return_focus).await;
+    let fields = mount.frame(&app, &[]).1;
+    assert!(
+        !fields.field(&id).1,
+        "A live old field underneath a modal cannot receive the stale focus task"
+    );
+    assert!(fields.field(&WidgetId::new("after-reference")).1);
+    assert!(!fields.field(&review_field).1);
+    let (messages, fields, _) = mount.frame(&app, &[(key(keyboard::key::Named::Tab, false), None)]);
+    assert!(messages.is_empty());
+    assert!(
+        fields.field(&review_field).1,
+        "Review entry ignores retained focus under its modal"
+    );
+    assert!(
+        !fields.field(&WidgetId::new("after-reference")).1,
+        "Modal focus acquisition deactivates background inputs"
+    );
+    let messages = mount.frame(&app, &typing("x")).0;
+    assert!(
+        messages.is_empty(),
+        "A character at the focused Review trigger cannot type into the Inspector below it"
+    );
+    let (messages, fields, _) = mount.frame(&app, &[(key(keyboard::key::Named::Tab, true), None)]);
+    assert!(messages.is_empty());
+    assert!(fields.field(&review_field).1);
+    assert!(!fields.field(&id).1);
+    assert_eq!(review(&app).recovery_snapshot().unwrap(), review_before);
+    assert_eq!(raw(&app), original);
+    assert_eq!(app.document.bundle(), &source);
+}
+
+#[tokio::test]
+async fn mounted_review_pointer_open_and_outside_dismissal_keep_background_input_inactive() {
+    let mut p = catalog();
+    trace(&mut p, Id::from_u128(300), OWNER, Id::from_u128(200));
+    let mut app = inspector(p, OWNER);
+    let original = raw(&app);
+    let source = app.document.bundle().clone();
+    let mut mount = Mount {
+        show_review: true,
+        ..Default::default()
+    };
+    let fields = mount.frame(&app, &[]).1;
+    let messages = mount.click(
+        &app,
+        fields.field(&WidgetId::new("after-reference")).0.center(),
+    );
+    mount.dispatch(&mut app, messages).await;
+    let _ = app.update(Message::StartSemanticReview(Id::from_u128(300)));
+    let facet = FacetSelector::Header(HeaderFacet::Parent);
+    send_review(&mut app, RowEvent::Select(facet.clone()));
+    send_review(
+        &mut app,
+        RowEvent::Decide(facet, Some(SemanticDecision::Candidate)),
+    );
+    let saved = review(&app).recovery_snapshot().unwrap();
+    let id = trigger::field_id(
+        review(&app)
+            .reference_form(app.project())
+            .unwrap()
+            .reference_generation(),
+        "/parent",
+    );
+    let fields = mount.frame(&app, &[]).1;
+    assert!(
+        fields.field(&WidgetId::new("after-reference")).1,
+        "Fixture retains Inspector focus before the modal receives input"
+    );
+    let messages = mount.click(&app, fields.field(&id).0.center());
+    mount.dispatch(&mut app, messages).await;
+    assert!(matches!(
+        &app.reference_authoring.opened.as_ref().unwrap().host,
+        Host::Review { .. }
+    ));
+    let fields = mount.frame(&app, &[]).1;
+    assert!(!fields.field(&WidgetId::new("after-reference")).1);
+    let messages = mount.click(&app, Point::new(359., 319.));
+    assert!(matches!(
+        messages.as_slice(),
+        [Message::Workflow(workflow::Event::Semantic(event))] if matches!(event.as_ref(),
+            semantic_review::Event::Row {
+                event: RowEvent::ReferenceEvent(chooser::Event {
+                    action: Action::Close(Close::Outside),
+                    ..
+                }),
+                ..
+            }
+        )
+    ));
+    for message in messages {
+        let task = app.update(message);
+        assert!(
+            iced_runtime::task::into_stream(task).is_none(),
+            "Outside dismissal must not request focus or apply"
+        );
+    }
+    let (messages, fields, popup) = mount.frame(&app, &typing("x"));
+    assert!(messages.is_empty() && popup.is_none());
+    assert!(!fields.field(&WidgetId::new("after-reference")).1);
+    assert_eq!(review(&app).recovery_snapshot().unwrap(), saved);
+    assert_eq!(raw(&app), original);
+    assert_eq!(app.document.bundle(), &source);
+}
+
+#[tokio::test]
+async fn mounted_reverse_review_required_rationale_remains_editable_beside_candidate_reference_form()
+ {
+    let mut p = persistence::decode(include_bytes!(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/../../harness/fixtures/interface-operation-probe/output/boundary-only.json"
+    )))
+    .unwrap();
+    let sa = p
+        .elements
+        .values()
+        .find(|element| element.alias == "operation_probe_43")
+        .unwrap()
+        .id;
+    let allocation = p
+        .relations
+        .values()
+        .find(|relation| relation.alias == "operation_probe_30")
+        .unwrap()
+        .id;
+    // The boundary fixture deliberately has no selected operation. Author one
+    // through the validated command path before testing reverse omission.
+    let mut message = p.elements[&sa].clone();
+    let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Exchange { operation, .. },
+        ..
+    }) = message.shared_mut()
+    else {
+        panic!("The operation fixture must contain an Exchange call")
+    };
+    *operation = Some(OperationUse {
+        allocation: Some(allocation),
+    });
+    p = execute_batch(&p, &[Command::EditElement(sa, message)]).unwrap();
+    assert!(matches!(
+        oa_core::operations::resolve(&p, sa).unwrap(),
+        oa_core::operations::OperationResolution::Selected(value)
+            if value.allocation == allocation
+    ));
+    let inspector_id = Id::new_v4();
+    element(
+        &mut p,
+        inspector_id,
+        Kind::DataType,
+        Layer::Oa,
+        "Inspector record",
+        None,
+    );
+    let scenario = p
+        .add_element(Kind::Scenario, Layer::Oa, "Operational counterpart", None)
+        .unwrap();
+    let oa = p
+        .add_element(
+            Kind::Occurrence,
+            Layer::Oa,
+            "Operational message",
+            Some(scenario),
+        )
+        .unwrap();
+    *p.elements.get_mut(&oa).unwrap().shared_mut().unwrap() = SharedBody::Occurrence {
+        body: OccurrenceBody::Exchange {
+            exchange: None,
+            sender: None,
+            receiver: None,
+            message_kind: MessageKind::Asynchronous,
+            reply_to: None,
+            values: vec![],
+            operation: None,
+        },
+        precondition: String::new(),
+        postcondition: String::new(),
+    };
+    p.elements
+        .get_mut(&scenario)
+        .unwrap()
+        .steps_mut()
+        .unwrap()
+        .push(oa);
+    let trace_id = Id::new_v4();
+    trace(&mut p, trace_id, oa, sa);
+    let mut app = inspector(p, inspector_id);
+    let source = app.document.bundle().clone();
+    let inspector_raw = raw(&app);
+    let _ = app.update(Message::StartSemanticReview(trace_id));
+    let _ = app.update(Message::Workflow(workflow::Event::semantic(
+        semantic_review::Event::Direction(TransitionDirection::SaToOa),
+    )));
+    let facet = FacetSelector::Header(HeaderFacet::Parent);
+    send_review(&mut app, RowEvent::Select(facet.clone()));
+    send_review(
+        &mut app,
+        RowEvent::Decide(facet, Some(SemanticDecision::Candidate)),
+    );
+    send_review(&mut app, RowEvent::OperationOmission(true));
+    assert_eq!(review(&app).direction, TransitionDirection::SaToOa);
+    assert_eq!(review(&app).operation_omission.as_deref(), Some(""));
+    let candidate = serde_json::to_value(
+        review(&app)
+            .reference_form(app.project())
+            .unwrap_or_else(|| {
+                panic!(
+                    "Reverse review candidate: selected={:?}, decisions={:?}, error={:?}",
+                    review(&app).selected,
+                    review(&app).decisions,
+                    review(&app).error
+                )
+            })
+            .recovery_snapshot(),
+    )
+    .unwrap();
+    let mut mount = Mount {
+        show_review: true,
+        ..Default::default()
+    };
+    let fields = mount.frame(&app, &[]).1;
+    let messages = mount.click(
+        &app,
+        fields.field(&WidgetId::new("review-rationale")).0.center(),
+    );
+    mount.dispatch(&mut app, messages).await;
+    let messages = mount.frame(&app, &typing("Engineering reason")).0;
+    assert_eq!(
+        messages.len(),
+        "Engineering reason".chars().count(),
+        "Every key reaches the legitimate sibling inside Review"
+    );
+    assert!(messages.iter().all(|message| matches!(
+        message,
+        Message::Workflow(workflow::Event::Semantic(event)) if matches!(event.as_ref(), semantic_review::Event::Row {
+            event: RowEvent::OperationRationale(_),
+            ..
+        })
+    )));
+    mount.dispatch(&mut app, messages).await;
+    assert_eq!(
+        review(&app).operation_omission.as_deref(),
+        Some("Engineering reason")
+    );
+    assert!(
+        mount
+            .frame(&app, &[])
+            .1
+            .field(&WidgetId::new("review-rationale"))
+            .1
+    );
+    assert_eq!(
+        serde_json::to_value(
+            review(&app)
+                .reference_form(app.project())
+                .unwrap()
+                .recovery_snapshot()
+        )
+        .unwrap(),
+        candidate
+    );
+    assert_eq!(raw(&app), inspector_raw);
+    assert_eq!(app.document.bundle(), &source);
+    assert!(!app.document.can_undo());
+}

crates/oa-desktop/src/app/repair_save_state_tests.rs

@@ -0,0 +1,263 @@
+use super::*;
+
+const VALID: &str = concat!(
+    "arcadia 7;\r\n",
+    "project repair \"Repair 救援\" id \"9e8f0000-0000-4000-8000-000000000001\" {\r\n",
+    "    oa_activity assess \"Assess\" id \"9e8f0000-0000-4000-8000-000000000002\" {}\r\n",
+    "}\r\n",
+);
+
+fn open(app: &mut App, path: &std::path::Path) {
+    let _ = app.update(Message::Loaded(Ok(Some(
+        read_snapshot(path.to_owned()).unwrap(),
+    ))));
+}
+
+fn edit(app: &mut App, text: &str) {
+    let _ = app.update(Message::SourceEdit(text_editor::Action::SelectAll));
+    let _ = app.update(Message::SourceEdit(text_editor::Action::Edit(
+        text_editor::Edit::Paste(Arc::new(text.into())),
+    )));
+}
+
+fn save(app: &mut App, path: &std::path::Path) {
+    let receipt = write_snapshot(
+        app.canvas_document,
+        app.document.revision(),
+        app.document.snapshot(),
+        path.to_owned(),
+        app.disk_project.clone(),
+    )
+    .unwrap();
+    let _ = app.update(Message::Saved(Ok(Some(receipt))));
+}
+
+#[test]
+fn repair_to_previous_saved_bytes_requires_save_at_new_destination_and_guards_close() {
+    for extra in [
+        "    include \"missing.arcadia\";\r\n",
+        "    oa_activity assess \"Duplicate\" id \"9e8f0000-0000-4000-8000-000000000003\" {}\r\n",
+    ] {
+        let first = tempfile::tempdir().unwrap();
+        let second = tempfile::tempdir().unwrap();
+        let first_path = first.path().canonicalize().unwrap().join("project.arcadia");
+        let second_path = second
+            .path()
+            .canonicalize()
+            .unwrap()
+            .join("project.arcadia");
+        let invalid = VALID.strip_suffix("}\r\n").unwrap().to_owned() + extra + "}\r\n";
+        std::fs::write(&first_path, VALID).unwrap();
+        std::fs::write(&second_path, &invalid).unwrap();
+        let mut app = App::with_project(Project::empty());
+        open(&mut app, &first_path);
+        assert!(!app.dirty());
+        let before = app.document.snapshot();
+        let revision = app.document.revision();
+        open(&mut app, &second_path);
+        assert!(!app.source_workspace.applied);
+        assert!(Arc::ptr_eq(&before, &app.document.snapshot()));
+        edit(&mut app, VALID);
+        assert!(app.apply_source(), "{}", app.status);
+        assert!(app.source_workspace.applied);
+        assert!(!app.source_dirty());
+        assert_eq!(app.document.bundle(), &before.bundle);
+        assert_eq!(app.project(), &before.decoded.project);
+        assert_eq!(app.document.revision(), revision);
+        assert!(
+            !app.document.can_undo(),
+            "Equal content creates no history step"
+        );
+        assert!(app.document.dirty());
+        assert_eq!(app.hosted_label(), "Unsaved changes");
+        assert_eq!(std::fs::read(&second_path).unwrap(), invalid.as_bytes());
+        assert_eq!(std::fs::read(&first_path).unwrap(), VALID.as_bytes());
+        let close = window::Id::unique();
+        let task = app.update(Message::Request(Pending::Close(close)));
+        assert!(iced_runtime::task::into_stream(task).is_none());
+        assert!(matches!(app.pending, Some(Pending::Close(id)) if id == close));
+        let _ = app.update(Message::Cancel);
+        save(&mut app, &second_path);
+        assert!(!app.dirty());
+        assert_eq!(app.hosted_label(), "All changes saved");
+        assert_eq!(std::fs::read(&second_path).unwrap(), VALID.as_bytes());
+        assert_eq!(std::fs::read(&first_path).unwrap(), VALID.as_bytes());
+    }
+}
+
+#[test]
+fn repair_history_compares_to_new_disk_baseline_and_then_successful_save() {
+    let directory = tempfile::tempdir().unwrap();
+    let path = directory
+        .path()
+        .canonicalize()
+        .unwrap()
+        .join("project.arcadia");
+    std::fs::write(&path, VALID).unwrap();
+    let mut app = App::with_project(Project::empty());
+    open(&mut app, &path);
+    let before = app.document.snapshot();
+    let invalid = format!("{VALID} unfinished {{");
+    std::fs::write(&path, &invalid).unwrap();
+    open(&mut app, &path);
+    let repaired = format!("{VALID}// Repaired rationale\r\n");
+    edit(&mut app, &repaired);
+    assert!(app.apply_source());
+    assert!(app.dirty());
+    let _ = app.update(Message::Undo);
+    assert_eq!(app.document.bundle(), &before.bundle);
+    assert!(
+        app.dirty(),
+        "Old saved bytes are not saved at the repair destination"
+    );
+    let _ = app.update(Message::Redo);
+    assert!(app.dirty());
+    assert_eq!(std::fs::read(&path).unwrap(), invalid.as_bytes());
+
+    std::fs::write(&path, "external edit").unwrap();
+    let failed = write_snapshot(
+        app.canvas_document,
+        app.document.revision(),
+        app.document.snapshot(),
+        path.clone(),
+        app.disk_project.clone(),
+    )
+    .unwrap_err();
+    let _ = app.update(Message::Saved(Err(failed)));
+    assert!(app.dirty());
+    assert_eq!(std::fs::read(&path).unwrap(), b"external edit");
+    std::fs::write(&path, &invalid).unwrap();
+    save(&mut app, &path);
+    assert!(!app.dirty());
+    let _ = app.update(Message::Undo);
+    assert!(app.dirty());
+    assert_eq!(app.document.bundle(), &before.bundle);
+    let _ = app.update(Message::Redo);
+    assert!(!app.dirty(), "Redo to the new saved snapshot is clean");
+    assert_eq!(std::fs::read(&path).unwrap(), repaired.as_bytes());
+}
+
+#[test]
+fn valid_equal_content_at_distinct_destinations_stays_clean() {
+    let first = tempfile::tempdir().unwrap();
+    let second = tempfile::tempdir().unwrap();
+    let first_path = first.path().canonicalize().unwrap().join("project.arcadia");
+    let second_path = second
+        .path()
+        .canonicalize()
+        .unwrap()
+        .join("project.arcadia");
+    std::fs::write(&first_path, VALID).unwrap();
+    std::fs::write(&second_path, VALID).unwrap();
+    let mut app = App::with_project(Project::empty());
+    open(&mut app, &first_path);
+    let before = app.document.bundle().clone();
+    open(&mut app, &second_path);
+    assert_eq!(app.document.bundle(), &before);
+    assert_eq!(app.path.as_ref(), Some(&second_path));
+    assert!(!app.dirty());
+    assert_eq!(app.hosted_label(), "All changes saved");
+}
+
+#[test]
+fn recovering_applied_repair_rebinds_rolled_back_disk_bytes_without_changing_model() {
+    let first = tempfile::tempdir().unwrap();
+    let second = tempfile::tempdir().unwrap();
+    let first_path = first.path().canonicalize().unwrap().join("project.arcadia");
+    let root = second.path().canonicalize().unwrap();
+    let path = root.join("project.arcadia");
+    let before = VALID.replace("Repair 救援", "Before 救援");
+    std::fs::write(&first_path, VALID).unwrap();
+    std::fs::write(&path, VALID).unwrap();
+    let journal = root.join(".arcadia-save-project.arcadia.journal");
+    std::fs::create_dir(&journal).unwrap();
+    std::fs::write(
+        journal.join("journal.json"),
+        br#"{"version":1,"entry":"project.arcadia","files":[{"path":"project.arcadia","before":true,"write":true}]}"#,
+    )
+    .unwrap();
+    std::fs::write(journal.join("0.before"), &before).unwrap();
+    std::fs::write(journal.join("0.after"), VALID).unwrap();
+    let mut app = App::with_project(Project::empty());
+    open(&mut app, &first_path);
+    let accepted = app.document.snapshot();
+    open(&mut app, &path);
+    assert_eq!(app.pending_recovery.as_ref(), Some(&path));
+    assert!(!app.source_workspace.applied);
+    assert!(app.apply_source());
+    assert!(
+        !app.dirty(),
+        "Current bytes still match disk before rollback"
+    );
+    let _ = app.update(Message::SourceRecovered(recover_snapshot(path.clone())));
+    assert!(app.pending_recovery.is_none());
+    assert!(!journal.exists());
+    assert_eq!(std::fs::read(&path).unwrap(), before.as_bytes());
+    assert!(Arc::ptr_eq(&accepted, &app.document.snapshot()));
+    assert!(!app.source_dirty());
+    assert!(app.dirty(), "Recovery changed disk, not the accepted model");
+    assert_eq!(app.hosted_label(), "Unsaved changes");
+    save(&mut app, &path);
+    assert!(!app.dirty());
+    assert_eq!(std::fs::read(&path).unwrap(), VALID.as_bytes());
+}
+
+#[test]
+fn recovery_missing_entry_or_failed_reload_preserves_current_destination_save_authority() {
+    for (current_destination, failed_reload) in
+        [(true, false), (false, false), (true, true), (false, true)]
+    {
+        let directory = tempfile::tempdir().unwrap();
+        let root = directory.path().canonicalize().unwrap();
+        let path = root.join("project.arcadia");
+        std::fs::write(&path, VALID).unwrap();
+        let mut app = App::with_project(Project::empty());
+        open(&mut app, &path);
+        let accepted = app.document.snapshot();
+        let journal = root.join(".arcadia-save-project.arcadia.journal");
+        std::fs::create_dir(&journal).unwrap();
+        std::fs::write(
+            journal.join("journal.json"),
+            br#"{"version":1,"entry":"project.arcadia","files":[{"path":"project.arcadia","before":false,"write":true}]}"#,
+        )
+        .unwrap();
+        std::fs::write(journal.join("0.after"), VALID).unwrap();
+        open(&mut app, &path);
+        assert!(app.apply_source());
+        assert!(!app.dirty());
+        let destination = tempfile::tempdir().unwrap();
+        let saved_elsewhere = destination
+            .path()
+            .canonicalize()
+            .unwrap()
+            .join("project.arcadia");
+        if !current_destination {
+            save(&mut app, &saved_elsewhere);
+            assert_eq!(app.path.as_ref(), Some(&saved_elsewhere));
+            assert_eq!(app.pending_recovery.as_ref(), Some(&path));
+        }
+        let mut receipt = recover_snapshot(path.clone()).unwrap();
+        assert!(
+            receipt.disk.as_ref().unwrap().bundle.files.is_empty(),
+            "Missing entry reloads as an empty repair workspace"
+        );
+        if failed_reload {
+            // Separately exercise the adapter's successful-recovery/failed-read
+            // boundary; first-save rollback itself does not cause a read error.
+            receipt.disk = Err("Injected post-recovery reload failure".into());
+        }
+        let _ = app.update(Message::SourceRecovered(Ok(receipt)));
+        assert!(!path.exists());
+        assert!(!journal.exists());
+        assert!(app.pending_recovery.is_none());
+        assert!(Arc::ptr_eq(&accepted, &app.document.snapshot()));
+        assert_eq!(app.dirty(), current_destination);
+        if current_destination {
+            let _ = app.update(Message::Request(Pending::New));
+            assert!(matches!(app.pending, Some(Pending::New)));
+        } else {
+            assert_eq!(app.path.as_ref(), Some(&saved_elsewhere));
+            assert_eq!(std::fs::read(&saved_elsewhere).unwrap(), VALID.as_bytes());
+        }
+    }
+}

crates/oa-desktop/src/app/review_navigation_tests.rs

@@ -16,7 +16,7 @@ fn state(app: &App) -> &State {
 }
 fn row_event(app: &mut App, event: RowEvent) {
     let event = state(app).address_event(event);
-    send(app, Message::Workflow(Event::Semantic(event)));
+    send(app, Message::Workflow(Event::semantic(event)));
 }
 fn fixture(reverse: bool, destination_view: bool) -> (App, Id, Id, Id, Option<Id>) {
     let mut p = Project::empty();

crates/oa-desktop/src/app/state_diagram.rs

@@ -114,6 +114,7 @@ impl App {
             }
         }
         match event {
+            Event::Remove(intent) => self.remove_from_diagram(intent),
             Event::Viewport(_, size) => {
                 if size.width.is_finite()
                     && size.height.is_finite()

crates/oa-desktop/src/behavior.rs

@@ -14,8 +14,16 @@ use iced::{
 };
 use oa_core::*;
 use std::collections::BTreeMap;
+pub(crate) mod canvas_workspace;
+#[cfg(test)]
+mod contextual_source_tests;
 pub(crate) mod creation;
+mod form_session;
 pub(crate) mod scenario;
+// Projection acceptance precedes the coordinated scenario renderer integration.
+#[cfg(test)]
+mod scenario_lifecycle;
+pub(crate) mod source_draft;
 pub(crate) mod state_canvas;
 pub(crate) mod state_edit;
 pub(crate) mod state_menu;
@@ -33,6 +41,7 @@ mod scenario_scroll {
     pub(super) fn observe<'a, R: renderer::Renderer + 'a>(
         context: scenario::Context,
         area: scenario::ScrollArea,
+        process: bool,
         restore: Option<scenario::ScrollRestore>,
         content: impl Into<Element<'a, Message, Theme, R>>,
     ) -> Element<'a, Message, Theme, R> {
@@ -40,28 +49,10 @@ mod scenario_scroll {
             content: content.into(),
             context,
             area,
-            process: false,
+            process,
             restore,
         })
     }
-    pub(super) fn observe_topology<'a>(
-        context: topology::Context,
-        area: scenario::ScrollArea,
-        content: impl Into<Element<'a, Message>>,
-    ) -> Element<'a, Message> {
-        Element::new(Observer {
-            content: content.into(),
-            context: scenario::Context {
-                document: context.document,
-                scenario: context.owner,
-                revision: context.revision,
-                epoch: context.epoch,
-            },
-            area,
-            process: true,
-            restore: None,
-        })
-    }
     struct Observer<'a, R = Renderer> {
         content: Element<'a, Message, Theme, R>,
         context: scenario::Context,
@@ -332,7 +323,7 @@ mod scenario_scroll {
         fn observer(height: f32, context: scenario::Context) -> Observer<'static, ()> {
             Observer {
                 context,
-                area: scenario::ScrollArea::Canvas,
+                area: scenario::ScrollArea::Page,
                 process: false,
                 restore: None,
                 content: scrollable(iced::widget::Space::new().width(200.).height(height))
@@ -402,97 +393,96 @@ mod scenario_scroll {
                     std::time::Instant::now(),
                 ))
             };
-            for area in [ScrollArea::Canvas, ScrollArea::Page] {
-                for returned_height in [600., 250.] {
-                    let (project, [a, _, _], [use_id, _, _]) = navigation_fixture();
-                    let mut app = App::with_project(project.clone());
-                    let _ = app.update(Message::Select(a));
-                    let _ = app.update(Message::Page(crate::app::Page::Behavior));
-                    let source = app.document.bundle().clone();
-                    let mut view = observer(600., app.scenario_context().unwrap());
-                    view.area = area;
-                    let mut tree = widget::Tree::new(&view as &dyn Widget<Message, Theme, ()>);
-                    for message in update(&mut view, &mut tree, redraw()).0 {
-                        let _ = app.update(message);
-                    }
-                    for message in update(
-                        &mut view,
-                        &mut tree,
-                        iced::Event::Mouse(mouse::Event::WheelScrolled {
-                            delta: mouse::ScrollDelta::Pixels { x: 0., y: -180. },
-                        }),
-                    )
-                    .0
-                    {
-                        let _ = app.update(message);
-                    }
-                    assert_eq!(actual_offset(&mut view, &mut tree), Vector::new(0., 180.));
-                    navigation_event(&mut app, |ctx| CanvasEvent::OpenUse(ctx, use_id));
-                    view = observer(600., app.scenario_context().unwrap());
-                    view.area = area;
-                    view.diff(&mut tree);
-                    for message in update(&mut view, &mut tree, redraw()).0 {
-                        let _ = app.update(message);
-                    }
-                    assert_eq!(actual_offset(&mut view, &mut tree), Vector::ZERO);
-                    navigation_event(&mut app, CanvasEvent::Back);
-                    assert_eq!(app.selected, use_id);
-                    let context = app.scenario_context().unwrap();
-                    let request = app.behavior.scenario.scroll_restore(context, area).unwrap();
-                    view = observer(returned_height, context);
-                    view.area = area;
-                    view.restore = Some(request);
-                    view.diff(&mut tree);
-                    let expected = Vector::new(0., (returned_height - 200.).min(180.));
-                    let messages = update(&mut view, &mut tree, redraw()).0;
-                    assert!(
-                        matches!(messages.as_slice(), [Message::ScenarioCanvas(CanvasEvent::Restored(_, _, _, actual))] if *actual == expected)
-                    );
-                    assert_eq!(actual_offset(&mut view, &mut tree), expected);
-                    for message in messages {
-                        let _ = app.update(message);
-                    }
-                    assert!(
-                        app.behavior
-                            .scenario
-                            .scroll_restore(app.scenario_context().unwrap(), area)
-                            .is_none()
-                    );
-                    // A delayed receipt leaves the same request in the view; later input must not snap back.
-                    for message in update(
-                        &mut view,
-                        &mut tree,
-                        iced::Event::Mouse(mouse::Event::WheelScrolled {
-                            delta: mouse::ScrollDelta::Pixels { x: 0., y: 20. },
-                        }),
-                    )
-                    .0
-                    {
-                        let _ = app.update(message);
-                    }
-                    let moved = expected - Vector::new(0., 20.);
-                    assert_eq!(actual_offset(&mut view, &mut tree), moved);
-                    view.context = app.scenario_context().unwrap();
-                    view.diff(&mut tree);
-                    assert!(update(&mut view, &mut tree, redraw()).0.is_empty());
-                    assert_eq!(actual_offset(&mut view, &mut tree), moved);
-                    navigation_event(&mut app, |ctx| {
-                        CanvasEvent::Restored(ctx, request.token, area, Vector::new(0., 999.))
-                    });
-                    let late_context = app.scenario_context().unwrap();
-                    let _ = app.update(Message::Page(crate::app::Page::Diagram));
-                    let epoch = app.canvas_epoch;
-                    let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Restored(
-                        late_context,
-                        request.token,
-                        area,
-                        Vector::ZERO,
-                    )));
-                    assert_eq!(app.canvas_epoch, epoch);
-                    assert_eq!(app.project(), &project);
-                    assert_eq!(app.document.bundle(), &source);
-                    assert!(!app.document.can_undo());
+            let area = ScrollArea::Page;
+            for returned_height in [600., 250.] {
+                let (project, [a, _, _], [use_id, _, _]) = navigation_fixture();
+                let mut app = App::with_project(project.clone());
+                let _ = app.update(Message::Select(a));
+                let _ = app.update(Message::Page(crate::app::Page::Behavior));
+                let source = app.document.bundle().clone();
+                let mut view = observer(600., app.scenario_context().unwrap());
+                view.area = area;
+                let mut tree = widget::Tree::new(&view as &dyn Widget<Message, Theme, ()>);
+                for message in update(&mut view, &mut tree, redraw()).0 {
+                    let _ = app.update(message);
                 }
+                for message in update(
+                    &mut view,
+                    &mut tree,
+                    iced::Event::Mouse(mouse::Event::WheelScrolled {
+                        delta: mouse::ScrollDelta::Pixels { x: 0., y: -180. },
+                    }),
+                )
+                .0
+                {
+                    let _ = app.update(message);
+                }
+                assert_eq!(actual_offset(&mut view, &mut tree), Vector::new(0., 180.));
+                navigation_event(&mut app, |ctx| CanvasEvent::OpenUse(ctx, use_id));
+                view = observer(600., app.scenario_context().unwrap());
+                view.area = area;
+                view.diff(&mut tree);
+                for message in update(&mut view, &mut tree, redraw()).0 {
+                    let _ = app.update(message);
+                }
+                assert_eq!(actual_offset(&mut view, &mut tree), Vector::ZERO);
+                navigation_event(&mut app, CanvasEvent::Back);
+                assert_eq!(app.selected, use_id);
+                let context = app.scenario_context().unwrap();
+                let request = app.behavior.scenario.scroll_restore(context, area).unwrap();
+                view = observer(returned_height, context);
+                view.area = area;
+                view.restore = Some(request);
+                view.diff(&mut tree);
+                let expected = Vector::new(0., (returned_height - 200.).min(180.));
+                let messages = update(&mut view, &mut tree, redraw()).0;
+                assert!(
+                    matches!(messages.as_slice(), [Message::ScenarioCanvas(CanvasEvent::Restored(_, _, _, actual))] if *actual == expected)
+                );
+                assert_eq!(actual_offset(&mut view, &mut tree), expected);
+                for message in messages {
+                    let _ = app.update(message);
+                }
+                assert!(
+                    app.behavior
+                        .scenario
+                        .scroll_restore(app.scenario_context().unwrap(), area)
+                        .is_none()
+                );
+                // A delayed receipt leaves the same request in the view; later input must not snap back.
+                for message in update(
+                    &mut view,
+                    &mut tree,
+                    iced::Event::Mouse(mouse::Event::WheelScrolled {
+                        delta: mouse::ScrollDelta::Pixels { x: 0., y: 20. },
+                    }),
+                )
+                .0
+                {
+                    let _ = app.update(message);
+                }
+                let moved = expected - Vector::new(0., 20.);
+                assert_eq!(actual_offset(&mut view, &mut tree), moved);
+                view.context = app.scenario_context().unwrap();
+                view.diff(&mut tree);
+                assert!(update(&mut view, &mut tree, redraw()).0.is_empty());
+                assert_eq!(actual_offset(&mut view, &mut tree), moved);
+                navigation_event(&mut app, |ctx| {
+                    CanvasEvent::Restored(ctx, request.token, area, Vector::new(0., 999.))
+                });
+                let late_context = app.scenario_context().unwrap();
+                let _ = app.update(Message::Page(crate::app::Page::Diagram));
+                let epoch = app.canvas_epoch;
+                let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Restored(
+                    late_context,
+                    request.token,
+                    area,
+                    Vector::ZERO,
+                )));
+                assert_eq!(app.canvas_epoch, epoch);
+                assert_eq!(app.project(), &project);
+                assert_eq!(app.document.bundle(), &source);
+                assert!(!app.document.can_undo());
             }
         }
         #[test]
@@ -574,9 +564,9 @@ mod scenario_scroll {
             other.scenario = Id::new_v4();
             let mut state = topology::State::default();
             state.enter(context.document, context.scenario);
-            state.scrolled(scenario::ScrollArea::Canvas, Vector::new(0., 180.));
+            state.scrolled(scenario::ScrollArea::Page, Vector::new(0., 180.));
             state.enter(other.document, other.scenario);
-            assert_eq!(state.scroll_offset(), Vector::ZERO);
+            assert_eq!(state.details_offset(), Vector::ZERO);
             view = observer(600., other);
             view.process = true;
             view.diff(&mut tree);
@@ -593,92 +583,91 @@ mod scenario_scroll {
          {
             use widget::operation::scrollable::{AbsoluteOffset, scroll_to};
             for process in [false, true] {
-                for area in [scenario::ScrollArea::Canvas, scenario::ScrollArea::Page] {
-                    for change in 0..4 {
-                        let context = scenario::direct_tests::context(Id::new_v4());
-                        let mut view = observer(600., context);
-                        view.process = process;
-                        view.area = area;
-                        let mut tree = widget::Tree::new(&view as &dyn Widget<Message, Theme, ()>);
-                        let node = view.layout(
-                            &mut tree,
-                            &(),
-                            &layout::Limits::new(Size::ZERO, Size::new(800., 700.)),
-                        );
-                        // Model a programmatic reveal before the observer has reported.
-                        // Mounted identity must not depend on its last scroll notification.
-                        let mut operation = scroll_to::<()>(
-                            widget::Id::new("observer-test"),
-                            AbsoluteOffset {
-                                x: None,
-                                y: Some(180.),
-                            },
-                        );
-                        view.operate(&mut tree, Layout::new(&node), &(), &mut operation);
-                        let mut next = context;
-                        match change {
-                            0 => next.scenario = Id::new_v4(),
-                            1 => next.document = Id::new_v4(),
-                            2 => {
-                                next.revision += 1;
-                                next.epoch += 5;
-                            }
-                            _ => {}
+                let area = scenario::ScrollArea::Page;
+                for change in 0..4 {
+                    let context = scenario::direct_tests::context(Id::new_v4());
+                    let mut view = observer(600., context);
+                    view.process = process;
+                    view.area = area;
+                    let mut tree = widget::Tree::new(&view as &dyn Widget<Message, Theme, ()>);
+                    let node = view.layout(
+                        &mut tree,
+                        &(),
+                        &layout::Limits::new(Size::ZERO, Size::new(800., 700.)),
+                    );
+                    // Model a programmatic reveal before the observer has reported.
+                    // Mounted identity must not depend on its last scroll notification.
+                    let mut operation = scroll_to::<()>(
+                        widget::Id::new("observer-test"),
+                        AbsoluteOffset {
+                            x: None,
+                            y: Some(180.),
+                        },
+                    );
+                    view.operate(&mut tree, Layout::new(&node), &(), &mut operation);
+                    let mut next = context;
+                    match change {
+                        0 => next.scenario = Id::new_v4(),
+                        1 => next.document = Id::new_v4(),
+                        2 => {
+                            next.revision += 1;
+                            next.epoch += 5;
                         }
-                        view = observer(if change == 3 { 800. } else { 600. }, next);
-                        view.process = process;
-                        view.area = area;
-                        view.diff(&mut tree);
-                        let redraw = || {
-                            iced::Event::Window(iced::window::Event::RedrawRequested(
-                                std::time::Instant::now(),
-                            ))
-                        };
-                        let (messages, _) = update(&mut view, &mut tree, redraw());
-                        let actual = messages
-                            .into_iter()
-                            .filter_map(|message| match message {
-                                Message::TopologyCanvas(topology::CanvasEvent::Scrolled(
-                                    c,
-                                    reported_area,
-                                    offset,
-                                )) => {
-                                    assert_eq!(
-                                        (c.document, c.owner, c.revision, c.epoch),
-                                        (next.document, next.scenario, next.revision, next.epoch)
-                                    );
-                                    assert_eq!(
-                                        std::mem::discriminant(&reported_area),
-                                        std::mem::discriminant(&area)
-                                    );
-                                    Some(offset)
-                                }
-                                Message::ScenarioCanvas(scenario::CanvasEvent::Scrolled(
-                                    c,
-                                    reported_area,
-                                    offset,
-                                )) => {
-                                    assert_eq!(c, next);
-                                    assert_eq!(
-                                        std::mem::discriminant(&reported_area),
-                                        std::mem::discriminant(&area)
-                                    );
-                                    Some(offset)
-                                }
-                                _ => None,
-                            })
-                            .collect::<Vec<_>>();
-                        assert_eq!(
-                            actual,
-                            vec![if change < 2 {
-                                Vector::ZERO
-                            } else {
-                                Vector::new(0., 180.)
-                            }],
-                            "process={process} area={area:?} change={change}"
-                        );
-                        assert!(update(&mut view, &mut tree, redraw()).0.is_empty());
+                        _ => {}
                     }
+                    view = observer(if change == 3 { 800. } else { 600. }, next);
+                    view.process = process;
+                    view.area = area;
+                    view.diff(&mut tree);
+                    let redraw = || {
+                        iced::Event::Window(iced::window::Event::RedrawRequested(
+                            std::time::Instant::now(),
+                        ))
+                    };
+                    let (messages, _) = update(&mut view, &mut tree, redraw());
+                    let actual = messages
+                        .into_iter()
+                        .filter_map(|message| match message {
+                            Message::TopologyCanvas(topology::CanvasEvent::Scrolled(
+                                c,
+                                reported_area,
+                                offset,
+                            )) => {
+                                assert_eq!(
+                                    (c.document, c.owner, c.revision, c.epoch),
+                                    (next.document, next.scenario, next.revision, next.epoch)
+                                );
+                                assert_eq!(
+                                    std::mem::discriminant(&reported_area),
+                                    std::mem::discriminant(&area)
+                                );
+                                Some(offset)
+                            }
+                            Message::ScenarioCanvas(scenario::CanvasEvent::Scrolled(
+                                c,
+                                reported_area,
+                                offset,
+                            )) => {
+                                assert_eq!(c, next);
+                                assert_eq!(
+                                    std::mem::discriminant(&reported_area),
+                                    std::mem::discriminant(&area)
+                                );
+                                Some(offset)
+                            }
+                            _ => None,
+                        })
+                        .collect::<Vec<_>>();
+                    assert_eq!(
+                        actual,
+                        vec![if change < 2 {
+                            Vector::ZERO
+                        } else {
+                            Vector::new(0., 180.)
+                        }],
+                        "process={process} area={area:?} change={change}"
+                    );
+                    assert!(update(&mut view, &mut tree, redraw()).0.is_empty());
                 }
             }
         }
@@ -739,6 +728,29 @@ pub enum Event {
     Submit,
 }
 impl Event {
+    pub fn is_source_back(&self) -> bool {
+        matches!(
+            self,
+            Self::Creation(creation::Event::Source(source_draft::Event::Edit(
+                _,
+                source_draft::Edit::Back
+            ))) | Self::Scenario(scenario::Event::Source(source_draft::Event::Edit(
+                _,
+                source_draft::Edit::Back
+            ))) | Self::Topology(topology::Event::Source(source_draft::Event::Edit(
+                _,
+                source_draft::Edit::Back
+            )))
+        )
+    }
+    pub fn is_source(&self) -> bool {
+        matches!(
+            self,
+            Self::Creation(creation::Event::Source(_))
+                | Self::Scenario(scenario::Event::Source(_))
+                | Self::Topology(topology::Event::Source(_))
+        )
+    }
     pub fn starts_form(&self) -> bool {
         matches!(
             self,
@@ -869,6 +881,18 @@ impl State {
 
     /// Clear the active form after its prepared command commits successfully.
     /// Rejected commands must leave the form available for repair and retry.
+    pub fn source_active(&self) -> bool {
+        self.creation.source_active()
+            || self.scenario.source_active()
+            || self.topology.source_active()
+    }
+    pub fn source_open(&self) -> bool {
+        self.creation.source_open() || self.scenario.source_open() || self.topology.source_open()
+    }
+    pub fn source_back(&mut self) -> bool {
+        self.creation.source_back() || self.scenario.source_back() || self.topology.source_back()
+    }
+
     pub fn acknowledge_commit(&mut self) {
         self.creation.acknowledge_commit();
         self.topology.acknowledge_commit();
@@ -916,6 +940,40 @@ pub fn view(app: &App) -> Element<'_, Message> {
     if let Some(card) = app.behavior.creation.view(p) {
         return card.map(|event| Message::Behavior(Event::Creation(event)));
     }
+    if let Some(owner) = app.behavior.pending_owner() {
+        let kind = p.elements.get(&owner).map(oa_core::Element::kind);
+        let unavailable = p.layer_of(owner) != Some(app.layer)
+            || (app.behavior.scenario.pending_owner().is_some() && kind != Some(Kind::Scenario))
+            || (app.behavior.topology.pending_owner().is_some()
+                && !matches!(kind, Some(Kind::Process | Kind::FunctionalChain)));
+        if unavailable {
+            let mut out=column![text("The pending behavior owner is unavailable").size(20),text("Your inputs are retained. Return from the source form or cancel this parent draft before choosing another behavior.").size(13)].spacing(12);
+            if let Some(name) = app
+                .behavior
+                .scenario
+                .pending_name()
+                .or_else(|| app.behavior.topology.pending_name())
+            {
+                out =
+                    out.push(text(format!("Pending consumer name: {}", short(name, 80))).size(14));
+            }
+            if let Some(child) = app.behavior.scenario.source_view(p) {
+                out = out.push(child.map(|e| Message::Behavior(Event::Scenario(e))));
+            } else if let Some(child) = app.behavior.topology.source_view(p) {
+                out = out.push(child.map(|e| Message::Behavior(Event::Topology(e))));
+            } else {
+                let cancel = if app.behavior.scenario.pending_owner().is_some() {
+                    Event::Scenario(scenario::Event::Cancel)
+                } else if app.behavior.topology.pending_owner().is_some() {
+                    Event::Topology(topology::Event::Cancel)
+                } else {
+                    Event::States(states::Event::Cancel)
+                };
+                out = out.push(button("Cancel retained draft").on_press(Message::Behavior(cancel)));
+            }
+            return container(out).padding(16).width(Fill).height(Fill).into();
+        }
+    }
     let choices = p
         .elements
         .values()
@@ -1081,7 +1139,7 @@ struct Scene {
     size: Size,
     selected: Id,
     scale: f32,
-    scroll_offset: iced::Vector,
+    camera_pan: iced::Vector,
     interaction: Option<(scenario::Context, scenario::CanvasTool, bool)>,
     pending_placement: Option<(scenario::Slot, Option<Id>)>,
     lanes: BTreeMap<Id, f32>,
@@ -1135,7 +1193,7 @@ impl Scene {
     fn sequence(p: &Project, owner: Id, selected: Id) -> Self {
         let mut scene = Self {
             scale: 1.,
-            scroll_offset: iced::Vector::ZERO,
+            camera_pan: iced::Vector::ZERO,
             boxes: vec![],
             lines: vec![],
             size: Size::new(700., 200.),
@@ -1746,8 +1804,7 @@ impl canvas::Program<Message> for Scene {
         if !editable {
             state.cancel();
         }
-        // Scrollable marks a pointer outside its visible viewport unavailable,
-        // even when it lies inside the full (scrolled) canvas rectangle.
+        // The viewport masks input outside its visible canvas bounds.
         let visible = cursor.position().is_some();
         if !visible
             && matches!(
@@ -1770,7 +1827,7 @@ impl canvas::Program<Message> for Scene {
                         SequencePress::Occurrence { .. } => {}
                     }
                 }
-                mouse::Cursor::Available(*position + self.scroll_offset)
+                mouse::Cursor::Available(*position)
             }
             canvas::Event::Mouse(mouse::Event::WheelScrolled { .. })
             | canvas::Event::Window(iced::window::Event::Resized(_))
@@ -1782,11 +1839,9 @@ impl canvas::Program<Message> for Scene {
             }
             canvas::Event::Mouse(
                 mouse::Event::ButtonPressed(_) | mouse::Event::ButtonReleased(_),
-            ) => state
-                .pointer
-                .map_or(cursor, |p| mouse::Cursor::Available(p + self.scroll_offset)),
+            ) => state.pointer.map_or(cursor, mouse::Cursor::Available),
             canvas::Event::Window(iced::window::Event::RedrawRequested(_)) => {
-                state.pointer = cursor.position().map(|p| p - self.scroll_offset);
+                state.pointer = cursor.position();
                 cursor
             }
             canvas::Event::Keyboard(iced::keyboard::Event::KeyPressed {
@@ -1798,9 +1853,12 @@ impl canvas::Program<Message> for Scene {
             }
             _ => cursor,
         };
-        let world = cursor
-            .position_in(bounds)
-            .map(|p| Point::new(p.x / self.scale, p.y / self.scale));
+        let world = cursor.position_in(bounds).map(|p| {
+            Point::new(
+                (p.x - self.camera_pan.x) / self.scale,
+                (p.y - self.camera_pan.y) / self.scale,
+            )
+        });
         match event {
             canvas::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)) => {
                 if !visible {
@@ -1820,14 +1878,14 @@ impl canvas::Program<Message> for Scene {
                         state.press = Some(SequencePress::Message {
                             source,
                             slot,
-                            start: cursor.position()? - self.scroll_offset,
+                            start: cursor.position()?,
                             first,
                             moved: false,
                         });
                         return Some(Action::request_redraw().and_capture());
                     }
                     if let CanvasTool::Add(tool) = tool {
-                        if !tool.canvas_occurrence() {
+                        if !tool.canvas_occurrence() && tool != scenario::Tool::Lifeline {
                             return None;
                         }
                         state.press = Some(SequencePress::Occurrence {
@@ -1837,11 +1895,19 @@ impl canvas::Program<Message> for Scene {
                         });
                         return Some(Action::request_redraw().and_capture());
                     }
-                    if self.reorder_handle().is_some_and(|r| r.contains(point)) {
+                    if let Some(occurrence) = self
+                        .hit(point)
+                        .filter(|id| self.rows.contains_key(id))
+                        .or_else(|| {
+                            self.reorder_handle()
+                                .filter(|r| r.contains(point))
+                                .map(|_| self.selected)
+                        })
+                    {
                         state.press = Some(SequencePress::Reorder {
-                            occurrence: self.selected,
-                            parent: self.rows[&self.selected].0,
-                            start: cursor.position()? - self.scroll_offset,
+                            occurrence,
+                            parent: self.rows[&occurrence].0,
+                            start: cursor.position()?,
                             moved: false,
                         });
                         return Some(Action::request_redraw().and_capture());
@@ -1915,6 +1981,18 @@ impl canvas::Program<Message> for Scene {
                             );
                         }
                     }
+                    SequencePress::Reorder {
+                        occurrence,
+                        moved: false,
+                        ..
+                    } => {
+                        return Some(
+                            Action::publish(Message::ScenarioCanvas(CanvasEvent::Select(
+                                context, occurrence,
+                            )))
+                            .and_capture(),
+                        );
+                    }
                     SequencePress::Reorder {
                         occurrence,
                         parent,
@@ -1952,6 +2030,7 @@ impl canvas::Program<Message> for Scene {
     ) -> Vec<canvas::Geometry> {
         let mut f = Frame::new(renderer, bounds.size());
         f.fill_rectangle(Point::ORIGIN, bounds.size(), Color::WHITE);
+        f.translate(self.camera_pan);
         f.scale(self.scale);
         for b in &self.boxes {
             let outline = matches!(
@@ -2063,9 +2142,12 @@ impl canvas::Program<Message> for Scene {
         }
         if let Some((context, tool, editable)) = self.interaction {
             let active = editable && state.context == Some(context) && state.tool == tool;
-            let point = cursor
-                .position_in(bounds)
-                .map(|p| Point::new(p.x / self.scale, p.y / self.scale));
+            let point = cursor.position_in(bounds).map(|p| {
+                Point::new(
+                    (p.x - self.camera_pan.x) / self.scale,
+                    (p.y - self.camera_pan.y) / self.scale,
+                )
+            });
             let source = active.then_some(state.source).flatten();
             let reorder = active.then_some(state.press).flatten().and_then(|press| {
                 if let SequencePress::Reorder { parent, .. } = press {
@@ -2110,6 +2192,18 @@ impl canvas::Program<Message> for Scene {
             } else {
                 None
             };
+            if reorder.is_some()
+                && slot.is_none()
+                && let Some(point) = point
+            {
+                f.fill_text(Text {
+                    content: "Other operand: move stays in the current sequence".into(),
+                    position: Point::new(point.x + 8., point.y + 12.),
+                    size: (11. / self.scale).into(),
+                    color: Color::from_rgb(0.75, 0.2, 0.15),
+                    ..Default::default()
+                });
+            }
             if let Some(slot) = slot {
                 f.stroke(
                     &Path::line(
@@ -2315,25 +2409,26 @@ mod direct_canvas_tests {
         }
     }
     #[test]
-    fn direct_scrolled_canvas_maps_raw_pointer_events_to_the_visible_slot() {
+    fn direct_panned_canvas_maps_ordered_pointer_events_to_the_visible_slot() {
         let (f, mut scene) = scene();
-        scene.scroll_offset = iced::Vector::new(35., 140.);
+        scene.camera_pan = iced::Vector::new(-35., -140.);
         let bounds = Rectangle::new(Point::new(20., 230.), scene.size);
         let slot = scene.slots.last().unwrap().slot;
         let y = scene.slots.last().unwrap().y;
-        let a = Point::new(bounds.x + scene.lanes[&f.sender], bounds.y + y) - scene.scroll_offset;
-        let b = Point::new(bounds.x + scene.lanes[&f.receiver], bounds.y + y) - scene.scroll_offset;
+        let a = Point::new(bounds.x + scene.lanes[&f.sender], bounds.y + y) + scene.camera_pan;
+        let b = Point::new(bounds.x + scene.lanes[&f.receiver], bounds.y + y) + scene.camera_pan;
+        assert!(bounds.contains(a) && bounds.contains(b));
         let mut state = SequenceInput::default();
-        // Iced Scrollable passes raw event coordinates and a translated cursor.
+        // Batched pointer events use their own positions with the final cursor.
         for event in [
             mouse::Event::CursorMoved { position: a },
             mouse::Event::ButtonPressed(mouse::Button::Left),
             mouse::Event::CursorMoved { position: b },
         ] {
-            send(&scene, &mut state, event, b + scene.scroll_offset, bounds);
+            send(&scene, &mut state, event, b, bounds);
         }
         assert!(
-            matches!(send(&scene, &mut state, mouse::Event::ButtonReleased(mouse::Button::Left), b + scene.scroll_offset, bounds), Some(CanvasEvent::Begin { sender, receiver, slot: actual, .. }) if sender == f.sender && receiver == f.receiver && actual == slot)
+            matches!(send(&scene, &mut state, mouse::Event::ButtonReleased(mouse::Button::Left), b, bounds), Some(CanvasEvent::Begin { sender, receiver, slot: actual, .. }) if sender == f.sender && receiver == f.receiver && actual == slot)
         );
     }
     #[test]

crates/oa-desktop/src/behavior/canvas_workspace.rs

@@ -0,0 +1,243 @@
+//! Shared presentation and input contract; contains no model commands.
+use crate::app::{App, Message};
+use iced::widget::{button, column, container, opaque, row, scrollable, stack, text, tooltip};
+use iced::{Element, Length::Fill, Point, Theme, Vector};
+use oa_core::Id;
+mod control;
+mod focus;
+mod viewport;
+pub use control::Control;
+pub use viewport::Viewport;
+
+pub fn keyboard_enabled(app: &crate::app::App) -> bool {
+    !app.busy
+        && !app.hosted.visible
+        && app.workflow.is_none()
+        && app.file_prompt.is_none()
+        && !app.delete_pending
+        && app.pending.is_none()
+        && app.model_menu.is_none()
+        && !app.reference_input_active()
+}
+
+pub fn controls<'a>(
+    scope: Scope,
+    keyboard: bool,
+    scale: f32,
+    details: Message,
+    focus: Option<Message>,
+    zoom: impl Fn(Option<f32>) -> Message,
+    publish: impl Fn(Event) -> Message + Copy + 'a,
+) -> Element<'a, Message> {
+    let control = |name: &'static str, label: &'static str, message: Option<Message>| {
+        let message = message.map(|message| intent(scope, name, message));
+        Control::new(
+            button(text(label).size(12))
+                .padding(6)
+                .on_press_maybe(message.clone()),
+            scope,
+            name,
+            keyboard,
+            message,
+            publish,
+        )
+    };
+    row![
+        control("Details", "Details", Some(details)),
+        tooltip(control("Canvas", "Canvas", focus),
+            container(text("F6: enter/leave canvas controls · Tab: next · Enter/Space: activate · Esc: leave").size(12)).padding(7).style(crate::style::card),
+            tooltip::Position::Bottom),
+        control("Fit", "Fit", Some(zoom(None))),
+        control("ZoomOut", "−", Some(zoom(Some(scale / 1.25)))),
+        text(format!("{:.0}%", scale * 100.)).size(12),
+        control("ZoomIn", "+", Some(zoom(Some(scale * 1.25)))),
+        control("ActualSize", "100%", Some(zoom(Some(1.)))),
+    ].spacing(4).align_y(iced::Center).into()
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Scope {
+    pub document: Id,
+    pub owner: Id,
+    pub revision: u64,
+    pub epoch: u64,
+}
+impl Scope {
+    pub(crate) fn current(app: &App) -> Option<Self> {
+        if let Some(context) = app.scenario_context() {
+            Some(Self {
+                document: context.document,
+                owner: context.scenario,
+                revision: context.revision,
+                epoch: app.camera_epoch,
+            })
+        } else {
+            let context = app.topology_context()?;
+            Some(Self {
+                document: context.document,
+                owner: context.owner,
+                revision: context.revision,
+                epoch: app.camera_epoch,
+            })
+        }
+    }
+    pub(crate) fn input_owner(app: &App) -> Option<Self> {
+        if keyboard_enabled(app)
+            && !app.behavior.has_pending()
+            && !app.draft_dirty()
+            && !app.source_dirty()
+        {
+            Self::current(app)
+        } else {
+            None
+        }
+    }
+
+    pub fn control_id(self, name: &str) -> iced::advanced::widget::Id {
+        iced::advanced::widget::Id::from(format!(
+            "behavior-control:{}:{}:{}:{name}",
+            self.document, self.owner, self.revision
+        ))
+    }
+}
+/// Only a live presentation intent may carry a toolbar action across its own pan.
+#[derive(Debug, Clone)]
+pub struct Intent {
+    pub scope: Scope,
+    pub name: &'static str,
+    pub message: Box<Message>,
+}
+pub fn intent(scope: Scope, name: &'static str, message: Message) -> Message {
+    Message::BehaviorControl(Intent {
+        scope,
+        name,
+        message: Box::new(message),
+    })
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Event {
+    CancelGesture,
+    Pan(Vector),
+    Zoom { factor: f32, at: Point, base: f32 },
+    Focus,
+    Traverse(bool),
+    ControlFocus(&'static str),
+    ToggleFocus,
+    Leave,
+}
+
+pub use focus::{focus_task, root as focus_root};
+/// Fold relative input in event order. The base scale is used only on leaving Fit.
+pub fn change(pan: &mut Vector, zoom: &mut Option<f32>, fit: &mut bool, event: Event) -> bool {
+    match event {
+        Event::Pan(delta) if delta.x.is_finite() && delta.y.is_finite() => {
+            let next = *pan + delta;
+            if next.x.is_finite() && next.y.is_finite() && next != *pan {
+                *pan = next;
+                true
+            } else {
+                false
+            }
+        }
+        Event::Zoom { factor, at, base }
+            if factor.is_finite()
+                && factor > 0.
+                && base.is_finite()
+                && base > 0.
+                && at.x.is_finite()
+                && at.y.is_finite() =>
+        {
+            let old = if *fit { base } else { zoom.unwrap_or(base) };
+            let next = (old * factor).clamp(0.05, 3.);
+            if old == next {
+                return false;
+            }
+            let anchor = Vector::new(at.x, at.y);
+            let next_pan = anchor - (anchor - *pan) * (next / old);
+            if !next_pan.x.is_finite() || !next_pan.y.is_finite() {
+                return false;
+            }
+            *pan = next_pan;
+            *zoom = Some(next);
+            *fit = false;
+            true
+        }
+        _ => false,
+    }
+}
+
+/// Constant-width labelled palette. Arming a tool never reallocates the canvas.
+pub fn palette<'a>(
+    scope: Scope,
+    keyboard: bool,
+    publish: impl Fn(Event) -> Message + Copy + 'a,
+    entries: impl IntoIterator<Item = (&'static str, &'static str, bool, Option<Message>)>,
+) -> Element<'a, Message> {
+    let mut tools = column![].spacing(3);
+    for (glyph, label, selected, message) in entries {
+        let message = message.map(|message| intent(scope, glyph, message));
+        tools = tools.push(tooltip(
+            container(Control::new(
+                button(text(glyph).size(12))
+                    .width(34)
+                    .height(30)
+                    .padding(3)
+                    .style(if selected {
+                        button::primary
+                    } else {
+                        crate::style::nav
+                    })
+                    .on_press_maybe(message.clone()),
+                scope,
+                glyph,
+                keyboard,
+                message,
+                publish,
+            ))
+            .id(format!("behavior-tool:{glyph}")),
+            container(text(label).size(12))
+                .padding(7)
+                .style(crate::style::card),
+            tooltip::Position::Left,
+        ));
+    }
+    container(scrollable(tools).id(scope.control_id("palette-scroll")))
+        .width(40)
+        .height(Fill)
+        .padding(3)
+        .style(crate::style::panel)
+        .into()
+}
+
+/// Header and palette are permanent. Details/editors overlay the same viewport.
+pub fn host<'a, Message: 'a, R: iced::advanced::text::Renderer + 'a>(
+    header: Element<'a, Message, Theme, R>,
+    palette: Element<'a, Message, Theme, R>,
+    canvas: Element<'a, Message, Theme, R>,
+    editor: Option<Element<'a, Message, Theme, R>>,
+) -> Element<'a, Message, Theme, R> {
+    let mut body = stack![canvas];
+    if let Some(editor) = editor {
+        body = body.push(
+            container(opaque(
+                container(editor)
+                    .width(300)
+                    .height(Fill)
+                    .style(crate::style::card),
+            ))
+            .align_right(Fill)
+            .height(Fill)
+            .padding(8),
+        );
+    }
+    column![header, row![body, palette].height(Fill)]
+        .spacing(6)
+        .padding(8)
+        .width(Fill)
+        .height(Fill)
+        .into()
+}
+
+#[cfg(test)]
+pub(crate) mod tests;

crates/oa-desktop/src/behavior/canvas_workspace/control.rs

@@ -0,0 +1,256 @@
+//! A real focusable keyboard target around the existing styled pointer button.
+use super::{Event as CameraEvent, Scope, focus::Member};
+use iced::advanced::{
+    Clipboard, Layout, Shell, Widget, layout, overlay, renderer,
+    widget::{Operation, Tree, operation, tree},
+};
+use iced::{Border, Element, Event, Length, Rectangle, Size, Theme, Vector, keyboard, mouse};
+
+#[derive(Default)]
+struct Input {
+    identity: Option<iced::advanced::widget::Id>,
+    focused: bool,
+}
+impl operation::Focusable for Input {
+    fn is_focused(&self) -> bool {
+        self.focused
+    }
+    fn focus(&mut self) {
+        self.focused = true;
+    }
+    fn unfocus(&mut self) {
+        self.focused = false;
+    }
+}
+pub struct Control<'a, Message, R = iced::Renderer>
+where
+    R: renderer::Renderer,
+{
+    content: Element<'a, Message, Theme, R>,
+    scope: Scope,
+    name: &'static str,
+    enabled: bool,
+    activate: Option<Message>,
+    publish: Box<dyn Fn(CameraEvent) -> Message + 'a>,
+}
+impl<'a, Message, R: renderer::Renderer> Control<'a, Message, R> {
+    pub fn new(
+        content: impl Into<Element<'a, Message, Theme, R>>,
+        scope: Scope,
+        name: &'static str,
+        enabled: bool,
+        activate: Option<Message>,
+        publish: impl Fn(CameraEvent) -> Message + 'a,
+    ) -> Self {
+        Self {
+            content: content.into(),
+            scope,
+            name,
+            enabled: enabled && activate.is_some(),
+            activate,
+            publish: Box::new(publish),
+        }
+    }
+}
+impl<Message: Clone, R: renderer::Renderer> Widget<Message, Theme, R> for Control<'_, Message, R> {
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<Input>()
+    }
+    fn state(&self) -> tree::State {
+        tree::State::new(Input {
+            identity: Some(self.scope.control_id(self.name)),
+            focused: false,
+        })
+    }
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+    fn diff(&self, tree: &mut Tree) {
+        let state = tree.state.downcast_mut::<Input>();
+        let identity = self.scope.control_id(self.name);
+        if state.identity.as_ref() != Some(&identity) || !self.enabled {
+            *state = Input {
+                identity: Some(identity),
+                focused: false,
+            };
+        }
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        operation: &mut dyn Operation,
+    ) {
+        let id = self.scope.control_id(self.name);
+        operation.container(Some(&id), layout.bounds());
+        if self.enabled {
+            operation.custom(Some(&id), layout.bounds(), &mut Member(self.scope));
+            operation.focusable(
+                Some(&id),
+                layout.bounds(),
+                tree.state.downcast_mut::<Input>(),
+            );
+        }
+        operation.traverse(&mut |operation| {
+            self.content.as_widget_mut().operate(
+                &mut tree.children[0],
+                layout,
+                renderer,
+                operation,
+            );
+        });
+    }
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        if shell.is_event_captured() {
+            return;
+        }
+        let state = tree.state.downcast_mut::<Input>();
+        if self.enabled {
+            if let Event::Keyboard(keyboard::Event::KeyPressed {
+                key,
+                modifiers,
+                repeat,
+                ..
+            }) = event
+                && state.focused
+            {
+                use keyboard::{Key, key::Named};
+                let action = match key.as_ref() {
+                    Key::Named(Named::Tab) => {
+                        Some((self.publish)(CameraEvent::Traverse(modifiers.shift())))
+                    }
+                    Key::Named(Named::Escape) => Some((self.publish)(CameraEvent::Leave)),
+                    Key::Named(Named::F6) if modifiers.is_empty() && !repeat => {
+                        Some((self.publish)(CameraEvent::ToggleFocus))
+                    }
+                    Key::Named(Named::Enter | Named::Space) if modifiers.is_empty() && !repeat => {
+                        self.activate.clone()
+                    }
+                    _ => None,
+                };
+                if let Some(action) = action {
+                    shell.publish(action);
+                    shell.capture_event();
+                    shell.request_redraw();
+                    return;
+                }
+            }
+            if matches!(
+                event,
+                Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+            ) && !layout
+                .bounds()
+                .intersection(viewport)
+                .is_some_and(|bounds| cursor.is_over(bounds))
+            {
+                state.focused = false;
+            }
+        }
+        if matches!(event, Event::Window(iced::window::Event::Unfocused)) {
+            state.focused = false;
+        }
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            style,
+            layout,
+            cursor,
+            viewport,
+        );
+        if self.enabled && tree.state.downcast_ref::<Input>().focused {
+            renderer.fill_quad(
+                renderer::Quad {
+                    bounds: layout.bounds(),
+                    border: Border {
+                        color: crate::style::INK,
+                        width: 2.,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                iced::Color::TRANSPARENT,
+            );
+        }
+    }
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout,
+            cursor,
+            viewport,
+            renderer,
+        )
+    }
+    fn overlay<'a>(
+        &'a mut self,
+        tree: &'a mut Tree,
+        layout: Layout<'a>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'a, Message, Theme, R>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}
+impl<'a, Message: Clone + 'a, R: renderer::Renderer + 'a> From<Control<'a, Message, R>>
+    for Element<'a, Message, Theme, R>
+{
+    fn from(control: Control<'a, Message, R>) -> Self {
+        Element::new(control)
+    }
+}

crates/oa-desktop/src/behavior/canvas_workspace/focus.rs

@@ -0,0 +1,293 @@
+//! Explicit canvas entry; ordinary initial Tab continues to belong to Inspector.
+use super::{Event, Scope};
+use iced::advanced::widget::{Id, Operation, Tree, operation};
+use iced::advanced::{Clipboard, Layout, Shell, Widget, layout, overlay, renderer};
+use iced::{Element, Event as InputEvent, Length, Rectangle, Size, Theme, Vector, mouse};
+
+pub(super) struct Member(pub Scope);
+
+pub fn focus_task<Message: Send + 'static>(scope: Scope, event: Event) -> iced::Task<Message> {
+    iced::advanced::widget::operate(Collect {
+        scope,
+        valid: false,
+        event,
+        members: vec![],
+        focused: None,
+        palette: None,
+    })
+}
+struct Collect {
+    scope: Scope,
+    valid: bool,
+    event: Event,
+    members: Vec<(Id, Rectangle)>,
+    focused: Option<usize>,
+    palette: Option<(Rectangle, Rectangle)>,
+}
+impl<T: Send + 'static> Operation<T> for Collect {
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation<T>)) {
+        visit(self);
+    }
+    fn custom(&mut self, id: Option<&Id>, bounds: Rectangle, value: &mut dyn std::any::Any) {
+        if let Some(owner) = value.downcast_ref::<Owner>() {
+            self.valid = owner.0 == Some(self.scope);
+        }
+        if self.valid
+            && value
+                .downcast_ref::<Member>()
+                .is_some_and(|m| m.0 == self.scope)
+            && let Some(id) = id
+        {
+            self.members.push((id.clone(), bounds));
+        }
+    }
+    fn focusable(&mut self, id: Option<&Id>, _: Rectangle, value: &mut dyn operation::Focusable) {
+        if value.is_focused() {
+            self.focused = self
+                .members
+                .iter()
+                .position(|(member, _)| Some(member) == id)
+                .or(self.focused);
+        }
+    }
+    fn scrollable(
+        &mut self,
+        id: Option<&Id>,
+        bounds: Rectangle,
+        content: Rectangle,
+        _: Vector,
+        _: &mut dyn operation::Scrollable,
+    ) {
+        if id == Some(&self.scope.control_id("palette-scroll")) {
+            self.palette = Some((bounds, content));
+        }
+    }
+    fn finish(&self) -> operation::Outcome<T> {
+        let canvas = self.scope.control_id("viewport");
+        // An enabled viewport witnesses the live lifetime. Hidden/dirty/modal
+        // owners expose no members; a delayed request cannot clear their focus.
+        if !self.valid || !self.members.iter().any(|(id, _)| *id == canvas) {
+            return operation::Outcome::None;
+        }
+        let target = match self.event {
+            Event::Focus => Some(canvas),
+            Event::ControlFocus(name) => Some(self.scope.control_id(name)),
+            Event::ToggleFocus if self.focused.is_none() => Some(canvas),
+            Event::ToggleFocus | Event::Leave if self.focused.is_some() => None,
+            Event::Traverse(back) => {
+                let Some(current) = self.focused else {
+                    return operation::Outcome::None;
+                };
+                let next = if back {
+                    (current + self.members.len() - 1) % self.members.len()
+                } else {
+                    (current + 1) % self.members.len()
+                };
+                Some(self.members[next].0.clone())
+            }
+            _ => return operation::Outcome::None,
+        };
+        if target
+            .as_ref()
+            .is_some_and(|target| !self.members.iter().any(|(id, _)| id == target))
+        {
+            return operation::Outcome::None;
+        }
+        let reveal = target.as_ref().and_then(|target| {
+            let (_, field) = self.members.iter().find(|(id, _)| id == target)?;
+            let (bounds, content) = self.palette?;
+            // Only the palette has member controls inside this scrollable.
+            (field.x >= bounds.x && field.x < bounds.x + bounds.width).then(|| {
+                (field.center_y() - bounds.y - bounds.height / 2.)
+                    .clamp(0., (content.height - bounds.height).max(0.))
+            })
+        });
+        operation::Outcome::Chain(Box::new(Apply {
+            scope: self.scope,
+            valid: false,
+            target,
+            members: self.members.iter().map(|(id, _)| id.clone()).collect(),
+            palette: self.scope.control_id("palette-scroll"),
+            reveal,
+        }))
+    }
+}
+struct Apply {
+    scope: Scope,
+    valid: bool,
+    target: Option<Id>,
+    members: Vec<Id>,
+    palette: Id,
+    reveal: Option<f32>,
+}
+impl<T> Operation<T> for Apply {
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation<T>)) {
+        visit(self);
+    }
+    fn custom(&mut self, _: Option<&Id>, _: Rectangle, value: &mut dyn std::any::Any) {
+        if let Some(owner) = value.downcast_ref::<Owner>() {
+            self.valid = owner.0 == Some(self.scope);
+        }
+    }
+    fn focusable(&mut self, id: Option<&Id>, _: Rectangle, state: &mut dyn operation::Focusable) {
+        if !self.valid {
+            return;
+        }
+        if self
+            .target
+            .as_ref()
+            .is_some_and(|target| Some(target) == id)
+        {
+            state.focus();
+        } else if self.target.is_some() || id.is_some_and(|id| self.members.contains(id)) {
+            state.unfocus();
+        }
+    }
+    fn scrollable(
+        &mut self,
+        id: Option<&Id>,
+        _: Rectangle,
+        _: Rectangle,
+        _: Vector,
+        state: &mut dyn operation::Scrollable,
+    ) {
+        if self.valid
+            && id == Some(&self.palette)
+            && let Some(y) = self.reveal
+        {
+            state.scroll_to(operation::scrollable::AbsoluteOffset {
+                x: None,
+                y: Some(y),
+            });
+        }
+    }
+}
+
+// Every Collect/Apply pass observes current ownership before touching any field.
+struct Owner(Option<Scope>);
+
+struct Root<'a, Message, R: renderer::Renderer> {
+    owner: Option<Scope>,
+    content: Element<'a, Message, Theme, R>,
+}
+
+pub fn root<'a, Message: 'a, R: renderer::Renderer + 'a>(
+    content: impl Into<Element<'a, Message, Theme, R>>,
+    owner: Option<Scope>,
+) -> Element<'a, Message, Theme, R> {
+    Element::new(Root {
+        owner,
+        content: content.into(),
+    })
+}
+
+impl<Message, R: renderer::Renderer> Widget<Message, Theme, R> for Root<'_, Message, R> {
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        operation: &mut dyn Operation,
+    ) {
+        operation.custom(None, layout.bounds(), &mut Owner(self.owner));
+        self.content
+            .as_widget_mut()
+            .operate(&mut tree.children[0], layout, renderer, operation);
+    }
+
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &InputEvent,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            style,
+            layout,
+            cursor,
+            viewport,
+        );
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout,
+            cursor,
+            viewport,
+            renderer,
+        )
+    }
+
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'b>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'b, Message, Theme, R>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}

crates/oa-desktop/src/behavior/canvas_workspace/tests.rs

@@ -0,0 +1,757 @@
+use super::*;
+use crate::app::{App, Message};
+use iced::advanced::{Layout, Shell, layout, widget};
+use iced::futures::{
+    StreamExt,
+    stream::{BoxStream, SelectAll},
+};
+use iced::{Rectangle, Size, mouse};
+use iced_runtime::{
+    Action,
+    user_interface::{Cache, UserInterface},
+};
+use std::collections::HashMap;
+
+type Pending = SelectAll<BoxStream<'static, Action<Message>>>;
+
+// iced_winit drains messages while collecting immediately ready actions. A
+// pending Task stream survives until its widget operation sends its result.
+fn enqueue(task: iced::Task<Message>, ready: &mut Vec<Action<Message>>, pending: &mut Pending) {
+    if let Some(mut stream) = iced_runtime::task::into_stream(task) {
+        let waker = iced::futures::task::noop_waker();
+        let mut context = std::task::Context::from_waker(&waker);
+        loop {
+            match stream.poll_next_unpin(&mut context) {
+                std::task::Poll::Ready(Some(action)) => ready.push(action),
+                std::task::Poll::Ready(None) => break,
+                std::task::Poll::Pending => {
+                    pending.push(stream);
+                    break;
+                }
+            }
+        }
+    }
+}
+
+#[derive(Default)]
+pub(crate) struct Geometry {
+    pub containers: HashMap<widget::Id, Rectangle>,
+    pub focused: Vec<(Option<widget::Id>, Rectangle, bool)>,
+    pub text_inputs: Vec<Rectangle>,
+    pub scrolls: HashMap<widget::Id, (Rectangle, Vector)>,
+}
+impl widget::Operation for Geometry {
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn widget::Operation)) {
+        visit(self);
+    }
+    fn focusable(
+        &mut self,
+        id: Option<&widget::Id>,
+        bounds: Rectangle,
+        state: &mut dyn widget::operation::Focusable,
+    ) {
+        self.focused.push((id.cloned(), bounds, state.is_focused()));
+    }
+    fn text_input(
+        &mut self,
+        _: Option<&widget::Id>,
+        bounds: Rectangle,
+        _: &mut dyn widget::operation::TextInput,
+    ) {
+        self.text_inputs.push(bounds);
+    }
+    fn container(&mut self, id: Option<&widget::Id>, bounds: Rectangle) {
+        if let Some(id) = id {
+            self.containers.insert(id.clone(), bounds);
+        }
+    }
+    fn scrollable(
+        &mut self,
+        id: Option<&widget::Id>,
+        bounds: Rectangle,
+        _: Rectangle,
+        offset: Vector,
+        _: &mut dyn widget::operation::Scrollable,
+    ) {
+        if let Some(id) = id {
+            self.scrolls.insert(id.clone(), (bounds, offset));
+        }
+    }
+}
+impl Geometry {
+    pub fn bounds(&self, id: &str) -> Rectangle {
+        self.containers[&widget::Id::from(id.to_owned())]
+    }
+}
+
+/// Mount the actual App root, production widgets and renderer. Events are
+/// delivered in order with Iced's final-batch cursor, then fed through App::update.
+/// This deliberately does not seed any private canvas gesture state.
+pub(crate) struct Mounted {
+    pub renderer: iced::Renderer,
+    cache: Cache,
+    pub operations: usize,
+}
+impl Mounted {
+    pub async fn unshown() -> Self {
+        use iced::advanced::renderer::Headless;
+        let renderer = <iced::Renderer as Headless>::new(iced::Font::DEFAULT, 16.into(), None)
+            .await
+            .expect("production mounted tests require the supported WGPU headless renderer");
+        Self {
+            renderer,
+            cache: Cache::new(),
+            operations: 0,
+        }
+    }
+    pub async fn new(app: &mut App) -> Self {
+        let mut mounted = Self::unshown().await;
+        mounted.settle(app).await;
+        mounted
+    }
+    pub fn geometry(&mut self, app: &App) -> Geometry {
+        let mut geometry = Geometry::default();
+        self.operate(app, &mut geometry);
+        geometry
+    }
+    /// One operation pass, including every nested overlay, via installed Iced.
+    pub fn operate(&mut self, app: &App, operation: &mut dyn widget::Operation) {
+        let mut ui = UserInterface::build(
+            app.view(),
+            app.window_size,
+            std::mem::take(&mut self.cache),
+            &mut self.renderer,
+        );
+        ui.operate(&self.renderer, operation);
+        self.cache = ui.into_cache();
+    }
+    pub async fn settle(&mut self, app: &mut App) {
+        for _ in 0..3 {
+            self.batch(
+                app,
+                &[iced::Event::Window(iced::window::Event::RedrawRequested(
+                    std::time::Instant::now(),
+                ))],
+                mouse::Cursor::Unavailable,
+            )
+            .await;
+        }
+    }
+    pub async fn batch(
+        &mut self,
+        app: &mut App,
+        events: &[iced::Event],
+        cursor: mouse::Cursor,
+    ) -> Vec<Message> {
+        let messages = self.input(app, events, cursor);
+        let mut ready = vec![];
+        let mut pending = Pending::new();
+        for message in messages.iter().cloned() {
+            enqueue(app.update(message), &mut ready, &mut pending);
+        }
+        self.drain(app, ready, pending).await;
+        messages
+    }
+    pub fn input(
+        &mut self,
+        app: &App,
+        events: &[iced::Event],
+        cursor: mouse::Cursor,
+    ) -> Vec<Message> {
+        let mut messages = vec![];
+        let mut ui = UserInterface::build(
+            app.view(),
+            app.window_size,
+            std::mem::take(&mut self.cache),
+            &mut self.renderer,
+        );
+        let _ = ui.update(
+            events,
+            cursor,
+            &mut self.renderer,
+            &mut iced::advanced::clipboard::Null,
+            &mut messages,
+        );
+        self.cache = ui.into_cache();
+        messages
+    }
+    pub async fn perform(&mut self, app: &mut App, task: iced::Task<Message>) {
+        let mut ready = vec![];
+        let mut pending = Pending::new();
+        enqueue(task, &mut ready, &mut pending);
+        self.drain(app, ready, pending).await;
+    }
+    async fn drain(
+        &mut self,
+        app: &mut App,
+        mut ready: Vec<Action<Message>>,
+        mut pending: Pending,
+    ) {
+        loop {
+            let mut outputs = vec![];
+            if !ready.is_empty() {
+                // Build only after all App messages in this cycle have run.
+                let mut ui = UserInterface::build(
+                    app.view(),
+                    app.window_size,
+                    std::mem::take(&mut self.cache),
+                    &mut self.renderer,
+                );
+                for action in ready.drain(..) {
+                    match action {
+                        Action::Output(message) => outputs.push(message),
+                        Action::Widget(mut operation) => {
+                            self.operations += 1;
+                            loop {
+                                ui.operate(&self.renderer, &mut *operation);
+                                match operation.finish() {
+                                    widget::operation::Outcome::Chain(next) => operation = next,
+                                    widget::operation::Outcome::None
+                                    | widget::operation::Outcome::Some(()) => break,
+                                }
+                            }
+                        }
+                        action => {
+                            panic!("Unexpected native action in mounted App harness: {action:?}")
+                        }
+                    }
+                }
+                self.cache = ui.into_cache();
+            }
+            for message in outputs {
+                enqueue(app.update(message), &mut ready, &mut pending);
+            }
+            if !ready.is_empty() {
+                continue;
+            }
+            let Some(action) = pending.next().await else {
+                break;
+            };
+            ready.push(action);
+            let waker = iced::futures::task::noop_waker();
+            let mut context = std::task::Context::from_waker(&waker);
+            while let std::task::Poll::Ready(Some(action)) = pending.poll_next_unpin(&mut context) {
+                ready.push(action);
+            }
+        }
+    }
+    pub fn pixels(&mut self, app: &App) -> Vec<u8> {
+        use iced::advanced::renderer::Headless;
+        let mut ui = UserInterface::build(
+            app.view(),
+            app.window_size,
+            std::mem::take(&mut self.cache),
+            &mut self.renderer,
+        );
+        // update initializes the nested overlay layout used by draw.
+        let mut messages = vec![];
+        let _ = ui.update(
+            &[],
+            mouse::Cursor::Unavailable,
+            &mut self.renderer,
+            &mut iced::advanced::clipboard::Null,
+            &mut messages,
+        );
+        assert!(
+            messages.is_empty(),
+            "An empty draw preparation must not drop App messages"
+        );
+        ui.draw(
+            &mut self.renderer,
+            &crate::style::theme(),
+            &iced::advanced::renderer::Style {
+                text_color: crate::style::INK,
+            },
+            mouse::Cursor::Unavailable,
+        );
+        self.cache = ui.into_cache();
+        Headless::screenshot(
+            &mut self.renderer,
+            Size::new(app.window_size.width as u32, app.window_size.height as u32),
+            1.,
+            crate::style::BG,
+        )
+    }
+    pub async fn click(&mut self, app: &mut App, point: Point) -> Vec<Message> {
+        self.batch(
+            app,
+            &[
+                iced::Event::Mouse(mouse::Event::CursorMoved { position: point }),
+                iced::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                iced::Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)),
+            ],
+            mouse::Cursor::Available(point),
+        )
+        .await
+    }
+    pub async fn pan(&mut self, app: &mut App, start: Point, end: Point) -> Vec<Message> {
+        self.batch(
+            app,
+            &[
+                iced::Event::Mouse(mouse::Event::CursorMoved { position: start }),
+                iced::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle)),
+                iced::Event::Mouse(mouse::Event::CursorMoved { position: end }),
+                iced::Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Middle)),
+            ],
+            mouse::Cursor::Available(end),
+        )
+        .await
+    }
+    pub fn scroll(&mut self, app: &App, id: &str, offset: f32) {
+        let mut operation = widget::operation::scrollable::scroll_to::<()>(
+            widget::Id::from(id.to_owned()),
+            widget::operation::scrollable::AbsoluteOffset {
+                x: None,
+                y: Some(offset),
+            },
+        );
+        self.operate(app, &mut operation);
+    }
+}
+
+pub(crate) fn key(named: iced::keyboard::key::Named) -> iced::Event {
+    use iced::keyboard::{self, Key};
+    iced::Event::Keyboard(keyboard::Event::KeyPressed {
+        key: Key::Named(named),
+        modified_key: Key::Named(named),
+        physical_key: keyboard::key::Physical::Unidentified(
+            keyboard::key::NativeCode::Unidentified,
+        ),
+        location: keyboard::Location::Standard,
+        modifiers: keyboard::Modifiers::empty(),
+        text: None,
+        repeat: false,
+    })
+}
+
+#[test]
+fn relative_camera_zoom_keeps_the_cursor_world_point_and_rejects_nonfinite_inputs() {
+    for scale in [0.05, 0.5, 1., 2.] {
+        let mut pan = Vector::new(-130., 75.);
+        let mut zoom = Some(scale);
+        let mut fit = false;
+        let at = Point::new(171., 93.);
+        let world = (at - Point::ORIGIN - pan) / scale;
+        change(
+            &mut pan,
+            &mut zoom,
+            &mut fit,
+            Event::Zoom {
+                factor: 1.25,
+                at,
+                base: scale,
+            },
+        );
+        let after = (at - Point::ORIGIN - pan) / zoom.unwrap();
+        assert!((after.x - world.x).abs() < 0.001 && (after.y - world.y).abs() < 0.001);
+        let before = (pan, zoom, fit);
+        for input in [
+            Event::Pan(Vector::new(f32::INFINITY, 0.)),
+            Event::Zoom {
+                factor: f32::NAN,
+                at,
+                base: scale,
+            },
+            Event::Zoom {
+                factor: 0.,
+                at,
+                base: scale,
+            },
+        ] {
+            assert!(!change(&mut pan, &mut zoom, &mut fit, input));
+            assert_eq!((pan, zoom, fit), before);
+        }
+    }
+}
+
+#[test]
+fn viewport_ordered_batch_uses_each_event_position_and_cancels_before_camera_motion() {
+    use iced::widget::Space;
+    let scope = Scope {
+        document: Id::new_v4(),
+        owner: Id::new_v4(),
+        revision: 2,
+        epoch: 0,
+    };
+    let mut view: Element<'_, Event, Theme, ()> = Viewport::new(
+        Space::new().width(Fill).height(Fill),
+        scope,
+        1.,
+        true,
+        |e| e,
+    )
+    .into();
+    let mut tree = widget::Tree::new(view.as_widget());
+    let node = view
+        .as_widget_mut()
+        .layout(
+            &mut tree,
+            &(),
+            &layout::Limits::new(Size::ZERO, Size::new(400., 300.)),
+        )
+        .move_to(Point::new(30., 80.));
+    let start = Point::new(90., 160.);
+    let middle = Point::new(125., 175.);
+    let end = Point::new(145., 185.);
+    let mut messages = vec![];
+    for event in [
+        mouse::Event::CursorMoved { position: start },
+        mouse::Event::ButtonPressed(mouse::Button::Middle),
+        mouse::Event::CursorMoved { position: middle },
+        mouse::Event::CursorMoved { position: end },
+        mouse::Event::ButtonReleased(mouse::Button::Middle),
+    ] {
+        view.as_widget_mut().update(
+            &mut tree,
+            &iced::Event::Mouse(event),
+            Layout::new(&node),
+            mouse::Cursor::Available(end),
+            &(),
+            &mut iced::advanced::clipboard::Null,
+            &mut Shell::new(&mut messages),
+            &Rectangle::with_size(Size::new(700., 600.)),
+        );
+    }
+    assert!(matches!(messages.first(), Some(Event::CancelGesture)));
+    let total = messages
+        .iter()
+        .fold(Vector::ZERO, |total, event| match event {
+            Event::Pan(delta) => total + *delta,
+            _ => total,
+        });
+    assert_eq!(total, end - start);
+}
+
+pub(crate) fn scope(app: &App) -> Scope {
+    if let Some(context) = app.scenario_context() {
+        Scope {
+            document: context.document,
+            owner: context.scenario,
+            revision: context.revision,
+            epoch: app.camera_epoch,
+        }
+    } else {
+        let context = app.topology_context().expect("mounted behavior owner");
+        Scope {
+            document: context.document,
+            owner: context.owner,
+            revision: context.revision,
+            epoch: app.camera_epoch,
+        }
+    }
+}
+pub(crate) fn focused(mounted: &mut Mounted, app: &App, name: &str) -> bool {
+    let id = scope(app).control_id(name);
+    mounted
+        .geometry(app)
+        .focused
+        .iter()
+        .any(|(member, _, focused)| member.as_ref() == Some(&id) && *focused)
+}
+pub(crate) async fn tab_to(mounted: &mut Mounted, app: &mut App, name: &str) {
+    for _ in 0..32 {
+        if focused(mounted, app, name) {
+            return;
+        }
+        mounted
+            .batch(
+                app,
+                &[key(iced::keyboard::key::Named::Tab)],
+                mouse::Cursor::Unavailable,
+            )
+            .await;
+    }
+    panic!("Keyboard traversal did not reach {name}");
+}
+pub(crate) fn camera_delta(messages: &[Message]) -> Message {
+    messages.iter().find(|m| matches!(m,
+        Message::ScenarioCanvas(crate::behavior::scenario::CanvasEvent::Camera(_, _, Event::Pan(delta)))
+        | Message::TopologyCanvas(crate::behavior::topology::CanvasEvent::Camera(_, _, Event::Pan(delta))) if *delta != Vector::ZERO
+    )).expect("actual nonzero camera delta from a mounted gesture").clone()
+}
+pub(crate) async fn press_middle(mounted: &mut Mounted, app: &mut App, point: Point) {
+    mounted
+        .batch(
+            app,
+            &[
+                iced::Event::Mouse(mouse::Event::CursorMoved { position: point }),
+                iced::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Middle)),
+            ],
+            mouse::Cursor::Available(point),
+        )
+        .await;
+}
+pub(crate) async fn release_middle(
+    mounted: &mut Mounted,
+    app: &mut App,
+    point: Point,
+) -> Vec<Message> {
+    mounted
+        .batch(
+            app,
+            &[
+                iced::Event::Mouse(mouse::Event::CursorMoved { position: point }),
+                iced::Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Middle)),
+            ],
+            mouse::Cursor::Available(point),
+        )
+        .await
+}
+pub(crate) fn assert_drawn_focus(before: &[u8], after: &[u8], size: Size, bounds: Rectangle) {
+    let width = size.width as usize;
+    assert_eq!(before.len(), width * size.height as usize * 4);
+    assert_eq!(after.len(), before.len());
+    let mut changed = 0;
+    for y in bounds.y.ceil() as usize..(bounds.y + bounds.height).floor() as usize {
+        for x in bounds.x.ceil() as usize..(bounds.x + bounds.width).floor() as usize {
+            if x as f32 - bounds.x > 2.
+                && bounds.x + bounds.width - x as f32 > 2.
+                && y as f32 - bounds.y > 2.
+                && bounds.y + bounds.height - y as f32 > 2.
+            {
+                continue;
+            }
+            let start = (y * width + x) * 4;
+            if before[start..start + 3] != after[start..start + 3] {
+                changed += 1;
+            }
+        }
+    }
+    assert!(
+        changed >= bounds.width.min(bounds.height) as usize,
+        "Focus must change visible border pixels, changed={changed}, bounds={bounds:?}"
+    );
+}
+
+pub(crate) fn character(value: &str) -> iced::Event {
+    let mut event = key(iced::keyboard::key::Named::Space);
+    if let iced::Event::Keyboard(iced::keyboard::Event::KeyPressed {
+        key,
+        modified_key,
+        text,
+        ..
+    }) = &mut event
+    {
+        *key = iced::keyboard::Key::Character(value.into());
+        *modified_key = key.clone();
+        *text = Some(value.into());
+    }
+    event
+}
+
+/// Inspect the action without stripping the lifetime from retained packets.
+pub(crate) fn intent_action(message: &Message) -> &Message {
+    match message {
+        Message::BehaviorControl(intent) => &intent.message,
+        message => message,
+    }
+}
+
+/// Deliberately retain a returned Chain to test the stronger ownership invariant.
+/// Native Iced runs Chain passes synchronously; this is not a native interleaving.
+pub(crate) async fn retained_focus_apply(
+    mounted: &mut Mounted,
+    app: &mut App,
+) -> Box<dyn widget::Operation> {
+    let entry = mounted.input(
+        app,
+        &[key(iced::keyboard::key::Named::F6)],
+        mouse::Cursor::Unavailable,
+    );
+    assert_eq!(
+        entry.len(),
+        1,
+        "actual initial F6 must emit one canvas focus request"
+    );
+    let mut stream = iced_runtime::task::into_stream(app.update(entry[0].clone()))
+        .expect("F6 returns a widget Task");
+    let Some(Action::Widget(mut operation)) = stream.next().await else {
+        panic!("F6 first action must be Collect");
+    };
+    mounted.operate(app, &mut *operation);
+    match operation.finish() {
+        widget::operation::Outcome::Chain(apply) => apply,
+        _ => panic!("Live Collect must produce its guarded Apply pass"),
+    }
+}
+
+pub(crate) async fn overflow_last_tool(mounted: &mut Mounted, app: &mut App, last: &'static str) {
+    use iced::keyboard::key::Named;
+    let geometry = mounted.geometry(app);
+    let last_bounds = geometry.containers[&scope(app).control_id(last)];
+    let (rail, offset) = geometry.scrolls[&scope(app).control_id("palette-scroll")];
+    assert_eq!(offset.y, 0.);
+    assert!(
+        last_bounds.y >= rail.y + rail.height,
+        "last tool starts fully below the overflowing palette: tool={last_bounds:?}, rail={rail:?}"
+    );
+    mounted
+        .batch(app, &[key(Named::F6)], mouse::Cursor::Unavailable)
+        .await;
+    tab_to(mounted, app, last).await;
+    let geometry = mounted.geometry(app);
+    let mut visible = geometry.containers[&scope(app).control_id(last)];
+    let (rail, offset) = geometry.scrolls[&scope(app).control_id("palette-scroll")];
+    assert!(offset.y > 0., "keyboard traversal must scroll the palette");
+    visible.x -= offset.x;
+    visible.y -= offset.y;
+    assert!(
+        visible.y >= rail.y && visible.y + visible.height <= rail.y + rail.height + 0.5,
+        "the entire last tool is revealed: tool={visible:?}, rail={rail:?}"
+    );
+    let messages = mounted
+        .batch(app, &[key(Named::Enter)], mouse::Cursor::Unavailable)
+        .await;
+    assert!(
+        messages.iter().any(
+            |message| matches!(message, Message::BehaviorControl(intent) if intent.name == last)
+        ),
+        "the revealed last tool is keyboard activated"
+    );
+    assert!(focused(mounted, app, last));
+    let on = mounted.pixels(app);
+    mounted
+        .batch(app, &[key(Named::Escape)], mouse::Cursor::Unavailable)
+        .await;
+    let off = mounted.pixels(app);
+    assert_drawn_focus(&off, &on, app.window_size, visible);
+}
+
+pub(crate) async fn retained_toolbar_boundaries(
+    mounted: &mut Mounted,
+    app: &mut App,
+    tool: &'static str,
+) {
+    use iced::keyboard::key::Named;
+    for boundary in ["Chooser", "Dirty", "Picker"] {
+        let mut packets = vec![];
+        for name in ["Fit", tool, "Details", "Panels", "Canvas"] {
+            packets.push(capture_toolbar(mounted, app, name));
+        }
+        let lifetime = app.camera_epoch;
+        let epoch = app.canvas_epoch;
+        let process = app.behavior.topology.camera_boundary();
+        let scenario = app.behavior.scenario.camera_boundary();
+        match boundary {
+            "Chooser" => {
+                let draft = app.draft.as_ref().unwrap();
+                let id = crate::forms::reference_chooser::trigger::field_id(
+                    draft.reference_generation(),
+                    "/parent",
+                );
+                let bounds = mounted
+                    .geometry(app)
+                    .focused
+                    .iter()
+                    .find(|(field, _, _)| field.as_ref() == Some(&id))
+                    .expect("real Inspector parent reference trigger")
+                    .1;
+                let request = draft.reference_open(app.project(), "/parent", bounds);
+                let task = app.update(Message::FieldReferenceOpen(request));
+                mounted.perform(app, task).await;
+                assert!(app.reference_input_active());
+                mounted
+                    .batch(app, &[key(Named::Escape)], mouse::Cursor::Unavailable)
+                    .await;
+                assert!(!app.reference_input_active());
+            }
+            "Dirty" => {
+                let task = app.update(Message::Field(
+                    "/name".into(),
+                    "Unsaved camera boundary".into(),
+                ));
+                mounted.perform(app, task).await;
+                assert!(app.draft_dirty());
+                // Every retained packet is also rejected while the owner is dirty.
+                for packet in packets.iter().cloned() {
+                    let task = app.update(packet);
+                    mounted.perform(app, task).await;
+                }
+                assert!(app.draft_dirty());
+                let task = app.update(Message::RevertProperties);
+                mounted.perform(app, task).await;
+                assert!(!app.draft_dirty());
+            }
+            "Picker" => {
+                // Public transitions, with cancellation injected at the external
+                // picker boundary. Never poll the native dialog future here.
+                let picker = app.update(Message::Save(true));
+                if cfg!(target_os = "linux") {
+                    assert!(app.file_prompt.is_some());
+                    mounted.perform(app, picker).await;
+                    let task = app.update(Message::CancelFile);
+                    mounted.perform(app, task).await;
+                } else {
+                    assert!(app.busy, "Save As enters the real native-picker busy state");
+                    drop(picker);
+                    for packet in packets.iter().cloned() {
+                        let task = app.update(packet);
+                        mounted.perform(app, task).await;
+                    }
+                    let task = app.update(Message::SavePath(None));
+                    mounted.perform(app, task).await;
+                    assert!(!app.busy);
+                }
+            }
+            _ => unreachable!(),
+        }
+        assert_ne!(
+            app.camera_epoch, lifetime,
+            "{boundary} changes the presentation lifetime"
+        );
+        assert_eq!(
+            app.canvas_epoch, epoch,
+            "{boundary} cycle leaves semantic context unchanged"
+        );
+        let focus_before = mounted
+            .geometry(app)
+            .focused
+            .into_iter()
+            .filter(|(_, _, value)| *value)
+            .collect::<Vec<_>>();
+        let current_lifetime = app.camera_epoch;
+        for packet in packets {
+            let task = app.update(packet);
+            mounted.perform(app, task).await;
+        }
+        assert_eq!(
+            app.camera_epoch, current_lifetime,
+            "{boundary} retained intents cannot start a new lifetime"
+        );
+        assert!(
+            app.behavior.topology.camera_boundary() == process,
+            "{boundary} retained toolbar packet changed process presentation"
+        );
+        assert!(
+            app.behavior.scenario.camera_boundary() == scenario,
+            "{boundary} retained toolbar packet changed scenario presentation"
+        );
+        assert_eq!(
+            mounted
+                .geometry(app)
+                .focused
+                .into_iter()
+                .filter(|(_, _, value)| *value)
+                .collect::<Vec<_>>(),
+            focus_before,
+            "{boundary} retained toolbar packet stole field focus"
+        );
+    }
+}
+
+pub(crate) fn capture_toolbar(mounted: &mut Mounted, app: &App, name: &'static str) -> Message {
+    let point = mounted.geometry(app).containers[&scope(app).control_id(name)].center();
+    mounted
+        .input(
+            app,
+            &[
+                iced::Event::Mouse(mouse::Event::CursorMoved { position: point }),
+                iced::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                iced::Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)),
+            ],
+            mouse::Cursor::Available(point),
+        )
+        .into_iter()
+        .find(|message| matches!(message, Message::BehaviorControl(intent) if intent.name == name))
+        .expect("actual production toolbar packet")
+}

crates/oa-desktop/src/behavior/canvas_workspace/viewport.rs

@@ -0,0 +1,426 @@
+use super::{Event as CameraEvent, Scope};
+use iced::advanced::{
+    Clipboard, Layout, Shell, Widget, layout, overlay, renderer,
+    widget::{Operation, Tree, operation, tree},
+};
+use iced::{Border, Element, Event, Length, Point, Rectangle, Size, Theme, Vector};
+use iced::{keyboard, mouse};
+
+#[derive(Default)]
+struct Input {
+    scope: Option<Scope>,
+    focused: bool,
+    pointer: Option<Point>,
+    pan: Option<(mouse::Button, Point)>,
+    space: bool,
+    bounds: Option<Rectangle>,
+}
+impl operation::Focusable for Input {
+    fn is_focused(&self) -> bool {
+        self.focused
+    }
+    fn focus(&mut self) {
+        self.focused = true;
+    }
+    fn unfocus(&mut self) {
+        self.focused = false;
+        self.pan = None;
+        self.space = false;
+    }
+}
+pub struct Viewport<'a, Message, R = iced::Renderer>
+where
+    R: renderer::Renderer,
+{
+    content: Element<'a, Message, Theme, R>,
+    scope: Scope,
+    scale: f32,
+    keyboard: bool,
+    blank_pan: bool,
+    publish: Box<dyn Fn(CameraEvent) -> Message + 'a>,
+}
+impl<'a, Message, R: renderer::Renderer> Viewport<'a, Message, R> {
+    pub fn new(
+        content: impl Into<Element<'a, Message, Theme, R>>,
+        scope: Scope,
+        scale: f32,
+        keyboard: bool,
+        publish: impl Fn(CameraEvent) -> Message + 'a,
+    ) -> Self {
+        Self {
+            content: content.into(),
+            scope,
+            scale,
+            keyboard,
+            blank_pan: false,
+            publish: Box::new(publish),
+        }
+    }
+    pub fn pan_background(mut self, enabled: bool) -> Self {
+        self.blank_pan = enabled;
+        self
+    }
+}
+impl<Message, R: renderer::Renderer> Widget<Message, Theme, R> for Viewport<'_, Message, R> {
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<Input>()
+    }
+    fn state(&self) -> tree::State {
+        tree::State::new(Input {
+            scope: Some(self.scope),
+            ..Default::default()
+        })
+    }
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+    fn diff(&self, tree: &mut Tree) {
+        let state = tree.state.downcast_mut::<Input>();
+        if state.scope.is_none_or(|s| {
+            (s.document, s.owner, s.revision)
+                != (self.scope.document, self.scope.owner, self.scope.revision)
+        }) {
+            *state = Input::default();
+        }
+        if state
+            .scope
+            .is_some_and(|scope| scope.epoch != self.scope.epoch)
+            || !self.keyboard
+        {
+            state.pan = None;
+            state.space = false;
+        }
+        if !self.keyboard {
+            state.focused = false;
+        }
+        state.scope = Some(self.scope);
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+    fn size(&self) -> Size<Length> {
+        Size::new(Length::Fill, Length::Fill)
+    }
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        operation: &mut dyn Operation,
+    ) {
+        if self.keyboard {
+            let id = self.scope.control_id("viewport");
+            operation.custom(
+                Some(&id),
+                layout.bounds(),
+                &mut super::focus::Member(self.scope),
+            );
+            operation.focusable(
+                Some(&id),
+                layout.bounds(),
+                tree.state.downcast_mut::<Input>(),
+            );
+        }
+        self.content
+            .as_widget_mut()
+            .operate(&mut tree.children[0], layout, renderer, operation);
+    }
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        if shell.is_event_captured() {
+            return;
+        }
+        let state = tree.state.downcast_mut::<Input>();
+        let changed_bounds = state.bounds.is_some_and(|bounds| bounds != layout.bounds());
+        state.bounds = Some(layout.bounds());
+        if changed_bounds || !self.keyboard {
+            state.pan = None;
+            state.space = false;
+        }
+        if !self.keyboard {
+            state.focused = false;
+        }
+        if let Event::Mouse(mouse::Event::CursorMoved { position }) = event {
+            state.pointer = Some(*position);
+        }
+        let pointer = match event {
+            Event::Mouse(
+                mouse::Event::ButtonPressed(_)
+                | mouse::Event::ButtonReleased(_)
+                | mouse::Event::WheelScrolled { .. },
+            ) => state.pointer.or_else(|| cursor.position()),
+            Event::Mouse(mouse::Event::CursorMoved { position }) => Some(*position),
+            _ => cursor.position().or(state.pointer),
+        };
+        let visible = layout.bounds().intersection(viewport);
+        let inside = pointer.is_some_and(|p| visible.is_some_and(|v| v.contains(p)))
+            && cursor.position().is_some();
+        if !self.keyboard {
+            state.space = false;
+        }
+        let mut cancel = changed_bounds;
+        let mut camera = None;
+        let mut capture = false;
+        match event {
+            Event::Window(iced::window::Event::Unfocused | iced::window::Event::Resized(_)) => {
+                state.pan = None;
+                state.space = false;
+                state.focused = false;
+            }
+            Event::Mouse(mouse::Event::CursorLeft) => {
+                state.pan = None;
+                state.pointer = None;
+            }
+            Event::Mouse(mouse::Event::ButtonPressed(button)) => {
+                if state.pan.is_some_and(|(held, _)| held != *button) || !inside {
+                    state.pan = None;
+                    state.space = false;
+                    cancel = true;
+                }
+                state.focused = inside && self.keyboard;
+                if inside
+                    && self.keyboard
+                    && (*button == mouse::Button::Middle
+                        || (*button == mouse::Button::Left && state.space))
+                {
+                    state.pan = pointer.map(|p| (*button, p));
+                    cancel = true;
+                    camera = Some(CameraEvent::CancelGesture);
+                    capture = true;
+                }
+            }
+            Event::Mouse(mouse::Event::CursorMoved { position }) => {
+                if let Some((button, previous)) = state.pan {
+                    state.pan = Some((button, *position));
+                    camera = Some(CameraEvent::Pan(*position - previous));
+                    capture = true;
+                }
+            }
+            Event::Mouse(mouse::Event::ButtonReleased(button)) => {
+                if let Some((held, previous)) = state.pan
+                    && held == *button
+                {
+                    state.pan = None;
+                    camera = pointer
+                        .filter(|_| inside)
+                        .map(|p| CameraEvent::Pan(p - previous));
+                    capture = true;
+                }
+            }
+            Event::Mouse(mouse::Event::WheelScrolled { delta }) if inside && state.focused => {
+                state.pan = None;
+                cancel = true;
+                let y = match delta {
+                    mouse::ScrollDelta::Lines { y, .. } => *y,
+                    mouse::ScrollDelta::Pixels { y, .. } => *y / 40.,
+                };
+                if y != 0. {
+                    let at = pointer.unwrap() - Vector::new(layout.bounds().x, layout.bounds().y);
+                    camera = Some(CameraEvent::Zoom {
+                        factor: 1.1_f32.powf(y.clamp(-8., 8.)),
+                        at,
+                        base: self.scale,
+                    });
+                    capture = true;
+                }
+            }
+            Event::Keyboard(keyboard::Event::KeyPressed {
+                key: keyboard::Key::Named(keyboard::key::Named::F6),
+                modifiers,
+                repeat: false,
+                ..
+            }) if self.keyboard && modifiers.is_empty() => {
+                camera = Some(CameraEvent::ToggleFocus);
+                capture = true;
+                cancel = true;
+            }
+            Event::Keyboard(keyboard::Event::KeyPressed { key, modifiers, .. })
+                if state.focused && self.keyboard =>
+            {
+                use keyboard::{Key, key::Named};
+                match key.as_ref() {
+                    Key::Named(Named::Space) => {
+                        state.space = true;
+                        cancel = true;
+                        camera = Some(CameraEvent::CancelGesture);
+                        capture = true;
+                    }
+                    Key::Named(Named::Tab) => {
+                        camera = Some(CameraEvent::Traverse(modifiers.shift()));
+                        capture = true;
+                    }
+                    Key::Named(Named::Escape) => {
+                        state.pan = None;
+                        state.space = false;
+                        camera = Some(CameraEvent::Leave);
+                        capture = true;
+                    }
+                    Key::Named(key) if modifiers.is_empty() => {
+                        let delta = match key {
+                            Named::ArrowLeft => Some(Vector::new(60., 0.)),
+                            Named::ArrowRight => Some(Vector::new(-60., 0.)),
+                            Named::ArrowUp => Some(Vector::new(0., 60.)),
+                            Named::ArrowDown => Some(Vector::new(0., -60.)),
+                            _ => None,
+                        };
+                        camera = delta.map(CameraEvent::Pan);
+                        capture = camera.is_some();
+                        cancel = capture;
+                    }
+                    _ => {}
+                }
+            }
+            Event::Keyboard(keyboard::Event::KeyReleased { key, .. })
+                if *key == keyboard::Key::Named(keyboard::key::Named::Space) =>
+            {
+                state.space = false;
+            }
+            _ => {}
+        }
+        if cancel {
+            self.content.as_widget_mut().update(
+                &mut tree.children[0],
+                &Event::Window(iced::window::Event::Unfocused),
+                layout,
+                cursor,
+                renderer,
+                clipboard,
+                shell,
+                viewport,
+            );
+        }
+        if let Some(event) = camera {
+            shell.publish((self.publish)(event));
+        }
+        if capture {
+            shell.capture_event();
+            shell.request_redraw();
+            return;
+        }
+        if matches!(event, Event::Keyboard(_)) && (!state.focused || !self.keyboard) {
+            return;
+        }
+        let child_cursor = if inside {
+            pointer.map_or(mouse::Cursor::Unavailable, mouse::Cursor::Available)
+        } else {
+            mouse::Cursor::Unavailable
+        };
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            child_cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+        // A semantic hit or armed creation tool gets first refusal. In Select,
+        // an otherwise unused blank press starts the same camera gesture.
+        if self.blank_pan
+            && self.keyboard
+            && inside
+            && !shell.is_event_captured()
+            && matches!(
+                event,
+                Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
+            )
+        {
+            state.pan = pointer.map(|p| (mouse::Button::Left, p));
+            shell.publish((self.publish)(CameraEvent::CancelGesture));
+            shell.capture_event();
+            shell.request_redraw();
+        }
+    }
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        renderer.with_layer(layout.bounds(), |renderer| {
+            self.content.as_widget().draw(
+                &tree.children[0],
+                renderer,
+                theme,
+                style,
+                layout,
+                cursor,
+                viewport,
+            );
+        });
+        if tree.state.downcast_ref::<Input>().focused && self.keyboard {
+            renderer.fill_quad(
+                renderer::Quad {
+                    bounds: layout.bounds(),
+                    border: Border {
+                        color: crate::style::TEAL,
+                        width: 1.,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                iced::Color::TRANSPARENT,
+            );
+        }
+    }
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        if tree.state.downcast_ref::<Input>().pan.is_some() {
+            mouse::Interaction::Grabbing
+        } else {
+            self.content.as_widget().mouse_interaction(
+                &tree.children[0],
+                layout,
+                cursor,
+                viewport,
+                renderer,
+            )
+        }
+    }
+    fn overlay<'a>(
+        &'a mut self,
+        tree: &'a mut Tree,
+        layout: Layout<'a>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'a, Message, Theme, R>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}
+impl<'a, Message: 'a, R: renderer::Renderer + 'a> From<Viewport<'a, Message, R>>
+    for Element<'a, Message, Theme, R>
+{
+    fn from(viewport: Viewport<'a, Message, R>) -> Self {
+        Element::new(viewport)
+    }
+}

crates/oa-desktop/src/behavior/creation.rs

@@ -75,6 +75,7 @@ impl Picker {
 }
 #[derive(Debug, Clone)]
 pub enum Event {
+    Source(super::source_draft::Event),
     Open(Layer),
     Choose(Family),
     Name(String),
@@ -97,6 +98,11 @@ struct Browser {
 #[derive(Clone, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 struct Draft {
+    #[serde(default)]
+    source: super::source_draft::State,
+    #[serde(default = "Id::new_v4")]
+    invocation: Id,
+
     version: u32,
     document: Id,
     layer: Layer,
@@ -125,6 +131,17 @@ pub struct Created {
 }
 
 impl State {
+    pub fn source_active(&self) -> bool {
+        self.draft.as_ref().is_some_and(|d| d.source.engaged())
+    }
+
+    pub fn source_open(&self) -> bool {
+        self.draft.as_ref().is_some_and(|d| d.source.is_open())
+    }
+    pub fn source_back(&mut self) -> bool {
+        self.draft.as_mut().is_some_and(|d| d.source.back())
+    }
+
     pub fn has_pending(&self) -> bool {
         self.draft.is_some()
     }
@@ -174,6 +191,49 @@ impl State {
             .command(p)
     }
     pub fn update(&mut self, p: &Project, event: Event) -> Result<Option<Command>, String> {
+        if let Event::Source(event) = event {
+            if self
+                .draft
+                .as_mut()
+                .ok_or("Start the consumer form first.")?
+                .source
+                .dismiss(&event)?
+            {
+                return Ok(None);
+            }
+            let d = self
+                .draft
+                .as_ref()
+                .ok_or("Start the consumer form first.")?;
+            if d.family != Some(Family::Machine) {
+                return Err("This reference does not support staged source creation.".into());
+            }
+            if d.document != p.id {
+                return Err("This behavior draft belongs to another document.".into());
+            }
+            let mut next = d.clone();
+            if let Some(id) = next.source.update(
+                p,
+                super::source_draft::Scope::Machine { layer: d.layer },
+                d.invocation,
+                event,
+            )? {
+                next.owner = Some(id);
+                let preview = next
+                    .source
+                    .preview(p, next.owner)?
+                    .ok_or("New owner preview is missing.")?;
+                if !eligible(&preview, next.layer, Picker::Owner, id) {
+                    return Err("This participant cannot own the machine.".into());
+                }
+            }
+            self.draft = Some(next);
+            return Ok(None);
+        }
+        if self.source_open() && !matches!(&event, Event::Cancel) {
+            return Err("Use the new source or go Back before editing the parent form.".into());
+        }
+
         match event {
             Event::Cancel => {
                 self.draft = None;
@@ -184,6 +244,8 @@ impl State {
                     return Err("Create or cancel the pending behavior first.".into());
                 }
                 self.draft = Some(Draft {
+                    source: Default::default(),
+                    invocation: Id::new_v4(),
                     version: 1,
                     document: p.id,
                     layer,
@@ -332,7 +394,7 @@ fn reference_context(p: &Project, e: &Element) -> String {
     };
     format!("{} · {} · {location}", e.kind(), e.alias)
 }
-fn reference_label(p: &Project, id: Id) -> String {
+pub(super) fn reference_label(p: &Project, id: Id) -> String {
     p.elements
         .get(&id)
         .map(|e| format!("{} · {}", e.name, reference_context(p, e)))
@@ -340,6 +402,15 @@ fn reference_label(p: &Project, id: Id) -> String {
 }
 impl Draft {
     fn command(&self, p: &Project) -> Result<Command, String> {
+        self.source.check_scope(
+            super::source_draft::Scope::Machine { layer: self.layer },
+            self.owner,
+        )?;
+        let preview = self.source.preview(p, self.owner)?;
+        let command = self.consumer_command(preview.as_ref().unwrap_or(p))?;
+        self.source.combine(p, self.owner, command)
+    }
+    fn consumer_command(&self, p: &Project) -> Result<Command, String> {
         if self.document != p.id {
             return Err("This draft belongs to another document.".into());
         }
@@ -475,6 +546,21 @@ impl State {
         p: &'a Project,
     ) -> Option<UiElement<'a, Event, iced::Theme, R>> {
         let d = self.draft.as_ref()?;
+        if let Some(view) = d.source.view(p) {
+            return Some(
+                column![
+                    text(format!(
+                        "State machine name: {}",
+                        crate::views::short(&d.name, 60)
+                    ))
+                    .size(12),
+                    view.map(Event::Source)
+                ]
+                .spacing(6)
+                .height(Fill)
+                .into(),
+            );
+        }
         let mut fields = column![].spacing(10);
         let title = if let Some(family) = d.family {
             fields = fields.push(
@@ -488,7 +574,7 @@ impl State {
                 Family::Sequence => {
                     fields = fields.push(
                         text(format!(
-                            "Owned by the {} layer root. Involve existing work after creation.",
+                            "Owned by the {} layer root. Add work and exchange contributions after creation.",
                             d.layer
                         ))
                         .size(12),
@@ -531,7 +617,17 @@ impl State {
                     }
                 }
                 Family::Machine => {
+                    if let Some(label) = d.source.label(d.owner) {
+                        fields = fields.push(text(label).size(13)).push(text("Create and open commits the new owner and machine together, including the first view only when selected.").size(12));
+                    }
                     fields = fields.push(picker_view(p, d, Picker::Owner));
+                    fields = fields.push(
+                        button("Create new owner…")
+                            .on_press(Event::Source(super::source_draft::Event::Open(
+                                d.invocation,
+                            )))
+                            .padding(7),
+                    );
                     fields = fields.push(
                         checkbox(d.first_view)
                             .label("Create the first state view")
@@ -544,9 +640,9 @@ impl State {
         } else {
             for family in [Family::Sequence, Family::Scenario, Family::Machine] {
                 let purpose = match family {
-                    Family::Sequence => "A path through existing work and exchanges",
+                    Family::Sequence => "A path through work and exchanges",
                     Family::Scenario => "Ordered interactions from an explicit viewpoint",
-                    Family::Machine => "States and modes of an existing participant",
+                    Family::Machine => "States and modes of an explicitly chosen participant",
                 };
                 fields = fields.push(
                     button(
@@ -616,7 +712,7 @@ fn picker_view<'a, R: iced::advanced::text::Renderer + 'a>(
     }
     if options.is_empty() {
         out = out.push(text(match picker {
-            Picker::Owner => "No matching participant. Refine the search, or cancel and create a participant in Architecture first.",
+            Picker::Owner => "No matching participant. Refine the search or choose Create new owner.",
             Picker::Context => "No matching context. Refine the search, or leave this optional reference empty.",
         }).size(12));
     }

crates/oa-desktop/src/behavior/form_session.rs

@@ -0,0 +1,148 @@
+//! Keep behavior field state within one editing session and reset it on replacement.
+use iced::advanced::widget::{Operation, Tree, tree};
+use iced::advanced::{Clipboard, Layout, Shell, Widget, layout, overlay, renderer};
+use iced::{Element, Event, Length, Rectangle, Size, Theme, Vector, mouse};
+use oa_core::Id;
+
+struct Identity(Id);
+
+struct Session<'a, Message, R: renderer::Renderer> {
+    identity: Id,
+    content: Element<'a, Message, Theme, R>,
+}
+
+pub(super) fn reset_on_change<'a, Message: 'a, R: renderer::Renderer + 'a>(
+    identity: Id,
+    content: impl Into<Element<'a, Message, Theme, R>>,
+) -> Element<'a, Message, Theme, R> {
+    Element::new(Session {
+        identity,
+        content: content.into(),
+    })
+}
+
+impl<Message, R: renderer::Renderer> Widget<Message, Theme, R> for Session<'_, Message, R> {
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<Identity>()
+    }
+
+    fn state(&self) -> tree::State {
+        tree::State::new(Identity(self.identity))
+    }
+
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        let retained = tree.state.downcast_mut::<Identity>();
+        if retained.0 != self.identity {
+            retained.0 = self.identity;
+            // Iced's keyed column preserves same-length child replacements.
+            // An editing-session replacement must instead get fresh field state.
+            tree.children = self.children();
+        } else {
+            tree.diff_children(std::slice::from_ref(&self.content));
+        }
+    }
+
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        operation: &mut dyn Operation,
+    ) {
+        self.content
+            .as_widget_mut()
+            .operate(&mut tree.children[0], layout, renderer, operation);
+    }
+
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            style,
+            layout,
+            cursor,
+            viewport,
+        );
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout,
+            cursor,
+            viewport,
+            renderer,
+        )
+    }
+
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'b>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'b, Message, Theme, R>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}

crates/oa-desktop/src/behavior/scenario.rs

@@ -4,7 +4,9 @@ use super::topology::{occurrence, unique_batch};
 use super::*;
 use iced::widget::{Column, column, text_input};
 use std::{cell::RefCell, collections::BTreeSet};
+pub(crate) mod focus;
 mod workspace;
+pub(crate) use workspace::NAME_INPUT;
 pub use workspace::{Shelf, view};
 
 #[cfg(test)]
@@ -97,7 +99,9 @@ pub enum CanvasEvent {
     Scrolled(Context, ScrollArea, iced::Vector),
     Restored(Context, Id, ScrollArea, iced::Vector),
     Viewport(Context, Size),
+    FormShown(Context, Id),
     Zoom(Context, Option<f32>),
+    Camera(Context, u64, super::canvas_workspace::Event),
     Focus(Context),
     Shelf(Context, Shelf),
     OpenUse(Context, Id),
@@ -125,8 +129,7 @@ pub enum CanvasEvent {
 }
 #[derive(Debug, Clone, Copy)]
 pub enum ScrollArea {
-    Canvas,
-    // Retained navigation channel, now the independent Selection/outline shelf.
+    // The independent Details/outline scroller; viewport motion uses Camera.
     Page,
 }
 impl CanvasEvent {
@@ -135,7 +138,9 @@ impl CanvasEvent {
             Self::Scrolled(context, _, _)
             | Self::Restored(context, ..)
             | Self::Viewport(context, _)
+            | Self::FormShown(context, _)
             | Self::Zoom(context, _)
+            | Self::Camera(context, ..)
             | Self::Focus(context)
             | Self::Shelf(context, _)
             | Self::OpenUse(context, _)
@@ -162,6 +167,7 @@ impl std::fmt::Display for Operator {
 }
 #[derive(Debug, Clone)]
 pub enum Event {
+    Source(super::source_draft::Event),
     Start(Id, Tool),
     Cancel,
     Submit,
@@ -197,11 +203,14 @@ const VALUE_PAGE_SIZE: usize = 24;
 #[derive(Default)]
 pub struct State {
     draft: Option<Draft>,
+    form_session: Id,
+    form_mount: Id,
+    form_focus_pending: bool,
     canvas_tool: Option<(Id, CanvasTool)>,
     call_choices: RefCell<Option<(CallChoiceContext, Vec<Choice>)>>,
-    scroll_offsets: [iced::Vector; 2],
+    details_offset: iced::Vector,
     return_to: Vec<Caller>,
-    restore: Option<ViewportRestore>,
+    restore: Option<DetailsRestore>,
     presentation: workspace::Presentation,
 }
 const CALLER_LIMIT: usize = 32;
@@ -211,15 +220,14 @@ pub(crate) struct Caller {
     pub occurrence: Id,
     target: Id,
     tool: CanvasTool,
-    offsets: [iced::Vector; 2],
+    details_offset: iced::Vector,
     presentation: workspace::Presentation,
 }
-struct ViewportRestore {
+struct DetailsRestore {
     document: Id,
     owner: Id,
     token: Id,
-    offsets: [iced::Vector; 2],
-    pending: [bool; 2],
+    offset: iced::Vector,
 }
 #[derive(Clone, Copy)]
 pub(super) struct ScrollRestore {
@@ -240,6 +248,13 @@ struct CallChoiceContext {
 #[derive(Clone, serde::Serialize, serde::Deserialize)]
 #[serde(deny_unknown_fields)]
 struct Draft {
+    #[serde(default)]
+    source: super::source_draft::State,
+    #[serde(default = "Id::new_v4")]
+    invocation: Id,
+    #[serde(default)]
+    source_origin: Option<(Id, oa_core::Element)>,
+
     owner: Id,
     parent: Id,
     before: Option<Id>,
@@ -272,6 +287,44 @@ struct Draft {
     choice_page: usize,
 }
 impl State {
+    pub(crate) fn camera_boundary(&self) -> impl PartialEq + use<> {
+        (
+            self.canvas_tool,
+            self.presentation.focused,
+            self.presentation.shelf,
+            self.presentation.viewport,
+            self.presentation.pan,
+            self.presentation.zoom,
+            self.presentation.fit,
+        )
+    }
+
+    pub(super) fn pending_name(&self) -> Option<&str> {
+        self.draft.as_ref().map(|d| d.name.as_str())
+    }
+    pub(super) fn source_view<'a>(&'a self, p: &'a Project) -> Option<iced::Element<'a, Event>> {
+        self.draft
+            .as_ref()?
+            .source
+            .view(p)
+            .map(|v| v.map(Event::Source))
+    }
+
+    pub fn source_active(&self) -> bool {
+        self.draft.as_ref().is_some_and(|d| d.source.engaged())
+    }
+
+    pub fn source_open(&self) -> bool {
+        self.draft.as_ref().is_some_and(|d| d.source.is_open())
+    }
+    pub fn source_back(&mut self) -> bool {
+        let returned = self.draft.as_mut().is_some_and(|d| d.source.back());
+        if returned {
+            self.remount_form();
+        }
+        returned
+    }
+
     pub(crate) fn enter(&mut self, document: Id, owner: Id) {
         if self.presentation.identity != Some((document, owner)) {
             self.presentation = workspace::Presentation {
@@ -279,16 +332,38 @@ impl State {
                 focused: self.presentation.focused,
                 ..Default::default()
             };
-            self.scroll_offsets = [iced::Vector::ZERO; 2];
+            self.details_offset = iced::Vector::ZERO;
             self.restore = None;
         }
     }
     pub(crate) fn viewport(&mut self, size: Size) -> bool {
         self.presentation.viewport(size)
     }
+    pub(crate) fn camera(&mut self, event: super::canvas_workspace::Event) -> bool {
+        let p = &mut self.presentation;
+        super::canvas_workspace::change(&mut p.pan, &mut p.zoom, &mut p.fit, event)
+    }
     pub(crate) fn zoom(&mut self, scale: Option<f32>) -> bool {
         self.presentation.zoom(scale)
     }
+    pub(crate) fn camera_zoom(&mut self, p: &Project, owner: Id, zoom: Option<f32>) -> bool {
+        let size = Scene::sequence(p, owner, owner).size;
+        let old = self.presentation.scale(size);
+        if let Some(next) = zoom {
+            let viewport = self.presentation.viewport.unwrap_or(Size::new(500., 300.));
+            self.camera(super::canvas_workspace::Event::Zoom {
+                factor: next / old,
+                at: Point::new(viewport.width / 2., viewport.height / 2.),
+                base: old,
+            })
+        } else {
+            self.zoom(None);
+            let fitted = self.presentation.scale(size);
+            self.zoom(Some(fitted));
+            self.presentation.pan = iced::Vector::ZERO;
+            true
+        }
+    }
     pub(crate) fn focused(&self) -> bool {
         self.presentation.focused
     }
@@ -317,11 +392,11 @@ impl State {
             occurrence,
             target,
             tool: self.canvas_tool(context.scenario),
-            offsets: self.scroll_offsets,
+            details_offset: self.details_offset,
             presentation: self.presentation.clone(),
         });
         self.canvas_tool = Some((target, CanvasTool::Select));
-        self.scroll_offsets = [iced::Vector::ZERO; 2];
+        self.details_offset = iced::Vector::ZERO;
         self.restore = None;
         Ok(target)
     }
@@ -348,34 +423,30 @@ impl State {
             return;
         }
         self.canvas_tool = Some((frame.owner, frame.tool));
-        self.scroll_offsets = frame.offsets;
+        self.details_offset = frame.details_offset;
         self.presentation = frame.presentation;
         self.presentation.identity = Some((context.document, context.scenario));
-        self.restore = Some(ViewportRestore {
+        self.restore = Some(DetailsRestore {
             document: context.document,
             owner: frame.owner,
             token: Id::new_v4(),
-            offsets: frame.offsets,
-            pending: [true; 2],
+            offset: frame.details_offset,
         });
     }
     pub(super) fn scroll_restore(
         &self,
         context: Context,
-        area: ScrollArea,
+        ScrollArea::Page: ScrollArea,
     ) -> Option<ScrollRestore> {
-        let index = match area {
-            ScrollArea::Canvas => 0,
-            ScrollArea::Page => 1,
-        };
-        let restore = self.restore.as_ref().filter(|r| {
-            r.document == context.document && r.owner == context.scenario && r.pending[index]
-        })?;
+        let restore = self
+            .restore
+            .as_ref()
+            .filter(|r| r.document == context.document && r.owner == context.scenario)?;
         Some(ScrollRestore {
             document: restore.document,
             owner: restore.owner,
             token: restore.token,
-            offset: restore.offsets[index],
+            offset: restore.offset,
         })
     }
     pub(crate) fn restored(
@@ -385,22 +456,12 @@ impl State {
         area: ScrollArea,
         offset: iced::Vector,
     ) -> bool {
-        let index = match area {
-            ScrollArea::Canvas => 0,
-            ScrollArea::Page => 1,
-        };
-        let Some(restore) = self.restore.as_mut().filter(|r| {
-            r.document == context.document
-                && r.owner == context.scenario
-                && r.token == token
-                && r.pending[index]
-        }) else {
+        if !self.restore.as_ref().is_some_and(|r| {
+            r.document == context.document && r.owner == context.scenario && r.token == token
+        }) {
             return false;
-        };
-        restore.pending[index] = false;
-        if !restore.pending.contains(&true) {
-            self.restore = None;
         }
+        self.restore = None;
         self.scrolled(area, offset)
     }
     pub(super) fn recovery_snapshot(&self) -> Result<Option<serde_json::Value>, String> {
@@ -413,28 +474,57 @@ impl State {
 
     pub(super) fn from_recovery(value: serde_json::Value) -> Result<Self, String> {
         let draft = serde_json::from_value(value).map_err(|e| e.to_string())?;
+        let session = Id::new_v4();
         Ok(Self {
             draft: Some(draft),
+            form_session: session,
+            form_mount: session,
+            form_focus_pending: true,
             ..Default::default()
         })
     }
 
-    pub(crate) fn scrolled(&mut self, area: ScrollArea, offset: iced::Vector) -> bool {
+    pub(crate) fn form_session(&self) -> Option<Id> {
+        self.draft.as_ref().map(|_| self.form_session)
+    }
+
+    pub(crate) fn form_mount(&self) -> Option<Id> {
+        self.draft
+            .as_ref()
+            .filter(|d| !d.source.is_open())
+            .map(|_| self.form_mount)
+    }
+
+    pub(crate) fn focus_stamp(&self, context: Context) -> Option<focus::Stamp> {
+        (self.draft.as_ref()?.owner == context.scenario).then_some(focus::Stamp::new(
+            context,
+            self.form_session,
+            self.form_mount()?,
+        ))
+    }
+
+    fn remount_form(&mut self) {
+        self.form_mount = Id::new_v4();
+        self.form_focus_pending = true;
+    }
+
+    pub(crate) fn take_form_focus(&mut self, mount: Id) -> bool {
+        if self.form_mount() == Some(mount) && self.form_focus_pending {
+            self.form_focus_pending = false;
+            true
+        } else {
+            false
+        }
+    }
+
+    pub(crate) fn scrolled(&mut self, ScrollArea::Page: ScrollArea, offset: iced::Vector) -> bool {
         if !offset.x.is_finite() || !offset.y.is_finite() || offset.x < 0. || offset.y < 0. {
             return false;
         }
-        let index = match area {
-            ScrollArea::Canvas => 0,
-            ScrollArea::Page => 1,
-        };
-        let changed = self.scroll_offsets[index] != offset;
-        self.scroll_offsets[index] = offset;
+        let changed = self.details_offset != offset;
+        self.details_offset = offset;
         changed
     }
-    fn scroll_offset(&self) -> iced::Vector {
-        // The former page scroll now belongs to a sibling outline shelf.
-        self.scroll_offsets[0]
-    }
     fn call_choices(&self, p: &Project, context: Context, draft: &Draft) -> Vec<Choice> {
         let key = CallChoiceContext {
             document: context.document,
@@ -452,8 +542,16 @@ impl State {
         }
         cached.as_ref().unwrap().1.clone()
     }
-    pub(crate) fn created_selection(&self, command: &Command) -> Option<Id> {
+    pub(crate) fn created_selection(&self, p: &Project, command: &Command) -> Option<Id> {
         let draft = self.draft.as_ref()?;
+        if self
+            .draft
+            .as_ref()
+            .is_some_and(|d| d.source.label(d.target).is_some())
+            && self.prepare_pending(p).ok().as_ref() != Some(command)
+        {
+            return None;
+        }
         fn created(command: &Command, parent: Id) -> Option<Id> {
             match command {
                 Command::CreateElement(element) if element.parent == Some(parent) => {
@@ -568,6 +666,66 @@ impl State {
     }
 
     pub fn update(&mut self, p: &Project, event: Event) -> Result<Option<Command>, String> {
+        if let Event::Source(event) = event {
+            if self
+                .draft
+                .as_mut()
+                .ok_or("Start the consumer form first.")?
+                .source
+                .dismiss(&event)?
+            {
+                self.remount_form();
+                return Ok(None);
+            }
+            let d = self
+                .draft
+                .as_ref()
+                .ok_or("Start the consumer form first.")?;
+            if d.tool != Tool::Lifeline {
+                return Err("This reference does not support staged source creation.".into());
+            }
+            if d.source_origin.as_ref().is_some_and(|(document, owner)| {
+                *document != p.id || p.elements.get(&d.owner) != Some(owner)
+            }) {
+                return Err("The original consumer changed. Cancel and reopen its form; the current draft is retained.".into());
+            }
+            if d.source_origin.is_none() && d.source.engaged() {
+                return Err("The recovered source draft has no original document binding. Go Back or cancel it.".into());
+            }
+            let mut next = d.clone();
+            if next.source_origin.is_none() && matches!(&event, super::source_draft::Event::Open(_))
+            {
+                next.source_origin = Some((
+                    p.id,
+                    p.elements
+                        .get(&d.owner)
+                        .ok_or("The consumer owner no longer exists.")?
+                        .clone(),
+                ));
+            }
+            if let Some(id) = next.source.update(
+                p,
+                super::source_draft::Scope::Lifeline {
+                    owner: d.owner,
+                    viewpoint: viewpoint(p, d.owner),
+                },
+                d.invocation,
+                event,
+            )? {
+                next.target = Some(id);
+                next.command(p)?;
+            }
+            let returned = d.source.is_open() && !next.source.is_open();
+            self.draft = Some(next);
+            if returned {
+                self.remount_form();
+            }
+            return Ok(None);
+        }
+        if self.source_open() && !matches!(&event, Event::Cancel) {
+            return Err("Use the new source or go Back before editing the parent form.".into());
+        }
+
         if self.draft.is_some() && matches!(&event, Event::Start(..)) {
             return Err(PENDING_DRAFT.into());
         }
@@ -576,7 +734,13 @@ impl State {
                 if p.elements.get(&owner).map(oa_core::Element::kind) != Some(Kind::Scenario) {
                     return Err("Choose a scenario.".into());
                 }
+                self.form_session = Id::new_v4();
+                self.form_mount = self.form_session;
+                self.form_focus_pending = true;
                 self.draft = Some(Draft {
+                    source: Default::default(),
+                    invocation: Id::new_v4(),
+                    source_origin: Some((p.id, p.elements[&owner].clone())),
                     owner,
                     parent: owner,
                     before: None,
@@ -940,7 +1104,14 @@ fn valid_body_choice(p: &Project, owner: Id, body: OccurrenceBody) -> bool {
     execute_batch(p, &[Command::CreateElement(e)]).is_ok()
 }
 fn sources(p: &Project, d: &Draft) -> Vec<Choice> {
-    let layer = p.elements[&d.owner].layer();
+    let Some(owner) = p
+        .elements
+        .get(&d.owner)
+        .filter(|e| e.kind() == Kind::Scenario)
+    else {
+        return vec![];
+    };
+    let layer = owner.layer();
     let mut values: Vec<_> = p
         .elements
         .values()
@@ -1256,6 +1427,28 @@ impl Draft {
         e
     }
     fn command(&self, p: &Project) -> Result<Command, String> {
+        if self.source.engaged()
+            && self.source_origin.as_ref().is_none_or(|(document, owner)| {
+                *document != p.id || p.elements.get(&self.owner) != Some(owner)
+            })
+        {
+            return Err("The original consumer document or owner changed. Cancel and reopen its form; your draft is retained.".into());
+        }
+        self.source.check_scope(
+            super::source_draft::Scope::Lifeline {
+                owner: self.owner,
+                viewpoint: viewpoint(p, self.owner),
+            },
+            self.target,
+        )?;
+        let preview = self.source.preview(p, self.target)?;
+        let command = self.consumer_command(preview.as_ref().unwrap_or(p))?;
+        self.source.combine(p, self.target, command)
+    }
+    fn consumer_command(&self, p: &Project) -> Result<Command, String> {
+        if p.elements.get(&self.owner).map(oa_core::Element::kind) != Some(Kind::Scenario) {
+            return Err("The scenario no longer exists. Cancel or restore its owner.".into());
+        }
         if !parents(p, self.owner).iter().any(|c| c.id == self.parent) {
             return Err("Choose this scenario or one of its operands as destination.".into());
         }
@@ -1266,6 +1459,8 @@ impl Draft {
             .unwrap_or(self.tool.label());
         let name = if self.name.trim().is_empty() {
             default
+        } else if self.source.label(self.target).is_some() {
+            self.name.as_str()
         } else {
             self.name.trim()
         };
@@ -1857,20 +2052,31 @@ pub(crate) mod direct_tests {
             navigation_event(&mut app, |ctx| {
                 CanvasEvent::Choose(ctx, CanvasTool::Add(Tool::Reuse))
             });
+            navigation_event(&mut app, |ctx| CanvasEvent::Zoom(ctx, None));
+            let camera_epoch = app.camera_epoch;
             navigation_event(&mut app, |ctx| {
-                CanvasEvent::Scrolled(ctx, ScrollArea::Canvas, iced::Vector::new(25., 170.))
+                CanvasEvent::Camera(
+                    ctx,
+                    camera_epoch,
+                    super::super::canvas_workspace::Event::Pan(iced::Vector::new(25., 170.)),
+                )
             });
             navigation_event(&mut app, |ctx| {
                 CanvasEvent::Scrolled(ctx, ScrollArea::Page, iced::Vector::new(0., 80.))
             });
             navigation_event(&mut app, |ctx| CanvasEvent::OpenUse(ctx, caller));
             assert_eq!(app.selected, b);
-            assert_eq!(app.behavior.scenario.scroll_offset(), iced::Vector::ZERO);
+            assert_eq!(app.behavior.scenario.presentation.pan, iced::Vector::ZERO);
             navigation_event(&mut app, |ctx| {
                 CanvasEvent::Choose(ctx, CanvasTool::Message(MessageStyle::Timer))
             });
+            let camera_epoch = app.camera_epoch;
             navigation_event(&mut app, |ctx| {
-                CanvasEvent::Scrolled(ctx, ScrollArea::Canvas, iced::Vector::new(0., 115.))
+                CanvasEvent::Camera(
+                    ctx,
+                    camera_epoch,
+                    super::super::canvas_workspace::Event::Pan(iced::Vector::new(0., 115.)),
+                )
             });
             navigation_event(&mut app, |ctx| CanvasEvent::OpenUse(ctx, nested));
             assert_eq!(app.selected, c);
@@ -1881,7 +2087,7 @@ pub(crate) mod direct_tests {
                 CanvasTool::Message(MessageStyle::Timer)
             );
             assert_eq!(
-                app.behavior.scenario.scroll_offset(),
+                app.behavior.scenario.presentation.pan,
                 iced::Vector::new(0., 115.)
             );
             navigation_event(&mut app, CanvasEvent::Back);
@@ -1892,11 +2098,11 @@ pub(crate) mod direct_tests {
                 CanvasTool::Add(Tool::Reuse)
             );
             assert_eq!(
-                app.behavior.scenario.scroll_offset(),
+                app.behavior.scenario.presentation.pan,
                 iced::Vector::new(25., 170.)
             );
             assert_eq!(
-                app.behavior.scenario.scroll_offsets[1],
+                app.behavior.scenario.details_offset,
                 iced::Vector::new(0., 80.),
                 "The caller's independent outline scroll is restored separately"
             );
@@ -2074,22 +2280,24 @@ pub(crate) mod direct_tests {
                     let before = app.document.bundle().clone();
                     let mut scene = Scene::sequence(app.project(), f.owner, f.call);
                     scene.interaction = Some((context, CanvasTool::Add(tool), true));
-                    scene.scroll_offset = iced::Vector::new(23., 80.);
-                    let bounds = Rectangle::new(Point::new(20., 40.), scene.size);
+                    scene.camera_pan = iced::Vector::new(23., 80.);
+                    let bounds = Rectangle::new(
+                        Point::new(20., 40.),
+                        Size::new(scene.size.width + 46., scene.size.height + 160.),
+                    );
                     let y = scene.slots.iter().find(|s| s.slot == slot).unwrap().y;
                     let x = if on_lifeline {
                         scene.lanes[&f.sender]
                     } else {
                         scene.size.width - 35.
                     };
-                    let point = Point::new(bounds.x + x, bounds.y + y);
+                    let point = Point::new(bounds.x + x, bounds.y + y) + scene.camera_pan;
+                    assert!(bounds.contains(point));
                     let mut input = SequenceInput::default();
                     canvas_mouse(
                         &scene,
                         &mut input,
-                        mouse::Event::CursorMoved {
-                            position: point - scene.scroll_offset,
-                        },
+                        mouse::Event::CursorMoved { position: point },
                         point,
                         bounds,
                     );
@@ -2265,10 +2473,10 @@ pub(crate) mod direct_tests {
             assert!(!app.behavior.has_pending());
         }
         let old_context = app.scenario_context().unwrap();
-        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Scrolled(
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Camera(
             old_context,
-            ScrollArea::Canvas,
-            iced::Vector::new(0., 100.),
+            app.camera_epoch,
+            super::super::canvas_workspace::Event::Pan(iced::Vector::new(0., 100.)),
         )));
         let _ = app.update(Message::ScenarioCanvas(event(old_context)));
         assert!(!app.behavior.has_pending());
@@ -2459,26 +2667,29 @@ pub(crate) mod direct_tests {
         );
     }
     #[test]
-    fn direct_busy_save_keeps_observed_scroll_current_for_the_next_pointer_gesture() {
+    fn direct_busy_save_keeps_details_current_and_camera_for_the_next_pointer_gesture() {
         let f = fixture();
         let mut app = App::with_project(f.project.clone());
         let _ = app.update(Message::Select(f.owner));
         let _ = app.update(Message::Page(crate::app::Page::Behavior));
         let context = app.scenario_context().unwrap();
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Camera(
+            context,
+            app.camera_epoch,
+            super::super::canvas_workspace::Event::Pan(iced::Vector::new(-25., -100.)),
+        )));
+        let context = app.scenario_context().unwrap();
         let original = app.document.snapshot();
         app.busy = true;
-        for (area, offset) in [
-            (ScrollArea::Canvas, iced::Vector::new(25., 100.)),
-            (ScrollArea::Page, iced::Vector::new(0., 40.)),
-        ] {
-            let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Scrolled(
-                context, area, offset,
-            )));
-        }
+        let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Scrolled(
+            context,
+            ScrollArea::Page,
+            iced::Vector::new(0., 40.),
+        )));
         assert!(app.busy);
         assert_eq!(
-            app.behavior.scenario.scroll_offset(),
-            iced::Vector::new(25., 100.)
+            app.behavior.scenario.details_offset,
+            iced::Vector::new(0., 40.)
         );
         assert_ne!(
             app.scenario_context(),
@@ -2489,14 +2700,14 @@ pub(crate) mod direct_tests {
         stale.document = Id::new_v4();
         let _ = app.update(Message::ScenarioCanvas(CanvasEvent::Scrolled(
             stale,
-            ScrollArea::Canvas,
+            ScrollArea::Page,
             iced::Vector::new(0., 900.),
         )));
         assert_eq!(
-            app.behavior.scenario.scroll_offset(),
-            iced::Vector::new(25., 100.)
+            app.behavior.scenario.details_offset,
+            iced::Vector::new(0., 40.)
         );
-        let root = std::path::PathBuf::from("scenario-scroll-save-fixture");
+        let root = std::path::PathBuf::from("scenario-details-save-fixture");
         let receipt = crate::app::FileSnapshot {
             document: context.document,
             revision: context.revision,
@@ -2517,12 +2728,17 @@ pub(crate) mod direct_tests {
         let context = app.scenario_context().unwrap();
         let mut scene = Scene::sequence(app.project(), f.owner, f.call);
         scene.interaction = Some((context, CanvasTool::Message(MessageStyle::CallReply), true));
-        scene.scroll_offset = app.behavior.scenario.scroll_offset();
+        assert_eq!(
+            app.behavior.scenario.presentation.pan,
+            iced::Vector::new(-25., -100.)
+        );
+        scene.camera_pan = app.behavior.scenario.presentation.pan;
         let slot = scene.slots.last().unwrap().slot;
         let bounds = Rectangle::new(Point::new(20., 250.), scene.size);
         let y = bounds.y + scene.slots.last().unwrap().y;
-        let a = Point::new(bounds.x + scene.lanes[&f.sender], y) - scene.scroll_offset;
-        let b = Point::new(bounds.x + scene.lanes[&f.receiver], y) - scene.scroll_offset;
+        let a = Point::new(bounds.x + scene.lanes[&f.sender], y) + scene.camera_pan;
+        let b = Point::new(bounds.x + scene.lanes[&f.receiver], y) + scene.camera_pan;
+        assert!(bounds.contains(a) && bounds.contains(b));
         let mut input = super::super::SequenceInput::default();
         let mut published = vec![];
         for event in [
@@ -2536,7 +2752,7 @@ pub(crate) mod direct_tests {
                 &mut input,
                 &canvas::Event::Mouse(event),
                 bounds,
-                mouse::Cursor::Available(b + scene.scroll_offset),
+                mouse::Cursor::Available(b),
             )
             .and_then(|action| action.into_inner().0)
             {

crates/oa-desktop/src/behavior/scenario/focus.rs

@@ -0,0 +1,334 @@
+//! A delayed focus request must still own the live parent tree when executed.
+//! Collect first: a missing target must not unfocus unrelated fields.
+use super::Context;
+use iced::advanced::widget::{Id, Operation, Tree, operation};
+use iced::advanced::{Clipboard, Layout, Shell, Widget, layout, overlay, renderer};
+use iced::{Element, Event, Length, Rectangle, Size, Task, Theme, Vector, mouse};
+use oa_core::Id as ModelId;
+use std::collections::BTreeMap;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) struct Stamp {
+    document: ModelId,
+    owner: ModelId,
+    revision: u64,
+    session: ModelId,
+    mount: ModelId,
+}
+impl Stamp {
+    pub(crate) fn new(context: Context, session: ModelId, mount: ModelId) -> Self {
+        Self {
+            document: context.document,
+            owner: context.scenario,
+            revision: context.revision,
+            session,
+            mount,
+        }
+    }
+}
+pub(crate) fn name_id(stamp: Stamp) -> Id {
+    Id::from(format!(
+        "{}:{}:{}:{}:{}:{}",
+        super::NAME_INPUT,
+        stamp.document,
+        stamp.owner,
+        stamp.revision,
+        stamp.session,
+        stamp.mount
+    ))
+}
+struct Owner(Option<Stamp>);
+struct Root<'a, Message, R: renderer::Renderer> {
+    content: Element<'a, Message, Theme, R>,
+    owner: Option<Stamp>,
+}
+pub(crate) fn root<'a, Message: 'a, R: renderer::Renderer + 'a>(
+    content: impl Into<Element<'a, Message, Theme, R>>,
+    owner: Option<Stamp>,
+) -> Element<'a, Message, Theme, R> {
+    Element::new(Root {
+        content: content.into(),
+        owner,
+    })
+}
+impl<Message, R: renderer::Renderer> Widget<Message, Theme, R> for Root<'_, Message, R> {
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+    fn diff(&self, tree: &mut Tree) {
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        op: &mut dyn Operation,
+    ) {
+        // This is computed from the current App view, never retained widget state.
+        op.custom(None, layout.bounds(), &mut Owner(self.owner));
+        self.content
+            .as_widget_mut()
+            .operate(&mut tree.children[0], layout, renderer, op);
+    }
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            style,
+            layout,
+            cursor,
+            viewport,
+        );
+    }
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout,
+            cursor,
+            viewport,
+            renderer,
+        )
+    }
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'b>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'b, Message, Theme, R>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}
+
+#[derive(Clone)]
+struct Scroll {
+    index: usize,
+    bounds: Rectangle,
+    capacity: Vector,
+    offset: Vector,
+}
+struct Collect {
+    stamp: Stamp,
+    valid: bool,
+    translation: Vector,
+    scrolls: Vec<Scroll>,
+    pending: Option<Scroll>,
+    index: usize,
+    target: Option<(Rectangle, Vec<Scroll>)>,
+}
+pub(crate) fn task<Message: Send + 'static>(stamp: Stamp) -> Task<Message> {
+    iced::advanced::widget::operate(Collect {
+        stamp,
+        valid: false,
+        translation: Vector::ZERO,
+        scrolls: vec![],
+        pending: None,
+        index: 0,
+        target: None,
+    })
+    .discard()
+}
+impl Operation for Collect {
+    fn custom(&mut self, _: Option<&Id>, _: Rectangle, state: &mut dyn std::any::Any) {
+        if let Some(owner) = state.downcast_ref::<Owner>() {
+            self.valid = owner.0 == Some(self.stamp);
+        }
+    }
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        let previous = (self.translation, self.scrolls.len());
+        if let Some(scroll) = self.pending.take() {
+            self.translation += scroll.offset;
+            self.scrolls.push(scroll);
+        }
+        visit(self);
+        self.translation = previous.0;
+        self.scrolls.truncate(previous.1);
+    }
+    fn scrollable(
+        &mut self,
+        _: Option<&Id>,
+        bounds: Rectangle,
+        content: Rectangle,
+        offset: Vector,
+        _: &mut dyn operation::Scrollable,
+    ) {
+        self.pending = Some(Scroll {
+            index: self.index,
+            bounds: translated(bounds, self.translation),
+            capacity: Vector::new(
+                (content.width - bounds.width).max(0.),
+                (content.height - bounds.height).max(0.),
+            ),
+            offset,
+        });
+        self.index += 1;
+    }
+    fn focusable(&mut self, id: Option<&Id>, bounds: Rectangle, _: &mut dyn operation::Focusable) {
+        if id == Some(&name_id(self.stamp)) {
+            self.target = Some((translated(bounds, self.translation), self.scrolls.clone()));
+        }
+    }
+    fn finish(&self) -> operation::Outcome<()> {
+        if !self.valid {
+            return operation::Outcome::None;
+        }
+        let Some((mut bounds, ancestors)) = self.target.clone() else {
+            return operation::Outcome::None;
+        };
+        let mut shifts = BTreeMap::new();
+        for ancestor in ancestors.iter().rev() {
+            let dx = reveal(
+                bounds.x,
+                bounds.width,
+                ancestor.bounds.x,
+                ancestor.bounds.width,
+            );
+            let dy = reveal(
+                bounds.y,
+                bounds.height,
+                ancestor.bounds.y,
+                ancestor.bounds.height,
+            );
+            // Drawing offsets are rounded; an already-visible axis must not
+            // acquire a scroll delta from a fractional capacity alone.
+            let delta = Vector::new(
+                if dx == 0. {
+                    0.
+                } else {
+                    (ancestor.offset.x + dx).clamp(0., ancestor.capacity.x) - ancestor.offset.x
+                },
+                if dy == 0. {
+                    0.
+                } else {
+                    (ancestor.offset.y + dy).clamp(0., ancestor.capacity.y) - ancestor.offset.y
+                },
+            );
+            if delta != Vector::ZERO {
+                shifts.insert(ancestor.index, delta);
+            }
+            bounds = translated(bounds, delta);
+        }
+        operation::Outcome::Chain(Box::new(Apply {
+            stamp: self.stamp,
+            valid: false,
+            shifts,
+            index: 0,
+        }))
+    }
+}
+fn translated(bounds: Rectangle, delta: Vector) -> Rectangle {
+    Rectangle {
+        x: bounds.x - delta.x,
+        y: bounds.y - delta.y,
+        ..bounds
+    }
+}
+fn reveal(start: f32, length: f32, viewport: f32, size: f32) -> f32 {
+    if start < viewport || length > size {
+        start - viewport
+    } else {
+        (start + length - viewport - size).max(0.)
+    }
+}
+struct Apply {
+    stamp: Stamp,
+    valid: bool,
+    shifts: BTreeMap<usize, Vector>,
+    index: usize,
+}
+impl Operation for Apply {
+    fn custom(&mut self, _: Option<&Id>, _: Rectangle, state: &mut dyn std::any::Any) {
+        if let Some(owner) = state.downcast_ref::<Owner>() {
+            self.valid = owner.0 == Some(self.stamp);
+        }
+    }
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        visit(self);
+    }
+    fn focusable(&mut self, id: Option<&Id>, _: Rectangle, state: &mut dyn operation::Focusable) {
+        if self.valid {
+            if id == Some(&name_id(self.stamp)) {
+                state.focus();
+            } else {
+                state.unfocus();
+            }
+        }
+    }
+    fn scrollable(
+        &mut self,
+        _: Option<&Id>,
+        bounds: Rectangle,
+        content: Rectangle,
+        _: Vector,
+        state: &mut dyn operation::Scrollable,
+    ) {
+        if self.valid
+            && let Some(delta) = self.shifts.get(&self.index)
+        {
+            state.scroll_by(
+                operation::scrollable::AbsoluteOffset {
+                    x: delta.x,
+                    y: delta.y,
+                },
+                bounds,
+                content,
+            );
+        }
+        self.index += 1;
+    }
+}

crates/oa-desktop/src/behavior/scenario_lifecycle.rs

@@ -0,0 +1,283 @@
+//! Read-only lifecycle geometry. Operand screen order is never execution order.
+use oa_core::{FragmentOperator, Id, Kind, MessageKind, OccurrenceBody, Project, SharedBody};
+use std::collections::{BTreeMap, BTreeSet};
+
+/// Maps already recorded by the sequence renderer. Rows carry their owning sequence.
+pub(crate) struct Geometry<'a> {
+    pub rows: &'a BTreeMap<Id, (Id, f32)>,
+    pub scopes: &'a BTreeMap<Id, (f32, f32)>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub(crate) struct Span {
+    pub start: f32,
+    pub end: f32,
+}
+impl Span {
+    fn valid(self) -> bool {
+        self.start.is_finite() && self.end.is_finite() && self.start <= self.end
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum Life {
+    Alive,
+    Absent,
+    Unresolved,
+}
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub(crate) struct Interval {
+    pub scope: Id,
+    pub span: Span,
+    pub life: Life,
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum MarkerKind {
+    Birth,
+    Death,
+}
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub(crate) struct Marker {
+    pub occurrence: Id,
+    pub scope: Id,
+    pub y: f32,
+    pub kind: MarkerKind,
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum UncertaintyReason {
+    Conditional,
+    Repeated,
+    Parallel,
+    MissingGeometry,
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) struct Uncertainty {
+    pub scope: Id,
+    pub reason: UncertaintyReason,
+}
+#[derive(Debug, Clone, PartialEq)]
+pub(crate) struct LaneLifetime {
+    pub lifeline: Id,
+    pub intervals: Vec<Interval>,
+    pub markers: Vec<Marker>,
+    pub uncertainties: Vec<Uncertainty>,
+}
+
+/// Stable lane-ID order; source/model/history and caller-owned geometry are untouched.
+/// An opaque ScenarioUse is a local use, not a caller birth/death contract.
+pub(crate) fn project_lifetimes(
+    project: &Project,
+    scenario: Id,
+    geometry: &Geometry<'_>,
+) -> Vec<LaneLifetime> {
+    if project
+        .elements
+        .get(&scenario)
+        .is_none_or(|e| e.kind() != Kind::Scenario)
+    {
+        return vec![];
+    }
+    project
+        .elements
+        .values()
+        .filter(|e| e.kind() == Kind::Lifeline && e.parent == Some(scenario))
+        .map(|e| {
+            let mut projection = Projection {
+                project,
+                geometry,
+                lane: e.id,
+                visiting: BTreeSet::new(),
+                result: LaneLifetime {
+                    lifeline: e.id,
+                    intervals: vec![],
+                    markers: vec![],
+                    uncertainties: vec![],
+                },
+            };
+            let initial = if projection.contains(scenario, Some(MarkerKind::Birth)) {
+                Life::Unresolved
+            } else {
+                Life::Alive
+            };
+            projection.sequence(scenario, initial);
+            projection.result
+        })
+        .collect()
+}
+
+struct Projection<'a, 'g> {
+    project: &'a Project,
+    geometry: &'a Geometry<'g>,
+    lane: Id,
+    visiting: BTreeSet<Id>,
+    result: LaneLifetime,
+}
+impl Projection<'_, '_> {
+    fn body(&self, id: Id) -> Option<&OccurrenceBody> {
+        match self.project.elements.get(&id)?.shared()? {
+            SharedBody::Occurrence { body, .. } => Some(body),
+            _ => None,
+        }
+    }
+    fn event(&self, id: Id) -> Option<MarkerKind> {
+        match self.body(id)? {
+            OccurrenceBody::Exchange {
+                receiver: Some(line),
+                message_kind,
+                ..
+            } if *line == self.lane => match message_kind {
+                MessageKind::Create => Some(MarkerKind::Birth),
+                MessageKind::Delete => Some(MarkerKind::Death),
+                _ => None,
+            },
+            _ => None,
+        }
+    }
+    fn contains(&self, scope: Id, kind: Option<MarkerKind>) -> bool {
+        // Local structural walk only: no guards, iteration simulation or reuse expansion.
+        let mut pending = vec![scope];
+        let mut seen = BTreeSet::new();
+        while let Some(id) = pending.pop() {
+            if !seen.insert(id) {
+                continue;
+            }
+            if self
+                .event(id)
+                .is_some_and(|event| kind.is_none_or(|k| event == k))
+            {
+                return true;
+            }
+            if let Some(steps) = self.project.elements.get(&id).and_then(|e| e.steps()) {
+                pending.extend(steps);
+            }
+            if let Some(OccurrenceBody::Fragment { branches, .. }) = self.body(id) {
+                pending.extend(branches);
+            }
+        }
+        false
+    }
+    fn span(&self, scope: Id) -> Option<Span> {
+        let &(start, end) = self.geometry.scopes.get(&scope)?;
+        let span = Span { start, end };
+        span.valid().then_some(span)
+    }
+    fn uncertain(&mut self, scope: Id, reason: UncertaintyReason) {
+        let value = Uncertainty { scope, reason };
+        if !self.result.uncertainties.contains(&value) {
+            self.result.uncertainties.push(value);
+        }
+    }
+    fn interval(&mut self, scope: Id, start: f32, end: f32, life: Life) {
+        if start < end && start.is_finite() && end.is_finite() {
+            self.result.intervals.push(Interval {
+                scope,
+                span: Span { start, end },
+                life,
+            });
+        }
+    }
+    fn sequence(&mut self, scope: Id, entry: Life) -> Life {
+        let Some(span) = self.span(scope) else {
+            self.uncertain(scope, UncertaintyReason::MissingGeometry);
+            return Life::Unresolved;
+        };
+        if !self.visiting.insert(scope) {
+            self.uncertain(scope, UncertaintyReason::MissingGeometry);
+            return Life::Unresolved;
+        }
+        let steps = self
+            .project
+            .elements
+            .get(&scope)
+            .and_then(|e| e.steps())
+            .cloned()
+            .unwrap_or_default();
+        // A creation directly in this sequence fixes its local birth boundary.
+        // A creation only in a nested operand cannot fix its ancestor's entry.
+        let mut life = if steps
+            .iter()
+            .any(|&id| self.event(id) == Some(MarkerKind::Birth))
+        {
+            Life::Absent
+        } else {
+            entry
+        };
+        let mut cursor = span.start;
+        for id in steps {
+            let event = self.event(id);
+            let fragment = match self.body(id) {
+                Some(OccurrenceBody::Fragment { operator, branches }) => {
+                    Some((*operator, branches.clone()))
+                }
+                _ => None,
+            };
+            if event.is_none() && fragment.is_none() {
+                continue;
+            }
+            let y = self
+                .geometry
+                .rows
+                .get(&id)
+                .filter(|(owner, y)| {
+                    *owner == scope && y.is_finite() && *y >= cursor && *y <= span.end
+                })
+                .map(|(_, y)| *y);
+            let Some(y) = y else {
+                self.uncertain(id, UncertaintyReason::MissingGeometry);
+                life = Life::Unresolved;
+                continue;
+            };
+            self.interval(scope, cursor, y, life);
+            cursor = y;
+            if let Some(kind) = event {
+                self.result.markers.push(Marker {
+                    occurrence: id,
+                    scope,
+                    y,
+                    kind,
+                });
+                life = match kind {
+                    MarkerKind::Birth => Life::Alive,
+                    MarkerKind::Death => Life::Absent,
+                };
+            }
+            if let Some((operator, branches)) = fragment {
+                let entry = life;
+                let mut missing = false;
+                for branch in branches {
+                    let bounds = self
+                        .span(branch)
+                        .filter(|s| s.start >= cursor && s.end <= span.end);
+                    if let Some(bounds) = bounds {
+                        // Every sibling inherits the same entry, never its displayed predecessor's exit.
+                        self.sequence(branch, entry);
+                        cursor = bounds.end;
+                    } else {
+                        self.uncertain(branch, UncertaintyReason::MissingGeometry);
+                        missing = true;
+                    }
+                }
+                if self.contains(id, None) {
+                    let reason = match operator {
+                        FragmentOperator::Alternative | FragmentOperator::Optional => {
+                            UncertaintyReason::Conditional
+                        }
+                        FragmentOperator::Loop => UncertaintyReason::Repeated,
+                        FragmentOperator::Parallel => UncertaintyReason::Parallel,
+                    };
+                    self.uncertain(id, reason);
+                    life = Life::Unresolved;
+                } else if missing {
+                    life = Life::Unresolved;
+                }
+            }
+        }
+        self.interval(scope, cursor, span.end, life);
+        self.visiting.remove(&scope);
+        life
+    }
+}
+
+#[cfg(test)]
+#[path = "scenario_lifecycle/tests.rs"]
+mod tests;

crates/oa-desktop/src/behavior/scenario_lifecycle/tests.rs

@@ -0,0 +1,470 @@
+use super::*;
+use oa_core::*;
+
+struct Fixture {
+    p: Project,
+    owner: Id,
+    a: Id,
+    b: Id,
+    exchange: Id,
+    rows: BTreeMap<Id, (Id, f32)>,
+    scopes: BTreeMap<Id, (f32, f32)>,
+}
+impl Fixture {
+    fn new(layer: Layer) -> Self {
+        let mut p = Project::empty();
+        let kind = if layer == Layer::Oa {
+            Kind::Activity
+        } else {
+            Kind::Function
+        };
+        let a = p.add_element(kind, layer, "Request", None).unwrap();
+        let b = p.add_element(kind, layer, "Provide", None).unwrap();
+        let owner = p
+            .add_element(Kind::Scenario, layer, "Lifecycle", None)
+            .unwrap();
+        let exchange = p.relate(
+            if layer == Layer::Oa {
+                RelationKind::Interaction
+            } else {
+                RelationKind::FunctionalExchange
+            },
+            "Service",
+            a,
+            b,
+        );
+        let line = |p: &mut Project, represented| {
+            let id = p
+                .add_element(Kind::Lifeline, layer, "Participant", Some(owner))
+                .unwrap();
+            *p.elements.get_mut(&id).unwrap().shared_mut().unwrap() = SharedBody::Lifeline {
+                represented: Some(represented),
+            };
+            id
+        };
+        let a = line(&mut p, a);
+        let b = line(&mut p, b);
+        Self {
+            p,
+            owner,
+            a,
+            b,
+            exchange,
+            rows: BTreeMap::new(),
+            scopes: [(owner, (0., 600.))].into(),
+        }
+    }
+    fn occurrence(&mut self, owner: Id, y: f32, body: OccurrenceBody) -> Id {
+        let mut e = self
+            .p
+            .make_element(
+                Kind::Occurrence,
+                self.p.elements[&owner].layer(),
+                "Occurrence",
+                Some(owner),
+            )
+            .unwrap();
+        let id = e.id;
+        *e.shared_mut().unwrap() = SharedBody::Occurrence {
+            body,
+            precondition: String::new(),
+            postcondition: String::new(),
+        };
+        self.p.elements.insert(id, e);
+        if let Some(steps) = self.p.elements.get_mut(&owner).unwrap().steps_mut() {
+            steps.push(id);
+        } else if let Some(SharedBody::Occurrence {
+            body: OccurrenceBody::Fragment { branches, .. },
+            ..
+        }) = self.p.elements.get_mut(&owner).unwrap().shared_mut()
+        {
+            branches.push(id);
+        }
+        self.rows.insert(id, (owner, y));
+        id
+    }
+    fn message(&mut self, owner: Id, y: f32, kind: MessageKind) -> Id {
+        self.occurrence(
+            owner,
+            y,
+            OccurrenceBody::Exchange {
+                exchange: Some(self.exchange),
+                sender: Some(self.a),
+                receiver: Some(self.b),
+                message_kind: kind,
+                operation: None,
+                reply_to: None,
+                values: vec![],
+            },
+        )
+    }
+    fn fragment(&mut self, owner: Id, y: f32, operator: FragmentOperator) -> Id {
+        self.occurrence(
+            owner,
+            y,
+            OccurrenceBody::Fragment {
+                operator,
+                branches: vec![],
+            },
+        )
+    }
+    fn branch(&mut self, fragment: Id, start: f32, end: f32) -> Id {
+        let id = self.occurrence(
+            fragment,
+            start,
+            OccurrenceBody::Branch {
+                guard: "condition".into(),
+                occurrences: vec![],
+            },
+        );
+        self.scopes.insert(id, (start, end));
+        id
+    }
+    fn project(&self) -> Vec<LaneLifetime> {
+        let errors: Vec<_> = validation::validate(&self.p)
+            .into_iter()
+            .filter(|i| i.severity == validation::Severity::Error)
+            .collect();
+        assert!(
+            errors.is_empty(),
+            "fixture must be ordinarily admitted: {errors:?}"
+        );
+        let before = self.p.clone();
+        let source = source_project::format_bundle(&self.p);
+        let geometry = Geometry {
+            rows: &self.rows,
+            scopes: &self.scopes,
+        };
+        let result = project_lifetimes(&self.p, self.owner, &geometry);
+        assert_eq!(result, project_lifetimes(&self.p, self.owner, &geometry));
+        assert_eq!(self.p, before);
+        assert_eq!(source_project::format_bundle(&self.p), source);
+        assert!(
+            result
+                .windows(2)
+                .all(|pair| pair[0].lifeline < pair[1].lifeline)
+        );
+        result
+    }
+    fn lane(&self) -> LaneLifetime {
+        self.project()
+            .into_iter()
+            .find(|lane| lane.lifeline == self.b)
+            .unwrap()
+    }
+}
+fn intervals(lane: &LaneLifetime, scope: Id) -> Vec<(f32, f32, Life)> {
+    lane.intervals
+        .iter()
+        .filter(|i| i.scope == scope)
+        .map(|i| (i.span.start, i.span.end, i.life))
+        .collect()
+}
+
+#[test]
+fn root_lifetime_has_exact_birth_death_boundaries_without_source_mutation() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let mut f = Fixture::new(layer);
+        let create = f.message(f.owner, 100., MessageKind::Create);
+        f.message(f.owner, 200., MessageKind::Asynchronous);
+        let delete = f.message(f.owner, 300., MessageKind::Delete);
+        let lane = f.lane();
+        assert_eq!(
+            intervals(&lane, f.owner),
+            vec![
+                (0., 100., Life::Absent),
+                (100., 300., Life::Alive),
+                (300., 600., Life::Absent)
+            ]
+        );
+        assert_eq!(
+            lane.markers,
+            vec![
+                Marker {
+                    occurrence: create,
+                    scope: f.owner,
+                    y: 100.,
+                    kind: MarkerKind::Birth
+                },
+                Marker {
+                    occurrence: delete,
+                    scope: f.owner,
+                    y: 300.,
+                    kind: MarkerKind::Death
+                },
+            ]
+        );
+        let sender = f
+            .project()
+            .into_iter()
+            .find(|lane| lane.lifeline == f.a)
+            .unwrap();
+        assert_eq!(intervals(&sender, f.owner), vec![(0., 600., Life::Alive)]);
+    }
+}
+
+#[test]
+fn alternative_death_does_not_kill_its_displayed_sibling() {
+    let mut f = Fixture::new(Layer::Sa);
+    let fragment = f.fragment(f.owner, 100., FragmentOperator::Alternative);
+    let left = f.branch(fragment, 120., 250.);
+    let right = f.branch(fragment, 300., 450.);
+    f.message(left, 200., MessageKind::Delete);
+    f.message(right, 350., MessageKind::Asynchronous);
+    let lane = f.lane();
+    assert_eq!(
+        intervals(&lane, left),
+        vec![(120., 200., Life::Alive), (200., 250., Life::Absent)]
+    );
+    assert_eq!(intervals(&lane, right), vec![(300., 450., Life::Alive)]);
+    assert_eq!(
+        intervals(&lane, f.owner),
+        vec![(0., 100., Life::Alive), (450., 600., Life::Unresolved)]
+    );
+    assert_eq!(
+        lane.uncertainties,
+        vec![Uncertainty {
+            scope: fragment,
+            reason: UncertaintyReason::Conditional
+        }]
+    );
+}
+
+#[test]
+fn conditional_birth_does_not_infer_absence_in_siblings_or_ancestors() {
+    for operator in [FragmentOperator::Alternative, FragmentOperator::Optional] {
+        let mut f = Fixture::new(Layer::Oa);
+        let fragment = f.fragment(f.owner, 100., operator);
+        let left = f.branch(fragment, 120., 250.);
+        let right = f.branch(fragment, 300., 450.);
+        f.message(left, 200., MessageKind::Create);
+        let lane = f.lane();
+        assert_eq!(
+            intervals(&lane, left),
+            vec![(120., 200., Life::Absent), (200., 250., Life::Alive)]
+        );
+        assert_eq!(
+            intervals(&lane, right),
+            vec![(300., 450., Life::Unresolved)]
+        );
+        assert_eq!(
+            intervals(&lane, f.owner),
+            vec![(0., 100., Life::Unresolved), (450., 600., Life::Unresolved)]
+        );
+    }
+}
+
+#[test]
+fn loop_lifetime_is_local_and_warning_bearing_loops_remain_drawable() {
+    for balanced in [true, false] {
+        let mut f = Fixture::new(Layer::Sa);
+        let fragment = f.fragment(f.owner, 100., FragmentOperator::Loop);
+        let iteration = f.branch(fragment, 120., 450.);
+        let create = f.message(iteration, 160., MessageKind::Create);
+        f.message(iteration, 250., MessageKind::Asynchronous);
+        if balanced {
+            f.message(iteration, 350., MessageKind::Delete);
+        }
+        let lane = f.lane();
+        assert_eq!(lane.markers.len(), if balanced { 2 } else { 1 });
+        assert_eq!(lane.markers[0].occurrence, create);
+        assert!(lane.uncertainties.contains(&Uncertainty {
+            scope: fragment,
+            reason: UncertaintyReason::Repeated
+        }));
+        assert_eq!(
+            intervals(&lane, f.owner).last().unwrap().2,
+            Life::Unresolved
+        );
+        assert_eq!(
+            validation::validate(&f.p)
+                .iter()
+                .any(|i| i.code == "lifeline_repetition"),
+            !balanced
+        );
+    }
+}
+
+#[test]
+fn optional_cleanup_inside_loop_does_not_claim_balanced_or_definite_exit() {
+    let mut f = Fixture::new(Layer::Sa);
+    let repeated = f.fragment(f.owner, 100., FragmentOperator::Loop);
+    let iteration = f.branch(repeated, 120., 500.);
+    f.message(iteration, 160., MessageKind::Create);
+    let optional = f.fragment(iteration, 280., FragmentOperator::Optional);
+    let cleanup = f.branch(optional, 320., 400.);
+    f.message(cleanup, 350., MessageKind::Delete);
+    let lane = f.lane();
+    assert_eq!(
+        intervals(&lane, cleanup),
+        vec![(320., 350., Life::Alive), (350., 400., Life::Absent)]
+    );
+    assert_eq!(
+        intervals(&lane, iteration),
+        vec![
+            (120., 160., Life::Absent),
+            (160., 280., Life::Alive),
+            (400., 500., Life::Unresolved)
+        ]
+    );
+    assert!(
+        validation::validate(&f.p)
+            .iter()
+            .any(|i| i.code == "lifeline_repetition")
+    );
+    assert!(lane.uncertainties.contains(&Uncertainty {
+        scope: optional,
+        reason: UncertaintyReason::Conditional
+    }));
+    assert!(lane.uncertainties.contains(&Uncertainty {
+        scope: repeated,
+        reason: UncertaintyReason::Repeated
+    }));
+}
+
+#[test]
+fn lifecycle_free_fragments_do_not_poison_other_lanes() {
+    let mut f = Fixture::new(Layer::Oa);
+    let fragment = f.fragment(f.owner, 100., FragmentOperator::Parallel);
+    let left = f.branch(fragment, 120., 250.);
+    let right = f.branch(fragment, 300., 450.);
+    f.message(left, 200., MessageKind::Delete);
+    let result = f.project();
+    let sender = result.iter().find(|lane| lane.lifeline == f.a).unwrap();
+    assert!(sender.intervals.iter().all(|i| i.life == Life::Alive));
+    assert!(sender.uncertainties.is_empty());
+    let target = result.iter().find(|lane| lane.lifeline == f.b).unwrap();
+    assert!(target.uncertainties.contains(&Uncertainty {
+        scope: fragment,
+        reason: UncertaintyReason::Parallel
+    }));
+    assert_eq!(intervals(target, right), vec![(300., 450., Life::Alive)]);
+}
+
+#[test]
+fn explicit_receiver_is_authoritative_even_with_missing_exchange() {
+    let mut f = Fixture::new(Layer::Oa);
+    let create = f.message(f.owner, 100., MessageKind::Create);
+    if let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Exchange { exchange, .. },
+        ..
+    }) = f.p.elements.get_mut(&create).unwrap().shared_mut()
+    {
+        *exchange = None;
+    }
+    assert_eq!(f.lane().markers[0].occurrence, create);
+    if let Some(SharedBody::Occurrence {
+        body: OccurrenceBody::Exchange {
+            receiver, exchange, ..
+        },
+        ..
+    }) = f.p.elements.get_mut(&create).unwrap().shared_mut()
+    {
+        *receiver = None;
+        *exchange = Some(f.exchange);
+    }
+    assert!(
+        f.lane().markers.is_empty(),
+        "exchange endpoints never invent a receiver"
+    );
+}
+
+#[test]
+fn missing_geometry_is_reported_without_nonfinite_or_guessed_markers() {
+    let mut f = Fixture::new(Layer::Oa);
+    let create = f.message(f.owner, 100., MessageKind::Create);
+    f.rows.insert(create, (f.owner, f32::NAN));
+    let lane = f.lane();
+    assert!(lane.markers.is_empty());
+    assert_eq!(
+        lane.uncertainties,
+        vec![Uncertainty {
+            scope: create,
+            reason: UncertaintyReason::MissingGeometry
+        }]
+    );
+    assert_eq!(
+        intervals(&lane, f.owner),
+        vec![(0., 600., Life::Unresolved)]
+    );
+    f.scopes.remove(&f.owner);
+    let lane = f.lane();
+    assert!(lane.intervals.is_empty());
+    assert_eq!(lane.uncertainties[0].scope, f.owner);
+}
+
+#[test]
+fn scenario_use_is_opaque_and_never_imports_callee_lifecycle_events() {
+    let mut f = Fixture::new(Layer::Oa);
+    let callee =
+        f.p.add_element(Kind::Scenario, Layer::Oa, "Callee", None)
+            .unwrap();
+    let remote_a =
+        f.p.add_element(Kind::Lifeline, Layer::Oa, "Remote A", Some(callee))
+            .unwrap();
+    let remote_b =
+        f.p.add_element(Kind::Lifeline, Layer::Oa, "Remote B", Some(callee))
+            .unwrap();
+    for (remote, local) in [(remote_a, f.a), (remote_b, f.b)] {
+        let body = f.p.elements[&local].shared().unwrap().clone();
+        *f.p.elements.get_mut(&remote).unwrap().shared_mut().unwrap() = body;
+    }
+    f.occurrence(
+        callee,
+        200.,
+        OccurrenceBody::Exchange {
+            exchange: Some(f.exchange),
+            sender: Some(remote_a),
+            receiver: Some(remote_b),
+            message_kind: MessageKind::Create,
+            operation: None,
+            reply_to: None,
+            values: vec![],
+        },
+    );
+    f.occurrence(
+        f.owner,
+        100.,
+        OccurrenceBody::ScenarioUse {
+            scenario: Some(callee),
+            bindings: vec![
+                LifelineBinding {
+                    referenced: remote_a,
+                    local: f.a,
+                },
+                LifelineBinding {
+                    referenced: remote_b,
+                    local: f.b,
+                },
+            ],
+        },
+    );
+    let lane = f.lane();
+    assert_eq!(intervals(&lane, f.owner), vec![(0., 600., Life::Alive)]);
+    assert!(lane.markers.is_empty());
+    assert!(lane.uncertainties.is_empty());
+}
+
+#[test]
+fn projection_retains_exact_authored_source_and_does_not_enter_history() {
+    use crate::document::Document;
+    let mut f = Fixture::new(Layer::Oa);
+    f.message(f.owner, 100., MessageKind::Create);
+    f.message(f.owner, 300., MessageKind::Delete);
+    let mut source = source_project::format_bundle(&f.p);
+    let text = source.files.get_mut(&source.entry).unwrap();
+    *text = format!("// Retained author note — 雨\r\n{text}\n");
+    let document =
+        Document::from_bundle(source.clone(), source_project::ProjectLimits::default()).unwrap();
+    let accepted = document.project().clone();
+    let geometry = Geometry {
+        rows: &f.rows,
+        scopes: &f.scopes,
+    };
+    let result = project_lifetimes(document.project(), f.owner, &geometry);
+    assert_eq!(result, f.project());
+    assert_eq!(document.bundle(), &source);
+    assert_eq!(document.project(), &accepted);
+    assert!(!document.can_undo());
+    assert!(!document.can_redo());
+}

crates/oa-desktop/src/behavior/source_draft.rs

@@ -0,0 +1,488 @@
+//! A prerequisite belongs to its pending consumer, never the accepted catalog.
+use iced::{
+    Element as UiElement, Fill,
+    widget::{button, column, container, row, scrollable, text, text_input},
+};
+use oa_core::*;
+use serde::{Deserialize, Serialize};
+use std::collections::BTreeMap;
+
+pub const NAME_INPUT: &str = "behavior-source-name";
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum Scope {
+    Lifeline {
+        owner: Id,
+        viewpoint: ScenarioViewpoint,
+    },
+    Work {
+        owner: Id,
+    },
+    Machine {
+        layer: Layer,
+    },
+}
+impl Scope {
+    fn owner(self) -> Option<Id> {
+        match self {
+            Self::Lifeline { owner, .. } | Self::Work { owner } => Some(owner),
+            Self::Machine { .. } => None,
+        }
+    }
+    fn layer(self, p: &Project) -> Result<Layer, String> {
+        match self {
+            Self::Machine { layer } => Ok(layer),
+            _ => p
+                .layer_of(self.owner().unwrap())
+                .ok_or("The consumer owner no longer exists.".into()),
+        }
+    }
+    fn kinds(self, layer: Layer) -> Vec<Kind> {
+        match self {
+            Self::Work { .. } => vec![if layer == Layer::Oa {
+                Kind::Activity
+            } else {
+                Kind::Function
+            }],
+            Self::Lifeline {
+                viewpoint: ScenarioViewpoint::OperationalActivity,
+                ..
+            } => vec![Kind::Activity],
+            Self::Lifeline {
+                viewpoint: ScenarioViewpoint::Functional,
+                ..
+            } => vec![Kind::Function],
+            Self::Lifeline {
+                viewpoint: ScenarioViewpoint::ParticipantInteraction,
+                ..
+            } => vec![Kind::Entity, Kind::Actor, Kind::Role],
+            Self::Lifeline {
+                viewpoint: ScenarioViewpoint::BoundaryInterface,
+                ..
+            } => vec![Kind::System, Kind::SystemActor],
+            Self::Machine { .. } if layer == Layer::Oa => vec![Kind::Entity, Kind::Actor],
+            Self::Machine { .. } => vec![Kind::System, Kind::SystemActor],
+            _ => vec![],
+        }
+    }
+}
+#[derive(Debug, Clone)]
+pub enum Event {
+    Open(Id),
+    Edit(Id, Edit),
+}
+#[derive(Debug, Clone)]
+pub enum Edit {
+    Name(String),
+    Kind(Kind),
+    Parent(Option<Id>),
+    Search(String),
+    Page(usize),
+    Back,
+    Use,
+}
+#[derive(Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct Draft {
+    token: Id,
+    document: Id,
+    scope: Scope,
+    layer: Layer,
+    owner: Option<Element>,
+    id: Id,
+    kind: Option<Kind>,
+    name: String,
+    parent: Option<Element>,
+    search: String,
+    page: usize,
+    identities: Vec<Id>,
+}
+#[derive(Clone, Default, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct State {
+    editing: Option<Draft>,
+    staged: Option<Draft>,
+    #[serde(default)]
+    engaged: bool,
+}
+impl State {
+    pub fn check_scope(&self, expected: Scope, selected: Option<Id>) -> Result<(), String> {
+        if self
+            .editing
+            .as_ref()
+            .or_else(|| self.staged.as_ref().filter(|d| Some(d.id) == selected))
+            .is_some_and(|d| d.scope != expected)
+        {
+            return Err("The recovered source request belongs to a different consumer context. Go Back or cancel this draft.".into());
+        }
+        Ok(())
+    }
+    pub fn dismiss(&mut self, event: &Event) -> Result<bool, String> {
+        if let Event::Edit(token, Edit::Back) = event {
+            if self.editing.as_ref().is_none_or(|d| d.token != *token) {
+                return Err("This Back action belongs to a previous source form.".into());
+            }
+            self.editing = None;
+            self.engaged = true;
+            return Ok(true);
+        }
+        Ok(false)
+    }
+
+    pub fn engaged(&self) -> bool {
+        self.engaged || self.editing.is_some() || self.staged.is_some()
+    }
+    pub fn is_open(&self) -> bool {
+        self.editing.is_some()
+    }
+    pub fn back(&mut self) -> bool {
+        self.editing.take().is_some()
+    }
+    pub fn label(&self, selected: Option<Id>) -> Option<String> {
+        self.staged
+            .as_ref()
+            .filter(|d| Some(d.id) == selected)
+            .map(|d| {
+                format!(
+                    "New · {} · {}",
+                    d.kind.map_or("Choose kind".into(), |k| k.to_string()),
+                    d.name
+                )
+            })
+    }
+    pub fn update(
+        &mut self,
+        p: &Project,
+        scope: Scope,
+        invocation: Id,
+        event: Event,
+    ) -> Result<Option<Id>, String> {
+        if self.dismiss(&event)? {
+            return Ok(None);
+        }
+        match event {
+            Event::Open(token) => {
+                if token != invocation || self.is_open() {
+                    return Err("This source request is stale. Use the current form.".into());
+                }
+                let layer = scope.layer(p)?;
+                let kinds = scope.kinds(layer);
+                if kinds.is_empty() {
+                    return Err("Create new sources requires a strict scenario viewpoint; use an existing source here.".into());
+                }
+                self.engaged = true;
+                self.editing = Some(Draft {
+                    token: Id::new_v4(),
+                    document: p.id,
+                    scope,
+                    layer,
+                    owner: scope.owner().and_then(|id| p.elements.get(&id).cloned()),
+                    id: Id::new_v4(),
+                    kind: (kinds.len() == 1).then_some(kinds[0]),
+                    name: String::new(),
+                    parent: None,
+                    search: String::new(),
+                    page: 0,
+                    identities: (0..match scope {
+                        Scope::Work { owner } => p.children(owner).count() + 4,
+                        Scope::Lifeline { .. } => 1,
+                        Scope::Machine { .. } => 0,
+                    })
+                        .map(|_| Id::new_v4())
+                        .collect(),
+                });
+                Ok(None)
+            }
+            Event::Edit(token, edit) => {
+                let d = self
+                    .editing
+                    .as_mut()
+                    .filter(|d| d.token == token && d.scope == scope && d.document == p.id)
+                    .ok_or("This source response is stale; return to the current form.")?;
+                match edit {
+                    Edit::Back => {
+                        self.editing = None;
+                        Ok(None)
+                    }
+                    Edit::Use => {
+                        d.command(p)?;
+                        let id = d.id;
+                        self.staged = self.editing.take();
+                        Ok(Some(id))
+                    }
+                    Edit::Name(name) => {
+                        d.name = name;
+                        Ok(None)
+                    }
+                    Edit::Kind(kind) => {
+                        if !scope.kinds(d.layer).contains(&kind) {
+                            return Err("Choose an explicitly supported source kind.".into());
+                        }
+                        d.kind = Some(kind);
+                        d.parent = None;
+                        d.page = 0;
+                        Ok(None)
+                    }
+                    Edit::Parent(parent) => {
+                        let kind = d.kind.ok_or("Choose the source kind first.")?;
+                        if !validation::can_parent(p, kind, d.layer, parent) {
+                            return Err("Choose a valid semantic parent.".into());
+                        }
+                        d.parent = parent.map(|id| p.elements[&id].clone());
+                        Ok(None)
+                    }
+                    Edit::Search(query) => {
+                        d.search = query;
+                        d.page = 0;
+                        Ok(None)
+                    }
+                    Edit::Page(page) => {
+                        d.page = page;
+                        Ok(None)
+                    }
+                }
+            }
+        }
+    }
+    pub fn preview(&self, p: &Project, selected: Option<Id>) -> Result<Option<Project>, String> {
+        if self.is_open() {
+            return Err("Use this new source or go Back before creating the consumer.".into());
+        }
+        self.staged
+            .as_ref()
+            .filter(|d| Some(d.id) == selected)
+            .map(|d| execute_batch(p, &[d.command(p)?]).map_err(|e| e.to_string()))
+            .transpose()
+    }
+    pub fn combine(
+        &self,
+        p: &Project,
+        selected: Option<Id>,
+        command: Command,
+    ) -> Result<Command, String> {
+        let Some(d) = self.staged.as_ref().filter(|d| Some(d.id) == selected) else {
+            return Ok(command);
+        };
+        let preview = execute_batch(p, &[d.command(p)?]).map_err(|e| e.to_string())?;
+        let mut commands = match command {
+            Command::Batch(commands) => commands,
+            other => vec![other],
+        };
+        let fresh: Vec<_> = commands
+            .iter()
+            .filter(|_| !matches!(d.scope, Scope::Machine { .. }))
+            .filter_map(|c| match c {
+                Command::CreateElement(e) => Some(e.id),
+                Command::CreateRelation(r) => Some(r.id),
+                _ => None,
+            })
+            .collect();
+        if fresh.len() > d.identities.len() {
+            return Err(
+                "The path grew beyond this draft. Return and create the source again.".into(),
+            );
+        }
+        let replacements: BTreeMap<_, _> = fresh
+            .into_iter()
+            .zip(d.identities.iter().copied())
+            .collect();
+        if replacements.values().any(|id| preview.contains(*id)) {
+            return Err(
+                "A reserved consumer identity is already used. Start a fresh source draft.".into(),
+            );
+        }
+        let remap = |id: &mut Id| {
+            if let Some(new) = replacements.get(id) {
+                *id = *new;
+            }
+        };
+        for c in &mut commands {
+            match c {
+                Command::CreateElement(e) => {
+                    remap(&mut e.id);
+                    references::visit_element_refs(e, remap);
+                    e.alias = preview.fresh_alias(&e.name, "contribution", e.id);
+                }
+                Command::CreateRelation(r) => {
+                    remap(&mut r.id);
+                    references::visit_relation_refs(r, remap);
+                    r.alias = preview.fresh_alias(&r.name, "path", r.id);
+                }
+                Command::EditRelation(_, r) => references::visit_relation_refs(r, remap),
+                Command::SetSteps(_, steps) => steps.iter_mut().for_each(remap),
+                // Machine commands already carry their reserved identities.
+                Command::CreateDiagram(_) | Command::Layout(_) => {}
+                _ => return Err("Unsupported prerequisite consumer operation.".into()),
+            }
+        }
+        commands.insert(0, d.command(p)?);
+        let command = super::topology::unique_batch(p, commands);
+        execute_batch(p, std::slice::from_ref(&command)).map_err(|e| e.to_string())?;
+        Ok(command)
+    }
+    pub fn view<'a, R: iced::advanced::text::Renderer + 'a>(
+        &'a self,
+        p: &'a Project,
+    ) -> Option<UiElement<'a, Event, iced::Theme, R>> {
+        let d = self.editing.as_ref()?;
+        let event = move |edit| Event::Edit(d.token, edit);
+        let mut fields = column![
+            text(format!("New source · {}", d.layer)).size(18),
+            text(match d.scope {
+                Scope::Lifeline { owner, viewpoint } =>
+                    format!("For a lifeline in {} · {:?}", p.named(owner), viewpoint),
+                Scope::Work { owner } => format!("For a contribution in {}", p.named(owner)),
+                Scope::Machine { .. } => "Owner for the pending state machine".into(),
+            })
+            .size(12),
+            text("The parent form is retained. This source is created only with its consumer.")
+                .size(12)
+        ]
+        .spacing(8);
+        for kind in d.scope.kinds(d.layer) {
+            fields = fields.push(
+                button(text(kind.to_string()))
+                    .on_press(event(Edit::Kind(kind)))
+                    .style(if d.kind == Some(kind) {
+                        button::primary
+                    } else {
+                        button::secondary
+                    }),
+            );
+        }
+        fields = fields.push(
+            text_input("Source name (independent of the consumer name)", &d.name)
+                .id(NAME_INPUT)
+                .on_input(move |v| event(Edit::Name(v)))
+                .padding(8),
+        );
+        fields = fields.push(
+            text(format!(
+                "Semantic parent: {}",
+                d.parent
+                    .as_ref()
+                    .map_or(format!("{} layer root", d.layer), |e| format!(
+                        "{} · {} · @{}",
+                        e.name,
+                        e.kind(),
+                        e.alias
+                    ))
+            ))
+            .size(12),
+        );
+        if let Some(kind) = d.kind {
+            fields = fields.push(button("Use layer root").on_press_maybe(
+                validation::can_parent(p, kind, d.layer, None).then(|| event(Edit::Parent(None))),
+            ));
+            fields = fields.push(
+                text_input("Find a semantic parent (optional)", &d.search)
+                    .on_input(move |v| event(Edit::Search(v)))
+                    .padding(6),
+            );
+            let query = d.search.to_lowercase();
+            let mut parents: Vec<_> = p
+                .elements
+                .values()
+                .filter(|e| validation::can_parent(p, kind, d.layer, Some(e.id)))
+                .map(|e| (e.id, super::creation::reference_label(p, e.id)))
+                .filter(|(_, label)| label.to_lowercase().contains(&query))
+                .collect();
+            parents.sort_by(|a, b| a.1.cmp(&b.1).then(a.0.cmp(&b.0)));
+            let page = d.page.min(parents.len().saturating_sub(1) / 6);
+            for (id, label) in parents.iter().skip(page * 6).take(6) {
+                fields = fields.push(
+                    button(text(label.clone()).size(12))
+                        .on_press(event(Edit::Parent(Some(*id))))
+                        .width(Fill),
+                );
+            }
+            if parents.len() > 6 {
+                fields = fields.push(
+                    row![
+                        button("Previous").on_press_maybe(
+                            (page > 0).then(|| event(Edit::Page(page.saturating_sub(1))))
+                        ),
+                        text(format!("{} / {}", page + 1, parents.len().div_ceil(6))),
+                        button("Next").on_press_maybe(
+                            ((page + 1) * 6 < parents.len()).then(|| event(Edit::Page(page + 1)))
+                        )
+                    ]
+                    .spacing(6),
+                );
+            }
+        }
+        let ready = d.command(p);
+        if let Err(error) = &ready {
+            fields = fields.push(text(error.clone()).size(12));
+        }
+        Some(
+            container(
+                column![
+                    scrollable(fields).id("behavior-source-fields").height(Fill),
+                    container(
+                        row![
+                            button("Back · Esc").on_press(event(Edit::Back)),
+                            button("Use this new source")
+                                .on_press_maybe(ready.is_ok().then(|| event(Edit::Use)))
+                        ]
+                        .spacing(8)
+                    )
+                    .id("behavior-source-actions")
+                ]
+                .spacing(10),
+            )
+            .padding(12)
+            .height(Fill)
+            .width(Fill)
+            .into(),
+        )
+    }
+}
+impl Draft {
+    fn command(&self, p: &Project) -> Result<Command, String> {
+        if self.document != p.id
+            || self.scope.layer(p)? != self.layer
+            || self
+                .owner
+                .as_ref()
+                .is_some_and(|e| p.elements.get(&e.id) != Some(e))
+        {
+            return Err(
+                "The source request's document or consumer changed. Go Back and reopen Create new."
+                    .into(),
+            );
+        }
+        let kind = self
+            .kind
+            .filter(|kind| self.scope.kinds(self.layer).contains(kind))
+            .ok_or("Choose the source kind explicitly.")?;
+        if self.name.trim().is_empty() {
+            return Err("Enter the source name.".into());
+        }
+        if p.contains(self.id) {
+            return Err(
+                "The reserved source identity is already used. Go Back and start again.".into(),
+            );
+        }
+        let parent = self.parent.as_ref().map(|e| e.id);
+        if self
+            .parent
+            .as_ref()
+            .is_some_and(|e| p.elements.get(&e.id) != Some(e))
+            || !validation::can_parent(p, kind, self.layer, parent)
+        {
+            return Err("The semantic parent changed. Choose its intended parent again.".into());
+        }
+        let e = Element {
+            id: self.id,
+            alias: p.fresh_alias(&self.name, "source", self.id),
+            name: self.name.clone(),
+            description: String::new(),
+            parent,
+            body: ElementBody::new(kind, self.layer)
+                .ok_or("This source kind is unavailable in this layer.")?,
+        };
+        let command = Command::CreateElement(e);
+        execute_batch(p, std::slice::from_ref(&command)).map_err(|e| e.to_string())?;
+        Ok(command)
+    }
+}

crates/oa-desktop/src/behavior/state_canvas.rs

@@ -38,7 +38,6 @@ pub struct State {
     context: Option<Context>,
     tool: Option<Tool>,
     pointer: Option<Point>,
-    focused: bool,
     press: Option<Press>,
     source: Option<Id>,
     preview: Option<(Id, Position)>,
@@ -771,7 +770,6 @@ impl canvas::Program<Event> for StateCanvas<'_> {
             }
             canvas::Event::Window(iced::window::Event::Unfocused) => {
                 state.reset();
-                state.focused = false;
                 return None;
             }
             _ => cursor,
@@ -779,14 +777,40 @@ impl canvas::Program<Event> for StateCanvas<'_> {
         let window = cursor.position();
         let local = window.map(|p| Point::new(p.x - bounds.x, p.y - bounds.y));
         let inside = local.is_some_and(|p| Self::content(bounds).contains(p));
-        if let canvas::Event::Keyboard(keyboard::Event::KeyPressed { key, modifiers, .. }) = event
-            && state.focused
-        {
+        if let canvas::Event::Keyboard(keyboard::Event::KeyPressed { key, modifiers, .. }) = event {
             use keyboard::{Key, key::Named};
             if *key == Key::Named(Named::Escape) {
                 state.reset();
                 return Some(Action::publish(Event::Choose(Tool::Select)).and_capture());
             }
+            if *key == Key::Named(Named::Delete)
+                && self.editable
+                && self.tool == Tool::Select
+                && state.press.is_none()
+                && state.pan_from.is_none()
+                && state.source.is_none()
+                && (modifiers.is_empty() || *modifiers == keyboard::Modifiers::SHIFT)
+            {
+                let scene = self.scene(state)?;
+                let placement = scene
+                    .view
+                    .nodes
+                    .iter()
+                    .find(|node| node.element == self.selected || node.id == self.selected);
+                let object = placement.map_or(self.selected, |node| node.element);
+                if placement.is_none() && !scene.view.edges.iter().any(|edge| edge.id == object) {
+                    return None;
+                }
+                return Some(
+                    Action::publish(Event::Remove(crate::app::diagram_removal::Intent {
+                        context: self.context,
+                        object,
+                        placement: placement.map(|node| node.id),
+                        model: modifiers.shift(),
+                    }))
+                    .and_capture(),
+                );
+            }
             if modifiers.is_empty() {
                 let pan = match key.as_ref() {
                     Key::Named(Named::ArrowLeft) => Some(Vector::new(60., 0.)),
@@ -804,7 +828,6 @@ impl canvas::Program<Event> for StateCanvas<'_> {
         let scene = self.scene(state)?;
         match event {
             canvas::Event::Mouse(mouse::Event::ButtonPressed(button)) => {
-                state.focused = inside;
                 if !inside {
                     return None;
                 }

crates/oa-desktop/src/behavior/state_edit.rs

@@ -24,6 +24,7 @@ pub enum Tool {
 
 #[derive(Debug, Clone)]
 pub enum Event {
+    Remove(crate::app::diagram_removal::Intent),
     Choose(Tool),
     CreateView(Id),
     Select(Context, Id),
@@ -70,6 +71,7 @@ pub enum Event {
 impl Event {
     pub fn context(&self) -> Option<Context> {
         match self {
+            Self::Remove(intent) => Some(intent.context),
             Self::Choose(_) | Self::CreateView(_) => None,
             Self::Select(c, _)
             | Self::Pan(c, _)

crates/oa-desktop/src/behavior/state_menu.rs

@@ -139,11 +139,14 @@ pub fn popup(app: &App, opened: &Opened, clean: bool) -> Option<Menu<Message>> {
                         true,
                     ));
                 }
-                entries.push(item(
-                    "Hide from this diagram",
-                    Message::Command(Command::Delete(node.id)),
-                    true,
-                ));
+                entries.push(
+                    item(
+                        "Hide from this diagram",
+                        Message::Command(Command::Delete(node.id)),
+                        true,
+                    )
+                    .shortcut("Delete"),
+                );
             }
         }
         if let Some(relation) = project.relations.get(&id)
@@ -184,7 +187,24 @@ pub fn popup(app: &App, opened: &Opened, clean: bool) -> Option<Menu<Message>> {
         }
         if id != project.id {
             entries.push(Entry::separator());
-            entries.push(item("Delete from model…", Message::Delete, true));
+            entries.push(item("Delete from model…", Message::Delete, true).shortcut(
+                if context.is_some_and(|context| {
+                    context.diagram != id
+                        && (request.placement.is_some()
+                            || projection::project_view(project, context.diagram)
+                                .edges
+                                .iter()
+                                .any(|edge| edge.id == id))
+                }) {
+                    if request.placement.is_some() {
+                        "Shift+Delete"
+                    } else {
+                        "Delete / Shift+Delete"
+                    }
+                } else {
+                    ""
+                },
+            ));
         }
     }
     Some(Menu {

crates/oa-desktop/src/behavior/state_view.rs

@@ -173,7 +173,12 @@ pub fn view<'a>(app: &'a App, machine: Id, mut out: Column<'a, Message>) -> Elem
     .width(Fill)
     .height(Fill)
     .into();
-    out = out.push(canvas.map(event));
+    out = out.push(crate::diagram::focus::wrap(
+        canvas.map(event),
+        context,
+        crate::app::diagram_removal::enabled(app),
+        Message::DiagramTraverse,
+    ));
     let base: Element<'_, Message> = container(out.spacing(8))
         .padding(14)
         .width(Fill)

crates/oa-desktop/src/behavior/topology.rs

@@ -38,6 +38,7 @@ impl Tool {
 }
 #[derive(Debug, Clone)]
 pub enum Event {
+    Source(super::source_draft::Event),
     Start(Id, Tool, Option<Id>),
     Cancel,
     Submit,
@@ -58,7 +59,6 @@ pub enum Event {
 }
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Shelf {
-    Tools,
     Selection,
 }
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -79,10 +79,11 @@ pub struct State {
     identity: Option<(Id, Id)>,
     tool: CanvasTool,
     expanded: BTreeSet<Id>,
-    scroll_offsets: [iced::Vector; 2],
-    return_to: Vec<(Id, Id, Option<oa_core::topology_context::ContextAddress>)>,
+    details_offset: iced::Vector,
+    return_to: Vec<direct::ReturnFrame>,
     draft: Option<Draft>,
     viewport: Option<Size>,
+    pan: iced::Vector,
     zoom: Option<f32>,
     fit: bool,
     pub(crate) focused: bool,
@@ -90,15 +91,22 @@ pub struct State {
     selected_context: Option<oa_core::topology_context::ContextAddress>,
     shelf: Option<Shelf>,
 }
-#[derive(Default, serde::Serialize, serde::Deserialize)]
+#[derive(Clone, Default, serde::Serialize, serde::Deserialize)]
 #[serde(deny_unknown_fields)]
 struct Browser {
     search: String,
     page: usize,
 }
-#[derive(serde::Serialize, serde::Deserialize)]
+#[derive(Clone, serde::Serialize, serde::Deserialize)]
 #[serde(deny_unknown_fields)]
 struct Draft {
+    #[serde(default)]
+    source: super::source_draft::State,
+    #[serde(default = "Id::new_v4")]
+    invocation: Id,
+    #[serde(default)]
+    source_origin: Option<(Id, oa_core::Element)>,
+
     #[serde(with = "recovery_insertion")]
     insertion: Insertion,
     fixed: bool,
@@ -117,6 +125,40 @@ struct Draft {
     contextual: Option<contextual::Draft>,
 }
 impl State {
+    pub(crate) fn camera_boundary(&self) -> impl PartialEq + use<> {
+        (
+            self.tool,
+            self.focused,
+            self.shelf,
+            self.viewport,
+            self.pan,
+            self.zoom,
+            self.fit,
+        )
+    }
+
+    pub(super) fn pending_name(&self) -> Option<&str> {
+        self.draft.as_ref().map(|d| d.name.as_str())
+    }
+    pub(super) fn source_view<'a>(&'a self, p: &'a Project) -> Option<iced::Element<'a, Event>> {
+        self.draft
+            .as_ref()?
+            .source
+            .view(p)
+            .map(|v| v.map(Event::Source))
+    }
+
+    pub fn source_active(&self) -> bool {
+        self.draft.as_ref().is_some_and(|d| d.source.engaged())
+    }
+
+    pub fn source_open(&self) -> bool {
+        self.draft.as_ref().is_some_and(|d| d.source.is_open())
+    }
+    pub fn source_back(&mut self) -> bool {
+        self.draft.as_mut().is_some_and(|d| d.source.back())
+    }
+
     pub(super) fn recovery_snapshot(&self) -> Result<Option<serde_json::Value>, String> {
         self.draft
             .as_ref()
@@ -152,6 +194,58 @@ impl State {
     }
 
     pub fn update(&mut self, p: &Project, event: Event) -> Result<Option<Command>, String> {
+        if let Event::Source(event) = event {
+            if self
+                .draft
+                .as_mut()
+                .ok_or("Start the consumer form first.")?
+                .source
+                .dismiss(&event)?
+            {
+                return Ok(None);
+            }
+            let d = self
+                .draft
+                .as_ref()
+                .ok_or("Start the consumer form first.")?;
+            if d.tool != Tool::Work {
+                return Err("This reference does not support staged source creation.".into());
+            }
+            if d.source_origin.as_ref().is_some_and(|(document, owner)| {
+                *document != p.id || p.elements.get(&d.owner) != Some(owner)
+            }) {
+                return Err("The original consumer changed. Cancel and reopen its form; the current draft is retained.".into());
+            }
+            if d.source_origin.is_none() && d.source.engaged() {
+                return Err("The recovered source draft has no original document binding. Go Back or cancel it.".into());
+            }
+            let mut next = d.clone();
+            if next.source_origin.is_none() && matches!(&event, super::source_draft::Event::Open(_))
+            {
+                next.source_origin = Some((
+                    p.id,
+                    p.elements
+                        .get(&d.owner)
+                        .ok_or("The consumer owner no longer exists.")?
+                        .clone(),
+                ));
+            }
+            if let Some(id) = next.source.update(
+                p,
+                super::source_draft::Scope::Work { owner: d.owner },
+                d.invocation,
+                event,
+            )? {
+                next.target = Some(id);
+                next.command(p)?;
+            }
+            self.draft = Some(next);
+            return Ok(None);
+        }
+        if self.source_open() && !matches!(&event, Event::Cancel) {
+            return Err("Use the new source or go Back before editing the parent form.".into());
+        }
+
         if self.draft.is_some() && matches!(&event, Event::Start(..)) {
             return Err(PENDING_DRAFT.into());
         }
@@ -184,6 +278,9 @@ impl State {
                     }
                 });
                 self.draft = Some(Draft {
+                    source: Default::default(),
+                    invocation: Id::new_v4(),
+                    source_origin: Some((p.id, p.elements[&owner].clone())),
                     insertion: Insertion::default(),
                     fixed: false,
                     browsers: Default::default(),
@@ -253,8 +350,8 @@ impl State {
     }
 
     fn fit_area(&self, fallback_width: f32) -> Size {
-        // The sensor measures the inner scroller, independent of graph content.
-        // Leave a small gutter for scrollbars; before first layout use a compact
+        // The sensor measures the viewport, independent of graph content.
+        // Leave a small content gutter; before first layout use a compact
         // provisional viewport and recompute when the sensor reports actual size.
         let viewport = self.viewport.unwrap_or(Size::new(fallback_width, 180.));
         Size::new(
@@ -263,10 +360,7 @@ impl State {
         )
     }
 
-    fn canvas_offset(&self) -> iced::Vector {
-        self.scroll_offsets[0]
-    }
-
+    #[cfg(test)]
     fn fit_limited(&self, graph: Size, fallback_width: f32) -> bool {
         let available = self.fit_area(fallback_width);
         self.fit && (graph.width * 0.05 > available.width || graph.height * 0.05 > available.height)
@@ -508,6 +602,22 @@ fn link(p: &Project, source: Id, target: Id, guard: &str) -> Command {
 }
 impl Draft {
     fn command(&self, p: &Project) -> Result<Command, String> {
+        if self.source.engaged()
+            && self.source_origin.as_ref().is_none_or(|(document, owner)| {
+                *document != p.id || p.elements.get(&self.owner) != Some(owner)
+            })
+        {
+            return Err("The original consumer document or owner changed. Cancel and reopen its form; your draft is retained.".into());
+        }
+        self.source.check_scope(
+            super::source_draft::Scope::Work { owner: self.owner },
+            self.target,
+        )?;
+        let preview = self.source.preview(p, self.target)?;
+        let command = self.consumer_command(preview.as_ref().unwrap_or(p))?;
+        self.source.combine(p, self.target, command)
+    }
+    fn consumer_command(&self, p: &Project) -> Result<Command, String> {
         let owner = p
             .elements
             .get(&self.owner)
@@ -615,6 +725,8 @@ impl Draft {
         });
         let name = if self.name.trim().is_empty() {
             default_name
+        } else if self.source.label(self.target).is_some() {
+            self.name.as_str()
         } else {
             self.name.trim()
         };
@@ -866,7 +978,8 @@ mod contextual_routing;
 struct Graph<'a> {
     project: &'a Project,
     interaction: Option<(Context, CanvasTool, bool)>,
-    scroll_offset: iced::Vector,
+    camera_pan: iced::Vector,
+    pending_insertion: Option<Insertion>,
     nodes: Vec<GraphNode>,
     edges: Vec<GraphEdge>,
     ordered_paths: Vec<OrderedPath>,
@@ -1198,7 +1311,8 @@ impl<'a> Graph<'a> {
         Self {
             project: p,
             interaction: None,
-            scroll_offset: iced::Vector::ZERO,
+            camera_pan: iced::Vector::ZERO,
+            pending_insertion: None,
             nodes,
             edges,
             ordered_paths,
@@ -1298,6 +1412,7 @@ impl canvas::Program<Message> for Graph<'_> {
     ) -> Vec<canvas::Geometry> {
         let mut f = Frame::new(renderer, bounds.size());
         f.fill_rectangle(Point::ORIGIN, bounds.size(), Color::WHITE);
+        f.translate(self.camera_pan);
         f.scale(self.scale);
         for pass in PAINT_PASSES {
             match pass {
@@ -1513,7 +1628,10 @@ impl canvas::Program<Message> for Graph<'_> {
         cursor: mouse::Cursor,
     ) -> mouse::Interaction {
         if cursor.position_in(bounds).is_some_and(|p| {
-            let p = Point::new(p.x / self.scale, p.y / self.scale);
+            let p = Point::new(
+                (p.x - self.camera_pan.x) / self.scale,
+                (p.y - self.camera_pan.y) / self.scale,
+            );
             self.nodes.iter().any(|n| n.rect.contains(p))
                 || self.ordered_paths.iter().any(|path| {
                     path.points.windows(2).any(|pair| {
@@ -1587,6 +1705,9 @@ mod tests {
     }
     fn branch(owner: Id, a: Id, b: Id, before: Id, after: Id) -> Draft {
         Draft {
+            source: Default::default(),
+            invocation: Id::new_v4(),
+            source_origin: None,
             insertion: Insertion::default(),
             fixed: false,
             browsers: Default::default(),
@@ -2043,7 +2164,6 @@ mod tests {
         let accepted = app.document.snapshot();
         assert!(app.behavior.prepare_pending(app.project()).is_err());
         for (shelf, expected) in [
-            (Shelf::Tools, Some(Shelf::Tools)),
             (Shelf::Selection, Some(Shelf::Selection)),
             (Shelf::Selection, None),
         ] {
@@ -2060,10 +2180,12 @@ mod tests {
     }
 
     #[test]
-    fn process_fit_canvas_selection_ignores_retained_ordered_page_scroll() {
+    fn process_camera_selection_ignores_independent_details_scroll() {
         let (p, owner, _, _, _, _) = fixture();
         let mut state = State::default();
-        state.scrolled(scenario::ScrollArea::Canvas, iced::Vector::new(11., 19.));
+        state.camera(crate::behavior::canvas_workspace::Event::Pan(
+            iced::Vector::new(11., 19.),
+        ));
         state.scrolled(scenario::ScrollArea::Page, iced::Vector::new(0., 370.));
         let context = Context {
             document: p.id,
@@ -2074,16 +2196,17 @@ mod tests {
         for scale in [0.45, 1.] {
             let mut graph = Graph::new(&p, owner, owner);
             graph.scale = scale;
-            graph.scroll_offset = state.canvas_offset();
+            graph.camera_pan = state.pan;
             graph.interaction = Some((context, CanvasTool::Select, true));
             let node = &graph.nodes[0];
             let id = node.id;
             let point = node.rect.center();
             let bounds = Rectangle::new(Point::new(40., 100.), Size::new(800., 300.));
             let screen = Point::new(
-                bounds.x + point.x * scale - 11.,
-                bounds.y + point.y * scale - 19.,
+                bounds.x + point.x * scale + 11.,
+                bounds.y + point.y * scale + 19.,
             );
+            assert!(bounds.contains(screen));
             let message = graph
                 .input(
                     &mut Input::default(),

crates/oa-desktop/src/behavior/topology/contextual.rs

@@ -33,7 +33,7 @@ pub enum Event {
     Search(String),
     Page(usize),
 }
-#[derive(Default, serde::Serialize, serde::Deserialize)]
+#[derive(Clone, Default, serde::Serialize, serde::Deserialize)]
 #[serde(deny_unknown_fields)]
 pub(super) struct Draft {
     edit: Option<Id>,
@@ -608,7 +608,11 @@ mod tests {
             "Authored endpoint is retained for explicit repair"
         );
         assert!(state.prepare_pending(&deleted).is_err());
-        state.remember(owner, reference);
+        state.remember(
+            owner,
+            reference,
+            super::super::direct::referenced(&p, owner, reference).unwrap(),
+        );
         assert_eq!(state.back(&deleted), Some((owner, reference)));
         assert!(state.selected_context.is_none());
         state.draft = None;

crates/oa-desktop/src/behavior/topology/direct.rs

@@ -60,6 +60,7 @@ pub enum CanvasEvent {
     Open(Context, Id),
     Back(Context),
     Zoom(Context, Option<f32>),
+    Camera(Context, u64, super::super::canvas_workspace::Event),
     Focus(Context),
     Viewport(Context, Size),
 }
@@ -77,6 +78,7 @@ impl CanvasEvent {
             | Self::Back(c)
             | Self::AppendExchange(c)
             | Self::Zoom(c, ..)
+            | Self::Camera(c, ..)
             | Self::Focus(c)
             | Self::Viewport(c, ..) => *c,
             Self::Begin { context, .. }
@@ -86,6 +88,19 @@ impl CanvasEvent {
         }
     }
 }
+pub(super) struct ReturnFrame {
+    identity: Option<(Id, Id)>,
+    owner: Id,
+    occurrence: Id,
+    target: Id,
+    address: Option<oa_core::topology_context::ContextAddress>,
+    pan: iced::Vector,
+    zoom: Option<f32>,
+    fit: bool,
+    viewport: Option<Size>,
+    expanded: BTreeSet<Id>,
+    contextual_expanded: BTreeSet<OccurrenceEndpoint>,
+}
 impl State {
     pub(crate) fn select_context(&mut self, address: oa_core::topology_context::ContextAddress) {
         self.selected_context = Some(address);
@@ -138,35 +153,49 @@ impl State {
         if self.identity != Some((document, owner)) {
             self.identity = Some((document, owner));
             self.tool = CanvasTool::Select;
+            self.pan = iced::Vector::ZERO;
             self.zoom = Some(1.);
             self.fit = false;
             self.viewport = None;
             self.expanded.clear();
-            self.scroll_offsets = [iced::Vector::ZERO; 2];
+            self.details_offset = iced::Vector::ZERO;
         }
     }
     #[cfg(test)]
-    pub(crate) fn scroll_offset(&self) -> iced::Vector {
-        self.scroll_offsets[0] + self.scroll_offsets[1]
+    pub(crate) fn details_offset(&self) -> iced::Vector {
+        self.details_offset
     }
-    pub(crate) fn scrolled(&mut self, area: scenario::ScrollArea, offset: iced::Vector) -> bool {
-        let index = match area {
-            scenario::ScrollArea::Canvas => 0,
-            scenario::ScrollArea::Page => 1,
-        };
-        let changed = self.scroll_offsets[index] != offset;
-        self.scroll_offsets[index] = offset;
+    pub(crate) fn scrolled(
+        &mut self,
+        scenario::ScrollArea::Page: scenario::ScrollArea,
+        offset: iced::Vector,
+    ) -> bool {
+        if !offset.x.is_finite() || !offset.y.is_finite() || offset.x < 0. || offset.y < 0. {
+            return false;
+        }
+        let changed = self.details_offset != offset;
+        self.details_offset = offset;
         changed
     }
     pub(crate) fn choose(&mut self, tool: CanvasTool) {
         // Choosing how to edit must retain the user's current view.
         self.tool = tool;
     }
+    pub(crate) fn camera(&mut self, event: super::super::canvas_workspace::Event) -> bool {
+        super::super::canvas_workspace::change(&mut self.pan, &mut self.zoom, &mut self.fit, event)
+    }
     pub(crate) fn zoom(&mut self, value: Option<f32>) {
         self.fit = value.is_none();
-        self.zoom = value.map(|v| v.clamp(0.5, 2.));
+        self.zoom = value.map(|v| v.clamp(0.05, 3.));
     }
     pub(crate) fn viewport(&mut self, size: Size) -> bool {
+        if !size.width.is_finite()
+            || !size.height.is_finite()
+            || size.width <= 0.
+            || size.height <= 0.
+        {
+            return false;
+        }
         let changed = self.viewport != Some(size);
         self.viewport = Some(size);
         changed
@@ -188,26 +217,83 @@ impl State {
         }
         true
     }
-    pub(crate) fn remember(&mut self, owner: Id, occurrence: Id) {
-        self.return_to
-            .push((owner, occurrence, self.selected_context.clone()));
+    pub(crate) fn remember(&mut self, owner: Id, occurrence: Id, target: Id) {
+        if self.return_to.len() == 32 {
+            self.return_to.remove(0);
+        }
+        self.return_to.push(ReturnFrame {
+            identity: self.identity,
+            owner,
+            occurrence,
+            target,
+            address: self.selected_context.clone(),
+            pan: self.pan,
+            zoom: self.zoom,
+            fit: self.fit,
+            viewport: self.viewport,
+            expanded: self.expanded.clone(),
+            contextual_expanded: self.contextual_expanded.clone(),
+        });
     }
     pub(crate) fn back(&mut self, p: &Project) -> Option<(Id, Id)> {
-        while let Some((owner, occurrence, address)) = self.return_to.pop() {
-            if is_contribution(p, owner, occurrence) {
-                self.selected_context = address.filter(|address| {
-                    address.owner == owner
-                        && oa_core::topology_context::TopologyIndex::new(p)
-                            .resolve(owner, &address.endpoint)
-                            .is_ok()
+        while let Some(frame) = self.return_to.pop() {
+            if frame.identity.map(|i| i.0) != self.identity.map(|i| i.0) {
+                continue;
+            }
+            let valid = referenced(p, frame.owner, frame.occurrence) == Some(frame.target)
+                || if let Some(address) = &frame.address {
+                    oa_core::topology_context::TopologyIndex::new(p)
+                        .resolve(frame.owner, &address.endpoint)
+                        .is_ok_and(|r| r.defining_sequence == frame.target)
+                } else {
+                    false
+                };
+            if valid && is_contribution(p, frame.owner, frame.occurrence) {
+                self.identity = frame.identity;
+                self.selected_context = frame.address.filter(|a| {
+                    oa_core::topology_context::TopologyIndex::new(p)
+                        .resolve(frame.owner, &a.endpoint)
+                        .is_ok()
                 });
-                return Some((owner, occurrence));
+                self.pan = frame.pan;
+                self.zoom = frame.zoom;
+                self.fit = frame.fit;
+                self.viewport = frame.viewport;
+                self.expanded = frame.expanded;
+                self.contextual_expanded = frame.contextual_expanded;
+                return Some((frame.owner, frame.occurrence));
             }
         }
         None
     }
-    pub(crate) fn created_selection(&self, command: &Command) -> Option<Id> {
+    pub(crate) fn camera_zoom(&mut self, p: &Project, owner: Id, zoom: Option<f32>) {
+        let graph =
+            Graph::expanded_qualified(p, owner, owner, &self.expanded, &self.contextual_expanded);
+        let old = self.scale(graph.size, 500.);
+        if let Some(next) = zoom {
+            let size = self.viewport.unwrap_or(Size::new(500., 300.));
+            self.camera(super::super::canvas_workspace::Event::Zoom {
+                factor: next / old,
+                at: Point::new(size.width / 2., size.height / 2.),
+                base: old,
+            });
+        } else {
+            self.zoom(None);
+            let fitted = self.scale(graph.size, 500.);
+            self.zoom(Some(fitted));
+            self.pan = iced::Vector::ZERO;
+        }
+    }
+    pub(crate) fn created_selection(&self, p: &Project, command: &Command) -> Option<Id> {
         let owner = self.pending_owner()?;
+        if self
+            .draft
+            .as_ref()
+            .is_some_and(|d| d.source.label(d.target).is_some())
+            && self.prepare_pending(p).ok().as_ref() != Some(command)
+        {
+            return None;
+        }
         if let Command::CreateRelation(r) | Command::EditRelation(_, r) = command
             && matches!(&r.body, RelationBody::ContextualLink { owner: caller, .. } if *caller == owner)
         {
@@ -539,7 +625,7 @@ impl Graph<'_> {
                 {
                     *moved |= position.distance(*start) >= 3.;
                 }
-                mouse::Cursor::Available(*position + self.scroll_offset)
+                mouse::Cursor::Available(*position)
             }
             canvas::Event::Mouse(mouse::Event::WheelScrolled { .. } | mouse::Event::CursorLeft)
             | canvas::Event::Window(
@@ -558,18 +644,19 @@ impl Graph<'_> {
             }
             canvas::Event::Mouse(
                 mouse::Event::ButtonPressed(_) | mouse::Event::ButtonReleased(_),
-            ) => state
-                .pointer
-                .map_or(cursor, |p| mouse::Cursor::Available(p + self.scroll_offset)),
+            ) => state.pointer.map_or(cursor, mouse::Cursor::Available),
             canvas::Event::Window(iced::window::Event::RedrawRequested(_)) => {
-                state.pointer = cursor.position().map(|p| p - self.scroll_offset);
+                state.pointer = cursor.position();
                 cursor
             }
             _ => cursor,
         };
-        let world = cursor
-            .position_in(bounds)
-            .map(|p| Point::new(p.x / self.scale, p.y / self.scale));
+        let world = cursor.position_in(bounds).map(|p| {
+            Point::new(
+                (p.x - self.camera_pan.x) / self.scale,
+                (p.y - self.camera_pan.y) / self.scale,
+            )
+        });
         let publish = |event| Some(Action::publish(Message::TopologyCanvas(event)).and_capture());
         match event {
             canvas::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)) if visible => {
@@ -583,7 +670,7 @@ impl Graph<'_> {
                 if !editable {
                     return None;
                 }
-                let start = cursor.position()? - self.scroll_offset;
+                let start = cursor.position()?;
                 match tool {
                     CanvasTool::Add(..) => {
                         state.press = Some(Press::Add {
@@ -722,15 +809,35 @@ impl Graph<'_> {
         let Some((context, tool, editable)) = self.interaction else {
             return;
         };
+        if let Some(insertion) = self.pending_insertion {
+            if let Some(edge) = insertion
+                .link
+                .and_then(|id| self.edges.iter().find(|e| e.id == id))
+            {
+                draw_arrow(f, &edge.points, style::TEAL, 3.);
+            } else if let Some(node) = insertion
+                .before
+                .and_then(|id| self.nodes.iter().find(|n| n.id == id))
+            {
+                f.stroke(
+                    &Path::rounded_rectangle(node.rect.position(), node.rect.size(), 10.into()),
+                    Stroke::default().with_color(style::TEAL).with_width(3.),
+                );
+            }
+        }
         if !editable {
             return;
         }
         let point = state
             .pointer
-            .map(|p| p + self.scroll_offset)
             .or_else(|| cursor.position())
             .filter(|p| bounds.contains(*p))
-            .map(|p| Point::new((p.x - bounds.x) / self.scale, (p.y - bounds.y) / self.scale));
+            .map(|p| {
+                Point::new(
+                    (p.x - bounds.x - self.camera_pan.x) / self.scale,
+                    (p.y - bounds.y - self.camera_pan.y) / self.scale,
+                )
+            });
         let live =
             state.context == Some(context) && state.tool == tool && state.bounds == Some(bounds);
         if live && let Some(source) = state.source {
@@ -845,12 +952,7 @@ impl Graph<'_> {
 }
 
 impl State {
-    pub(crate) fn selection_offset(
-        &self,
-        p: &Project,
-        owner: Id,
-        id: Id,
-    ) -> Option<scrollable::AbsoluteOffset> {
+    pub(crate) fn reveal_selection(&mut self, p: &Project, owner: Id, id: Id) -> bool {
         let graph =
             Graph::expanded_qualified(p, owner, id, &self.expanded, &self.contextual_expanded);
         let scale = self.scale(graph.size, 500.);
@@ -862,10 +964,25 @@ impl State {
                 self.qualified_selection(p, owner)
                     .map_or(n.rect, |a| n.endpoint_rect(&a.endpoint))
             })
-            .or_else(|| graph.edges.iter().find(|e| e.id == id).map(|e| e.label))?;
-        Some(scrollable::AbsoluteOffset {
-            x: (rect.x * scale - 12.).max(0.),
-            y: (rect.y * scale - 12.).max(0.),
-        })
+            .or_else(|| graph.edges.iter().find(|e| e.id == id).map(|e| e.label));
+        let Some(rect) = rect else {
+            return false;
+        };
+        let viewport = self.viewport.unwrap_or(Size::new(500., 300.));
+        let x = rect.x * scale + self.pan.x;
+        let y = rect.y * scale + self.pan.y;
+        let delta = iced::Vector::new(
+            if x < 12. || x + rect.width * scale > viewport.width - 12. {
+                12. - x
+            } else {
+                0.
+            },
+            if y < 12. || y + rect.height * scale > viewport.height - 12. {
+                12. - y
+            } else {
+                0.
+            },
+        );
+        self.camera(super::super::canvas_workspace::Event::Pan(delta))
     }
 }

crates/oa-desktop/src/behavior/topology/direct_tests.rs

@@ -540,7 +540,7 @@ fn send(
         input,
         &canvas::Event::Mouse(event),
         bounds,
-        mouse::Cursor::Available(point + graph.scroll_offset),
+        mouse::Cursor::Available(point),
     )
     .and_then(|a| a.into_inner().0)
 }
@@ -554,16 +554,20 @@ fn position(graph: &Graph<'_>, id: Id) -> Point {
         .center()
 }
 #[test]
-fn direct_process_production_click_click_drag_insert_and_scroll_coordinates() {
+fn direct_process_production_click_click_drag_insert_and_camera_coordinates() {
     let f = fixture(Layer::Oa);
     for drag in [false, true] {
         let mut graph = graph(&f, CanvasTool::Connect);
-        graph.scroll_offset = iced::Vector::new(35., 90.);
-        let bounds = Rectangle::new(Point::new(10., 20.), graph.size);
+        graph.camera_pan = iced::Vector::new(35., 90.);
+        let bounds = Rectangle::new(
+            Point::new(10., 20.),
+            Size::new(graph.size.width + 70., graph.size.height + 180.),
+        );
         let screen =
-            |id| position(&graph, id) + iced::Vector::new(bounds.x, bounds.y) - graph.scroll_offset;
+            |id| position(&graph, id) + iced::Vector::new(bounds.x, bounds.y) + graph.camera_pan;
         let a = screen(f.nodes[0]);
         let b = screen(f.nodes[2]);
+        assert!(bounds.contains(a) && bounds.contains(b));
         let mut input = Input::default();
         send(
             &graph,
@@ -732,7 +736,7 @@ fn direct_process_readable_default_fit_expansion_and_bounded_choices() {
     state.zoom(None);
     assert!(state.scale(Size::new(3262., 220.), 500.) < 0.2);
     state.zoom(Some(0.1));
-    assert_eq!(state.scale(Size::new(3262., 220.), 500.), 0.5);
+    assert_eq!(state.scale(Size::new(3262., 220.), 500.), 0.1);
     state.enter(Id::new_v4(), f.owner);
     assert_eq!(state.scale(Size::new(3262., 220.), 500.), 1.);
     let mut all = Vec::new();
@@ -1331,7 +1335,9 @@ fn direct_process_palette_preserves_fit_and_manual_camera() {
         let document = Id::new_v4();
         state.enter(document, f.owner);
         state.viewport(Size::new(500., 300.));
-        state.scrolled(scenario::ScrollArea::Canvas, iced::Vector::new(35., 90.));
+        state.camera(super::super::canvas_workspace::Event::Pan(
+            iced::Vector::new(35., 90.),
+        ));
         state.scrolled(scenario::ScrollArea::Page, iced::Vector::new(0., 120.));
         for camera in [None, Some(0.75), Some(1.5)] {
             state.zoom(camera);
@@ -1353,90 +1359,16 @@ fn direct_process_palette_preserves_fit_and_manual_camera() {
                     "{layer:?} {camera:?} {tool:?}"
                 );
                 assert_eq!(state.fit, camera.is_none());
-                assert_eq!(state.scroll_offset(), iced::Vector::new(35., 210.));
+                assert_eq!(state.pan, iced::Vector::new(35., 90.));
+                assert_eq!(state.details_offset(), iced::Vector::new(0., 120.));
                 state.enter(document, f.owner);
                 assert_eq!(state.scale(size, 500.), before);
             }
         }
         state.enter(Id::new_v4(), f.owner);
         assert_eq!(state.scale(Size::new(690., 250.), 500.), 1.);
-        assert_eq!(state.scroll_offset(), iced::Vector::ZERO);
-    }
-}
-
-#[test]
-fn direct_process_pending_form_diff_retains_the_canvas_scroll_state() {
-    use iced::advanced::widget::{Tree, tree};
-    use std::rc::Rc;
-    fn path_to(tree: &Tree, tag: tree::Tag) -> Option<Vec<usize>> {
-        if tree.tag == tag {
-            return Some(Vec::new());
-        }
-        tree.children.iter().enumerate().find_map(|(index, child)| {
-            let mut path = path_to(child, tag)?;
-            path.insert(0, index);
-            Some(path)
-        })
-    }
-    fn at<'a>(mut tree: &'a mut Tree, path: &[usize]) -> &'a mut Tree {
-        for &index in path {
-            tree = &mut tree.children[index];
-        }
-        tree
-    }
-    for layer in [Layer::Oa, Layer::Sa] {
-        for size in [Size::new(1440., 900.), Size::new(1100., 700.)] {
-            for tool in [Tool::Control, Tool::Branch, Tool::Connect] {
-                let f = fixture(layer);
-                let mut app = App::with_project(f.p.clone());
-                let _ = app.update(Message::Select(f.nodes[1]));
-                let _ = app.update(Message::Page(crate::app::Page::Behavior));
-                app.window_size = size;
-                let original = app.document.snapshot();
-                let graph: Element<'_, Message> =
-                    canvas::Canvas::new(Graph::new(app.project(), f.owner, f.nodes[1])).into();
-                let canvas_tag = Tree::new(graph.as_widget()).tag;
-                drop(graph);
-                let scroll: Element<'_, Message> = scrollable(text("")).into();
-                let scroll_tag = Tree::new(scroll.as_widget()).tag;
-                let mut tree = Tree::new(view::view(&app, f.owner, Column::new()).as_widget());
-                let mut scroll_path = path_to(&tree, canvas_tag).unwrap();
-                scroll_path.pop();
-                assert_eq!(at(&mut tree, &scroll_path).tag, scroll_tag);
-                // Scrollable::diff treats its local state as opaque. A retained marker
-                // proves the real Iced diff preserves the state that owns the offsets.
-                // No layout or input operation runs on this test-only marker state.
-                let marker = Rc::new(());
-                at(&mut tree, &scroll_path).state = tree::State::new(Rc::clone(&marker));
-                let _ = app.update(Message::Behavior(super::super::Event::Topology(
-                    Event::Start(f.owner, tool, Some(f.nodes[1])),
-                )));
-                assert!(app.behavior.has_pending());
-                tree.diff(view::view(&app, f.owner, Column::new()).as_widget());
-                assert_eq!(
-                    Rc::strong_count(&marker),
-                    2,
-                    "form open: {layer:?} {size:?} {tool:?}"
-                );
-                let mut current_path = path_to(&tree, canvas_tag).unwrap();
-                current_path.pop();
-                assert_eq!(current_path, scroll_path);
-                assert!(Rc::ptr_eq(
-                    at(&mut tree, &scroll_path).state.downcast_ref::<Rc<()>>(),
-                    &marker,
-                ));
-                let _ = app.update(Message::Behavior(super::super::Event::Topology(
-                    Event::Cancel,
-                )));
-                tree.diff(view::view(&app, f.owner, Column::new()).as_widget());
-                assert_eq!(
-                    Rc::strong_count(&marker),
-                    2,
-                    "form cancel: {layer:?} {size:?} {tool:?}"
-                );
-                assert!(std::sync::Arc::ptr_eq(&app.document.snapshot(), &original));
-            }
-        }
+        assert_eq!(state.pan, iced::Vector::ZERO);
+        assert_eq!(state.details_offset(), iced::Vector::ZERO);
     }
 }
 
@@ -1447,15 +1379,18 @@ fn direct_process_scaled_control_and_link_gestures_use_visible_positions() {
         for scale in [0.15, 0.6898551, 1.5] {
             let mut graph = graph(&f, CanvasTool::Add(Tool::Control, ControlKind::Choice));
             graph.scale = scale;
-            graph.scroll_offset = iced::Vector::new(11., 19.);
+            graph.camera_pan = iced::Vector::new(11., 19.);
             let bounds = Rectangle::new(
                 Point::new(40., 70.),
-                Size::new(graph.size.width * scale, graph.size.height * scale),
+                Size::new(
+                    graph.size.width * scale + 22.,
+                    graph.size.height * scale + 38.,
+                ),
             );
             let screen = |world: Point| {
                 Point::new(
-                    world.x * scale + bounds.x - 11.,
-                    world.y * scale + bounds.y - 19.,
+                    world.x * scale + bounds.x + 11.,
+                    world.y * scale + bounds.y + 19.,
                 )
             };
             let edge = &graph.edges[0];
@@ -1463,6 +1398,7 @@ fn direct_process_scaled_control_and_link_gestures_use_visible_positions() {
                 (edge.points[0].x + edge.points[1].x) / 2.,
                 edge.points[0].y,
             ));
+            assert!(bounds.contains(point));
             let mut input = Input::default();
             send(
                 &graph,
@@ -1493,6 +1429,7 @@ fn direct_process_scaled_control_and_link_gestures_use_visible_positions() {
                 let mut input = Input::default();
                 let a = screen(position(&graph, f.nodes[0]));
                 let b = screen(position(&graph, f.nodes[2]));
+                assert!(bounds.contains(a) && bounds.contains(b));
                 send(
                     &graph,
                     &mut input,

crates/oa-desktop/src/behavior/topology/view.rs

@@ -66,107 +66,7 @@ pub(super) fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Ele
     let pending = state.draft.is_some();
     let ordered = !legacy_order(p, owner).is_empty();
     let selected = is_contribution(p, owner, app.selected).then_some(app.selected);
-    let choose = |tool| Message::TopologyCanvas(CanvasEvent::Choose(context, tool));
-    let mut controls = Column::new().spacing(6);
-    if !pending {
-        controls = controls
-            .push(
-                row![
-                    button("Select / reorder")
-                        .style(if state.tool == CanvasTool::Select {
-                            button::primary
-                        } else {
-                            style::nav
-                        })
-                        .on_press(choose(CanvasTool::Select)),
-                    button("Work")
-                        .style(
-                            if state.tool == CanvasTool::Add(Tool::Work, ControlKind::Choice) {
-                                button::primary
-                            } else {
-                                style::nav
-                            }
-                        )
-                        .on_press(choose(CanvasTool::Add(Tool::Work, ControlKind::Choice))),
-                    button("Exchange")
-                        .style(
-                            if state.tool == CanvasTool::Add(Tool::Exchange, ControlKind::Choice) {
-                                button::primary
-                            } else {
-                                style::nav
-                            }
-                        )
-                        .on_press(choose(CanvasTool::Add(Tool::Exchange, ControlKind::Choice))),
-                    button("Reuse")
-                        .style(
-                            if state.tool == CanvasTool::Add(Tool::Reuse, ControlKind::Choice) {
-                                button::primary
-                            } else {
-                                style::nav
-                            }
-                        )
-                        .on_press(choose(CanvasTool::Add(Tool::Reuse, ControlKind::Choice)))
-                ]
-                .spacing(6),
-            )
-            .push(
-                row![
-                    pick_list(
-                        vec![
-                            ControlKind::Choice,
-                            ControlKind::Merge,
-                            ControlKind::Fork,
-                            ControlKind::Join,
-                            ControlKind::Loop
-                        ]
-                        .into_iter()
-                        .map(ControlChoice)
-                        .collect::<Vec<_>>(),
-                        if let CanvasTool::Add(Tool::Control, kind) = state.tool {
-                            Some(ControlChoice(kind))
-                        } else {
-                            None
-                        },
-                        move |c| Message::TopologyCanvas(CanvasEvent::Choose(
-                            context,
-                            CanvasTool::Add(Tool::Control, c.0)
-                        ))
-                    )
-                    .placeholder("Draw control…")
-                    .text_size(12)
-                    .padding(8),
-                    button("Sequence link")
-                        .style(if state.tool == CanvasTool::Connect {
-                            button::primary
-                        } else {
-                            style::nav
-                        })
-                        .on_press(choose(CanvasTool::Connect)),
-                    button("Two paths…").on_press(event(Event::Start(
-                        owner,
-                        Tool::Branch,
-                        selected
-                    )))
-                ]
-                .spacing(6),
-            );
-    }
-    controls=controls.push(label(if pending{"Pending contribution · apply or cancel below"}else if ordered{"Ordered exchange path · click a path to insert or empty canvas to continue; the edit preserves its order"}else{match state.tool{
-        CanvasTool::Select=>"Select local contributions and paths · drag path endpoints to reconnect · ↕ reorders within a column",
-        CanvasTool::Connect=>"Sequence link · click or drag from preceding to following contribution · Escape cancels",
-        CanvasTool::Add(..)=>"Choose a highlighted path or contribution position · existing work stays shared · Escape cancels"}}));
-    if !pending && ordered {
-        controls = controls.push(button("Append exchange…").on_press(Message::TopologyCanvas(
-            CanvasEvent::AppendExchange(context),
-        )));
-        let commands = preserved_order(p, owner, None);
-        if !commands.is_empty() {
-            controls = controls.push(
-                button("Edit path links and guards")
-                    .on_press(Message::Command(unique_batch(p, commands))),
-            );
-        }
-    }
+    let clean = !app.behavior.has_pending() && !app.draft_dirty() && !app.source_dirty();
     // A fixed sibling keeps Iced's canvas scroll state through selection/form changes.
     let mut navigation = column![].spacing(6);
     if let Some(Relation {
@@ -211,11 +111,6 @@ pub(super) fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Ele
             );
         }
     }
-    if !pending {
-        controls = controls.push(button("Qualified link / assembly…").on_press(event(
-            Event::Start(owner, Tool::Contextual, Some(app.selected)),
-        )));
-    }
     if let Some(id) = selected {
         let mut actions =
             row![button("Contribution properties").on_press(Message::EditProperties(id))]
@@ -256,27 +151,79 @@ pub(super) fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Ele
             button("Back to caller").on_press(Message::TopologyCanvas(CanvasEvent::Back(context))),
         );
     }
-    let diagram = {
-        let mut graph = Graph::expanded_qualified(
-            p,
-            owner,
-            app.selected,
-            &state.expanded,
-            &state.contextual_expanded,
+    navigation = navigation
+        .push(
+            button("Two paths...").on_press_maybe(clean.then_some(event(Event::Start(
+                owner,
+                Tool::Branch,
+                selected,
+            )))),
+        )
+        .push(
+            button("Qualified link / assembly...").on_press_maybe(clean.then_some(event(
+                Event::Start(owner, Tool::Contextual, Some(app.selected)),
+            ))),
         );
-        graph.scale = state.scale(graph.size, (app.window_size.width - 600.).max(200.));
-        graph.interaction = Some((
-            context,
-            state.tool,
-            !app.behavior.has_pending() && !app.draft_dirty() && !app.source_dirty(),
-        ));
-        // Explicit graphs no longer have a scrolling page ancestor. A retained
-        // offset from an ordered view must not distort their pointer coordinates.
-        graph.scroll_offset = state.canvas_offset();
-        let scale = graph.scale;
-        let mut header = column![
-            row![
-                out.width(Fill),
+    if ordered {
+        navigation = navigation.push(button("Append exchange...").on_press_maybe(clean.then_some(
+            Message::TopologyCanvas(CanvasEvent::AppendExchange(context)),
+        )));
+        let commands = preserved_order(p, owner, None);
+        if !commands.is_empty() {
+            navigation = navigation.push(
+                button("Edit path links and guards")
+                    .on_press_maybe(clean.then_some(Message::Command(unique_batch(p, commands)))),
+            );
+        }
+    }
+    let mut graph = Graph::expanded_qualified(
+        p,
+        owner,
+        app.selected,
+        &state.expanded,
+        &state.contextual_expanded,
+    );
+    graph.scale = state.scale(graph.size, (app.window_size.width - 600.).max(200.));
+    graph.camera_pan = state.pan;
+    graph.pending_insertion = state
+        .draft
+        .as_ref()
+        .filter(|d| d.owner == owner && d.fixed)
+        .map(|d| d.insertion);
+    graph.interaction = Some((context, state.tool, clean));
+    let scale = graph.scale;
+    let scope = super::super::canvas_workspace::Scope {
+        document: context.document,
+        owner,
+        revision: context.revision,
+        epoch: app.camera_epoch,
+    };
+    let keyboard = clean && super::super::canvas_workspace::keyboard_enabled(app);
+    let camera = move |e| Message::TopologyCanvas(CanvasEvent::Camera(context, scope.epoch, e));
+    let canvas = container(
+        iced::widget::sensor(
+            super::super::canvas_workspace::Viewport::new(
+                canvas::Canvas::new(graph).width(Fill).height(Fill),
+                scope,
+                scale,
+                keyboard,
+                camera,
+            )
+            .pan_background(state.tool == CanvasTool::Select),
+        )
+        .key((context.document, owner))
+        .on_show(move |size| Message::TopologyCanvas(CanvasEvent::Viewport(context, size)))
+        .on_resize(move |size| Message::TopologyCanvas(CanvasEvent::Viewport(context, size))),
+    )
+    .id("process-viewport")
+    .width(Fill)
+    .height(Fill)
+    .style(style::card)
+    .into();
+    let header = column![
+        row![
+            out.width(Fill),
+            super::super::canvas_workspace::Control::new(
                 button(
                     text(if state.focused {
                         "Restore panels"
@@ -285,368 +232,352 @@ pub(super) fn view<'a>(app: &'a App, owner: Id, out: Column<'a, Message>) -> Ele
                     })
                     .size(12)
                 )
-                .on_press(Message::TopologyCanvas(CanvasEvent::Focus(context)))
                 .padding(6)
-            ]
-            .spacing(6)
-            .align_y(iced::Center),
-            row![
-                button(text("Tools").size(12))
-                    .padding(6)
-                    .style(if state.shelf == Some(Shelf::Tools) {
-                        button::primary
-                    } else {
-                        style::nav
-                    })
-                    .on_press(event(Event::Shelf(Shelf::Tools))),
-                button(text("Selection details").size(12))
-                    .padding(6)
-                    .style(if state.shelf == Some(Shelf::Selection) {
-                        button::primary
-                    } else {
-                        style::nav
-                    })
-                    .on_press(event(Event::Shelf(Shelf::Selection))),
-                button(text("Fit overview").size(12))
-                    .padding(6)
-                    .on_press(Message::TopologyCanvas(CanvasEvent::Zoom(context, None))),
-                button(text("−").size(12))
-                    .padding(6)
-                    .on_press(Message::TopologyCanvas(CanvasEvent::Zoom(
-                        context,
-                        Some(scale / 1.25)
-                    ))),
-                label(format!("{:.0}%", scale * 100.)),
-                button(text("+").size(12))
-                    .padding(6)
-                    .on_press(Message::TopologyCanvas(CanvasEvent::Zoom(
-                        context,
-                        Some(scale * 1.25)
-                    ))),
-                button(text("100%").size(12))
-                    .padding(6)
-                    .on_press(Message::TopologyCanvas(CanvasEvent::Zoom(
-                        context,
-                        Some(1.)
-                    )))
-            ]
-            .spacing(6)
-            .wrap(),
+                .on_press(super::super::canvas_workspace::intent(
+                    scope,
+                    "Panels",
+                    Message::TopologyCanvas(CanvasEvent::Focus(context))
+                )),
+                scope,
+                "Panels",
+                keyboard,
+                Some(super::super::canvas_workspace::intent(
+                    scope,
+                    "Panels",
+                    Message::TopologyCanvas(CanvasEvent::Focus(context))
+                )),
+                camera
+            )
         ]
-        .spacing(6);
-        if state.fit_limited(graph.size, (app.window_size.width - 600.).max(200.)) {
-            header = header
-                .push(text("Minimum zoom reached · scroll to see the remaining graph.").size(11));
-        }
-        if graph.nodes.is_empty() {
-            controls = controls.push(label(
-                "Choose Work, Exchange, Reuse or a control, then click the canvas to start.",
-            ));
-        }
-        let size = Size::new(graph.size.width * scale, graph.size.height * scale);
-        let canvas = scrollable(
-            canvas::Canvas::new(graph)
-                .width(size.width)
-                .height(size.height),
-        )
-        .id("process-canvas")
-        .direction(scrollable::Direction::Both {
-            vertical: scrollable::Scrollbar::default(),
-            horizontal: scrollable::Scrollbar::default(),
-        })
-        .width(Fill)
-        .height(Fill);
-        let canvas = container(
-            iced::widget::sensor(super::super::scenario_scroll::observe_topology(
+        .spacing(6),
+        super::super::canvas_workspace::controls(
+            scope,
+            keyboard,
+            scale,
+            event(Event::Shelf(Shelf::Selection)),
+            clean.then_some(Message::TopologyCanvas(CanvasEvent::Camera(
                 context,
-                scenario::ScrollArea::Canvas,
-                canvas,
-            ))
-            .on_show(move |size| Message::TopologyCanvas(CanvasEvent::Viewport(context, size)))
-            .on_resize(move |size| Message::TopologyCanvas(CanvasEvent::Viewport(context, size))),
+                scope.epoch,
+                super::super::canvas_workspace::Event::Focus
+            ))),
+            move |zoom| Message::TopologyCanvas(CanvasEvent::Zoom(context, zoom)),
+            camera
         )
-        .padding(8)
-        .width(Fill)
-        .height(Fill)
-        .style(style::card);
-        let details: Element<'_, Message> = match state.shelf {
-            Some(Shelf::Tools) => controls.into(),
-            _ => navigation.push(text("Full qualified identities and definition actions appear here for the selected contribution or link.").size(11)).into(),
-        };
-        explicit_pane(
-            header.into(),
-            details,
-            canvas.into(),
-            state.shelf.is_some(),
-            pending,
-        )
-    };
+    ]
+    .spacing(4);
+    let entries = [
+        ("S", "Select contributions or paths", CanvasTool::Select),
+        (
+            "W",
+            "Work: click a path or empty space",
+            CanvasTool::Add(Tool::Work, ControlKind::Choice),
+        ),
+        (
+            "E",
+            "Exchange: click a path or empty space",
+            CanvasTool::Add(Tool::Exchange, ControlKind::Choice),
+        ),
+        (
+            "ref",
+            "Reuse process / chain",
+            CanvasTool::Add(Tool::Reuse, ControlKind::Choice),
+        ),
+        (
+            "OR",
+            "Choice",
+            CanvasTool::Add(Tool::Control, ControlKind::Choice),
+        ),
+        (
+            "M",
+            "Merge",
+            CanvasTool::Add(Tool::Control, ControlKind::Merge),
+        ),
+        (
+            "AND",
+            "Fork",
+            CanvasTool::Add(Tool::Control, ControlKind::Fork),
+        ),
+        (
+            "J",
+            "Join",
+            CanvasTool::Add(Tool::Control, ControlKind::Join),
+        ),
+        (
+            "IT",
+            "Loop",
+            CanvasTool::Add(Tool::Control, ControlKind::Loop),
+        ),
+        (
+            "->",
+            "Sequence link: click or drag between contributions",
+            CanvasTool::Connect,
+        ),
+    ];
+    let palette = super::super::canvas_workspace::palette(
+        scope,
+        keyboard,
+        camera,
+        entries.into_iter().map(|(glyph, label, choice)| {
+            (
+                glyph,
+                label,
+                choice == state.tool,
+                clean.then_some(Message::TopologyCanvas(CanvasEvent::Choose(
+                    context, choice,
+                ))),
+            )
+        }),
+    );
+    let details = scrollable(navigation.push(text("Layout is derived. The reorder handle changes display order within its column; it does not author a position.").size(11)))
+        .id("process-details").width(Fill).height(Fill).into();
     let mut form_panel: Element<'_, Message> = iced::widget::Space::new().height(0).into();
     if let Some(d) = state.draft.as_ref().filter(|d| d.owner == owner) {
-        let mut form = column![text(d.tool.title()).size(16)].spacing(8);
-        if let Some(contextual) = &d.contextual {
-            form = form
-                .push(
-                    text_input("Link name (retain current when blank)", &d.name)
-                        .on_input(|v| event(Event::Name(v)))
-                        .padding(8)
-                        .size(12),
-                )
-                .push(super::contextual::view(p, owner, contextual));
+        if let Some(child) = d.source.view(p) {
+            form_panel = column![
+                text(format!(
+                    "Consumer name: {}",
+                    crate::views::short(&d.name, 60)
+                ))
+                .size(12),
+                child.map(|e| event(Event::Source(e)))
+            ]
+            .spacing(6)
+            .height(Fill)
+            .into();
         } else {
-            if let Some(link) = d.insertion.link.and_then(|id| p.relations.get(&id)) {
-                let guard = if let RelationBody::SequenceLink { guard, .. } = &link.body {
-                    guard.as_str()
-                } else {
-                    ""
-                };
-                form = form.push(label(format!(
-                    "Insert on {} → {} · preserve path identity and condition [{}]",
-                    p.named(link.source()),
-                    p.named(link.target()),
-                    guard
-                )));
-            } else if d.fixed && ordered {
-                form = form.push(label(match (d.before, d.after) {
-                    (Some(before), Some(after)) => format!(
-                        "Insert between {} → {} · preserve the ordered path",
-                        p.named(before),
-                        p.named(after)
-                    ),
-                    (Some(before), None) => format!("Continue after {}", p.named(before)),
-                    (None, Some(after)) => format!("Insert before {}", p.named(after)),
-                    _ => "Start the ordered path".into(),
-                }));
-            } else if d.fixed
-                && d.tool == Tool::Exchange
-                && let Some(before) = d.before
-            {
-                form = form.push(label(format!(
-                    "Append after {} → new exchange · Create adds an explicit sequence link",
-                    p.named(before)
-                )));
-            } else if d.fixed && d.tool != Tool::Connect {
-                form = form.push(label(
-                    d.insertion
-                        .before
-                        .map_or("Append an unconnected contribution".into(), |id| {
-                            format!("Unconnected contribution before {}", p.named(id))
-                        }),
-                ));
-            }
-            if !legacy_order(p, owner).is_empty() {
-                form = form.push(label(
+            let mut form = column![text(d.tool.title()).size(16)].spacing(8);
+            if let Some(contextual) = &d.contextual {
+                form = form
+                    .push(
+                        text_input("Link name (retain current when blank)", &d.name)
+                            .on_input(|v| event(Event::Name(v)))
+                            .padding(8)
+                            .size(12),
+                    )
+                    .push(super::contextual::view(p, owner, contextual));
+            } else {
+                if let Some(link) = d.insertion.link.and_then(|id| p.relations.get(&id)) {
+                    let guard = if let RelationBody::SequenceLink { guard, .. } = &link.body {
+                        guard.as_str()
+                    } else {
+                        ""
+                    };
+                    form = form.push(label(format!(
+                        "Insert on {} → {} · preserve path identity and condition [{}]",
+                        p.named(link.source()),
+                        p.named(link.target()),
+                        guard
+                    )));
+                } else if d.fixed && ordered {
+                    form = form.push(label(match (d.before, d.after) {
+                        (Some(before), Some(after)) => format!(
+                            "Insert between {} → {} · preserve the ordered path",
+                            p.named(before),
+                            p.named(after)
+                        ),
+                        (Some(before), None) => format!("Continue after {}", p.named(before)),
+                        (None, Some(after)) => format!("Insert before {}", p.named(after)),
+                        _ => "Start the ordered path".into(),
+                    }));
+                } else if d.fixed
+                    && d.tool == Tool::Exchange
+                    && let Some(before) = d.before
+                {
+                    form = form.push(label(format!(
+                        "Append after {} → new exchange · Create adds an explicit sequence link",
+                        p.named(before)
+                    )));
+                } else if d.fixed && d.tool != Tool::Connect {
+                    form = form.push(label(
+                        d.insertion
+                            .before
+                            .map_or("Append an unconnected contribution".into(), |id| {
+                                format!("Unconnected contribution before {}", p.named(id))
+                            }),
+                    ));
+                }
+                if d.tool == Tool::Work {
+                    if let Some(title) = d.source.label(d.target) {
+                        form = form.push(label(title)).push(label("Create commits the new work and contribution together at the chosen path position."));
+                    }
+                    form = form.push(button("Create new source…").on_press(event(Event::Source(
+                        super::super::source_draft::Event::Open(d.invocation),
+                    ))));
+                }
+                if !legacy_order(p, owner).is_empty() {
+                    form = form.push(label(
                     "This edit preserves the ordered path as explicit links in the same undo step.",
                 ));
-            }
-            if matches!(
-                d.tool,
-                Tool::Work | Tool::Exchange | Tool::Reuse | Tool::Branch
-            ) {
-                let choices = targets(p, owner, d.tool)
-                    .into_iter()
-                    .filter(|c| compatible_source(p, d, c.id))
-                    .collect();
-                if d.tool == Tool::Branch {
-                    form = form.push(label("First path work"));
                 }
-                form = form.push(picker(
-                    choices,
-                    d,
-                    0,
-                    d.target,
+                if matches!(
+                    d.tool,
+                    Tool::Work | Tool::Exchange | Tool::Reuse | Tool::Branch
+                ) {
+                    let choices = targets(p, owner, d.tool)
+                        .into_iter()
+                        .filter(|c| compatible_source(p, d, c.id))
+                        .collect();
                     if d.tool == Tool::Branch {
-                        "Choose first path work…"
+                        form = form.push(label("First path work"));
+                    }
+                    form = form.push(picker(
+                        choices,
+                        d,
+                        0,
+                        d.target,
+                        if d.tool == Tool::Branch {
+                            "Choose first path work…"
+                        } else {
+                            "Choose existing source…"
+                        },
+                        Event::Target,
+                    ));
+                }
+                if d.tool != Tool::Connect {
+                    form = form.push(
+                        text_input("Contribution name (defaults to source)", &d.name)
+                            .on_input(|v| event(Event::Name(v)))
+                            .padding(8)
+                            .size(12),
+                    );
+                }
+                if matches!(d.tool, Tool::Control | Tool::Branch) {
+                    let kinds = if d.tool == Tool::Branch {
+                        vec![ControlKind::Choice, ControlKind::Fork]
                     } else {
-                        "Choose existing source…"
-                    },
-                    Event::Target,
-                ));
-            }
-            if d.tool != Tool::Connect {
-                form = form.push(
-                    text_input("Contribution name (defaults to source)", &d.name)
-                        .on_input(|v| event(Event::Name(v)))
+                        vec![
+                            ControlKind::Choice,
+                            ControlKind::Merge,
+                            ControlKind::Fork,
+                            ControlKind::Join,
+                            ControlKind::Loop,
+                        ]
+                    };
+                    form = form.push(
+                        pick_list(
+                            kinds.into_iter().map(ControlChoice).collect::<Vec<_>>(),
+                            Some(ControlChoice(d.control)),
+                            |v| event(Event::Control(v)),
+                        )
+                        .padding(8)
+                        .text_size(12),
+                    );
+                }
+                if d.tool == Tool::Branch {
+                    form = form.push(label("Second path work")).push(picker(
+                        targets(p, owner, Tool::Work),
+                        d,
+                        1,
+                        d.alternate,
+                        "Second path work…",
+                        Event::Alternate,
+                    ));
+                    if d.control != ControlKind::Fork {
+                        form = form
+                            .push(label("First path guard"))
+                            .push(
+                                text_input("First path guard", &d.guard)
+                                    .on_input(|v| event(Event::Guard(v)))
+                                    .padding(8),
+                            )
+                            .push(label("Second path guard"))
+                            .push(
+                                text_input("Second path guard (e.g. else)", &d.alternate_guard)
+                                    .on_input(|v| event(Event::AlternateGuard(v)))
+                                    .padding(8),
+                            );
+                    }
+                }
+                if d.fixed {
+                    if let (Some(a), Some(b)) = (d.before, d.after) {
+                        form = form.push(label(format!("{} → {}", p.named(a), p.named(b))));
+                    }
+                } else {
+                    form = form
+                        .push(label("Preceding contribution"))
+                        .push(picker(
+                            contributions(p, owner),
+                            d,
+                            2,
+                            d.before,
+                            "After contribution…",
+                            Event::Before,
+                        ))
+                        .push(button("Clear preceding").on_press(event(Event::ClearBefore)))
+                        .push(label("Following contribution"))
+                        .push(picker(
+                            contributions(p, owner),
+                            d,
+                            3,
+                            d.after,
+                            "Before contribution…",
+                            Event::After,
+                        ))
+                        .push(button("Clear following").on_press(event(Event::ClearAfter)));
+                }
+                if d.tool != Tool::Branch
+                    && d.insertion.link.is_none()
+                    && (d.before.is_some() || d.tool == Tool::Connect)
+                {
+                    form = form.push(
+                        text_input(
+                            "Path condition (empty remains a Choice / Loop warning)",
+                            &d.guard,
+                        )
+                        .on_input(|v| event(Event::Guard(v)))
                         .padding(8)
                         .size(12),
-                );
+                    );
+                }
             }
-            if matches!(d.tool, Tool::Control | Tool::Branch) {
-                let kinds = if d.tool == Tool::Branch {
-                    vec![ControlKind::Choice, ControlKind::Fork]
+            let valid = match d.command(p) {
+                Ok(_) => true,
+                Err(problem) => {
+                    form = form.push(label(problem));
+                    false
+                }
+            };
+            let actions = row![
+                button(if d.contextual.is_some() {
+                    "Apply link"
                 } else {
-                    vec![
-                        ControlKind::Choice,
-                        ControlKind::Merge,
-                        ControlKind::Fork,
-                        ControlKind::Join,
-                        ControlKind::Loop,
-                    ]
-                };
-                form = form.push(
-                    pick_list(
-                        kinds.into_iter().map(ControlChoice).collect::<Vec<_>>(),
-                        Some(ControlChoice(d.control)),
-                        |v| event(Event::Control(v)),
-                    )
-                    .padding(8)
-                    .text_size(12),
-                );
-            }
-            if d.tool == Tool::Branch {
-                form = form.push(label("Second path work")).push(picker(
-                    targets(p, owner, Tool::Work),
-                    d,
-                    1,
-                    d.alternate,
-                    "Second path work…",
-                    Event::Alternate,
-                ));
-                if d.control != ControlKind::Fork {
-                    form = form
-                        .push(label("First path guard"))
-                        .push(
-                            text_input("First path guard", &d.guard)
-                                .on_input(|v| event(Event::Guard(v)))
-                                .padding(8),
-                        )
-                        .push(label("Second path guard"))
-                        .push(
-                            text_input("Second path guard (e.g. else)", &d.alternate_guard)
-                                .on_input(|v| event(Event::AlternateGuard(v)))
-                                .padding(8),
-                        );
-                }
-            }
-            if d.fixed {
-                if let (Some(a), Some(b)) = (d.before, d.after) {
-                    form = form.push(label(format!("{} → {}", p.named(a), p.named(b))));
-                }
-            } else {
-                form = form
-                    .push(label("Preceding contribution"))
-                    .push(picker(
-                        contributions(p, owner),
-                        d,
-                        2,
-                        d.before,
-                        "After contribution…",
-                        Event::Before,
-                    ))
-                    .push(button("Clear preceding").on_press(event(Event::ClearBefore)))
-                    .push(label("Following contribution"))
-                    .push(picker(
-                        contributions(p, owner),
-                        d,
-                        3,
-                        d.after,
-                        "Before contribution…",
-                        Event::After,
-                    ))
-                    .push(button("Clear following").on_press(event(Event::ClearAfter)));
-            }
-            if d.tool != Tool::Branch
-                && d.insertion.link.is_none()
-                && (d.before.is_some() || d.tool == Tool::Connect)
-            {
-                form = form.push(
-                    text_input(
-                        "Path condition (empty remains a Choice / Loop warning)",
-                        &d.guard,
-                    )
-                    .on_input(|v| event(Event::Guard(v)))
-                    .padding(8)
-                    .size(12),
-                );
-            }
+                    "Create"
+                })
+                .on_press_maybe(valid.then(|| event(Event::Submit))),
+                button("Cancel").on_press(event(Event::Cancel))
+            ]
+            .spacing(7);
+            form_panel = editor_panel(d.invocation, actions.into(), form.into());
         }
-        let valid = match d.command(p) {
-            Ok(_) => true,
-            Err(problem) => {
-                form = form.push(label(problem));
-                false
-            }
-        };
-        let actions = row![
-            button(if d.contextual.is_some() {
-                "Apply link"
-            } else {
-                "Create"
-            })
-            .on_press_maybe(valid.then(|| event(Event::Submit))),
-            button("Cancel").on_press(event(Event::Cancel))
-        ]
-        .spacing(7);
-        form_panel = editor_panel(actions.into(), form.into());
     }
-    panes(diagram, form_panel, pending)
-}
-
-/// A permanent three-slot tree: variable controls never remount the canvas.
-/// The shelf scrolls independently; the canvas receives actual remaining height.
-fn explicit_pane<'a, R: iced::advanced::text::Renderer + 'a>(
-    header: iced::Element<'a, Message, iced::Theme, R>,
-    details: iced::Element<'a, Message, iced::Theme, R>,
-    canvas: iced::Element<'a, Message, iced::Theme, R>,
-    show_details: bool,
-    pending: bool,
-) -> iced::Element<'a, Message, iced::Theme, R> {
-    // Column::push drops Fixed(0) children. from_vec retains the closed shelf
-    // slot so its disclosure cannot move/remount the following canvas tree.
-    Column::from_vec(vec![
-        container(header).width(Fill).into(),
-        scrollable(details)
-            .id("process-details")
-            .width(Fill)
-            .height(if show_details {
-                if pending { 64. } else { 112. }
-            } else {
-                0.
-            })
-            .into(),
-        container(canvas).width(Fill).height(Fill).into(),
-    ])
-    .spacing(6)
-    .padding(8)
-    .width(Fill)
-    .height(Fill)
-    .into()
-}
-
-/// Keep the diagram mounted while an independent editor uses the remaining
-/// workspace height. The editor must never be clipped by the page scrollable.
-fn panes<'a, R: iced::advanced::Renderer + 'a>(
-    diagram: iced::Element<'a, Message, iced::Theme, R>,
-    form: iced::Element<'a, Message, iced::Theme, R>,
-    pending: bool,
-) -> iced::Element<'a, Message, iced::Theme, R> {
-    column![
-        container(diagram).width(Fill).height(if pending {
-            iced::Length::FillPortion(1)
-        } else {
-            Fill
-        }),
-        container(form).width(Fill).height(if pending {
-            iced::Length::FillPortion(1)
-        } else {
-            iced::Length::Shrink
-        }),
-    ]
-    .width(Fill)
-    .height(Fill)
-    .into()
+    let editor = if pending {
+        Some(form_panel)
+    } else {
+        state.shelf.map(|_| details)
+    };
+    super::super::canvas_workspace::host(header.into(), palette, canvas, editor)
 }
 
 fn editor_panel<'a, R: iced::advanced::text::Renderer + 'a>(
+    session: Id,
     actions: iced::Element<'a, Message, iced::Theme, R>,
     fields: iced::Element<'a, Message, iced::Theme, R>,
 ) -> iced::Element<'a, Message, iced::Theme, R> {
     container(
-        container(column![actions, scrollable(fields).id("process-form").height(Fill)].spacing(8))
-            .width(Fill)
-            .height(Fill)
-            .padding(12)
-            .style(style::card),
+        container(
+            column![
+                container(actions).id("process-actions"),
+                super::super::form_session::reset_on_change(
+                    session,
+                    scrollable(fields).id("process-form").height(Fill)
+                )
+            ]
+            .spacing(8),
+        )
+        .width(Fill)
+        .height(Fill)
+        .padding(12)
+        .style(style::card),
     )
     .width(Fill)
     .height(Fill)

crates/oa-desktop/src/diagram.rs

@@ -34,9 +34,15 @@ mod view_options_tests;
 #[path = "diagram/port_labels.rs"]
 mod port_labels;
 pub use port_labels::PortLabels;
+#[path = "diagram/focus.rs"]
+pub(crate) mod focus;
+#[path = "diagram/work_drag.rs"]
+mod work_drag;
+pub use work_drag::WorkFeedback;
 
 #[derive(Clone, Copy)]
 pub struct DiagramCanvas<'a> {
+    pub allocation: Option<crate::app::allocation_drag::Capability<'a>>,
     pub project: &'a Project,
     pub view_index: Option<&'a oa_core::view_options::ViewIndex>,
     pub diagram: Id,
@@ -51,8 +57,9 @@ pub struct DiagramCanvas<'a> {
 }
 #[derive(Default)]
 pub struct State {
+    work: Option<Arc<crate::app::allocation_drag::Press>>,
+    work_cache: RefCell<Option<Arc<Scene>>>,
     pointer: Option<Point>,
-    keyboard_focus: bool,
     drag: Option<(Id, Point, Position)>,
     preview: Option<Position>,
     pan_start: Option<(mouse::Button, Point)>,
@@ -64,6 +71,7 @@ pub struct State {
     cache: RefCell<Option<CachedScene>>,
 }
 struct Scene {
+    work: Option<Arc<crate::app::allocation_drag::Preview>>,
     view: ProjectedView,
     routed: Arc<RoutedView>,
 }
@@ -450,6 +458,26 @@ impl DiagramCanvas<'_> {
         }
     }
     fn scene(&self, state: &State) -> Arc<Scene> {
+        if let Some(preview) = self.work_preview()
+            && state
+                .work
+                .as_ref()
+                .is_some_and(|p| p.token == preview.token)
+        {
+            if let Some(scene) = state.work_cache.borrow().as_ref()
+                && scene.work.as_ref().is_some_and(|p| Arc::ptr_eq(p, preview))
+            {
+                return scene.clone();
+            }
+            let scene = Arc::new(Scene {
+                work: Some(preview.clone()),
+                view: preview.placement.view.clone(),
+                routed: preview.routed.clone(),
+            });
+            *state.work_cache.borrow_mut() = Some(scene.clone());
+            return scene;
+        }
+        *state.work_cache.borrow_mut() = None;
         let preview = if state.context == Some(self.context) {
             state.preview
         } else {
@@ -496,7 +524,11 @@ impl DiagramCanvas<'_> {
                 route_diagram(self.project, &diagram, &view)
             },
         );
-        let scene = Arc::new(Scene { view, routed });
+        let scene = Arc::new(Scene {
+            work: None,
+            view,
+            routed,
+        });
         *state.cache.borrow_mut() = Some(CachedScene {
             context: self.context,
             preview,
@@ -527,7 +559,26 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
         bounds: Rectangle,
         cursor: mouse::Cursor,
     ) -> Option<Action<Message>> {
+        // A completed work click retires App's allocation epoch before the
+        // retained canvas sees a redraw. Its already-idle press must not eat
+        // the first Delete. A live or not-yet-dispatched press stays guarded.
+        if matches!(event, canvas::Event::Keyboard(iced::keyboard::Event::KeyPressed { key, .. })
+            if *key == iced::keyboard::Key::Named(iced::keyboard::key::Named::Delete))
+            && self.allocation.is_some_and(|capability| {
+                capability.clean
+                    && state
+                        .work
+                        .as_ref()
+                        .is_some_and(|press| press.stamp.epoch != capability.state.epoch)
+            })
+        {
+            state.work = None;
+        }
+        if let Some(action) = self.work_lifetime(state, event, bounds) {
+            return Some(action);
+        }
         if state.context != Some(self.context) {
+            state.work = None;
             state.pointer = None;
             state.port_drag = None;
             state.connection_press = None;
@@ -593,9 +644,6 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
         let local = cursor
             .position()
             .map(|p| Point::new(p.x - bounds.x, p.y - bounds.y));
-        if matches!(event, canvas::Event::Mouse(mouse::Event::ButtonPressed(_))) {
-            state.keyboard_focus = cursor.is_over(bounds);
-        }
         match event {
             canvas::Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Right))
                 if cursor.is_over(bounds) =>
@@ -615,7 +663,8 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
             }
             canvas::Event::Keyboard(iced::keyboard::Event::KeyPressed {
                 key, modifiers, ..
-            }) if state.keyboard_focus => {
+            }) => {
+                // The mounted focus::Owner is the sole keyboard admission gate.
                 use iced::keyboard::{Key, key::Named};
                 match key.as_ref() {
                     Key::Named(Named::F2)
@@ -670,10 +719,37 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                     Key::Named(Named::Delete)
                         if self.editable
                             && self.connection.is_none()
-                            && modifiers.is_empty()
-                            && self.selected_bend.is_some() =>
+                            && !self.placing
+                            && state.drag.is_none()
+                            && state.route_drag.is_none()
+                            && state.port_drag.is_none()
+                            && state.pan_start.is_none()
+                            && state.work.is_none()
+                            && (modifiers.is_empty()
+                                || *modifiers == iced::keyboard::Modifiers::SHIFT) =>
                     {
-                        Some(Action::publish(Message::Route(RouteEvent::RemoveBend)).and_capture())
+                        // An invalid/stale bend never falls through to whole-item removal.
+                        if self.selected_bend.is_some() {
+                            return modifiers.is_empty().then(|| {
+                                Action::publish(Message::Route(RouteEvent::RemoveBend))
+                                    .and_capture()
+                            });
+                        }
+                        let request = self.selection_context_request(state, bounds);
+                        if request.object == self.diagram {
+                            return None;
+                        }
+                        Some(
+                            Action::publish(Message::DiagramRemove(
+                                crate::app::diagram_removal::Intent {
+                                    context: self.context,
+                                    object: request.object,
+                                    placement: request.placement,
+                                    model: modifiers.shift(),
+                                },
+                            ))
+                            .and_capture(),
+                        )
                     }
                     _ => None,
                 }
@@ -714,6 +790,22 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                 let scene = self.scene(state);
                 let view = &scene.view;
                 let world = self.world(p);
+                if self.work_dirty_press(view, &scene.routed, p) {
+                    state.work = None;
+                    state.drag = None;
+                    state.preview = None;
+                    state.port_drag = None;
+                    state.route_drag = None;
+                    return Some(
+                        Action::publish(Message::WorkDrag(
+                            crate::app::allocation_drag::Event::Refused(
+                                self.allocation.unwrap().state.epoch,
+                                crate::app::allocation_drag::FINISH_EDIT.into(),
+                            ),
+                        ))
+                        .and_capture(),
+                    );
+                }
                 if self.placing && self.editable {
                     return Some(
                         Action::publish(Message::Architecture(
@@ -795,6 +887,16 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                     return Some(Action::publish(Message::Select(port.element)).and_capture());
                 }
                 if let Some(id) = self.hit(view, p) {
+                    if self.work_eligible(id) {
+                        return Some(self.begin_work(
+                            state,
+                            id,
+                            cursor.position()?,
+                            bounds,
+                            view,
+                            &scene.routed,
+                        ));
+                    }
                     let position = self
                         .project
                         .diagrams
@@ -833,6 +935,18 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                 }
             }
             canvas::Event::Mouse(mouse::Event::CursorMoved { .. }) => {
+                if let Some(press) = &state.work {
+                    return Some(
+                        Action::publish(Message::WorkDrag(
+                            crate::app::allocation_drag::Event::Preview(
+                                press.stamp,
+                                press.token,
+                                cursor.position(),
+                            ),
+                        ))
+                        .and_capture(),
+                    );
+                }
                 let p = local?;
                 if let Some((button, start)) = state.pan_start {
                     state.pan_start = Some((button, p));
@@ -865,6 +979,18 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                 None
             }
             canvas::Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)) => {
+                if let Some(press) = state.work.take() {
+                    return Some(
+                        Action::publish(Message::WorkDrag(
+                            crate::app::allocation_drag::Event::Release(
+                                press.stamp,
+                                press.token,
+                                cursor.position(),
+                            ),
+                        ))
+                        .and_capture(),
+                    );
+                }
                 if let Some((button, start)) = state.pan_start {
                     if button == mouse::Button::Middle {
                         return Some(Action::capture());
@@ -1011,6 +1137,10 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
         f.translate(self.pan);
         f.scale(self.zoom);
         let scene = self.scene(state);
+        let project = scene
+            .work
+            .as_ref()
+            .map_or(self.project, |p| p.semantic.project());
         let view = &scene.view;
         let containers = view
             .nodes
@@ -1019,10 +1149,10 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
             .collect::<BTreeSet<_>>();
         for n in &view.nodes {
             if containers.contains(&n.id) {
-                paint_node(&mut f, self.project, n, self.selected, true);
+                paint_node(&mut f, project, n, self.selected, true);
             }
         }
-        let highlighted = highlighted_exchanges(self.project, self.selected);
+        let highlighted = highlighted_exchanges(project, self.selected);
         for edge in &view.edges {
             let Some(routed) = scene.routed.edges.get(&edge.id) else {
                 continue;
@@ -1045,7 +1175,7 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
             } else {
                 Color::from_rgb8(144, 158, 173)
             };
-            let capability_label = relationship_stereotype(self.project, edge.id);
+            let capability_label = relationship_stereotype(project, edge.id);
             let mut stroke =
                 Stroke::default()
                     .with_color(color)
@@ -1093,7 +1223,7 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                     ..Default::default()
                 });
             }
-            if let Some(relation) = self.project.relations.get(&edge.id) {
+            if let Some(relation) = project.relations.get(&edge.id) {
                 for end in routing::association_end_geometry(relation, routed) {
                     if end.navigable {
                         let [a, tip, b] = navigation_mark(end.tip, end.inward);
@@ -1127,13 +1257,13 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
         }
         for n in &view.nodes {
             if !containers.contains(&n.id) {
-                paint_node(&mut f, self.project, n, self.selected, false);
+                paint_node(&mut f, project, n, self.selected, false);
             } else {
                 // Container headers stay readable when relationships traverse
                 // the allocation enclosure. Children remain on top.
                 let mut header = n.clone();
                 header.size.height = 62.;
-                paint_node(&mut f, self.project, &header, self.selected, true);
+                paint_node(&mut f, project, &header, self.selected, true);
             }
         }
         for port in &view.ports {
@@ -1141,17 +1271,17 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                 style::TEAL
             } else {
                 style::kind_color(
-                    self.project.elements[&port.element]
+                    project.elements[&port.element]
                         .parent
-                        .and_then(|id| self.project.elements.get(&id))
+                        .and_then(|id| project.elements.get(&id))
                         .map(|e| e.kind())
                         .unwrap_or(Kind::Port),
                 )
             };
             let origin = Point::new(port.position.x - 7., port.position.y - 7.);
-            let glyph = port_glyph(&self.project.elements[&port.element]);
+            let glyph = port_glyph(&project.elements[&port.element]);
             let path = if glyph == PortGlyph::Function {
-                let corners = port_triangle(&self.project.elements[&port.element], port);
+                let corners = port_triangle(&project.elements[&port.element], port);
                 Path::new(|p| {
                     p.move_to(corners[0]);
                     p.line_to(corners[1]);
@@ -1181,7 +1311,7 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
             if matches!(glyph, PortGlyph::Flow(_)) {
                 f.stroke(
                     &Path::new(|p| {
-                        for [a, b] in flow_mark(&self.project.elements[&port.element], port) {
+                        for [a, b] in flow_mark(&project.elements[&port.element], port) {
                             p.move_to(a);
                             p.line_to(b);
                         }
@@ -1343,7 +1473,8 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
     ) -> mouse::Interaction {
         if (self.connection.is_some() || self.placing) && cursor.is_over(bounds) {
             mouse::Interaction::Crosshair
-        } else if state.drag.is_some()
+        } else if state.work.is_some()
+            || state.drag.is_some()
             || state.pan_start.is_some()
             || state.route_drag.is_some()
             || state.port_drag.is_some()
@@ -1900,6 +2031,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
             diagram,
             selected: p.id,
             zoom: 1.,
@@ -1974,6 +2106,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
             diagram,
             selected: p.id,
             zoom: 0.6,
@@ -2098,6 +2231,7 @@ mod tests {
                 editable: true,
                 placing: false,
                 connection: Some(&session),
+                allocation: None,
             };
             let bounds = Rectangle::new(Point::new(260., 300.), Size::new(2400., 1600.));
             let at = |port: &oa_core::projection::ProjectedPort| {
@@ -2171,6 +2305,7 @@ mod tests {
             armed.start(&p, &view, source.element);
             let armed_canvas = DiagramCanvas {
                 connection: Some(&armed),
+                allocation: None,
                 ..canvas
             };
             // Winit updates cursor coordinates through CursorMoved, not the
@@ -2200,6 +2335,7 @@ mod tests {
             // A tool cancellation or navigation invalidates a queued release.
             let cancelled = DiagramCanvas {
                 connection: None,
+                allocation: None,
                 context: Context {
                     epoch: 1,
                     ..context
@@ -2271,6 +2407,7 @@ mod tests {
                 editable: true,
                 placing: false,
                 connection: None,
+                allocation: None,
             };
             let mut state = State::default();
             let pin = Point::new(400. * zoom + 150., -100. * zoom + 300.);
@@ -2346,6 +2483,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
         };
         let mut state = State::default();
         let pin = Point::new(350., 250.);
@@ -2442,6 +2580,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
         };
         let mut state = State::default();
         let first = canvas.scene(&state);
@@ -2569,6 +2708,7 @@ mod tests {
                 editable: true,
                 placing: false,
                 connection: None,
+                allocation: None,
             };
             for end in ends {
                 assert!(svg.contains(&format!(
@@ -2622,6 +2762,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
         };
         let mut state = State::default();
         let scene = canvas.scene(&state);
@@ -2695,6 +2836,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
         };
         assert!(
             matches!(pointer(&canvas,&mut state,mouse::Event::ButtonPressed(mouse::Button::Left),point(cover)+canvas.pan),Some(Message::SelectNode(id)) if id==node.id)
@@ -2727,6 +2869,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
         };
         let span = &routed.edges[&edge].points;
         let pick = point(oa_core::routing::point_along_polyline(span, 0.4).unwrap());

crates/oa-desktop/src/diagram/focus.rs

@@ -0,0 +1,244 @@
+//! Iced focus ownership shared by architecture and persisted state canvases.
+//! Focus operations (including clean Inspector focus) unfocus this widget.
+use crate::route_edit::Context;
+use iced::advanced::widget::{Operation, Tree, operation};
+use iced::advanced::{Clipboard, Layout, Shell, Widget, layout, overlay, renderer};
+use iced::{Element, Event as InputEvent, Length, Point, Rectangle, Size, Theme, Vector, mouse};
+#[derive(Default)]
+struct Input {
+    context: Option<Context>,
+    focused: bool,
+    traversing: bool,
+    pointer: Option<Point>,
+}
+impl operation::Focusable for Input {
+    fn is_focused(&self) -> bool {
+        self.focused
+    }
+    fn focus(&mut self) {
+        self.focused = true;
+        self.traversing = false;
+    }
+    fn unfocus(&mut self) {
+        self.focused = false;
+        self.traversing = false;
+    }
+}
+struct Owner<'a, Message, R: renderer::Renderer> {
+    context: Context,
+    enabled: bool,
+    traverse: Box<dyn Fn(bool) -> Message + 'a>,
+    content: Element<'a, Message, Theme, R>,
+}
+pub fn wrap<'a, Message: 'a, R: renderer::Renderer + 'a>(
+    content: impl Into<Element<'a, Message, Theme, R>>,
+    context: Context,
+    enabled: bool,
+    traverse: impl Fn(bool) -> Message + 'a,
+) -> Element<'a, Message, Theme, R> {
+    Element::new(Owner {
+        context,
+        enabled,
+        traverse: Box::new(traverse),
+        content: content.into(),
+    })
+}
+impl<Message, R: renderer::Renderer> Widget<Message, Theme, R> for Owner<'_, Message, R> {
+    fn tag(&self) -> iced::advanced::widget::tree::Tag {
+        iced::advanced::widget::tree::Tag::of::<Input>()
+    }
+    fn state(&self) -> iced::advanced::widget::tree::State {
+        iced::advanced::widget::tree::State::new(Input {
+            context: Some(self.context),
+            ..Default::default()
+        })
+    }
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+
+    fn diff(&self, tree: &mut Tree) {
+        let state = tree.state.downcast_mut::<Input>();
+        if state.context != Some(self.context) || !self.enabled {
+            state.focused = false;
+            state.traversing = false;
+            state.pointer = None;
+        }
+        state.context = Some(self.context);
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        operation: &mut dyn Operation,
+    ) {
+        if self.enabled {
+            operation.focusable(
+                Some(&iced::advanced::widget::Id::from("diagram-keyboard-owner")),
+                layout.bounds(),
+                tree.state.downcast_mut::<Input>(),
+            );
+        }
+        self.content
+            .as_widget_mut()
+            .operate(&mut tree.children[0], layout, renderer, operation);
+    }
+
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &InputEvent,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        let state = tree.state.downcast_mut::<Input>();
+        if let InputEvent::Mouse(mouse::Event::CursorMoved { position }) = event {
+            state.pointer = Some(*position);
+        }
+        if matches!(
+            event,
+            InputEvent::Window(iced::window::Event::Unfocused | iced::window::Event::Resized(_))
+        ) || !self.enabled
+        {
+            state.focused = false;
+            state.traversing = false;
+            state.pointer = None;
+        }
+        if matches!(event, InputEvent::Mouse(mouse::Event::ButtonPressed(_))) {
+            state.traversing = false;
+            let pointer = state.pointer.or_else(|| cursor.position());
+            state.focused = self.enabled
+                && !shell.is_event_captured()
+                && cursor.position().is_some()
+                && pointer.is_some_and(|p| {
+                    layout
+                        .bounds()
+                        .intersection(viewport)
+                        .is_some_and(|b| b.contains(p))
+                });
+        }
+        if let InputEvent::Keyboard(iced::keyboard::Event::KeyPressed {
+            key: iced::keyboard::Key::Named(iced::keyboard::key::Named::Tab),
+            modifiers,
+            ..
+        }) = event
+            && state.focused
+            && !state.traversing
+            && self.enabled
+            && !shell.is_event_captured()
+            && (*modifiers == iced::keyboard::Modifiers::SHIFT || modifiers.is_empty())
+        {
+            // The focus task runs after the native batch. Retain focus for its
+            // traversal count, but reject later keys in this same batch now.
+            state.traversing = true;
+            shell.publish((self.traverse)(modifiers.shift()));
+            shell.capture_event();
+            return;
+        }
+        if matches!(event, InputEvent::Keyboard(_))
+            && (!state.focused || state.traversing || !self.enabled)
+        {
+            return;
+        }
+        if shell.is_event_captured() {
+            return;
+        }
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            style,
+            layout,
+            cursor,
+            viewport,
+        );
+        let state = tree.state.downcast_ref::<Input>();
+        if state.focused && !state.traversing && self.enabled {
+            renderer.fill_quad(
+                renderer::Quad {
+                    bounds: layout.bounds(),
+                    border: iced::Border {
+                        color: crate::style::TEAL,
+                        width: 1.,
+                        ..Default::default()
+                    },
+                    ..Default::default()
+                },
+                iced::Color::TRANSPARENT,
+            );
+        }
+    }
+
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        self.content.as_widget().mouse_interaction(
+            &tree.children[0],
+            layout,
+            cursor,
+            viewport,
+            renderer,
+        )
+    }
+
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'b>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'b, Message, Theme, R>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}

crates/oa-desktop/src/diagram/lifecycle_tests.rs

@@ -64,6 +64,7 @@ fn canvas(app: &App) -> DiagramCanvas<'_> {
         editable: true,
         placing: false,
         connection: app.connection.as_ref(),
+        allocation: None,
     }
 }
 fn screen(app: &App, id: Id) -> Point {

crates/oa-desktop/src/diagram/pointer_tests.rs

@@ -72,6 +72,7 @@ fn canvas(app: &App, zoom: f32) -> DiagramCanvas<'_> {
         editable: true,
         placing: false,
         connection: app.connection.as_ref(),
+        allocation: None,
     }
 }
 fn event(

crates/oa-desktop/src/diagram/port_hit_tests.rs

@@ -18,6 +18,7 @@ fn canvas(project: &Project, diagram: Id, zoom: f32) -> DiagramCanvas<'_> {
         editable: true,
         placing: false,
         connection: None,
+        allocation: None,
     }
 }
 

crates/oa-desktop/src/diagram/port_labels.rs

@@ -58,6 +58,9 @@ impl canvas::Program<Message> for PortLabels<'_> {
         bounds: Rectangle,
         cursor: mouse::Cursor,
     ) -> Vec<canvas::Geometry> {
+        if self.0.work_preview().is_some() {
+            return vec![]; // The candidate canvas already paints its own ports.
+        }
         if state.context == Some(self.0.context) && state.held_buttons != 0 {
             return vec![];
         }
@@ -185,6 +188,7 @@ mod tests {
             editable: true,
             placing: false,
             connection: None,
+            allocation: None,
         })
     }
 

crates/oa-desktop/src/diagram/work_drag.rs

@@ -0,0 +1,205 @@
+use super::*;
+use crate::app::allocation_drag::{self as input, Event, Press, Stamp};
+
+impl DiagramCanvas<'_> {
+    pub(crate) fn work_dirty_point(&self, bounds: Rectangle, screen: Point) -> bool {
+        let diagram = &self.project.diagrams[&self.diagram];
+        let view = self.projected(diagram);
+        let routed = routing::route_diagram(self.project, diagram, &view);
+        self.work_dirty_press(
+            &view,
+            &routed,
+            Point::new(screen.x - bounds.x, screen.y - bounds.y),
+        )
+    }
+    pub(super) fn work_preview(&self) -> Option<&Arc<input::Preview>> {
+        let capability = self.allocation?;
+        let feedback = capability.state.feedback.as_ref()?;
+        (capability.clean
+            && feedback.press.stamp.context == self.context
+            && feedback.press.stamp.epoch == capability.state.epoch
+            && feedback.press.stamp.pan == self.pan
+            && feedback.press.stamp.zoom == self.zoom)
+            .then_some(capability.state.preview.as_ref())
+            .flatten()
+    }
+    pub(super) fn work_eligible(&self, placement: Id) -> bool {
+        self.allocation.is_some()
+            && self.project.diagrams[&self.diagram].projection == ProjectionKind::Allocation
+            && self.project.diagrams[&self.diagram]
+                .nodes
+                .get(&placement)
+                .and_then(|n| self.project.elements.get(&n.element))
+                .is_some_and(|e| e.kind().is_work())
+    }
+    pub(super) fn work_dirty_press(
+        &self,
+        view: &ProjectedView,
+        routed: &RoutedView,
+        local: Point,
+    ) -> bool {
+        self.allocation.is_some_and(|c| !c.clean)
+            && !self.placing
+            && self.connection.is_none()
+            && self.project.diagrams[&self.diagram].projection == ProjectionKind::Allocation
+            && (self.hit(view, local).is_some()
+                || self.hit_port(view, local).is_some()
+                || self.hit_edge(routed, local).is_some()
+                || self.hit_label(routed, local).is_some()
+                || self.hit_association_label(routed, local).is_some())
+    }
+    pub(super) fn begin_work(
+        &self,
+        state: &mut State,
+        node: Id,
+        screen: Point,
+        bounds: Rectangle,
+        view: &ProjectedView,
+        routed: &RoutedView,
+    ) -> Action<Message> {
+        let capability = self.allocation.unwrap();
+        state.drag = None;
+        state.preview = None;
+        state.port_drag = None;
+        state.route_drag = None;
+        if !capability.clean {
+            return Action::publish(Message::WorkDrag(Event::Refused(
+                capability.state.epoch,
+                input::FINISH_EDIT.into(),
+            )))
+            .and_capture();
+        }
+        let work = self.project.diagrams[&self.diagram].nodes[&node].element;
+        let scope = match crate::allocation_drag::capture(self.project, self.diagram, work, node) {
+            Ok(scope) => scope,
+            Err(reason) => {
+                return Action::publish(Message::WorkDrag(Event::Refused(
+                    capability.state.epoch,
+                    input::refusal(&reason),
+                )))
+                .and_capture();
+            }
+        };
+        let frozen = input::Frozen::capture(self.project, &scope, view, routed, self.zoom);
+        let press = Arc::new(Press {
+            stamp: Stamp {
+                context: self.context,
+                epoch: capability.state.epoch,
+                snapshot: capability.snapshot,
+                bounds,
+                pan: self.pan,
+                zoom: self.zoom,
+            },
+            token: Id::new_v4(),
+            start: screen,
+            scope,
+            frozen,
+            arrange: capability.state.arrange_next,
+        });
+        state.work = Some(press.clone());
+        Action::publish(Message::WorkDrag(Event::Press(press))).and_capture()
+    }
+    pub(super) fn work_lifetime(
+        &self,
+        state: &mut State,
+        event: &canvas::Event,
+        bounds: Rectangle,
+    ) -> Option<Action<Message>> {
+        let press = state.work.as_ref()?;
+        let cancel = self
+            .allocation
+            .is_none_or(|c| !c.clean || c.state.epoch != press.stamp.epoch)
+            || press.stamp.context != self.context
+            || press.stamp.bounds != bounds
+            || press.stamp.pan != self.pan
+            || press.stamp.zoom != self.zoom
+            || matches!(
+                event,
+                canvas::Event::Window(iced::window::Event::Unfocused)
+                    | canvas::Event::Mouse(mouse::Event::CursorLeft)
+                    | canvas::Event::Mouse(mouse::Event::ButtonPressed(
+                        mouse::Button::Middle | mouse::Button::Right
+                    ))
+                    | canvas::Event::Mouse(mouse::Event::WheelScrolled { .. })
+            )
+            || matches!(event, canvas::Event::Keyboard(iced::keyboard::Event::KeyPressed { key, .. })
+                if *key == iced::keyboard::Key::Named(iced::keyboard::key::Named::Escape));
+        if cancel {
+            let token = press.token;
+            state.work = None;
+            state.pointer = None;
+            return Some(Action::publish(Message::WorkDrag(Event::Cancel(token))).and_capture());
+        }
+        None
+    }
+}
+
+/// Separate passive layer: frozen target labels remain above all candidate card
+/// text. It does not acquire input or use a second independent semantic scene.
+pub struct WorkFeedback<'a>(pub DiagramCanvas<'a>);
+impl canvas::Program<Message> for WorkFeedback<'_> {
+    type State = ();
+    fn draw(
+        &self,
+        _: &(),
+        renderer: &Renderer,
+        _: &Theme,
+        bounds: Rectangle,
+        _: mouse::Cursor,
+    ) -> Vec<canvas::Geometry> {
+        let Some(capability) = self.0.allocation else {
+            return vec![];
+        };
+        let Some(feedback) = &capability.state.feedback else {
+            return vec![];
+        };
+        if feedback.press.stamp.epoch != capability.state.epoch
+            || feedback.press.stamp.context != self.0.context
+            || feedback.press.stamp.bounds != bounds
+        {
+            return vec![];
+        }
+        let mut frame = Frame::new(renderer, bounds.size());
+        let color = if feedback.refused {
+            Color::from_rgb8(173, 66, 41)
+        } else {
+            style::TEAL
+        };
+        for index in &feedback.targets {
+            let target = &feedback.press.frozen.targets[*index];
+            let region = target.region;
+            let top = Point::new(
+                region.x * self.0.zoom + self.0.pan.x,
+                region.y * self.0.zoom + self.0.pan.y,
+            );
+            frame.stroke(
+                &Path::rectangle(
+                    top,
+                    iced::Size::new(region.width * self.0.zoom, region.height * self.0.zoom),
+                ),
+                Stroke::default().with_color(color).with_width(3.),
+            );
+            let label = target.label;
+            let top = Point::new(
+                label.position.x * self.0.zoom + self.0.pan.x,
+                label.position.y * self.0.zoom + self.0.pan.y,
+            );
+            frame.fill_rectangle(
+                top,
+                iced::Size::new(
+                    label.size.width * self.0.zoom,
+                    label.size.height * self.0.zoom,
+                ),
+                Color::WHITE,
+            );
+            frame.fill_text(Text {
+                content: target.name.clone(),
+                position: top,
+                size: (16. * self.0.zoom).into(),
+                color,
+                ..Default::default()
+            });
+        }
+        vec![frame.into_geometry()]
+    }
+}

crates/oa-desktop/src/document.rs

@@ -95,7 +95,7 @@ pub struct Document {
     past: Vec<HistoryEntry>,
     future: Vec<HistoryEntry>,
     current_bytes: usize,
-    saved: Arc<SourceBundle>,
+    saved: Option<Arc<SourceBundle>>,
     revision: u64,
     view_index: std::cell::OnceCell<oa_core::view_options::ViewIndex>,
     limits: ProjectLimits,
@@ -125,7 +125,7 @@ impl Document {
             current_bytes,
             past: Vec::new(),
             future: Vec::new(),
-            saved: Arc::new(bundle),
+            saved: Some(Arc::new(bundle)),
             revision: 0,
             view_index: Default::default(),
             limits,
@@ -156,7 +156,7 @@ impl Document {
     }
 
     pub fn dirty(&self) -> bool {
-        self.recovered_unsaved || self.bundle() != self.saved.as_ref()
+        self.recovered_unsaved || self.saved.as_deref() != Some(self.bundle())
     }
 
     /// Recovered work is a detached copy until explicitly saved by its user.
@@ -181,10 +181,24 @@ impl Document {
     /// Records the bytes actually saved, even when later edits remain current.
     /// The I/O adapter owns document identity and save completion ordering.
     pub fn mark_saved(&mut self, snapshot: Arc<CompiledSourceProject>) {
-        self.saved = Arc::new(snapshot.bundle.clone());
+        self.saved = Some(Arc::new(snapshot.bundle.clone()));
         self.recovered_unsaved = false;
     }
 
+    /// Bind an installed or recovered repair destination to source read there.
+    /// These bytes may be invalid or differ from the retained accepted model,
+    /// but must replace the previous disk baseline. Accepted history is retained;
+    /// applying or undoing to old saved content does not save this destination.
+    pub(crate) fn bind_repair_baseline(&mut self, source: SourceBundle) {
+        self.saved = Some(Arc::new(source));
+    }
+
+    /// Recovery changed the current destination, but its source could not be
+    /// reloaded. No accepted or historical snapshot is known to be saved there.
+    pub(crate) fn invalidate_saved_baseline(&mut self) {
+        self.saved = None;
+    }
+
     /// Check a source Save as before writing any files. A retained included file
     /// must never be displaced by the new entry, including on a later Undo.
     pub fn check_save_entry(&self, entry: &str) -> Result<(), DocumentError> {

crates/oa-desktop/src/forms.rs

@@ -18,6 +18,7 @@ mod context_fields;
 mod data_fields;
 mod history_fields;
 mod port_fields;
+pub(crate) mod reference_chooser;
 mod view_fields;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -85,6 +86,8 @@ pub struct Draft {
     pub value_browsers: BTreeMap<String, ValueBrowser>,
     pub reference_browsers: BTreeMap<String, ReferenceBrowser>,
     history: history_fields::State,
+    reference_session: Id,
+    reference_generation: Id,
 }
 
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
@@ -209,11 +212,14 @@ impl Draft {
             value_browsers: BTreeMap::new(),
             reference_browsers: BTreeMap::new(),
             history: Default::default(),
+            reference_session: Id::new_v4(),
+            reference_generation: Id::new_v4(),
         };
         draft.rebuild();
         Some(draft)
     }
     fn rebuild(&mut self) {
+        self.reference_generation = Id::new_v4();
         // Array/variant edits can change the meaning of a row path.
         self.value_browsers.clear();
         self.inputs.clear();
@@ -274,6 +280,9 @@ impl Draft {
             .unwrap_or_else(|| self.materialize().unwrap_or_else(|_| self.value.clone()))
     }
     pub fn set_context(&mut self, context: Option<Value>) {
+        if self.context != context {
+            self.reference_generation = Id::new_v4();
+        }
         self.context = context;
     }
     /// Materialize selected scalar subtrees without parsing retained, unselected drafts.
@@ -359,6 +368,9 @@ impl Draft {
     }
     pub fn input(&mut self, path: &str, value: String) {
         if let Some(input) = self.inputs.get_mut(path) {
+            if input.raw != value {
+                self.reference_generation = Id::new_v4();
+            }
             input.editor = text_editor::Content::with_text(&value);
             input.raw = value;
         }
@@ -366,7 +378,11 @@ impl Draft {
     pub fn edit_text(&mut self, path: &str, action: text_editor::Action) {
         if let Some(input) = self.inputs.get_mut(path) {
             input.editor.perform(action);
-            input.raw = input.editor.text();
+            let raw = input.editor.text();
+            if input.raw != raw {
+                self.reference_generation = Id::new_v4();
+            }
+            input.raw = raw;
         }
     }
     pub fn shape(&mut self, path: &str, value: Value) -> Result<(), String> {
@@ -1795,7 +1811,7 @@ pub fn view<'a>(draft: &'a Draft, project: &'a Project) -> View<'a, Message> {
             ));
         }
     }
-    content.into()
+    reference_chooser::trigger::scope(content, draft.reference_session)
 }
 
 /// Render one closed property subtree for a workflow-owned typed draft.
@@ -1937,41 +1953,12 @@ fn property<'a>(
         return out.into();
     }
     if reference(path) && (value.is_string() || value.is_null()) {
-        let raw = draft
-            .inputs
-            .get(path)
-            .map(|v| v.raw.as_str())
-            .or_else(|| value.as_str());
-        let current = raw.and_then(|s| s.parse::<Id>().ok()).unwrap_or(Id::nil());
-        let choices = reference_choices(draft, project, path, current);
-        let selected = choices.iter().find(|c| c.id == current).cloned();
-        let owned_path = path.to_string();
-        let optional = optional_reference(path);
-        let mut content = column![
+        return column![
             label_view(),
-            pick_list(choices, selected, move |choice| Message::FieldShape(
-                owned_path.clone(),
-                if choice.id.is_nil() && optional {
-                    Value::Null
-                } else {
-                    json!(choice.id)
-                }
-            ))
-            .text_size(12)
-            .padding(8)
-            .width(Fill)
+            reference_chooser::adapter::field(draft, project, path)
         ]
-        .spacing(5);
-        if let Some(raw) = raw
-            && raw.parse::<Id>().is_err()
-        {
-            content = content.push(
-                text(format!("Invalid reference retained in the draft: {raw}"))
-                    .size(11)
-                    .color(style::MUTED),
-            );
-        }
-        return content.into();
+        .spacing(5)
+        .into();
     }
     match value {
         Value::Object(map) => {

crates/oa-desktop/src/forms/data_fields.rs

@@ -670,7 +670,7 @@ mod tests {
     }
     fn semantic_send(app: &mut crate::app::App, event: crate::semantic_review::RowEvent) {
         let event = semantic_state(app).address_event(event);
-        let _ = app.update(Message::Workflow(crate::workflow::Event::Semantic(event)));
+        let _ = app.update(Message::Workflow(crate::workflow::Event::semantic(event)));
     }
     fn semantic_decide(app: &mut crate::app::App, facet: FieldFacet, decision: SemanticDecision) {
         use crate::semantic_review::RowEvent as Event;

crates/oa-desktop/src/forms/reference_chooser.rs

@@ -0,0 +1,389 @@
+//! Isolated live-reference chooser experiment, declared only under cfg(test).
+//! The host supplies an eligible catalog and revalidates every
+//! Write intent against the current document before changing a staged scalar.
+//! No core command, draft serialization, or App message belongs in this module.
+use oa_core::Id;
+use std::collections::BTreeSet;
+
+pub mod adapter;
+#[cfg(test)]
+mod tests;
+pub mod trigger;
+pub mod widget;
+
+pub const MAX_ROWS: usize = 6;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Context {
+    pub document: Id,
+    pub revision: u64,
+    pub draft: Id,
+    pub record: Id,
+    pub path: String,
+    pub optional: bool,
+}
+impl Context {
+    /// This is an additional historical-path guard, not live schema discovery.
+    /// Call only after the parent form has identified a live reference field.
+    pub fn live(
+        document: Id,
+        revision: u64,
+        draft: Id,
+        record: Id,
+        path: impl Into<String>,
+        optional: bool,
+    ) -> Result<Self, &'static str> {
+        let path = path.into();
+        if !path.starts_with('/') || path.split('/').any(|part| part == "baseline") {
+            return Err("The chooser requires a live reference property.");
+        }
+        Ok(Self {
+            document,
+            revision,
+            draft,
+            record,
+            path,
+            optional,
+        })
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Candidate {
+    /// For a diagram placement this is the placement ID, not its element ID.
+    pub id: Id,
+    pub name: String,
+    pub alias: String,
+    pub kind: String,
+    pub scope: String,
+    pub containment: String,
+}
+impl Candidate {
+    pub fn context_label(&self) -> String {
+        format!("{} · {} · {}", self.scope, self.kind, self.containment)
+    }
+    pub fn detail(&self) -> String {
+        format!(
+            "{} · @{} · {} · {}",
+            self.name,
+            self.alias,
+            self.context_label(),
+            self.id
+        )
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Current {
+    Unassigned,
+    Valid(Candidate),
+    Incompatible(Candidate),
+    Missing(Id),
+    InvalidRaw(String),
+}
+impl Current {
+    pub fn label(&self) -> String {
+        match self {
+            Self::Unassigned => "Not assigned".into(),
+            Self::Valid(c) => format!("Current: {} · @{}", c.name, c.alias),
+            Self::Incompatible(c) => {
+                format!("Current choice needs review: {} · @{}", c.name, c.alias)
+            }
+            Self::Missing(id) => format!("Missing reference: {id}"),
+            Self::InvalidRaw(raw) => format!("Invalid reference retained: {raw}"),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+struct Searchable {
+    candidate: Candidate,
+    all: String,
+    alias: String,
+    name: String,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Stamp {
+    pub context: Context,
+    pub invocation: Id,
+    pub results: u64,
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Close {
+    Escape,
+    Tab { backwards: bool },
+    Outside,
+    WindowChanged,
+}
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Action {
+    /// The mounted text input numbers emitted edits. Multiple edits in one
+    /// runtime batch may share the old result stamp; none may be dropped.
+    Query {
+        text: String,
+        serial: u64,
+    },
+    Move {
+        delta: i32,
+        rows: usize,
+    },
+    Page {
+        delta: i32,
+        rows: usize,
+    },
+    Highlight(Id),
+    Choose(Id),
+    Clear,
+    Close(Close),
+}
+impl Action {
+    pub fn writes_staged_value(&self) -> bool {
+        matches!(self, Self::Choose(_) | Self::Clear)
+    }
+}
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Event {
+    pub stamp: Stamp,
+    pub action: Action,
+}
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Outcome {
+    Ignored,
+    Browsed,
+    Closed(Close),
+    /// The host must still check current eligibility and scoped draft guards.
+    Write {
+        context: Context,
+        value: Option<Id>,
+    },
+}
+
+#[derive(Debug, Clone)]
+pub struct State {
+    context: Context,
+    invocation: Id,
+    results: u64,
+    serial: u64,
+    open: bool,
+    candidates: Vec<Searchable>,
+    filtered: Vec<usize>,
+    query: String,
+    start: usize,
+    highlight: Option<usize>,
+    pub current: Current,
+    pub scope_label: String,
+}
+impl State {
+    pub fn open(
+        context: Context,
+        candidates: Vec<Candidate>,
+        current: Current,
+        scope_label: impl Into<String>,
+    ) -> Result<Self, &'static str> {
+        // Context fields are public for host comparisons; check again in case
+        // a caller constructed one without the live-path constructor.
+        if !context.path.starts_with('/') || context.path.split('/').any(|p| p == "baseline") {
+            return Err("Historical values are not live reference candidates.");
+        }
+        let mut seen = BTreeSet::new();
+        let mut indexed = Vec::with_capacity(candidates.len());
+        for candidate in candidates {
+            if candidate.id.is_nil() || !seen.insert(candidate.id) {
+                return Err("Eligible references must have distinct, non-nil identities.");
+            }
+            indexed.push(Searchable {
+                all: candidate.detail().to_lowercase(),
+                alias: candidate.alias.to_lowercase(),
+                name: candidate.name.to_lowercase(),
+                candidate,
+            });
+        }
+        indexed.sort_by(|a, b| {
+            (&a.name, &a.alias, a.candidate.id).cmp(&(&b.name, &b.alias, b.candidate.id))
+        });
+        let filtered: Vec<_> = (0..indexed.len()).collect();
+        let highlight = (!filtered.is_empty()).then_some(0);
+        Ok(Self {
+            context,
+            invocation: Id::new_v4(),
+            results: 0,
+            serial: 0,
+            open: true,
+            candidates: indexed,
+            filtered,
+            query: String::new(),
+            start: 0,
+            highlight,
+            current,
+            scope_label: scope_label.into(),
+        })
+    }
+    pub fn stamp(&self) -> Stamp {
+        Stamp {
+            context: self.context.clone(),
+            invocation: self.invocation,
+            results: self.results,
+        }
+    }
+    pub fn event(&self, action: Action) -> Event {
+        Event {
+            stamp: self.stamp(),
+            action,
+        }
+    }
+    pub fn is_open(&self) -> bool {
+        self.open
+    }
+    pub fn query(&self) -> &str {
+        &self.query
+    }
+    pub fn query_serial(&self) -> u64 {
+        self.serial
+    }
+    pub fn count(&self) -> usize {
+        self.filtered.len()
+    }
+    pub fn start(&self) -> usize {
+        self.start
+    }
+    pub fn optional(&self) -> bool {
+        self.context.optional
+    }
+    pub fn highlighted(&self) -> Option<&Candidate> {
+        self.highlight.and_then(|i| self.at(i))
+    }
+    fn at(&self, index: usize) -> Option<&Candidate> {
+        self.filtered
+            .get(index)
+            .map(|i| &self.candidates[*i].candidate)
+    }
+    pub fn visible(&self, rows: usize) -> impl Iterator<Item = &Candidate> {
+        self.filtered
+            .iter()
+            .skip(self.start)
+            .take(rows.min(MAX_ROWS))
+            .map(|index| &self.candidates[*index].candidate)
+    }
+    /// The host calls this before rendering on any path/document/facet/context
+    /// replacement. Existing events remain tied to the old invocation.
+    pub fn invalidate(&mut self) {
+        self.open = false;
+    }
+
+    pub fn update(&mut self, event: Event) -> Outcome {
+        if !self.open
+            || event.stamp.context != self.context
+            || event.stamp.invocation != self.invocation
+        {
+            return Outcome::Ignored;
+        }
+        // Absolute row actions require exactly the presented result set.
+        // Relative navigation and dismissal are processed in input order within
+        // this session: typing must not make a following Escape stale.
+        if matches!(event.action, Action::Choose(_) | Action::Highlight(_))
+            && event.stamp.results != self.results
+        {
+            return Outcome::Ignored;
+        }
+        match event.action {
+            Action::Query { text, serial } => {
+                if serial <= self.serial {
+                    return Outcome::Ignored;
+                }
+                self.serial = serial;
+                self.query = text;
+                let query = self.query.to_lowercase();
+                let terms: Vec<_> = query.split_whitespace().collect();
+                self.filtered = self
+                    .candidates
+                    .iter()
+                    .enumerate()
+                    .filter_map(|(i, c)| {
+                        terms
+                            .iter()
+                            .all(|term| match term.strip_prefix('@') {
+                                Some(alias) => c.alias.contains(alias),
+                                None => c.all.contains(term),
+                            })
+                            .then_some(i)
+                    })
+                    .collect();
+                self.start = 0;
+                self.highlight = (!self.filtered.is_empty()).then_some(0);
+            }
+            Action::Page { delta, rows } => {
+                let rows = rows.clamp(1, MAX_ROWS);
+                if self.filtered.is_empty() {
+                    return Outcome::Ignored;
+                }
+                let relative = self
+                    .highlight
+                    .unwrap_or(self.start)
+                    .saturating_sub(self.start)
+                    .min(rows - 1);
+                let last_page = (self.filtered.len() - 1) / rows * rows;
+                self.start = (self.start as i64 + i64::from(delta) * rows as i64)
+                    .clamp(0, last_page as i64) as usize;
+                self.highlight = Some((self.start + relative).min(self.filtered.len() - 1));
+            }
+            Action::Move { delta, rows } => {
+                let rows = rows.clamp(1, MAX_ROWS);
+                if self.filtered.is_empty() {
+                    return Outcome::Ignored;
+                }
+                let current = self.highlight.unwrap_or(self.start) as i64;
+                let next =
+                    (current + i64::from(delta)).clamp(0, self.filtered.len() as i64 - 1) as usize;
+                self.highlight = Some(next);
+                if next < self.start {
+                    self.start = next;
+                }
+                if next >= self.start + rows {
+                    self.start = next + 1 - rows;
+                }
+            }
+            Action::Highlight(id) => {
+                let Some(index) = self
+                    .filtered
+                    .iter()
+                    .position(|i| self.candidates[*i].candidate.id == id)
+                else {
+                    return Outcome::Ignored;
+                };
+                if self.highlight == Some(index) {
+                    return Outcome::Ignored;
+                }
+                self.highlight = Some(index);
+            }
+            Action::Choose(id) => {
+                if !self
+                    .filtered
+                    .iter()
+                    .any(|i| self.candidates[*i].candidate.id == id)
+                {
+                    return Outcome::Ignored;
+                }
+                self.open = false;
+                return Outcome::Write {
+                    context: self.context.clone(),
+                    value: Some(id),
+                };
+            }
+            Action::Clear if self.context.optional => {
+                self.open = false;
+                return Outcome::Write {
+                    context: self.context.clone(),
+                    value: None,
+                };
+            }
+            Action::Clear => return Outcome::Ignored,
+            Action::Close(reason) => {
+                self.open = false;
+                return Outcome::Closed(reason);
+            }
+        }
+        self.results = self.results.wrapping_add(1);
+        Outcome::Browsed
+    }
+}

crates/oa-desktop/src/forms/reference_chooser/adapter.rs

@@ -0,0 +1,307 @@
+//! Live form adapter. Compatibility stays in the existing parent adapter;
+//! browser metadata and scoped writes never reinterpret historical UUID text.
+use super::super::{Draft, friendly, history_fields, optional_reference, reference, reference_ids};
+use super::{Candidate, Context, Current, State, trigger};
+use crate::{app::Message, style};
+use iced::{
+    Element, Fill, Rectangle,
+    widget::{column, container, row, text, tooltip},
+};
+use oa_core::{Id, Project};
+use serde_json::{Value, json};
+use std::collections::BTreeSet;
+
+#[derive(Debug, Clone)]
+pub struct Open {
+    pub document: Id,
+    pub session: Id,
+    pub generation: Id,
+    pub record: Id,
+    pub path: String,
+    pub anchor: Rectangle,
+}
+#[derive(Debug, Clone)]
+pub struct Set {
+    pub context: Context,
+    pub generation: Id,
+    pub value: Option<Id>,
+}
+impl Draft {
+    pub fn reference_session(&self) -> Id {
+        self.reference_session
+    }
+    pub fn reference_generation(&self) -> Id {
+        self.reference_generation
+    }
+    pub fn reference_open(&self, project: &Project, path: &str, anchor: Rectangle) -> Open {
+        Open {
+            document: project.id,
+            session: self.reference_session,
+            generation: self.reference_generation,
+            record: self.original,
+            path: path.into(),
+            anchor,
+        }
+    }
+    pub fn reference_matches(&self, request: &Open) -> bool {
+        self.reference_session == request.session
+            && self.reference_generation == request.generation
+            && self.original == request.record
+            && self.live_reference(&request.path)
+    }
+    fn live_reference(&self, path: &str) -> bool {
+        !history_fields::is_path(path)
+            && reference(path)
+            && self
+                .value
+                .pointer(path)
+                .is_some_and(|v| v.is_string() || v.is_null())
+    }
+    pub fn reference_catalog(
+        &self,
+        project: &Project,
+        request: &Open,
+        revision: u64,
+    ) -> Result<State, String> {
+        if request.document != project.id || !self.reference_matches(request) {
+            return Err("The reference field changed. Open its chooser again.".into());
+        }
+        let allowed: BTreeSet<_> = reference_ids(self, project, &request.path)
+            .into_iter()
+            .filter(|id| !id.is_nil())
+            .collect();
+        let candidates = allowed
+            .iter()
+            .filter_map(|id| candidate(project, *id))
+            .collect();
+        let raw = self
+            .inputs
+            .get(&request.path)
+            .map(|v| v.raw.as_str())
+            .or_else(|| self.value.pointer(&request.path).and_then(Value::as_str));
+        let current = match raw {
+            None => Current::Unassigned,
+            Some(raw) => match raw.parse::<Id>() {
+                Ok(id) if id.is_nil() => Current::Unassigned,
+                Ok(id) => match candidate(project, id) {
+                    Some(c) if allowed.contains(&id) => Current::Valid(c),
+                    Some(c) => Current::Incompatible(c),
+                    None => Current::Missing(id),
+                },
+                Err(_) => Current::InvalidRaw(raw.into()),
+            },
+        };
+        let context = Context::live(
+            project.id,
+            revision,
+            self.reference_session,
+            self.original,
+            &request.path,
+            optional_reference(&request.path),
+        )
+        .map_err(str::to_owned)?;
+        State::open(
+            context,
+            candidates,
+            current,
+            format!(
+                "{} · compatible references",
+                friendly(request.path.rsplit('/').next().unwrap_or("Reference"))
+            ),
+        )
+        .map_err(str::to_owned)
+    }
+    pub fn reference_set(&mut self, project: &Project, intent: &Set) -> Result<(), String> {
+        let value = self.reference_value(project, intent)?;
+        self.shape_scoped(&intent.context.path, value)
+    }
+    pub fn reference_value(&self, project: &Project, intent: &Set) -> Result<Value, String> {
+        let context = &intent.context;
+        if context.document != project.id
+            || context.draft != self.reference_session
+            || context.record != self.original
+            || intent.generation != self.reference_generation
+            || !self.live_reference(&context.path)
+            || context.optional != optional_reference(&context.path)
+        {
+            return Err("The originating reference field is no longer current.".into());
+        }
+        let value = match intent.value {
+            Some(id)
+                if !id.is_nil() && reference_ids(self, project, &context.path).contains(&id) =>
+            {
+                json!(id)
+            }
+            None if context.optional => Value::Null,
+            _ => return Err("Choose a currently compatible reference.".into()),
+        };
+        Ok(value)
+    }
+}
+
+fn named(project: &Project, id: Id) -> String {
+    if let Some(e) = project.elements.get(&id) {
+        format!("{} · @{}", e.name, e.alias)
+    } else {
+        project.named(id).into()
+    }
+}
+fn ancestry(project: &Project, id: Id) -> String {
+    let mut parts = vec![];
+    let mut seen = BTreeSet::new();
+    let mut current = project.elements.get(&id).and_then(|e| e.parent);
+    while let Some(id) = current {
+        if !seen.insert(id) {
+            parts.push("[containment cycle]".into());
+            break;
+        }
+        parts.push(named(project, id));
+        current = project.elements.get(&id).and_then(|e| e.parent);
+    }
+    parts.reverse();
+    if parts.is_empty() {
+        project.name.clone()
+    } else {
+        parts.join(" / ")
+    }
+}
+pub(crate) fn candidate(project: &Project, id: Id) -> Option<Candidate> {
+    let layer = |layer| format!("{layer:?}").to_uppercase();
+    if id == project.id {
+        return Some(Candidate {
+            id,
+            name: project.name.clone(),
+            alias: project.alias.clone(),
+            kind: "Project".into(),
+            scope: "Model".into(),
+            containment: "Model root".into(),
+        });
+    }
+    if let Some(e) = project.elements.get(&id) {
+        return Some(Candidate {
+            id,
+            name: e.name.clone(),
+            alias: e.alias.clone(),
+            kind: e.kind().to_string(),
+            scope: layer(e.layer()),
+            containment: ancestry(project, id),
+        });
+    }
+    if let Some(r) = project.relations.get(&id) {
+        return Some(Candidate {
+            id,
+            name: r.name.clone(),
+            alias: r.alias.clone(),
+            kind: r.kind().to_string(),
+            scope: project.layer_of(id).map_or_else(|| "Model".into(), layer),
+            containment: format!(
+                "{} → {}",
+                named(project, r.source()),
+                named(project, r.target())
+            ),
+        });
+    }
+    for diagram in project.diagrams.values() {
+        if id == diagram.id {
+            return Some(Candidate {
+                id,
+                name: diagram.name.clone(),
+                alias: diagram.alias.clone(),
+                kind: format!("{:?} diagram", diagram.projection),
+                scope: layer(diagram.layer),
+                containment: project.name.clone(),
+            });
+        }
+        if let Some(node) = diagram.nodes.get(&id) {
+            return Some(Candidate {
+                id,
+                name: project.named(node.element).into(),
+                alias: node.alias.clone(),
+                kind: "Placement".into(),
+                scope: layer(diagram.layer),
+                containment: format!(
+                    "{} · @{} / {}",
+                    diagram.name,
+                    diagram.alias,
+                    named(project, node.element)
+                ),
+            });
+        }
+    }
+    if let Some(link) = project.artifact_links.get(&id) {
+        return Some(Candidate {
+            id,
+            name: link.name.clone(),
+            alias: link.alias.clone(),
+            kind: "Artifact link".into(),
+            scope: project
+                .layer_of(link.owner)
+                .map_or_else(|| "Model".into(), layer),
+            containment: named(project, link.owner),
+        });
+    }
+    project.traces.get(&id).map(|trace| Candidate {
+        id,
+        name: trace.name.clone(),
+        alias: trace.alias.clone(),
+        kind: "Trace".into(),
+        scope: "OA ↔ SA".into(),
+        containment: format!(
+            "{} ↔ {}",
+            named(project, trace.oa),
+            named(project, trace.sa)
+        ),
+    })
+}
+
+pub fn field<'a, R: iced::advanced::text::Renderer<Font = iced::Font> + 'a>(
+    draft: &'a Draft,
+    project: &'a Project,
+    path: &str,
+) -> Element<'a, Message, iced::Theme, R> {
+    let raw = draft
+        .inputs
+        .get(path)
+        .map(|v| v.raw.as_str())
+        .or_else(|| draft.value.pointer(path).and_then(Value::as_str));
+    let (label, detail) = match raw {
+        None => (
+            if optional_reference(path) {
+                "Not assigned"
+            } else {
+                "Choose a reference…"
+            }
+            .into(),
+            String::new(),
+        ),
+        Some(raw) => match raw.parse::<Id>() {
+            Ok(id) if id.is_nil() => ("Choose a reference…".into(), String::new()),
+            Ok(id) => match candidate(project, id) {
+                Some(c) => (format!("{} · @{}", c.name, c.alias), c.detail()),
+                None => ("Missing reference".into(), raw.into()),
+            },
+            Err(_) => ("Invalid reference retained".into(), raw.into()),
+        },
+    };
+    let label = crate::views::short(&label, 35);
+    let body = container(row![text(label).size(12).width(Fill), text("⌄").size(12)].spacing(6))
+        .padding(8)
+        .width(Fill);
+    let path = path.to_owned();
+    let id = trigger::field_id(draft.reference_generation, &path);
+    let field = trigger::Field::new(body, id, move |anchor| {
+        Message::FieldReferenceOpen(draft.reference_open(project, &path, anchor))
+    });
+    if detail.is_empty() {
+        field.into()
+    } else {
+        tooltip(
+            field,
+            container(column![text(detail).size(11)])
+                .padding(8)
+                .style(style::card),
+            tooltip::Position::Left,
+        )
+        .into()
+    }
+}

crates/oa-desktop/src/forms/reference_chooser/tests.rs

@@ -0,0 +1,803 @@
+use super::*;
+use iced::{
+    Element, Event as Input, Point, Rectangle, Size, Theme, Vector,
+    advanced::{Layout, Shell, layout, widget::Tree},
+    keyboard, mouse,
+    widget::{Space, mouse_area},
+};
+
+fn context(optional: bool) -> Context {
+    Context::live(
+        Id::from_u128(1),
+        7,
+        Id::from_u128(2),
+        Id::from_u128(3),
+        "/body/SequenceUse/sequence",
+        optional,
+    )
+    .unwrap()
+}
+fn candidate(index: u128) -> Candidate {
+    Candidate {
+        id: Id::from_u128(10_000 + index),
+        name: "Control".into(),
+        alias: format!("controller_{index:04}"),
+        kind: "Function".into(),
+        scope: "SA".into(),
+        containment: format!("System / Subsystem {} / Controller", index / 100),
+    }
+}
+fn thousand(current: Current, optional: bool) -> State {
+    // Reverse the fixture input to falsify accidental dependence on ingestion
+    // order. Expected IDs and aliases below are literal fixture identities.
+    State::open(
+        context(optional),
+        (0..1_000).rev().map(candidate).collect(),
+        current,
+        "SA · compatible functions",
+    )
+    .unwrap()
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+enum Message {
+    Chooser(Event),
+    UnderPress,
+    UnderRelease,
+}
+
+#[derive(Default)]
+struct Clipboard(Option<String>);
+impl iced::advanced::Clipboard for Clipboard {
+    fn read(&self, _: iced::advanced::clipboard::Kind) -> Option<String> {
+        self.0.clone()
+    }
+    fn write(&mut self, _: iced::advanced::clipboard::Kind, text: String) {
+        self.0 = Some(text);
+    }
+}
+
+struct Mount {
+    tree: Option<Tree>,
+    size: Size,
+    anchor: Rectangle,
+    clipboard: Clipboard,
+}
+impl Default for Mount {
+    fn default() -> Self {
+        Self {
+            tree: None,
+            size: Size::new(1100., 700.),
+            anchor: Rectangle {
+                x: 790.,
+                y: 640.,
+                width: 278.,
+                height: 32.,
+            },
+            clipboard: Clipboard::default(),
+        }
+    }
+}
+impl Mount {
+    fn batch(
+        &mut self,
+        state: Option<&State>,
+        events: &[(Input, Option<Point>)],
+    ) -> (Vec<Message>, Option<layout::Node>) {
+        let underneath: Element<'_, Message, Theme, ()> =
+            mouse_area(Space::new().width(iced::Fill).height(iced::Fill))
+                .on_press(Message::UnderPress)
+                .on_release(Message::UnderRelease)
+                .into();
+        let mut view: Element<'_, Message, Theme, ()> =
+            widget::Popup::new(underneath, state, self.anchor, Message::Chooser).into();
+        let tree = self.tree.get_or_insert_with(|| Tree::new(view.as_widget()));
+        view.as_widget().diff(tree);
+        let node =
+            view.as_widget_mut()
+                .layout(tree, &(), &layout::Limits::new(Size::ZERO, self.size));
+        let viewport = Rectangle::with_size(self.size);
+        let overlay_node = view
+            .as_widget_mut()
+            .overlay(tree, Layout::new(&node), &(), &viewport, Vector::ZERO)
+            .map(|mut overlay| overlay.as_overlay_mut().layout(&(), self.size));
+        let mut messages = Vec::new();
+        for (event, point) in events {
+            let cursor = point.map_or(mouse::Cursor::Unavailable, mouse::Cursor::Available);
+            let mut shell = Shell::new(&mut messages);
+            if let Some(overlay_node) = &overlay_node {
+                // Reconstruct the overlay between layout and every input, as
+                // Iced does. Geometry must live in the measured layout tree.
+                let mut overlay = view
+                    .as_widget_mut()
+                    .overlay(tree, Layout::new(&node), &(), &viewport, Vector::ZERO)
+                    .unwrap();
+                overlay.as_overlay_mut().update(
+                    event,
+                    Layout::new(overlay_node),
+                    cursor,
+                    &(),
+                    &mut self.clipboard,
+                    &mut shell,
+                );
+                overlay.as_overlay().draw(
+                    &mut (),
+                    &crate::style::theme(),
+                    &iced::advanced::renderer::Style {
+                        text_color: iced::Color::BLACK,
+                    },
+                    Layout::new(overlay_node),
+                    cursor,
+                );
+                if matches!(
+                    event,
+                    Input::Mouse(_) | Input::Keyboard(_) | Input::Touch(_) | Input::InputMethod(_)
+                ) {
+                    assert!(shell.is_event_captured(), "An open chooser owns input");
+                }
+            } else {
+                view.as_widget_mut().update(
+                    tree,
+                    event,
+                    Layout::new(&node),
+                    cursor,
+                    &(),
+                    &mut self.clipboard,
+                    &mut shell,
+                    &viewport,
+                );
+            }
+        }
+        (messages, overlay_node)
+    }
+    fn send(&mut self, state: &mut State, event: Input) -> Vec<Outcome> {
+        let (messages, _) = self.batch(Some(state), &[(event, None)]);
+        messages
+            .into_iter()
+            .map(|message| match message {
+                Message::Chooser(event) => state.update(event),
+                _ => panic!("Popup leaked input to its parent"),
+            })
+            .collect()
+    }
+    fn type_text(&mut self, state: &mut State, text: &str) -> Vec<Outcome> {
+        let (messages, _) = self.batch(Some(state), &typing(text));
+        messages
+            .into_iter()
+            .map(|message| match message {
+                Message::Chooser(event) => state.update(event),
+                _ => panic!("Typing leaked input to its parent"),
+            })
+            .collect()
+    }
+    fn geometry(&mut self, state: &State) -> widget::Geometry {
+        let (_, node) = self.batch(Some(state), &[]);
+        widget::Geometry::from_bounds(node.unwrap().children()[0].bounds())
+    }
+    fn click(&mut self, state: &State, point: Point) -> Vec<Message> {
+        self.batch(
+            Some(state),
+            &[
+                (
+                    Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                    Some(point),
+                ),
+                (
+                    Input::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)),
+                    Some(point),
+                ),
+            ],
+        )
+        .0
+    }
+}
+
+fn named(key: keyboard::key::Named) -> Input {
+    Input::Keyboard(keyboard::Event::KeyPressed {
+        key: keyboard::Key::Named(key),
+        modified_key: keyboard::Key::Named(key),
+        physical_key: keyboard::key::Physical::Code(keyboard::key::Code::Space),
+        location: keyboard::Location::Standard,
+        modifiers: keyboard::Modifiers::empty(),
+        text: None,
+        repeat: false,
+    })
+}
+// Iced 0.14's physical-key path intentionally inserts one scalar from text.
+// Whole-string typing is several key events; paste and IME commit are separate
+// input paths and are exercised below rather than faked as one physical key.
+fn typed(character: char) -> Input {
+    let text = character.to_string();
+    Input::Keyboard(keyboard::Event::KeyPressed {
+        key: keyboard::Key::Character(text.clone().into()),
+        modified_key: keyboard::Key::Character(text.clone().into()),
+        physical_key: keyboard::key::Physical::Code(keyboard::key::Code::KeyA),
+        location: keyboard::Location::Standard,
+        modifiers: keyboard::Modifiers::empty(),
+        text: Some(text.into()),
+        repeat: false,
+    })
+}
+fn typing(text: &str) -> Vec<(Input, Option<Point>)> {
+    text.chars()
+        .map(|character| (typed(character), None))
+        .collect()
+}
+fn query(state: &mut State, value: &str) {
+    let event = state.event(Action::Query {
+        text: value.into(),
+        serial: state.query_serial() + 1,
+    });
+    assert_eq!(state.update(event), Outcome::Browsed);
+}
+
+#[test]
+fn catalog_search_disambiguates_repeated_names_containment_alias_and_exact_placement_identity() {
+    let mut state = thousand(Current::Unassigned, false);
+    assert_eq!(
+        state.visible(6).map(|c| c.id).collect::<Vec<_>>(),
+        (10_000..10_006).map(Id::from_u128).collect::<Vec<_>>()
+    );
+    query(&mut state, "control subsystem 6 @controller_0617");
+    assert_eq!(state.count(), 1);
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(10_617));
+    query(&mut state, "OA");
+    assert_eq!(state.count(), 0);
+    query(&mut state, &Id::from_u128(10_617).to_string());
+    assert_eq!(state.count(), 1);
+    assert_eq!(state.highlighted().unwrap().alias, "controller_0617");
+
+    let placement = Candidate {
+        id: Id::from_u128(20_001),
+        name: "Control".into(),
+        alias: "control_placement".into(),
+        kind: "Placement".into(),
+        scope: "SA".into(),
+        containment: "Architecture / Main diagram / Control".into(),
+    };
+    let mut state = State::open(
+        context(false),
+        vec![placement],
+        Current::Unassigned,
+        "SA · placements",
+    )
+    .unwrap();
+    query(&mut state, "placement main");
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(20_001));
+    let event = state.event(Action::Choose(Id::from_u128(20_000)));
+    assert_eq!(
+        state.update(event),
+        Outcome::Ignored,
+        "Semantic ID is not the placement identity"
+    );
+    assert!(
+        State::open(
+            context(false),
+            vec![candidate(1), candidate(1)],
+            Current::Unassigned,
+            "SA"
+        )
+        .is_err()
+    );
+}
+
+#[test]
+fn mounted_overlay_clamps_at_three_field_positions_and_keeps_results_and_query_bounded() {
+    let state = thousand(Current::InvalidRaw("not a uuid".into()), true);
+    for size in [
+        Size::new(1100., 700.),
+        Size::new(1600., 1000.),
+        Size::new(320., 320.),
+    ] {
+        for y in [5., size.height / 2., size.height - 34.] {
+            let mut mount = Mount {
+                size,
+                anchor: Rectangle {
+                    x: size.width - 300.,
+                    y,
+                    width: 278.,
+                    height: 32.,
+                },
+                ..Default::default()
+            };
+            let (_, node) = mount.batch(Some(&state), &[]);
+            let node = node.unwrap();
+            let bounds = node.children()[0].bounds();
+            let geometry = widget::Geometry::from_bounds(bounds);
+            assert!(bounds.x >= 8. && bounds.y >= 8.);
+            assert!(bounds.x + bounds.width <= size.width - 8.);
+            assert!(bounds.y + bounds.height <= size.height - 8.);
+            assert!(bounds.width <= 420. && bounds.height <= 360.);
+            assert!(geometry.rows > 0 && geometry.rows <= 6);
+            assert_eq!(geometry.rows, if size.height == 320. { 4 } else { 6 });
+            let search = node.children()[1].bounds();
+            assert!(
+                bounds.contains(search.position())
+                    && bounds.contains(Point::new(
+                        search.x + search.width,
+                        search.y + search.height
+                    ))
+            );
+            assert!(geometry.row(geometry.rows - 1).y + 34. <= geometry.detail.y);
+            assert_eq!(state.visible(geometry.rows).count(), geometry.rows);
+        }
+    }
+}
+
+#[test]
+fn mounted_input_preserves_rapid_same_batch_typing_and_cursor_across_controlled_rebuilds() {
+    let mut state = thousand(Current::Unassigned, false);
+    let mut mount = Mount::default();
+    let (messages, _) = mount.batch(Some(&state), &[(typed('a'), None), (typed('b'), None)]);
+    assert_eq!(
+        messages.len(),
+        2,
+        "Actual focused input must publish each edit"
+    );
+    let mut queries = Vec::new();
+    for message in messages {
+        let Message::Chooser(event) = message else {
+            panic!("Unexpected parent event")
+        };
+        let Action::Query { text, .. } = &event.action else {
+            panic!("Typing must not choose a reference")
+        };
+        queries.push(text.clone());
+        assert_eq!(state.update(event), Outcome::Browsed);
+    }
+    assert_eq!(queries, ["a", "ab"]);
+    assert_eq!(state.query(), "ab");
+    assert!(
+        mount
+            .send(&mut state, named(keyboard::key::Named::Home))
+            .is_empty()
+    );
+    assert_eq!(mount.send(&mut state, typed('z')), [Outcome::Browsed]);
+    assert_eq!(
+        state.query(),
+        "zab",
+        "Rebuilding the controlled widget must not refocus at the end"
+    );
+    assert_eq!(state.current, Current::Unassigned);
+}
+
+#[test]
+fn mounted_keyboard_pages_and_selects_only_the_highlighted_visible_candidate_once() {
+    let mut state = thousand(Current::Unassigned, false);
+    let mut mount = Mount::default();
+    assert_eq!(
+        mount.send(&mut state, named(keyboard::key::Named::PageDown)),
+        [Outcome::Browsed]
+    );
+    assert_eq!(state.start(), 6);
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(10_006));
+    assert_eq!(
+        mount.send(&mut state, named(keyboard::key::Named::ArrowDown)),
+        [Outcome::Browsed]
+    );
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(10_007));
+    let (messages, _) = mount.batch(
+        Some(&state),
+        &[
+            (named(keyboard::key::Named::Enter), None),
+            (named(keyboard::key::Named::Enter), None),
+        ],
+    );
+    assert_eq!(messages.len(), 1);
+    let Message::Chooser(event) = messages.into_iter().next().unwrap() else {
+        panic!()
+    };
+    assert!(event.action.writes_staged_value());
+    assert_eq!(
+        state.update(event),
+        Outcome::Write {
+            context: context(false),
+            value: Some(Id::from_u128(10_007))
+        }
+    );
+    assert!(!state.is_open());
+}
+
+#[test]
+fn mounted_filtered_row_click_uses_the_displayed_identity_and_scoped_write_intent() {
+    let mut state = thousand(Current::Missing(Id::from_u128(99)), false);
+    let mut mount = Mount::default();
+    let query = "@controller_0731";
+    assert_eq!(
+        mount.type_text(&mut state, query),
+        vec![Outcome::Browsed; query.chars().count()]
+    );
+    assert_eq!(state.query(), query);
+    assert_eq!(state.count(), 1);
+    let point = mount.geometry(&state).row(0).center();
+    let messages = mount.click(&state, point);
+    assert_eq!(messages.len(), 1);
+    let Message::Chooser(event) = messages[0].clone() else {
+        panic!()
+    };
+    assert_eq!(
+        state.update(event),
+        Outcome::Write {
+            context: context(false),
+            value: Some(Id::from_u128(10_731))
+        }
+    );
+    assert_eq!(state.current, Current::Missing(Id::from_u128(99)));
+}
+
+#[test]
+fn mounted_query_change_rejects_old_release_and_old_result_events_without_locking_popup() {
+    let mut state = thousand(Current::Unassigned, false);
+    let mut mount = Mount::default();
+    let point = mount.geometry(&state).row(4).center();
+    let captured = mount.click(&state, point);
+    let Message::Chooser(old_choice) = captured[0].clone() else {
+        panic!()
+    };
+    query(&mut state, "@controller_0700");
+    assert_eq!(state.update(old_choice), Outcome::Ignored);
+    // The rejected old Choose had marked the widget closing; a changed result
+    // context must unlock it so an explicit current click can complete.
+    let point = mount.geometry(&state).row(0).center();
+    let messages = mount.click(&state, point);
+    assert_eq!(messages.len(), 1);
+    let Message::Chooser(event) = messages[0].clone() else {
+        panic!()
+    };
+    assert_eq!(
+        state.update(event),
+        Outcome::Write {
+            context: context(false),
+            value: Some(Id::from_u128(10_700))
+        }
+    );
+
+    let mut state = thousand(Current::Unassigned, false);
+    let point = mount.geometry(&state).row(0).center();
+    assert!(
+        mount
+            .batch(
+                Some(&state),
+                &[(
+                    Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                    Some(point)
+                )]
+            )
+            .0
+            .is_empty()
+    );
+    query(&mut state, "@controller_0319");
+    assert!(
+        mount
+            .batch(
+                Some(&state),
+                &[(
+                    Input::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)),
+                    Some(point)
+                )]
+            )
+            .0
+            .is_empty()
+    );
+    assert!(state.is_open());
+}
+
+#[test]
+fn captured_choice_cannot_cross_document_revision_draft_record_or_array_path() {
+    let source = thousand(Current::Unassigned, false);
+    let mut mount = Mount::default();
+    let point = mount.geometry(&source).row(0).center();
+    let Message::Chooser(event) = mount.click(&source, point).remove(0) else {
+        panic!()
+    };
+    for changed in 0..6 {
+        let mut destination = context(false);
+        match changed {
+            0 => destination.document = Id::from_u128(999),
+            1 => destination.revision += 1,
+            2 => destination.draft = Id::from_u128(999),
+            3 => destination.record = Id::from_u128(999),
+            4 => destination.path = "/body/SomeList/members/1/scenario".into(),
+            _ => {} // A new invocation even with every semantic ID unchanged.
+        }
+        let mut state = State::open(
+            destination,
+            vec![candidate(0)],
+            Current::InvalidRaw("unfinished".into()),
+            "SA",
+        )
+        .unwrap();
+        assert_eq!(state.update(event.clone()), Outcome::Ignored);
+        assert_eq!(state.current, Current::InvalidRaw("unfinished".into()));
+        assert!(state.is_open());
+    }
+    let mut invalidated = source.clone();
+    invalidated.invalidate();
+    assert_eq!(invalidated.update(event), Outcome::Ignored);
+}
+
+#[test]
+fn empty_search_escape_tab_and_optional_clear_do_not_silently_choose_nil() {
+    for current in [
+        Current::Missing(Id::from_u128(999)),
+        Current::InvalidRaw("@incomplete/".into()),
+        Current::Incompatible(candidate(999)),
+    ] {
+        let mut state = thousand(current.clone(), false);
+        let mut mount = Mount::default();
+        let query = "no match exists";
+        assert_eq!(
+            mount.type_text(&mut state, query),
+            vec![Outcome::Browsed; query.chars().count()]
+        );
+        assert_eq!(state.query(), query);
+        assert_eq!(
+            state.count(),
+            0,
+            "Verify actual input reached the empty-result state before Enter"
+        );
+        assert!(
+            mount
+                .send(&mut state, named(keyboard::key::Named::Enter))
+                .is_empty()
+        );
+        assert!(state.is_open());
+        assert_eq!(state.current, current);
+        assert_eq!(
+            mount.send(&mut state, named(keyboard::key::Named::Escape)),
+            [Outcome::Closed(Close::Escape)]
+        );
+        assert_eq!(state.current, current);
+    }
+    let mut state = thousand(Current::Unassigned, false);
+    let mut mount = Mount::default();
+    assert_eq!(
+        mount.send(&mut state, named(keyboard::key::Named::Tab)),
+        [Outcome::Closed(Close::Tab { backwards: false })]
+    );
+    let mut state = thousand(Current::InvalidRaw("?".into()), true);
+    let point = mount.geometry(&state).clear.center();
+    let Message::Chooser(event) = mount.click(&state, point).remove(0) else {
+        panic!()
+    };
+    assert_eq!(
+        state.update(event),
+        Outcome::Write {
+            context: context(true),
+            value: None
+        }
+    );
+    let mut required = thousand(Current::Unassigned, false);
+    let clear = required.event(Action::Clear);
+    assert_eq!(required.update(clear), Outcome::Ignored);
+}
+
+#[test]
+fn dismissal_swallows_matching_release_across_closed_rebuild_but_next_click_reaches_parent() {
+    let mut state = thousand(Current::Unassigned, false);
+    let mut mount = Mount::default();
+    let outside = Point::new(20., 20.);
+    let (messages, _) = mount.batch(
+        Some(&state),
+        &[(
+            Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+            Some(outside),
+        )],
+    );
+    let [Message::Chooser(event)] = messages.as_slice() else {
+        panic!("Expected only popup dismissal")
+    };
+    assert_eq!(state.update(event.clone()), Outcome::Closed(Close::Outside));
+    let release = Input::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left));
+    assert!(
+        mount
+            .batch(None, &[(release.clone(), Some(outside))])
+            .0
+            .is_empty()
+    );
+    assert_eq!(
+        mount
+            .batch(
+                None,
+                &[
+                    (
+                        Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                        Some(outside)
+                    ),
+                    (release, Some(outside)),
+                ]
+            )
+            .0,
+        [Message::UnderPress, Message::UnderRelease]
+    );
+}
+
+#[test]
+fn historical_paths_never_open_and_only_explicit_choice_or_clear_is_a_write() {
+    for path in [
+        "/baseline",
+        "/baseline/oa/value",
+        "/baseline/sa/value/TypeRef/Named",
+    ] {
+        assert!(
+            Context::live(
+                Id::from_u128(1),
+                0,
+                Id::from_u128(2),
+                Id::from_u128(3),
+                path,
+                true
+            )
+            .is_err()
+        );
+        let mut forged = context(true);
+        forged.path = path.into();
+        assert!(State::open(forged, vec![candidate(0)], Current::Unassigned, "History").is_err());
+    }
+    for action in [
+        Action::Query {
+            text: "Control".into(),
+            serial: 1,
+        },
+        Action::Highlight(Id::from_u128(10_000)),
+        Action::Move { delta: 1, rows: 6 },
+        Action::Page { delta: 1, rows: 6 },
+        Action::Close(Close::Escape),
+    ] {
+        assert!(!action.writes_staged_value());
+    }
+    assert!(Action::Choose(Id::from_u128(10_000)).writes_staged_value());
+    assert!(Action::Clear.writes_staged_value());
+}
+
+#[test]
+fn out_of_order_query_serials_cannot_restore_obsolete_results() {
+    let mut state = thousand(Current::Unassigned, false);
+    let old = state.event(Action::Query {
+        text: "@controller_0001".into(),
+        serial: 1,
+    });
+    let new = state.event(Action::Query {
+        text: "@controller_0999".into(),
+        serial: 2,
+    });
+    assert_eq!(state.update(new), Outcome::Browsed);
+    assert_eq!(state.update(old), Outcome::Ignored);
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(10_999));
+}
+
+#[test]
+fn mounted_query_then_escape_in_one_batch_closes_and_relative_keys_keep_input_order() {
+    let mut state = thousand(Current::InvalidRaw("unfinished".into()), false);
+    let mut mount = Mount::default();
+    let query = "@controller_0720";
+    let mut inputs = typing(query);
+    inputs.push((named(keyboard::key::Named::Escape), None));
+    let (messages, _) = mount.batch(Some(&state), &inputs);
+    let outcomes: Vec<_> = messages
+        .into_iter()
+        .map(|message| {
+            let Message::Chooser(event) = message else {
+                panic!("Input escaped the popup")
+            };
+            state.update(event)
+        })
+        .collect();
+    let mut expected = vec![Outcome::Browsed; query.chars().count()];
+    expected.push(Outcome::Closed(Close::Escape));
+    assert_eq!(outcomes, expected);
+    assert_eq!(state.query(), "@controller_0720");
+    assert_eq!(state.current, Current::InvalidRaw("unfinished".into()));
+
+    let mut state = thousand(Current::Unassigned, false);
+    let old_absolute_row = state.event(Action::Choose(Id::from_u128(10_000)));
+    let (messages, _) = mount.batch(
+        Some(&state),
+        &[
+            (named(keyboard::key::Named::PageDown), None),
+            (named(keyboard::key::Named::PageDown), None),
+            (named(keyboard::key::Named::ArrowUp), None),
+        ],
+    );
+    assert_eq!(messages.len(), 3);
+    for message in messages {
+        let Message::Chooser(event) = message else {
+            panic!("Input escaped the popup")
+        };
+        assert_eq!(state.update(event), Outcome::Browsed);
+    }
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(10_011));
+    assert_eq!(state.start(), 11);
+    assert_eq!(state.update(old_absolute_row), Outcome::Ignored);
+    assert!(state.is_open());
+}
+
+#[test]
+fn mounted_clipboard_paste_and_ime_commit_preserve_whole_strings_without_selecting() {
+    let mut state = thousand(Current::Unassigned, false);
+    let mut mount = Mount::default();
+    mount.clipboard.0 = Some("@controller_0472".into());
+    let paste = Input::Keyboard(keyboard::Event::KeyPressed {
+        key: keyboard::Key::Character("v".into()),
+        modified_key: keyboard::Key::Character("v".into()),
+        physical_key: keyboard::key::Physical::Code(keyboard::key::Code::KeyV),
+        location: keyboard::Location::Standard,
+        modifiers: keyboard::Modifiers::COMMAND,
+        text: None,
+        repeat: false,
+    });
+    let (messages, _) = mount.batch(
+        Some(&state),
+        &[
+            (
+                Input::Keyboard(keyboard::Event::ModifiersChanged(
+                    keyboard::Modifiers::COMMAND,
+                )),
+                None,
+            ),
+            (paste, None),
+            (
+                Input::Keyboard(keyboard::Event::ModifiersChanged(
+                    keyboard::Modifiers::empty(),
+                )),
+                None,
+            ),
+        ],
+    );
+    let [Message::Chooser(event)] = messages.as_slice() else {
+        panic!("Paste should emit exactly one whole-string query")
+    };
+    assert_eq!(state.update(event.clone()), Outcome::Browsed);
+    assert_eq!(state.query(), "@controller_0472");
+    assert_eq!(state.count(), 1);
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(10_472));
+    assert_eq!(state.current, Current::Unassigned);
+    assert!(state.is_open());
+
+    let unicode_name = "Режим Δ負荷";
+    let unicode = Candidate {
+        id: Id::from_u128(30_111),
+        name: unicode_name.into(),
+        alias: "mode_unicode".into(),
+        kind: "Function".into(),
+        scope: "SA".into(),
+        containment: "Система / 控制".into(),
+    };
+    let mut state = State::open(
+        context(false),
+        vec![unicode],
+        Current::InvalidRaw("retained".into()),
+        "SA",
+    )
+    .unwrap();
+    use iced::advanced::input_method::Event as Ime;
+    let preedit = [
+        (Input::InputMethod(Ime::Opened), None),
+        (
+            Input::InputMethod(Ime::Preedit(unicode_name.into(), None)),
+            None,
+        ),
+    ];
+    assert!(
+        mount.batch(Some(&state), &preedit).0.is_empty(),
+        "Composition is not a committed query"
+    );
+    assert_eq!(state.query(), "");
+    let (messages, _) = mount.batch(
+        Some(&state),
+        &[
+            (Input::InputMethod(Ime::Preedit(String::new(), None)), None),
+            (Input::InputMethod(Ime::Commit(unicode_name.into())), None),
+            (Input::InputMethod(Ime::Closed), None),
+        ],
+    );
+    let [Message::Chooser(event)] = messages.as_slice() else {
+        panic!("IME commit should emit one complete query")
+    };
+    assert_eq!(state.update(event.clone()), Outcome::Browsed);
+    assert_eq!(state.query(), unicode_name);
+    assert_eq!(state.count(), 1);
+    assert_eq!(state.highlighted().unwrap().id, Id::from_u128(30_111));
+    assert_eq!(state.current, Current::InvalidRaw("retained".into()));
+    assert!(state.is_open());
+}

crates/oa-desktop/src/forms/reference_chooser/trigger.rs

@@ -0,0 +1,447 @@
+//! Keyboard entry and focus operations scoped to one property form. Focus
+//! targets include the draft generation so delayed operations cannot focus a
+//! replacement array row or a recovered document with the same semantic IDs.
+use crate::style;
+use iced::{
+    Border, Color, Element, Event, Length, Rectangle, Size, Task, Theme, Vector,
+    advanced::{
+        Clipboard, Layout, Shell, Widget, layout, overlay, renderer,
+        widget::{Id, Operation, Tree, operation, tree},
+    },
+    keyboard, mouse,
+    widget::container,
+};
+use oa_core::Id as ModelId;
+mod focus;
+
+#[derive(Clone, Copy)]
+pub struct FormScope {
+    pub session: ModelId,
+    pub modal: bool,
+}
+pub(super) struct FormOwner(pub Option<FormScope>);
+const REVIEW_MODAL: &str = "reference-owning-review-modal";
+
+/// Marks the entire Review dialog without changing its layout or event flow.
+pub fn modal<'a, Message: 'a, R: renderer::Renderer + 'a>(
+    content: impl Into<Element<'a, Message, Theme, R>>,
+) -> Element<'a, Message, Theme, R> {
+    Field {
+        content: content.into(),
+        id: Some(Id::new(REVIEW_MODAL)),
+        on_open: None,
+    }
+    .into()
+}
+
+pub fn field_id(generation: ModelId, path: &str) -> Id {
+    Id::from(format!("reference:{generation}:{path}"))
+}
+pub fn scope_id(session: ModelId) -> Id {
+    Id::from(format!("reference-form:{session}"))
+}
+
+#[derive(Default)]
+struct Interaction {
+    focused: bool,
+    pressed: bool,
+    identity: Option<Id>,
+    anchor: Option<Rectangle>,
+}
+impl operation::Focusable for Interaction {
+    fn is_focused(&self) -> bool {
+        self.focused
+    }
+    fn focus(&mut self) {
+        self.focused = true;
+    }
+    fn unfocus(&mut self) {
+        self.focused = false;
+        self.pressed = false;
+    }
+}
+pub struct Field<'a, Message, R = iced::Renderer>
+where
+    R: renderer::Renderer,
+{
+    content: Element<'a, Message, Theme, R>,
+    id: Option<Id>,
+    on_open: Option<Box<dyn Fn(Rectangle) -> Message + 'a>>,
+}
+impl<'a, Message, R: renderer::Renderer> Field<'a, Message, R> {
+    pub fn new(
+        content: impl Into<Element<'a, Message, Theme, R>>,
+        id: Id,
+        on_open: impl Fn(Rectangle) -> Message + 'a,
+    ) -> Self {
+        Self {
+            content: content.into(),
+            id: Some(id),
+            on_open: Some(Box::new(on_open)),
+        }
+    }
+}
+pub fn scope<'a, Message: 'a, R: renderer::Renderer + 'a>(
+    content: impl Into<Element<'a, Message, Theme, R>>,
+    session: ModelId,
+) -> Element<'a, Message, Theme, R> {
+    container(Field {
+        content: content.into(),
+        id: None,
+        on_open: None,
+    })
+    .id(scope_id(session))
+    .width(Length::Fill)
+    .into()
+}
+
+fn run<Message, R: renderer::Renderer>(
+    content: &mut Element<'_, Message, Theme, R>,
+    tree: &mut Tree,
+    layout: Layout<'_>,
+    renderer: &R,
+    mut operation: Box<dyn Operation>,
+) -> bool {
+    let mut changed = false;
+    loop {
+        content
+            .as_widget_mut()
+            .operate(tree, layout, renderer, &mut *operation);
+        match operation.finish() {
+            operation::Outcome::Chain(next) => {
+                operation = next;
+                changed = true;
+            }
+            _ => break,
+        }
+    }
+    changed
+}
+
+pub(super) fn tab<Message, R: renderer::Renderer>(
+    content: &mut Element<'_, Message, Theme, R>,
+    tree: &mut Tree,
+    layout: Layout<'_>,
+    renderer: &R,
+    scope: FormScope,
+    backwards: bool,
+) -> bool {
+    run(
+        content,
+        tree,
+        layout,
+        renderer,
+        Box::new(focus::relative(scope.session, backwards, scope.modal)),
+    )
+}
+pub(super) fn own_input<Message, R: renderer::Renderer>(
+    content: &mut Element<'_, Message, Theme, R>,
+    tree: &mut Tree,
+    layout: Layout<'_>,
+    renderer: &R,
+) {
+    content
+        .as_widget_mut()
+        .operate(tree, layout, renderer, &mut focus::exclusive());
+}
+impl<Message, R: renderer::Renderer> Widget<Message, Theme, R> for Field<'_, Message, R> {
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<Interaction>()
+    }
+    fn state(&self) -> tree::State {
+        tree::State::new(Interaction {
+            identity: self.id.clone(),
+            ..Default::default()
+        })
+    }
+    fn children(&self) -> Vec<Tree> {
+        vec![Tree::new(self.content.as_widget())]
+    }
+    fn diff(&self, tree: &mut Tree) {
+        let state = tree.state.downcast_mut::<Interaction>();
+        if state.identity != self.id {
+            *state = Interaction {
+                identity: self.id.clone(),
+                ..Default::default()
+            };
+        }
+        tree.diff_children(std::slice::from_ref(&self.content));
+    }
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        operation: &mut dyn Operation,
+    ) {
+        if let Some(id) = &self.id
+            && self.on_open.is_some()
+        {
+            operation.focusable(
+                Some(id),
+                layout.bounds(),
+                tree.state.downcast_mut::<Interaction>(),
+            );
+            operation.custom(
+                Some(id),
+                layout.bounds(),
+                tree.state.downcast_mut::<Interaction>(),
+            );
+        }
+        if self.on_open.is_none() {
+            operation.container(self.id.as_ref(), layout.bounds());
+            operation.traverse(&mut |operation| {
+                self.content.as_widget_mut().operate(
+                    &mut tree.children[0],
+                    layout,
+                    renderer,
+                    operation,
+                )
+            });
+        } else {
+            self.content.as_widget_mut().operate(
+                &mut tree.children[0],
+                layout,
+                renderer,
+                operation,
+            );
+        }
+    }
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        if let Some(on_open) = &self.on_open {
+            let state = tree.state.downcast_mut::<Interaction>();
+            let visible = layout.bounds().intersection(viewport);
+            let hovered = visible.is_some_and(|bounds| cursor.is_over(bounds));
+            let activate = match event {
+                Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)) if hovered => {
+                    state.focused = true;
+                    state.pressed = true;
+                    shell.capture_event();
+                    shell.request_redraw();
+                    false
+                }
+                Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left)) => {
+                    let activate = state.pressed && hovered;
+                    if state.pressed {
+                        shell.capture_event();
+                    }
+                    state.pressed = false;
+                    activate
+                }
+                Event::Keyboard(keyboard::Event::KeyPressed {
+                    key:
+                        keyboard::Key::Named(keyboard::key::Named::Enter | keyboard::key::Named::Space),
+                    repeat: false,
+                    ..
+                }) if state.focused => true,
+                Event::Mouse(mouse::Event::ButtonPressed(_)) => {
+                    state.focused = false;
+                    state.pressed = false;
+                    false
+                }
+                _ => false,
+            };
+            if activate && let Some(bounds) = state.anchor {
+                shell.publish(on_open(bounds));
+                shell.capture_event();
+                return;
+            }
+        }
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        renderer_style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        if self.on_open.is_some() {
+            let focus = tree.state.downcast_ref::<Interaction>().focused;
+            renderer.fill_quad(
+                renderer::Quad {
+                    bounds: layout.bounds(),
+                    border: Border {
+                        color: if focus || cursor.is_over(layout.bounds()) {
+                            style::TEAL
+                        } else {
+                            style::LINE
+                        },
+                        width: if focus { 2. } else { 1. },
+                        radius: 5.into(),
+                    },
+                    ..Default::default()
+                },
+                Color::WHITE,
+            );
+        }
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            renderer_style,
+            layout,
+            cursor,
+            viewport,
+        );
+    }
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        if self.on_open.is_some() && cursor.is_over(layout.bounds()) {
+            mouse::Interaction::Pointer
+        } else {
+            self.content.as_widget().mouse_interaction(
+                &tree.children[0],
+                layout,
+                cursor,
+                viewport,
+                renderer,
+            )
+        }
+    }
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'b>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'b, Message, Theme, R>> {
+        self.content.as_widget_mut().overlay(
+            &mut tree.children[0],
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
+    }
+}
+
+/// Scrollable child updates use content coordinates. The root visits the
+/// retained tree before each input, so field anchors use current window
+/// coordinates even when a wheel event and activation share one runtime batch.
+pub(super) fn measure<Message, R: renderer::Renderer>(
+    content: &mut Element<'_, Message, Theme, R>,
+    tree: &mut Tree,
+    layout: Layout<'_>,
+    renderer: &R,
+    viewport: Rectangle,
+) {
+    content.as_widget_mut().operate(
+        tree,
+        layout,
+        renderer,
+        &mut Measure {
+            translation: Vector::ZERO,
+            viewport: Some(viewport),
+            pending: None,
+        },
+    );
+}
+struct Measure {
+    translation: Vector,
+    viewport: Option<Rectangle>,
+    pending: Option<(Vector, Option<Rectangle>)>,
+}
+impl Operation for Measure {
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        let previous = (self.translation, self.viewport);
+        if let Some((translation, viewport)) = self.pending.take() {
+            self.translation = translation;
+            self.viewport = viewport;
+        }
+        visit(self);
+        (self.translation, self.viewport) = previous;
+    }
+    fn scrollable(
+        &mut self,
+        _: Option<&Id>,
+        bounds: Rectangle,
+        _: Rectangle,
+        translation: Vector,
+        _: &mut dyn operation::Scrollable,
+    ) {
+        let bounds = Rectangle {
+            x: bounds.x - self.translation.x,
+            y: bounds.y - self.translation.y,
+            ..bounds
+        };
+        self.pending = Some((
+            self.translation + translation,
+            self.viewport
+                .and_then(|viewport| viewport.intersection(&bounds)),
+        ));
+    }
+    fn custom(&mut self, _: Option<&Id>, bounds: Rectangle, state: &mut dyn std::any::Any) {
+        if let Some(state) = state.downcast_mut::<Interaction>() {
+            let bounds = Rectangle {
+                x: bounds.x - self.translation.x,
+                y: bounds.y - self.translation.y,
+                ..bounds
+            };
+            state.anchor = self
+                .viewport
+                .and_then(|viewport| viewport.intersection(&bounds));
+        }
+    }
+}
+impl<'a, Message: 'a, R: renderer::Renderer + 'a> From<Field<'a, Message, R>>
+    for Element<'a, Message, Theme, R>
+{
+    fn from(field: Field<'a, Message, R>) -> Self {
+        Element::new(field)
+    }
+}
+
+pub fn focus_operation(
+    session: ModelId,
+    generation: ModelId,
+    path: &str,
+    step: i32,
+) -> impl Operation + 'static {
+    focus::exact(session, generation, path, step)
+}
+pub fn focus<Message: Send + 'static>(
+    session: ModelId,
+    generation: ModelId,
+    path: &str,
+    step: i32,
+) -> Task<Message> {
+    iced::advanced::widget::operate(focus_operation(session, generation, path, step)).discard()
+}

crates/oa-desktop/src/forms/reference_chooser/trigger/focus.rs

@@ -0,0 +1,313 @@
+//! Focus movement and reveal share one root traversal. A form may be inside a
+//! scrollable; restricting traversal to its container would hide that ancestor.
+use super::{FormOwner, Id, ModelId, Operation, Rectangle, Vector, field_id, operation, scope_id};
+use std::collections::BTreeMap;
+
+enum Origin {
+    Current,
+    Exact(Id),
+}
+#[derive(Clone)]
+struct Scroll {
+    index: usize,
+    bounds: Rectangle,
+    capacity: Vector,
+    offset: Vector,
+}
+struct Field {
+    id: Option<Id>,
+    bounds: Rectangle,
+    ancestors: Vec<Scroll>,
+}
+pub(super) struct Collect {
+    scope: Id,
+    origin: Origin,
+    step: i32,
+    inside: bool,
+    entering: Option<bool>,
+    translation: Vector,
+    scrolls: Vec<Scroll>,
+    pending_scroll: Option<Scroll>,
+    scroll_index: usize,
+    fields: Vec<Field>,
+    focused: Option<usize>,
+    outside_focused: bool,
+    modal: bool,
+    owner_valid: bool,
+}
+impl Collect {
+    fn new(scope: Id, origin: Origin, step: i32) -> Self {
+        let owner_valid = matches!(origin, Origin::Current);
+        Self {
+            scope,
+            origin,
+            step,
+            inside: false,
+            entering: None,
+            translation: Vector::ZERO,
+            scrolls: vec![],
+            pending_scroll: None,
+            scroll_index: 0,
+            fields: vec![],
+            focused: None,
+            outside_focused: false,
+            modal: false,
+            owner_valid,
+        }
+    }
+}
+pub(super) fn relative(session: ModelId, backwards: bool, modal: bool) -> Collect {
+    Collect {
+        modal,
+        ..Collect::new(
+            scope_id(session),
+            Origin::Current,
+            if backwards { -1 } else { 1 },
+        )
+    }
+}
+pub(super) fn exact(session: ModelId, generation: ModelId, path: &str, step: i32) -> Collect {
+    Collect::new(
+        scope_id(session),
+        Origin::Exact(field_id(generation, path)),
+        step,
+    )
+}
+impl Operation for Collect {
+    fn custom(&mut self, _: Option<&Id>, _: Rectangle, state: &mut dyn std::any::Any) {
+        if let Some(owner) = state.downcast_ref::<FormOwner>() {
+            self.owner_valid = owner
+                .0
+                .is_some_and(|owner| scope_id(owner.session) == self.scope);
+            self.modal = owner.0.is_some_and(|owner| owner.modal);
+        }
+    }
+    fn container(&mut self, id: Option<&Id>, _: Rectangle) {
+        self.entering = Some(self.inside || id == Some(&self.scope));
+    }
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        let previous = (self.inside, self.translation, self.scrolls.len());
+        if let Some(inside) = self.entering.take() {
+            self.inside = inside;
+        }
+        if let Some(scroll) = self.pending_scroll.take() {
+            self.translation += scroll.offset;
+            self.scrolls.push(scroll);
+        }
+        visit(self);
+        self.inside = previous.0;
+        self.translation = previous.1;
+        self.scrolls.truncate(previous.2);
+    }
+    fn scrollable(
+        &mut self,
+        _: Option<&Id>,
+        bounds: Rectangle,
+        content: Rectangle,
+        offset: Vector,
+        _: &mut dyn operation::Scrollable,
+    ) {
+        self.pending_scroll = Some(Scroll {
+            index: self.scroll_index,
+            bounds: translated(bounds, self.translation),
+            capacity: Vector::new(
+                (content.width - bounds.width).max(0.),
+                (content.height - bounds.height).max(0.),
+            ),
+            offset,
+        });
+        self.scroll_index += 1;
+    }
+    fn focusable(
+        &mut self,
+        id: Option<&Id>,
+        bounds: Rectangle,
+        state: &mut dyn operation::Focusable,
+    ) {
+        if !self.inside {
+            self.outside_focused |= state.is_focused();
+            return;
+        }
+        if state.is_focused() {
+            self.focused = Some(self.fields.len());
+        }
+        self.fields.push(Field {
+            id: id.cloned(),
+            bounds: translated(bounds, self.translation),
+            ancestors: self.scrolls.clone(),
+        });
+    }
+    fn finish(&self) -> operation::Outcome<()> {
+        if !self.owner_valid || self.fields.is_empty() {
+            return operation::Outcome::None;
+        }
+        let origin = match &self.origin {
+            Origin::Current if self.focused.is_none() && self.outside_focused && !self.modal => {
+                return operation::Outcome::None;
+            }
+            Origin::Current => self
+                .focused
+                .map(|index| index as i64)
+                .unwrap_or(if self.step < 0 {
+                    self.fields.len() as i64
+                } else {
+                    -1
+                }),
+            Origin::Exact(id) => {
+                let Some(index) = self
+                    .fields
+                    .iter()
+                    .position(|field| field.id.as_ref() == Some(id))
+                else {
+                    return operation::Outcome::None;
+                };
+                index as i64
+            }
+        };
+        // A form keeps a reachable focus at both boundaries. Initial Tab enters
+        // the first field; initial Shift+Tab enters the last field.
+        let target = (origin + i64::from(self.step)).rem_euclid(self.fields.len() as i64) as usize;
+        let field = &self.fields[target];
+        let mut bounds = field.bounds;
+        let mut shifts = BTreeMap::new();
+        for ancestor in field.ancestors.iter().rev() {
+            let dx = reveal_axis(
+                bounds.x,
+                bounds.width,
+                ancestor.bounds.x,
+                ancestor.bounds.width,
+            );
+            let dy = reveal_axis(
+                bounds.y,
+                bounds.height,
+                ancestor.bounds.y,
+                ancestor.bounds.height,
+            );
+            // Iced reports rounded drawing offsets, while capacity can be
+            // fractional. Clamping an already-visible axis can move it a pixel.
+            let delta = Vector::new(
+                if dx == 0. {
+                    0.
+                } else {
+                    (ancestor.offset.x + dx).clamp(0., ancestor.capacity.x) - ancestor.offset.x
+                },
+                if dy == 0. {
+                    0.
+                } else {
+                    (ancestor.offset.y + dy).clamp(0., ancestor.capacity.y) - ancestor.offset.y
+                },
+            );
+            if delta != Vector::ZERO {
+                shifts.insert(ancestor.index, delta);
+            }
+            bounds = translated(bounds, delta);
+        }
+        operation::Outcome::Chain(Box::new(Apply {
+            scope: self.scope.clone(),
+            inside: false,
+            entering: None,
+            target,
+            field_index: 0,
+            scroll_index: 0,
+            shifts,
+            owner_valid: matches!(self.origin, Origin::Current),
+            clear_outside: self.modal,
+            preserve_inside: false,
+        }))
+    }
+}
+fn translated(bounds: Rectangle, delta: Vector) -> Rectangle {
+    Rectangle {
+        x: bounds.x - delta.x,
+        y: bounds.y - delta.y,
+        ..bounds
+    }
+}
+fn reveal_axis(start: f32, length: f32, viewport_start: f32, viewport_length: f32) -> f32 {
+    if start < viewport_start || length > viewport_length {
+        start - viewport_start
+    } else {
+        (start + length - viewport_start - viewport_length).max(0.)
+    }
+}
+pub(super) struct Apply {
+    scope: Id,
+    inside: bool,
+    entering: Option<bool>,
+    target: usize,
+    field_index: usize,
+    scroll_index: usize,
+    shifts: BTreeMap<usize, Vector>,
+    owner_valid: bool,
+    clear_outside: bool,
+    preserve_inside: bool,
+}
+pub(super) fn exclusive() -> Apply {
+    Apply {
+        scope: Id::new(super::REVIEW_MODAL),
+        inside: false,
+        entering: None,
+        target: 0,
+        field_index: 0,
+        scroll_index: 0,
+        shifts: BTreeMap::new(),
+        owner_valid: true,
+        clear_outside: true,
+        preserve_inside: true,
+    }
+}
+impl Operation for Apply {
+    fn custom(&mut self, _: Option<&Id>, _: Rectangle, state: &mut dyn std::any::Any) {
+        if let Some(owner) = state.downcast_ref::<FormOwner>() {
+            self.owner_valid = owner
+                .0
+                .is_some_and(|owner| scope_id(owner.session) == self.scope);
+            self.clear_outside = owner.0.is_some_and(|owner| owner.modal);
+        }
+    }
+    fn container(&mut self, id: Option<&Id>, _: Rectangle) {
+        self.entering = Some(self.inside || id == Some(&self.scope));
+    }
+    fn traverse(&mut self, visit: &mut dyn FnMut(&mut dyn Operation)) {
+        let previous = self.inside;
+        if let Some(inside) = self.entering.take() {
+            self.inside = inside;
+        }
+        visit(self);
+        self.inside = previous;
+    }
+    fn scrollable(
+        &mut self,
+        _: Option<&Id>,
+        bounds: Rectangle,
+        content: Rectangle,
+        _: Vector,
+        state: &mut dyn operation::Scrollable,
+    ) {
+        if self.owner_valid
+            && let Some(delta) = self.shifts.get(&self.scroll_index)
+        {
+            state.scroll_by(
+                operation::scrollable::AbsoluteOffset {
+                    x: delta.x,
+                    y: delta.y,
+                },
+                bounds,
+                content,
+            );
+        }
+        self.scroll_index += 1;
+    }
+    fn focusable(&mut self, _: Option<&Id>, _: Rectangle, state: &mut dyn operation::Focusable) {
+        if self.owner_valid && self.inside && !self.preserve_inside {
+            if self.field_index == self.target {
+                state.focus();
+            } else {
+                state.unfocus();
+            }
+            self.field_index += 1;
+        } else if self.owner_valid && !self.inside && self.clear_outside {
+            state.unfocus();
+        }
+    }
+}

crates/oa-desktop/src/forms/reference_chooser/widget.rs

@@ -0,0 +1,994 @@
+//! Root overlay adapter. Keep the wrapper mounted while closed so the release
+//! from a dismissal gesture cannot reach the underlying content. Parent modal
+//! ownership is supplied by the host (pass no chooser while a modal is active).
+use super::{Action, Close, Event as ChoiceEvent, MAX_ROWS, Stamp, State as Chooser};
+use crate::style;
+use iced::{
+    Border, Color, Element, Event, Font, Length, Point, Rectangle, Size, Theme, Vector,
+    advanced::{
+        Clipboard, Layout, Shell, Widget, layout, overlay, renderer,
+        text::{self, Paragraph as _},
+        widget::{Operation, Tree, tree},
+    },
+    alignment, keyboard, mouse, touch,
+    widget::text_input,
+    window,
+};
+use std::{cell::Cell, rc::Rc};
+
+const ROW: f32 = 34.;
+const MARGIN: f32 = 8.;
+
+#[derive(Debug, Clone, Copy)]
+pub(super) struct Geometry {
+    pub popup: Rectangle,
+    pub search: Rectangle,
+    pub current: Rectangle,
+    pub detail: Rectangle,
+    pub close: Rectangle,
+    pub previous: Rectangle,
+    pub next: Rectangle,
+    pub clear: Rectangle,
+    pub rows: usize,
+}
+impl Geometry {
+    fn new(anchor: Rectangle, viewport: Size) -> Self {
+        let width = anchor
+            .width
+            .clamp(278., 420.)
+            .min((viewport.width - 2. * MARGIN).max(0.));
+        let height = 360f32.min((viewport.height - 2. * MARGIN).max(0.));
+        let x = anchor.x.clamp(
+            MARGIN.min(viewport.width / 2.),
+            (viewport.width - MARGIN - width).max(MARGIN.min(viewport.width / 2.)),
+        );
+        let below = anchor.y + anchor.height + 4.;
+        let preferred = if below + height + MARGIN <= viewport.height {
+            below
+        } else {
+            anchor.y - height - 4.
+        };
+        let y = preferred.clamp(
+            MARGIN.min(viewport.height / 2.),
+            (viewport.height - MARGIN - height).max(MARGIN.min(viewport.height / 2.)),
+        );
+        Self::from_bounds(Rectangle {
+            x,
+            y,
+            width,
+            height,
+        })
+    }
+    pub(super) fn from_bounds(popup: Rectangle) -> Self {
+        let inner = (popup.width - 16.).max(0.);
+        let rect = |left, top, width, height| Rectangle {
+            x: popup.x + left,
+            y: popup.y + top,
+            width,
+            height,
+        };
+        let footer = (popup.height - 32.).max(0.);
+        let detail_height = if popup.height >= 180. { 32. } else { 0. };
+        let detail_top = (footer - detail_height - 4.).max(84.);
+        let rows = (((detail_top - 88.).max(0.) / ROW) as usize).min(MAX_ROWS);
+        Self {
+            popup,
+            search: rect(8., 28., inner, 30.),
+            current: rect(8., 62., inner, 18.),
+            detail: rect(8., detail_top, inner, detail_height),
+            close: rect((popup.width - 58.).max(0.), 4., 50f32.min(popup.width), 22.),
+            previous: rect(8., footer, 28., 24.),
+            next: rect(40., footer, 28., 24.),
+            clear: rect((popup.width - 84.).max(0.), footer, 76., 24.),
+            rows,
+        }
+    }
+    pub fn row(&self, index: usize) -> Rectangle {
+        Rectangle {
+            x: self.popup.x + 8.,
+            y: self.popup.y + 84. + index as f32 * ROW,
+            width: (self.popup.width - 16.).max(0.),
+            height: ROW,
+        }
+    }
+    fn hit(&self, chooser: &Chooser, point: Point) -> Option<Action> {
+        if self.close.contains(point) {
+            return Some(Action::Close(Close::Escape));
+        }
+        if self.previous.contains(point) && chooser.start() > 0 {
+            return Some(Action::Page {
+                delta: -1,
+                rows: self.rows,
+            });
+        }
+        if self.next.contains(point) && chooser.start() + self.rows < chooser.count() {
+            return Some(Action::Page {
+                delta: 1,
+                rows: self.rows,
+            });
+        }
+        if self.clear.contains(point) && chooser.optional() {
+            return Some(Action::Clear);
+        }
+        chooser
+            .visible(self.rows)
+            .enumerate()
+            .find_map(|(i, c)| self.row(i).contains(point).then_some(Action::Choose(c.id)))
+    }
+}
+
+#[derive(Default)]
+struct Interaction {
+    stamp: Option<Stamp>,
+    serial: u64,
+    pressed: Option<(ChoiceEvent, Pointer)>,
+    closing: bool,
+    swallow_mouse: Option<mouse::Button>,
+    swallow_touch: Option<touch::Finger>,
+    held_mouse: Option<mouse::Button>,
+    held_touch: Option<touch::Finger>,
+    detail_scroll: f32,
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum Pointer {
+    Mouse,
+    Touch(touch::Finger),
+}
+impl Interaction {
+    fn swallow(&mut self, event: &Event) -> bool {
+        match event {
+            Event::Mouse(mouse::Event::ButtonReleased(button))
+                if self.swallow_mouse == Some(*button) =>
+            {
+                self.swallow_mouse = None;
+                true
+            }
+            Event::Touch(
+                touch::Event::FingerLifted { id, .. } | touch::Event::FingerLost { id, .. },
+            ) if self.swallow_touch == Some(*id) => {
+                self.swallow_touch = None;
+                true
+            }
+            _ => false,
+        }
+    }
+}
+
+pub struct Popup<'a, Message, R = iced::Renderer>
+where
+    R: text::Renderer<Font = Font>,
+{
+    content: Element<'a, Message, Theme, R>,
+    input: Element<'a, String, Theme, R>,
+    chooser: Option<&'a Chooser>,
+    anchor: Rectangle,
+    on_event: Rc<dyn Fn(ChoiceEvent) -> Message + 'a>,
+    focus_scope: Option<super::trigger::FormScope>,
+}
+impl<'a, Message: Clone + 'a, R: text::Renderer<Font = Font> + 'a> Popup<'a, Message, R> {
+    pub fn new(
+        content: impl Into<Element<'a, Message, Theme, R>>,
+        chooser: Option<&'a Chooser>,
+        anchor: Rectangle,
+        on_event: impl Fn(ChoiceEvent) -> Message + 'a,
+    ) -> Self {
+        let chooser = chooser.filter(|state| state.is_open());
+        let input = text_input(
+            "Name, @alias, kind or containment",
+            chooser.map_or("", Chooser::query),
+        )
+        .on_input(std::convert::identity)
+        .size(12)
+        .padding(6)
+        .width(Length::Fill)
+        .into();
+        Self {
+            content: content.into(),
+            input,
+            chooser,
+            anchor,
+            on_event: Rc::new(on_event),
+            focus_scope: None,
+        }
+    }
+    pub fn focus_scope(mut self, scope: Option<super::trigger::FormScope>) -> Self {
+        self.focus_scope = scope;
+        self
+    }
+    fn reconcile(&self, tree: &mut Tree) {
+        let state = tree.state.downcast_mut::<Interaction>();
+        let stamp = self.chooser.map(Chooser::stamp);
+        if state.stamp.as_ref().map(|s| s.invocation) != stamp.as_ref().map(|s| s.invocation) {
+            let input = tree.children[1]
+                .state
+                .downcast_mut::<text_input::State<R::Paragraph>>();
+            if stamp.is_some() {
+                input.focus();
+            } else {
+                input.unfocus();
+            }
+            state.closing = false;
+            state.serial = self.chooser.map_or(0, Chooser::query_serial);
+        }
+        if state.stamp != stamp {
+            state.pressed = None;
+            // A queued Choose can be rejected after a preceding query changed
+            // the result generation. Reconciliation must unlock this view.
+            state.closing = false;
+            state.detail_scroll = 0.;
+        }
+        state.stamp = stamp;
+    }
+}
+impl<Message: Clone, R: text::Renderer<Font = Font>> Widget<Message, Theme, R>
+    for Popup<'_, Message, R>
+{
+    fn tag(&self) -> tree::Tag {
+        tree::Tag::of::<Interaction>()
+    }
+    fn state(&self) -> tree::State {
+        tree::State::new(Interaction::default())
+    }
+    fn children(&self) -> Vec<Tree> {
+        vec![
+            Tree::new(self.content.as_widget()),
+            Tree::new(self.input.as_widget()),
+        ]
+    }
+    fn diff(&self, tree: &mut Tree) {
+        tree.children[0].diff(self.content.as_widget());
+        tree.children[1].diff(self.input.as_widget());
+        self.reconcile(tree);
+    }
+    fn size(&self) -> Size<Length> {
+        self.content.as_widget().size()
+    }
+    fn layout(&mut self, tree: &mut Tree, renderer: &R, limits: &layout::Limits) -> layout::Node {
+        self.reconcile(tree);
+        self.content
+            .as_widget_mut()
+            .layout(&mut tree.children[0], renderer, limits)
+    }
+    fn operate(
+        &mut self,
+        tree: &mut Tree,
+        layout: Layout<'_>,
+        renderer: &R,
+        operation: &mut dyn Operation,
+    ) {
+        let mut owner =
+            super::trigger::FormOwner(self.focus_scope.filter(|_| self.chooser.is_none()));
+        operation.custom(None, layout.bounds(), &mut owner);
+        self.content
+            .as_widget_mut()
+            .operate(&mut tree.children[0], layout, renderer, operation);
+    }
+    fn update(
+        &mut self,
+        tree: &mut Tree,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+        viewport: &Rectangle,
+    ) {
+        let state = tree.state.downcast_mut::<Interaction>();
+        if state.swallow(event) || self.chooser.is_some() && is_input(event) {
+            shell.capture_event();
+            return;
+        }
+        if is_input(event) && self.focus_scope.is_some_and(|scope| scope.modal) {
+            super::trigger::own_input(&mut self.content, &mut tree.children[0], layout, renderer);
+        }
+        if let Event::Keyboard(keyboard::Event::KeyPressed {
+            key: keyboard::Key::Named(keyboard::key::Named::Tab),
+            modifiers,
+            ..
+        }) = event
+            && let Some(scope) = self.focus_scope
+            && super::trigger::tab(
+                &mut self.content,
+                &mut tree.children[0],
+                layout,
+                renderer,
+                scope,
+                modifiers.shift(),
+            )
+        {
+            shell.capture_event();
+            shell.request_redraw();
+            return;
+        }
+        super::trigger::measure(
+            &mut self.content,
+            &mut tree.children[0],
+            layout,
+            renderer,
+            *viewport,
+        );
+        self.content.as_widget_mut().update(
+            &mut tree.children[0],
+            event,
+            layout,
+            cursor,
+            renderer,
+            clipboard,
+            shell,
+            viewport,
+        );
+    }
+    fn draw(
+        &self,
+        tree: &Tree,
+        renderer: &mut R,
+        theme: &Theme,
+        style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+    ) {
+        self.content.as_widget().draw(
+            &tree.children[0],
+            renderer,
+            theme,
+            style,
+            layout,
+            if self.chooser.is_some() {
+                mouse::Cursor::Unavailable
+            } else {
+                cursor
+            },
+            viewport,
+        );
+    }
+    fn mouse_interaction(
+        &self,
+        tree: &Tree,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        viewport: &Rectangle,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        if self.chooser.is_some() {
+            mouse::Interaction::None
+        } else {
+            self.content.as_widget().mouse_interaction(
+                &tree.children[0],
+                layout,
+                cursor,
+                viewport,
+                renderer,
+            )
+        }
+    }
+    fn overlay<'b>(
+        &'b mut self,
+        tree: &'b mut Tree,
+        layout: Layout<'b>,
+        renderer: &R,
+        viewport: &Rectangle,
+        translation: Vector,
+    ) -> Option<overlay::Element<'b, Message, Theme, R>> {
+        if let Some(chooser) = self.chooser {
+            Some(overlay::Element::new(Box::new(ChooserOverlay {
+                chooser,
+                anchor: self.anchor,
+                state: tree.state.downcast_mut(),
+                input: &mut self.input,
+                input_tree: &mut tree.children[1],
+                on_event: &*self.on_event,
+            })))
+        } else {
+            self.content.as_widget_mut().overlay(
+                &mut tree.children[0],
+                layout,
+                renderer,
+                viewport,
+                translation,
+            )
+        }
+    }
+}
+impl<'a, Message: Clone + 'a, R: text::Renderer<Font = Font> + 'a> From<Popup<'a, Message, R>>
+    for Element<'a, Message, Theme, R>
+{
+    fn from(popup: Popup<'a, Message, R>) -> Self {
+        Element::new(popup)
+    }
+}
+
+struct ChooserOverlay<'b, 'a, Message, R: text::Renderer<Font = Font>> {
+    chooser: &'a Chooser,
+    anchor: Rectangle,
+    state: &'b mut Interaction,
+    input: &'b mut Element<'a, String, Theme, R>,
+    input_tree: &'b mut Tree,
+    on_event: &'b dyn Fn(ChoiceEvent) -> Message,
+}
+impl<Message, R: text::Renderer<Font = Font>> ChooserOverlay<'_, '_, Message, R> {
+    fn geometry(&self, layout: Layout<'_>) -> Geometry {
+        Geometry::from_bounds(
+            layout
+                .children()
+                .next()
+                .expect("measured chooser bounds")
+                .bounds(),
+        )
+    }
+    fn publish(&mut self, action: Action, shell: &mut Shell<'_, Message>) {
+        if self.state.closing {
+            return;
+        }
+        if action.writes_staged_value() || matches!(action, Action::Close(_)) {
+            self.state.closing = true;
+            self.state.swallow_mouse = self.state.held_mouse.or(self.state.swallow_mouse);
+            self.state.swallow_touch = self.state.held_touch.or(self.state.swallow_touch);
+        }
+        shell.publish((self.on_event)(self.chooser.event(action)));
+    }
+    fn press(
+        &mut self,
+        point: Point,
+        pointer: Pointer,
+        geometry: Geometry,
+        shell: &mut Shell<'_, Message>,
+    ) {
+        if !geometry.popup.contains(point) {
+            self.publish(Action::Close(Close::Outside), shell);
+        } else {
+            self.state.pressed = geometry
+                .hit(self.chooser, point)
+                .map(|action| (self.chooser.event(action), pointer));
+        }
+    }
+    fn release(
+        &mut self,
+        point: Point,
+        pointer: Pointer,
+        geometry: Geometry,
+        shell: &mut Shell<'_, Message>,
+    ) {
+        if let Some((pressed, origin)) = self.state.pressed.take()
+            && origin == pointer
+            && pressed.stamp == self.chooser.stamp()
+            && geometry.hit(self.chooser, point).as_ref() == Some(&pressed.action)
+        {
+            self.publish(pressed.action, shell);
+        }
+    }
+}
+impl<Message: Clone, R: text::Renderer<Font = Font>> overlay::Overlay<Message, Theme, R>
+    for ChooserOverlay<'_, '_, Message, R>
+{
+    fn layout(&mut self, renderer: &R, bounds: Size) -> layout::Node {
+        let geometry = Geometry::new(self.anchor, bounds);
+        let input = self
+            .input
+            .as_widget_mut()
+            .layout(
+                self.input_tree,
+                renderer,
+                &layout::Limits::new(Size::ZERO, geometry.search.size()),
+            )
+            .move_to(geometry.search.position());
+        layout::Node::with_children(
+            bounds,
+            vec![
+                layout::Node::new(geometry.popup.size()).move_to(geometry.popup.position()),
+                input,
+            ],
+        )
+    }
+    fn operate(&mut self, layout: Layout<'_>, renderer: &R, operation: &mut dyn Operation) {
+        self.input.as_widget_mut().operate(
+            self.input_tree,
+            layout.children().nth(1).unwrap(),
+            renderer,
+            operation,
+        );
+    }
+    fn update(
+        &mut self,
+        event: &Event,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+        clipboard: &mut dyn Clipboard,
+        shell: &mut Shell<'_, Message>,
+    ) {
+        let geometry = self.geometry(layout);
+        match event {
+            Event::Mouse(mouse::Event::ButtonPressed(button)) => {
+                self.state.held_mouse = Some(*button)
+            }
+            Event::Mouse(mouse::Event::ButtonReleased(button))
+                if self.state.held_mouse == Some(*button) =>
+            {
+                self.state.held_mouse = None
+            }
+            Event::Touch(touch::Event::FingerPressed { id, .. }) => {
+                self.state.held_touch = Some(*id)
+            }
+            Event::Touch(
+                touch::Event::FingerLifted { id, .. } | touch::Event::FingerLost { id, .. },
+            ) if self.state.held_touch == Some(*id) => self.state.held_touch = None,
+            _ => {}
+        }
+        if self.state.swallow(event) {
+            shell.capture_event();
+            return;
+        }
+        if self.state.closing {
+            if is_input(event) {
+                shell.capture_event();
+            }
+            return;
+        }
+        let mut handled = false;
+        match event {
+            Event::Keyboard(keyboard::Event::KeyPressed { key, modifiers, .. }) => {
+                use keyboard::key::Named;
+                let action = match key {
+                    keyboard::Key::Named(Named::Escape) => Some(Action::Close(Close::Escape)),
+                    keyboard::Key::Named(Named::Tab) => Some(Action::Close(Close::Tab {
+                        backwards: modifiers.shift(),
+                    })),
+                    keyboard::Key::Named(Named::ArrowDown) => Some(Action::Move {
+                        delta: 1,
+                        rows: geometry.rows,
+                    }),
+                    keyboard::Key::Named(Named::ArrowUp) => Some(Action::Move {
+                        delta: -1,
+                        rows: geometry.rows,
+                    }),
+                    keyboard::Key::Named(Named::PageDown) => Some(Action::Page {
+                        delta: 1,
+                        rows: geometry.rows,
+                    }),
+                    keyboard::Key::Named(Named::PageUp) => Some(Action::Page {
+                        delta: -1,
+                        rows: geometry.rows,
+                    }),
+                    keyboard::Key::Named(Named::Enter) => {
+                        handled = true;
+                        self.chooser
+                            .highlighted()
+                            .filter(|c| self.chooser.visible(geometry.rows).any(|v| v.id == c.id))
+                            .map(|c| Action::Choose(c.id))
+                    }
+                    keyboard::Key::Character(c)
+                        if modifiers.control()
+                            && modifiers.shift()
+                            && c.eq_ignore_ascii_case("c") =>
+                    {
+                        clipboard.write(
+                            iced::advanced::clipboard::Kind::Standard,
+                            self.chooser
+                                .highlighted()
+                                .map_or_else(|| self.chooser.current.label(), |c| c.detail()),
+                        );
+                        handled = true;
+                        None
+                    }
+                    _ => None,
+                };
+                if let Some(action) = action {
+                    self.publish(action, shell);
+                    handled = true;
+                }
+            }
+            Event::Window(window::Event::Resized(_) | window::Event::Unfocused) => {
+                self.publish(Action::Close(Close::WindowChanged), shell);
+                handled = true;
+            }
+            Event::Mouse(mouse::Event::ButtonPressed(button)) => {
+                if let Some(point) = cursor.position() {
+                    if !geometry.popup.contains(point) {
+                        self.state.swallow_mouse = Some(*button);
+                        self.press(point, Pointer::Mouse, geometry, shell);
+                        handled = true;
+                    } else if *button == mouse::Button::Left && !geometry.search.contains(point) {
+                        self.press(point, Pointer::Mouse, geometry, shell);
+                        handled = true;
+                    }
+                }
+            }
+            Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
+                if self.state.pressed.is_some() =>
+            {
+                if let Some(point) = cursor.position() {
+                    self.release(point, Pointer::Mouse, geometry, shell);
+                } else {
+                    self.state.pressed = None;
+                }
+                handled = true;
+            }
+            Event::Mouse(mouse::Event::CursorMoved { position })
+                if self.state.pressed.is_none() =>
+            {
+                if let Some(Action::Choose(id)) = geometry.hit(self.chooser, *position)
+                    && self
+                        .chooser
+                        .highlighted()
+                        .is_none_or(|candidate| candidate.id != id)
+                {
+                    self.publish(Action::Highlight(id), shell);
+                }
+            }
+            Event::Mouse(mouse::Event::WheelScrolled { delta }) => {
+                let (x, y) = match delta {
+                    mouse::ScrollDelta::Lines { x, y } => (*x * 24., *y * 24.),
+                    mouse::ScrollDelta::Pixels { x, y } => (*x, *y),
+                };
+                self.state.pressed = None;
+                if cursor
+                    .position()
+                    .is_some_and(|p| geometry.detail.contains(p))
+                {
+                    let detail = self
+                        .chooser
+                        .highlighted()
+                        .map_or_else(|| self.chooser.current.label(), |c| c.detail());
+                    let max = (measure::<R>(&detail, 11., renderer.default_font())
+                        - geometry.detail.width)
+                        .max(0.);
+                    self.state.detail_scroll =
+                        (self.state.detail_scroll - if x != 0. { x } else { y }).clamp(0., max);
+                    shell.request_redraw();
+                } else if y != 0. {
+                    self.publish(
+                        Action::Page {
+                            delta: if y < 0. { 1 } else { -1 },
+                            rows: geometry.rows,
+                        },
+                        shell,
+                    );
+                }
+                handled = true;
+            }
+            Event::Touch(touch::Event::FingerPressed { id, position })
+                if !geometry.search.contains(*position) =>
+            {
+                if !geometry.popup.contains(*position) {
+                    self.state.swallow_touch = Some(*id);
+                }
+                self.press(*position, Pointer::Touch(*id), geometry, shell);
+                handled = true;
+            }
+            Event::Touch(touch::Event::FingerLifted { id, position })
+                if self.state.pressed.is_some() =>
+            {
+                self.release(*position, Pointer::Touch(*id), geometry, shell);
+                handled = true;
+            }
+            Event::Touch(touch::Event::FingerLost { .. } | touch::Event::FingerMoved { .. }) => {
+                self.state.pressed = None;
+            }
+            _ => {}
+        }
+        if !handled {
+            let mut messages = Vec::new();
+            let mut input_shell = Shell::new(&mut messages);
+            self.input.as_widget_mut().update(
+                self.input_tree,
+                event,
+                layout.children().nth(1).unwrap(),
+                cursor,
+                renderer,
+                clipboard,
+                &mut input_shell,
+                &geometry.popup,
+            );
+            let serial = Cell::new(self.state.serial);
+            shell.merge(input_shell, |text| {
+                serial.set(serial.get().saturating_add(1));
+                (self.on_event)(self.chooser.event(Action::Query {
+                    text,
+                    serial: serial.get(),
+                }))
+            });
+            self.state.serial = serial.get();
+        }
+        if is_input(event) {
+            shell.capture_event();
+        }
+    }
+    fn draw(
+        &self,
+        renderer: &mut R,
+        theme: &Theme,
+        renderer_style: &renderer::Style,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+    ) {
+        let geometry = self.geometry(layout);
+        renderer.fill_quad(
+            renderer::Quad {
+                bounds: geometry.popup,
+                border: Border {
+                    color: style::LINE,
+                    width: 1.,
+                    radius: 8.into(),
+                },
+                ..Default::default()
+            },
+            Color::WHITE,
+        );
+        renderer.with_layer(geometry.popup, |renderer| {
+            label(
+                renderer,
+                &self.chooser.scope_label,
+                11.,
+                style::MUTED,
+                Rectangle {
+                    x: geometry.popup.x + 8.,
+                    y: geometry.popup.y + 4.,
+                    width: (geometry.popup.width - 78.).max(0.),
+                    height: 22.,
+                },
+            );
+            label(renderer, "Close", 11., style::TEAL, geometry.close);
+            label(
+                renderer,
+                &self.chooser.current.label(),
+                11.,
+                style::MUTED,
+                geometry.current,
+            );
+            for (i, candidate) in self.chooser.visible(geometry.rows).enumerate() {
+                let row = geometry.row(i);
+                if self
+                    .chooser
+                    .highlighted()
+                    .is_some_and(|c| c.id == candidate.id)
+                {
+                    renderer.fill_quad(
+                        renderer::Quad {
+                            bounds: row,
+                            ..Default::default()
+                        },
+                        Color::from_rgb8(218, 238, 235),
+                    );
+                }
+                let alias_width = (row.width * 0.42).min(
+                    measure::<R>(
+                        &format!("@{}", candidate.alias),
+                        11.,
+                        renderer.default_font(),
+                    ) + 4.,
+                );
+                label(
+                    renderer,
+                    &candidate.name,
+                    12.,
+                    style::INK,
+                    Rectangle {
+                        width: (row.width - alias_width - 6.).max(0.),
+                        height: 17.,
+                        ..row
+                    },
+                );
+                label(
+                    renderer,
+                    &format!("@{}", candidate.alias),
+                    11.,
+                    style::INK,
+                    Rectangle {
+                        x: row.x + row.width - alias_width,
+                        width: alias_width,
+                        height: 17.,
+                        ..row
+                    },
+                );
+                label(
+                    renderer,
+                    &candidate.context_label(),
+                    10.,
+                    style::MUTED,
+                    Rectangle {
+                        y: row.y + 17.,
+                        height: 17.,
+                        ..row
+                    },
+                );
+            }
+            if self.chooser.count() == 0 {
+                label(
+                    renderer,
+                    "No compatible matches. Clear the query.",
+                    11.,
+                    style::MUTED,
+                    geometry.row(0),
+                );
+            }
+            let detail = self
+                .chooser
+                .highlighted()
+                .map_or_else(|| self.chooser.current.label(), |c| c.detail());
+            renderer.with_layer(geometry.detail, |renderer| {
+                raw_label(
+                    renderer,
+                    detail,
+                    11.,
+                    style::MUTED,
+                    Rectangle {
+                        x: geometry.detail.x - self.state.detail_scroll,
+                        width: geometry.detail.width + self.state.detail_scroll,
+                        height: 16.,
+                        ..geometry.detail
+                    },
+                );
+                label(
+                    renderer,
+                    "Scroll details · Ctrl+Shift+C copies",
+                    10.,
+                    style::MUTED,
+                    Rectangle {
+                        y: geometry.detail.y + 16.,
+                        height: 16.,
+                        ..geometry.detail
+                    },
+                );
+            });
+            label(
+                renderer,
+                "‹",
+                15.,
+                if self.chooser.start() > 0 {
+                    style::TEAL
+                } else {
+                    style::MUTED
+                },
+                geometry.previous,
+            );
+            label(
+                renderer,
+                "›",
+                15.,
+                if self.chooser.start() + geometry.rows < self.chooser.count() {
+                    style::TEAL
+                } else {
+                    style::MUTED
+                },
+                geometry.next,
+            );
+            let count = if self.chooser.count() == 0 {
+                "0 results".into()
+            } else {
+                format!(
+                    "{}–{} / {}",
+                    self.chooser.start() + 1,
+                    (self.chooser.start() + geometry.rows).min(self.chooser.count()),
+                    self.chooser.count()
+                )
+            };
+            label(
+                renderer,
+                &count,
+                11.,
+                style::MUTED,
+                Rectangle {
+                    x: geometry.next.x + 30.,
+                    width: (geometry.clear.x - geometry.next.x - 32.).max(0.),
+                    ..geometry.next
+                },
+            );
+            if self.chooser.optional() {
+                label(
+                    renderer,
+                    "Clear reference",
+                    10.,
+                    style::TEAL,
+                    geometry.clear,
+                );
+            }
+            self.input.as_widget().draw(
+                self.input_tree,
+                renderer,
+                theme,
+                renderer_style,
+                layout.children().nth(1).unwrap(),
+                cursor,
+                &geometry.popup,
+            );
+        });
+    }
+    fn mouse_interaction(
+        &self,
+        layout: Layout<'_>,
+        cursor: mouse::Cursor,
+        renderer: &R,
+    ) -> mouse::Interaction {
+        let geometry = self.geometry(layout);
+        if cursor
+            .position()
+            .is_some_and(|p| geometry.hit(self.chooser, p).is_some())
+        {
+            mouse::Interaction::Pointer
+        } else {
+            self.input.as_widget().mouse_interaction(
+                self.input_tree,
+                layout.children().nth(1).unwrap(),
+                cursor,
+                &geometry.popup,
+                renderer,
+            )
+        }
+    }
+}
+
+fn is_input(event: &Event) -> bool {
+    matches!(
+        event,
+        Event::Mouse(_) | Event::Touch(_) | Event::Keyboard(_) | Event::InputMethod(_)
+    )
+}
+fn measure<R: text::Renderer<Font = Font>>(content: &str, size: f32, font: Font) -> f32 {
+    R::Paragraph::with_text(text::Text {
+        content,
+        bounds: Size::INFINITE,
+        size: size.into(),
+        line_height: text::LineHeight::default(),
+        font,
+        align_x: text::Alignment::Left,
+        align_y: alignment::Vertical::Center,
+        shaping: text::Shaping::Advanced,
+        wrapping: text::Wrapping::None,
+    })
+    .min_width()
+}
+fn label<R: text::Renderer<Font = Font>>(
+    renderer: &mut R,
+    content: &str,
+    size: f32,
+    color: Color,
+    bounds: Rectangle,
+) {
+    let font = renderer.default_font();
+    let mut display = content.to_owned();
+    if measure::<R>(content, size, font) > bounds.width {
+        let ends: Vec<_> = content
+            .char_indices()
+            .map(|(i, _)| i)
+            .chain(std::iter::once(content.len()))
+            .collect();
+        let (mut low, mut high) = (0, ends.len());
+        while low + 1 < high {
+            let middle = (low + high) / 2;
+            if measure::<R>(&format!("{}…", &content[..ends[middle]]), size, font) <= bounds.width
+            {
+                low = middle;
+            } else {
+                high = middle;
+            }
+        }
+        display = format!("{}…", &content[..ends[low]]);
+    }
+    raw_label(renderer, display, size, color, bounds);
+}
+fn raw_label<R: text::Renderer<Font = Font>>(
+    renderer: &mut R,
+    content: String,
+    size: f32,
+    color: Color,
+    bounds: Rectangle,
+) {
+    renderer.fill_text(
+        text::Text {
+            content,
+            bounds: bounds.size(),
+            size: size.into(),
+            line_height: text::LineHeight::default(),
+            font: renderer.default_font(),
+            align_x: text::Alignment::Left,
+            align_y: alignment::Vertical::Center,
+            shaping: text::Shaping::Advanced,
+            wrapping: text::Wrapping::None,
+        },
+        Point::new(bounds.x, bounds.center_y()),
+        color,
+        bounds,
+    );
+}

crates/oa-desktop/src/guide.rs

@@ -188,7 +188,7 @@ fn article(topic: Topic) -> Article {
                                 "Choose New in the top bar. Use Project properties to name the model and describe its purpose. Apply changes commits the property draft.",
                                 "On Architecture, choose Create architecture view. Architecture · allocated work shows work inside its performer.",
                                 "Expand the diagram's side palette to see tool names. Choose Entity, click its position in the diagram, enter Rescue coordinator and press Enter. Escape cancels the draft. Use Actor for an external participant such as a Vessel in distress. Right-clicking a blank area also offers Create Entity here.",
-                                "Right-click Rescue coordinator and choose Add activity. Enter Assess incident and press Enter to create the activity and its performer allocation together. Ordinary Activity creation in the palette leaves work unallocated; use + Relationship with Allocation to assign existing work. The allocated-work view shows work inside its performer.",
+                                "Right-click Rescue coordinator and choose Add activity. Enter Assess incident and press Enter to create the activity and its performer allocation together. Ordinary Activity creation in the palette leaves work unallocated. In the allocated-work view, drag existing work into exposed space inside its performer to assign it; the highlighted performer and status explain the proposed change.",
                                 "Use Add existing to place an element that is already in the model. The initial choices match this view; no search is required. Include already shown offers Locate for elements already placed here.",
                                 "Add a second activity for another participant. Select an activity, choose + Relationship, select Interaction and choose the compatible target. Name the exchange after what is conveyed.",
                                 "Visit Model checks to review unfinished work. Save all writes the accepted model and applied drafts to your chosen file.",
@@ -263,7 +263,7 @@ fn article(topic: Topic) -> Article {
                             &[
                                 "Choose the Operational or System perspective. Create participants using Entity/Actor in OA or System/System actor in SA.",
                                 "In the diagram's side palette, choose Activity in OA or Function in SA, click its position, enter a name and press Enter. Escape cancels without creating an element. Select a card and press F2 to rename it in place. For semantic decomposition, use Model explorer, select existing work and use + In selected to create smaller work units.",
-                                "Right-click a participant and choose Add activity or Add function to create new work and its allocation together. To assign existing leaf work, use + Relationship with Allocation from the participant to the work. Model explorer also offers + Allocated when a participant and the appropriate work kind are selected.",
+                                "Right-click a participant and choose Add activity or Add function to create new work and its allocation together. In Architecture · allocated work, drag existing work into a performer to assign it, between performers to reassign it, or onto empty canvas to remove its direct assignment. + Relationship with Allocation and Model explorer's + Allocated provide explicit alternatives.",
                                 "Choose Architecture · allocated work to review responsibilities. Choose Functional dataflow to review the activity/function hierarchy and its exchanges independently.",
                             ],
                         ),
@@ -289,7 +289,7 @@ fn article(topic: Topic) -> Article {
             const {
                 Article {
                     summary: "A diagram is a view of the model. Its boxes, positions and nesting reveal selected relationships; moving a box does not redefine engineering ownership.",
-                    keywords: "containment semantic parent hierarchy nested nesting allocation deployment diagram placement arrange fit fold hide zoom resize routing connection bend waypoint detour label reset selective visibility category categories coverage process context duplicate copy items",
+                    keywords: "containment semantic parent hierarchy nested nesting allocation deployment diagram placement arrange next drag Alt+A auto-layout fit fold hide zoom resize routing connection bend waypoint detour label reset selective visibility category categories coverage process context duplicate copy items",
                     sections: &[
                         explain(
                             "Three things to distinguish",
@@ -309,7 +309,7 @@ fn article(topic: Topic) -> Article {
                                 "Use the diagram selector or + View to work with a focused diagram. View properties edits its name, perspective, projection and Saved view visibility. Apply changes commits the view settings.",
                                 "Choose Containment for semantic children, Architecture · allocated work for responsibilities, Functional dataflow for work and exchanges, or Missions & capabilities for outcomes. All relationships is a broader exploration view; OA ↔ SA traceability displays counterparts.",
                                 "Select an element and edit Semantic parent to change ownership. Use an Allocation relationship to change responsibility. Apply changes validates the semantic change.",
-                                "Drag nodes to arrange the current view, scroll to zoom and use Fit to frame its contents. Arrange changes diagram geometry. Export SVG produces a shareable view.",
+                                "Scroll to zoom and use Fit to frame the current view. In allocated-work views, dragging work changes its assignment and placement together. Choose Arrange next drag or press Alt+A to move work without changing responsibility for that one drag; Escape cancels the armed action. Auto-layout arranges the whole view. Export SVG produces a shareable view.",
                                 "Select a diagram node to access Placement, Fold / unfold and Hide. Hide removes its view placement; Delete from model removes model records and requires review of the affected references.",
                             ],
                         ),
@@ -317,6 +317,14 @@ fn article(topic: Topic) -> Article {
                             "Keep diagrams readable",
                             "Use separate views for responsibility, decomposition and cross-layer coverage. Place existing elements with Show in this diagram. A placement's Diagram field can relocate it while preserving its identity and artifact references. Do not duplicate a semantic element merely to show it in another view.",
                         ),
+                        walkthrough(
+                            "Move work between performers",
+                            &[
+                                "Finish or cancel property and source edits, then drag an Activity or Function body in Architecture · allocated work. Aim at exposed performer space. Read the highlighted destination and status before releasing; release outside the canvas or press Escape to cancel.",
+                                "The move preserves work ownership and identities. A uniformly assigned work group moves its leaves together; a group distributed across performers asks you to choose a leaf. Role responsibilities remain explicit: an outward drag that would leave a role-derived performer explains why it cannot remove that responsibility.",
+                                "Make room when headers, labels or other cards would overlap. Move the view or zoom in if the work and destination are not readable. A refused drop keeps the model and history unchanged. One Undo reverses an accepted assignment and placement together; Save all writes the corresponding source changes.",
+                            ],
+                        ),
                         walkthrough(
                             "Save a focused exchange view",
                             &[
@@ -336,7 +344,7 @@ fn article(topic: Topic) -> Article {
                             &[
                                 "Select an architecture connection and drag a segment to add a bend. Right-click a line for Add bend here; right-click a circle for Remove bend. With the canvas focused, Insert adds a bend and Delete removes the selected bend. Drag the label independently. Escape cancels a gesture; Undo reverses one completed drag. Shift+F10 opens the selected diagram item's context menu; use arrow keys and Enter to choose an action.",
                                 "Automatic orthogonal routing avoids cards and container headers where space permits. Amber connections need attention: move an obstructing element or a bend. In Select / move, drag a port to any border of its owner. Manual positions are per diagram; right-click Reset automatic position restores connection-aware placement. Ports remain attached to their actual owners. Manual routes are saved separately for each diagram and appear in source, API and SVG export.",
-                                "Right-click a connection and choose Reset routing to clear its pins and label position in this view. The Properties Actions menu provides the same commands. Arrange preserves pins. Moving one endpoint keeps pins fixed; moving a container carrying both endpoints translates their pins. When folding promotes an endpoint, expand it again to resume and edit its saved route.",
+                                "Right-click a connection and choose Reset routing to clear its pins and label position in this view. The Properties Actions menu provides the same commands. Auto-layout preserves pins. Moving one endpoint keeps pins fixed; moving a container carrying both endpoints translates their pins. When folding promotes an endpoint, expand it again to resume and edit its saved route.",
                             ],
                         ),
                         explain(
@@ -445,28 +453,32 @@ fn article(topic: Topic) -> Article {
                         walkthrough(
                             "Describe a path through exchanges",
                             &[
-                                "First create the activities/functions and their exchanges. Check the source and target work for every exchange.",
+                                "A blank path offers Add first activity/function contribution. You can use existing work or stage a new source in that form; exchanges still need explicit compatible source and target work.",
                                 "Open Behavior & scenarios → New. Choose Operational process in OA or Functional chain in SA, enter its exact name, then Create and open. The new behavior belongs at the layer root and opens immediately; Undo removes the creation as one edit.",
-                                "Open Tools and choose Work or Exchange, then a highlighted path or contribution position to involve an existing source. Each contribution keeps its own identity while referring to the shared engineering definition.",
-                                "In Tools, choose Sequence link and click or drag from the preceding contribution to the following contribution. Choose Tools → Select / reorder to drag a selected path endpoint and reconnect it; a contribution's ↕ handle changes its position within a column. These are local contributions and sequence links, not new architecture exchanges.",
-                                "Select a contribution, then add another after it. Tools → Two paths… creates a split, two paths and their merge in one undoable edit. Enter explicit alternative conditions. Fit overview uses the visible canvas area; 100% keeps working scale with scrollbars. If the minimum zoom is reached, scroll to inspect the remainder.",
+                                "Choose Work (W) or Exchange (E) from the permanent palette on the right, then a highlighted position. Hover a palette button to read its tool name. In Work, Create new source keeps the contribution name and position while you name its Activity/Function and choose its semantic parent. Use this new source stages it; Create commits source and contribution in one Undo. An adjacent exchange may require a particular existing work identity.",
+                                "Choose Sequence link (->) and click or drag from the preceding contribution to the following contribution. Choose Select contributions or paths (S) to drag a selected path endpoint and reconnect it. A contribution's ↕ handle reorders contributions within the same column; links determine the columns. These are local contributions and sequence links, not new architecture exchanges.",
+                                "Select a contribution, then add another after it. Details → Two paths... creates a split, two paths and their merge in one undoable edit. Enter explicit alternative conditions.",
                                 "Use Chain involvement from the Process/Functional chain to the capability it supports. Read Model checks for unfinished or disconnected paths.",
                             ],
                         ),
+                        explain(
+                            "Navigate the canvas",
+                            "The header and palette stay available while Details and creation forms overlay the canvas. Fit frames the contents; −/+ changes zoom and 100% restores working scale. Focus the canvas to zoom with the wheel or pan with middle-button drag or Space + left drag. F6 enters or leaves canvas controls; Tab moves to the next control, Enter/Space activates it, and Escape leaves canvas controls or cancels a gesture.",
+                        ),
                         explain(
                             "Choose the right behavioral description",
                             "A chain concentrates on a route through existing exchanges. A scenario can also carry actions, state observations, lifelines and nested fragments. The architecture diagram remains a view of the possible relationships rather than an execution trace.",
                         ),
                         explain(
                             "Review the path as an engineer",
-                            "Check that exchanges express meaningful handoffs and that the links and branch guards support the selected outcome. Use Tools → Reuse to involve an existing process or chain as a nested reference. For an imported ordered exchange path, Append exchange… continues that path; Convert ordered path to explicit links exposes its implied links for topology editing. Conversion preserves the original order in one undoable change.",
+                            "Check that exchanges express meaningful handoffs and that the links and branch guards support the selected outcome. Use Reuse process / chain (ref) in the palette to involve an existing process or chain as a nested reference. For an imported ordered exchange path, Details → Append exchange... continues that path; Edit path links and guards exposes its implied links for topology editing. Conversion preserves the original order in one undoable change.",
                         ),
                         walkthrough(
                             "Connect a particular use of a procedure",
                             &[
-                                "Choose Focus canvas for more working space; Restore panels brings the explorer and properties back. Select a contribution inside a reusable preview, then open Selection details to read its complete caller and reference identity.",
-                                "In Selection details, use Expand nested reference or Fold nested reference to inspect that instance. Open source or Open contribution definition visits the shared definition; Back to caller returns to the original caller context.",
-                                "Open Tools → Qualified link / assembly… and choose its source and target. Use Enter reference to open an instance's contributions, Up one reference for its caller scope, or Root for the link owner. Search and page through all contributions in that scope, then select the exact endpoint. The first and second uses of a procedure remain different choices even when their work has the same name.",
+                                "Choose Focus canvas for more working space; Restore panels brings the explorer and properties back. Select a contribution inside a reusable preview, then open Details to read its complete caller and reference identity.",
+                                "In Details, use Expand nested reference or Fold nested reference to inspect that instance. Open source or Open contribution definition visits the shared definition; Back to caller returns to the original caller context.",
+                                "Open Details → Qualified link / assembly... and choose its source and target. Use Enter reference to open an instance's contributions, Up one reference for its caller scope, or Root for the link owner. Search and page through all contributions in that scope, then select the exact endpoint. The first and second uses of a procedure remain different choices even when their work has the same name.",
                                 "Choose Precedence to describe order and its guard, Exchange assembly to identify a work exchange between the contributions, or Common work incidence to state that both use the same work. Select the engineering identity when required, then Apply link.",
                             ],
                         ),
@@ -490,19 +502,23 @@ fn article(topic: Topic) -> Article {
                             "Create a scenario",
                             &[
                                 "Open Behavior & scenarios → New → Scenario and enter its name. Explicitly choose Activities or Participants in OA, or Functions or System boundary in SA. Add optional context only when needed: this is a reference, while the scenario itself belongs at the layer root. Create and open starts the empty scenario.",
-                                "Use + Lifeline and choose the participant or work it represents. Choices follow the scenario's viewpoint: operational activities, operational participants, system functions or system boundary participants.",
-                                "Choose + Message and its style. Call + correlated reply creates both occurrences in one edit. Select the exchange and compatible sending/receiving lifelines. Reply to existing call offers valid unanswered calls.",
-                                "Use Action, Observe state or Fragment for other behavior. A local timer has an expression and a lifeline, with no global exchange. Create and delete messages describe participant lifetime; Model checks also flag risks inside repeated loops.",
-                                "Choose a message style and Draw message. Start at a highlighted sequence position on a lifeline, then click or drag to the receiving lifeline. The form retains the chosen position while you select the exchange and details. Escape cancels the gesture.",
-                                "In Select / reorder, click an occurrence and drag its ↕ handle to another position within the same sequence. The ordered list's up/down controls provide another way to reorder. Select an occurrence to inspect its particular use of the exchange, including its message values.",
+                                "Choose Lifeline (L) in the permanent palette on the right, then click the canvas. Choose existing work/participant or Create new source. The explicit viewpoint limits its kinds; choose participant kinds deliberately. Source name and lifeline name are separate, and the source semantic parent is independent of the scenario. No allocation or capability involvement is inferred.",
+                                "Choose a message style from the palette; hover a button to read its tool name. Start at a highlighted sequence position on a lifeline, then click or drag to the receiving lifeline. Complete the exchange and details in the form, which retains that sequence position. Escape cancels the gesture.",
+                                "Call and correlated reply (C/R) creates both occurrences in one edit. Reply to existing call offers valid unanswered calls. A local timer has an expression and a lifeline, with no global exchange. Create and delete messages describe participant lifetime; Model checks also flag risks inside repeated loops.",
+                                "Choose Action (A), State observation (St), Reuse scenario (ref) or Fragment (alt) and click the intended sequence position. Clicking an action or observation on a lifeline also selects that lifeline. Complete any remaining choices before Create.",
+                                "Choose Select / reorder occurrences (S) and drag an occurrence itself to another position within the same sequence. A drag into another fragment operand is refused. Open Details for the ordered list's up/down controls or Properties for the selected occurrence, including its message values.",
                             ],
                         ),
+                        explain(
+                            "Navigate the canvas",
+                            "The header and palette stay available while Details and creation forms overlay the canvas. Fit frames the contents; −/+ changes zoom and 100% restores working scale. Focus the canvas to zoom with the wheel or pan with middle-button drag or Space + left drag. F6 enters or leaves canvas controls; Tab moves to the next control, Enter/Space activates it, and Escape leaves canvas controls or cancels a gesture.",
+                        ),
                         walkthrough(
                             "Describe alternatives",
                             &[
-                                "Choose Fragment and select ALT, PAR, LOOP or OPT. Enter the branch conditions; the tool creates the fragment and its operands together.",
-                                "Use the Destination selector in subsequent message or action forms to choose the intended operand. New occurrences append to that operand's ordered behavior.",
-                                "Use Reuse scenario to refer to existing behavior. Bind every referenced lifeline to a compatible local lifeline explicitly. Open source follows the original scenario without copying its contents.",
+                                "Choose Fragment (alt), click its sequence position and select ALT, PAR, LOOP or OPT. Enter the branch conditions; the tool creates the fragment and its operands together.",
+                                "Click the highlighted position inside an operand to place the next message, action or reference there. The form shows its destination and insertion position. Append to this sequence instead explicitly moves the pending insertion to that sequence's end.",
+                                "Choose Reuse scenario and click its position, then bind every referenced lifeline to a compatible local lifeline explicitly. Select the resulting use and choose Details → Open definition. Back returns to that exact use and its viewport after you apply or cancel pending edits.",
                                 "Inspect the scenario projection and Model checks. State exactly what each guard means, including units and assumptions where relevant.",
                             ],
                         ),
@@ -543,7 +559,8 @@ fn article(topic: Topic) -> Article {
                         walkthrough(
                             "Build a state machine",
                             &[
-                                "In Behavior & scenarios → New → State machine, enter its name and search for the existing same-layer participant that owns it. Candidate labels show parent context and alias to distinguish repeated names. If the participant does not exist yet, cancel and create it in Architecture first.",
+                                "In Behavior & scenarios → New → State machine, enter its name and search for the existing same-layer participant that owns it. Candidate labels show parent context and alias to distinguish repeated names.",
+                                "If the owner does not exist, Create new owner retains the machine name and first-view option. Choose its participant kind and semantic parent explicitly. Use this new source returns without changing the model; Create and open commits owner, machine and optional view together.",
                                 "Optionally select Create the first state view, then Create and open. The new machine starts without regions or states. For an existing machine, Create diagram places its existing regions and vertices in a saved view; + View creates another independent layout.",
                                 "Choose + Region and click the highlighted machine, or a State/Mode for a nested region. Choose Initial, State, Mode or another kind from + State / symbol, then click its highlighted owning region. Rename the new element in Properties.",
                                 "Choose Transition and drag from a source vertex to a compatible target, or click the source and then the target. In Select / move, drag states or containers to arrange them; a container moves its descendant placements without changing ownership.",
@@ -697,6 +714,10 @@ fn article(topic: Topic) -> Article {
                             "Map references by meaning",
                             "Reference mapping connect exact OA and SA identities used by the proposed change. Similar names are not sufficient. Map the records that play the same engineering role, including enclosing fields in qualified message-value paths. Mapping a referenced record does not authorize creating, moving or editing that record. If it needs a counterpart, establish that correspondence first.",
                         ),
+                        explain(
+                            "Edit stored observations deliberately",
+                            "In a trace's Properties, Edit stored history (advanced)… edits the observations retained by that trace. Choose the fact and enter its Operational and System observations explicitly. Not applicable, an observed absent value, and no stored fact have different meanings. Historical references may retain the exact UUID of a deleted record. Apply changes validates the complete history; Undo restores it. These history edits leave both counterpart records unchanged. Use Review counterpart changes… for Keep/Take decisions about their current engineering content.",
+                        ),
                         walkthrough(
                             "Review one message value or lifeline binding",
                             &[
@@ -897,7 +918,7 @@ fn article(topic: Topic) -> Article {
                         ),
                         explain(
                             "A new behavior is still a draft",
-                            "Behavior → New keeps the exact name, owner and viewpoint choices outside the model until Create and open succeeds. Cancel or Escape discards only this draft; if a dialog is open, the first Escape dismisses that dialog. New refuses other unfinished property, source or behavior drafts without applying them. Recovery restores the creation form in its original layer, including rejected raw text, for correction or cancellation.",
+                            "Inside a source subform, Back or the first Escape returns to the unchanged parent. Use this new source stages the prerequisite only. Canceling the parent discards it; choosing an existing reference excludes the staged source from creation. Recovery retains both forms and their reserved identities. An open dialog still receives Escape first. Behavior → New keeps the exact name, owner and viewpoint choices outside the model until Create and open succeeds. Cancel or Escape discards only this draft; if a dialog is open, the first Escape dismisses that dialog. New refuses other unfinished property, source or behavior drafts without applying them. Recovery restores the creation form in its original layer, including rejected raw text, for correction or cancellation.",
                         ),
                         explain(
                             "Aliases and references",

crates/oa-desktop/src/main.rs

@@ -1,4 +1,6 @@
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
+mod allocation_drag;
+mod allocation_input;
 mod app;
 mod behavior;
 mod connection_edit;

crates/oa-desktop/src/model_menu.rs

@@ -415,7 +415,9 @@ pub fn popup(app: &App) -> Option<Menu<Message>> {
                     true,
                 ));
                 entries.push(item("Placement properties", Message::Select(node.id), true));
-                entries.push(item("Hide from this diagram", Message::HideSelected, true));
+                entries.push(
+                    item("Hide from this diagram", Message::HideSelected, true).shortcut("Delete"),
+                );
             } else if e.kind() != Kind::Port
                 && let Some(d) = app.active_diagram.and_then(|d| p.diagrams.get(&d))
             {
@@ -465,7 +467,25 @@ pub fn popup(app: &App) -> Option<Menu<Message>> {
             true,
         ));
         if id != p.id {
-            entries.push(item("Delete from model…", Message::Delete, true));
+            entries.push(
+                item("Delete from model…", Message::Delete, true).shortcut(
+                    if request.canvas.is_some_and(|context| context.diagram != id)
+                        && (request.placement.is_some()
+                            || p.relations.contains_key(&id)
+                            || p.elements
+                                .get(&id)
+                                .is_some_and(|element| element.kind() == Kind::Port))
+                    {
+                        if request.placement.is_some() {
+                            "Shift+Delete"
+                        } else {
+                            "Delete / Shift+Delete"
+                        }
+                    } else {
+                        ""
+                    },
+                ),
+            );
         }
     }
     Some(Menu {

crates/oa-desktop/src/semantic_review.rs

@@ -87,6 +87,9 @@ pub enum RowEvent {
     ValuePath(String, crate::data_values::FieldPathKey),
     ValueBrowse(String, Option<crate::data_values::FieldPathKey>, usize),
     ReferenceBrowse(String, String, usize),
+    ReferenceOpen(crate::forms::reference_chooser::adapter::Open),
+    ReferenceEvent(crate::forms::reference_chooser::Event),
+    ReferenceSet(crate::forms::reference_chooser::adapter::Set),
     OperationOmission(bool),
     OperationRationale(String),
     Tab(Tab),

crates/oa-desktop/src/semantic_review/batch.rs

@@ -296,6 +296,51 @@ impl State {
         }
         Ok(())
     }
+    pub(crate) fn reference_form(&self, project: &Project) -> Option<&Draft> {
+        let facet = self.active.selected.as_ref()?;
+        if self.frozen(project).is_err()
+            || self.active.tab != Tab::Facts
+            || self.active.decisions.get(facet) != Some(&SemanticDecision::Candidate)
+        {
+            return None;
+        }
+        self.active.candidate_draft(facet)
+    }
+    pub(crate) fn reference_draft(
+        &self,
+        project: &Project,
+        address: Option<RowAddress>,
+        facet: &FacetSelector,
+        path: &str,
+    ) -> Option<&Draft> {
+        if self.frozen(project).is_err()
+            || self.active_address != address
+            || self.active.tab != Tab::Facts
+        {
+            return None;
+        }
+        self.active.reference_draft(project, facet, path)
+    }
+    pub(crate) fn set_reference(
+        &mut self,
+        project: &Project,
+        address: Option<RowAddress>,
+        facet: &FacetSelector,
+        intent: crate::forms::reference_chooser::adapter::Set,
+    ) -> Result<(), String> {
+        self.reference_draft(project, address, facet, &intent.context.path)
+            .ok_or("The originating review row or property is no longer active.")?
+            .reference_value(project, &intent)?;
+        self.update(
+            project,
+            Event::Row {
+                address,
+                facet: Some(facet.clone()),
+                event: RowEvent::ReferenceSet(intent),
+            },
+        );
+        Ok(())
+    }
     pub fn update(&mut self, project: &Project, event: impl Into<Event>) {
         let event = event.into();
         #[cfg(test)]
@@ -303,6 +348,30 @@ impl State {
             Event::Editor(event) => self.address_event(event),
             other => other,
         };
+        match &event {
+            Event::Row {
+                event: RowEvent::ReferenceOpen(_) | RowEvent::ReferenceEvent(_),
+                ..
+            }
+            | Event::Editor(RowEvent::ReferenceOpen(_) | RowEvent::ReferenceEvent(_)) => return,
+            Event::Row {
+                address,
+                facet,
+                event: RowEvent::ReferenceSet(intent),
+            } => {
+                let valid = facet
+                    .as_ref()
+                    .and_then(|facet| {
+                        self.reference_draft(project, *address, facet, &intent.context.path)
+                    })
+                    .is_some_and(|draft| draft.reference_value(project, intent).is_ok());
+                if !valid {
+                    return;
+                }
+            }
+            Event::Editor(RowEvent::ReferenceSet(_)) => return,
+            _ => {}
+        }
         if let Err(error) = self.frozen(project) {
             // Withdrawing a pending reset is authored intent only. Retain it while
             // keeping the original accepted base and disabling every stale plan.
@@ -464,7 +533,8 @@ impl State {
                             );
                             let scoped_edit = matches!(
                                 event,
-                                RowEvent::Input(_, _)
+                                RowEvent::ReferenceSet(_)
+                                    | RowEvent::Input(_, _)
                                     | RowEvent::Text(_, _)
                                     | RowEvent::Shape(_, _)
                                     | RowEvent::Variant(_, _)
@@ -624,7 +694,7 @@ impl State {
             Fill,
             widget::{button, checkbox, column, pick_list, row, text},
         };
-        let message = |event| Message::Workflow(crate::workflow::Event::Semantic(event));
+        let message = |event| Message::Workflow(crate::workflow::Event::semantic(event));
         let mut available: Vec<_> = self
             .base
             .traces
@@ -747,13 +817,19 @@ impl State {
         if let Some(notice) = &self.notice {
             header = header.push(text(notice).size(11));
         }
-        self.active
+        let view = self
+            .active
             .view(&self.base, header.into(), self.can_apply())
             .map(move |message| match message {
-                Message::Workflow(crate::workflow::Event::Semantic(Event::Editor(event))) => {
-                    Message::Workflow(crate::workflow::Event::Semantic(self.address_event(event)))
+                Message::Workflow(crate::workflow::Event::Semantic(event)) => {
+                    let event = match *event {
+                        Event::Editor(event) => self.address_event(event),
+                        other => other,
+                    };
+                    Message::Workflow(crate::workflow::Event::semantic(event))
                 }
                 other => other,
-            })
+            });
+        crate::forms::reference_chooser::trigger::modal(view)
     }
 }

crates/oa-desktop/src/semantic_review/batch_tests.rs

@@ -522,10 +522,10 @@ fn batch_apply_is_one_exact_source_and_history_undo_redo_roundtrip() {
         &mut app,
         RowEvent::Input(path(f.direction, "minimum"), "120".into()),
     );
-    let _ = app.update(Message::Workflow(crate::workflow::Event::Semantic(
+    let _ = app.update(Message::Workflow(crate::workflow::Event::semantic(
         Event::ChooseTrace(view::choice(&f.project, f.traces[1])),
     )));
-    let _ = app.update(Message::Workflow(crate::workflow::Event::Semantic(
+    let _ = app.update(Message::Workflow(crate::workflow::Event::semantic(
         Event::OpenTrace,
     )));
     tests::decide(

crates/oa-desktop/src/semantic_review/row.rs

@@ -166,6 +166,14 @@ impl ReviewRow {
     pub fn update(&mut self, project: &Project, event: RowEvent) {
         let mut replan = true;
         let result = match event {
+            // Browser messages belong to the app overlay and must never replan.
+            RowEvent::ReferenceOpen(_) | RowEvent::ReferenceEvent(_) => return,
+            RowEvent::ReferenceSet(intent) => {
+                let path = intent.context.path.clone();
+                self.edit(project, &path, |draft| {
+                    draft.reference_set(project, &intent)
+                })
+            }
             RowEvent::OperationOmission(enabled) => {
                 self.operation_omission =
                     enabled.then(|| self.operation_omission.clone().unwrap_or_default());
@@ -518,6 +526,25 @@ impl ReviewRow {
         }
     }
 
+    pub(super) fn reference_draft(
+        &self,
+        project: &Project,
+        facet: &FacetSelector,
+        path: &str,
+    ) -> Option<&Draft> {
+        if self.selected.as_ref() != Some(facet)
+            || self.decisions.get(facet) != Some(&SemanticDecision::Candidate)
+            || matches!(path, "/id" | "/alias" | "/body" | "/layer")
+            || !self
+                .candidate_roots(project, facet)?
+                .iter()
+                .any(|root| path == root || path.starts_with(&format!("{root}/")))
+        {
+            return None;
+        }
+        self.candidate_draft(facet)
+    }
+
     fn edit(
         &mut self,
         project: &Project,
@@ -895,7 +922,9 @@ pub fn form_event(message: Message) -> Message {
         Message::FieldReferenceBrowse(path, query, page) => {
             RowEvent::ReferenceBrowse(path, query, page)
         }
+        Message::FieldReferenceOpen(request) => RowEvent::ReferenceOpen(request),
+        Message::FieldReferenceEvent(event) => RowEvent::ReferenceEvent(event),
         _ => RowEvent::Preview,
     };
-    Message::Workflow(crate::workflow::Event::Semantic(Event::Editor(event)))
+    Message::Workflow(crate::workflow::Event::semantic(Event::Editor(event)))
 }

crates/oa-desktop/src/semantic_review/tests.rs

@@ -3,7 +3,7 @@ use crate::{app::App, document::Document, workflow::Workflow};
 use serde_json::json;
 
 pub(super) fn send(app: &mut App, event: RowEvent) {
-    let _ = app.update(Message::Workflow(crate::workflow::Event::Semantic(
+    let _ = app.update(Message::Workflow(crate::workflow::Event::semantic(
         state(app).address_event(event),
     )));
 }

crates/oa-desktop/src/semantic_review/view.rs

@@ -13,7 +13,7 @@ use iced::{
 mod reserved_artifact_tests;
 
 fn event(event: RowEvent) -> Message {
-    Message::Workflow(crate::workflow::Event::Semantic(Event::Editor(event)))
+    Message::Workflow(crate::workflow::Event::semantic(Event::Editor(event)))
 }
 fn action<'a>(
     label: impl Into<String>,
@@ -867,7 +867,13 @@ impl ReviewRow {
         ) {
             detail = detail.push(text("Attached facts are separate from referenced definitions. Removing membership never implies deleting a semantic object.").size(11).color(style::MUTED));
         }
-        detail.into()
+        if self.decisions.get(&fact.selector) == Some(&SemanticDecision::Candidate)
+            && let Some(draft) = self.candidate_draft(&fact.selector)
+        {
+            crate::forms::reference_chooser::trigger::scope(detail, draft.reference_session())
+        } else {
+            detail.into()
+        }
     }
 
     fn members_view<'a>(&'a self, project: &'a Project) -> Element<'a, Message> {

crates/oa-desktop/src/views.rs

@@ -284,7 +284,7 @@ pub fn view(app: &App) -> View<'_, Message> {
     )
     .padding([4, 16])
     .style(style::panel);
-    let root: View<'_, Message> = column![header, task_nav, body, footer].into();
+    let root = crate::allocation_input::root(app, column![header, task_nav, body, footer]);
     if app.architecture.as_ref().is_some_and(|s| s.modal()) {
         return modal_width(
             root,
@@ -343,8 +343,8 @@ pub fn view(app: &App) -> View<'_, Message> {
             .into(),
         );
     }
-    if app.delete_pending {
-        return modal(root,column![text("Delete from model?").size(21),text(format!("{} and its owned elements will be removed. Incident relationships, occurrences and view placements are updated together. Counterparts in the other layer remain.",p.named(app.selected))).size(13),label("Undo restores the complete change. Use Hide for diagram-only removal."),row![action("Cancel",Message::CancelDelete),button("Delete from model").style(button::danger).padding(10).on_press(Message::ConfirmDelete)].spacing(10)].spacing(16).into());
+    if let Some(target) = app.delete_target.as_ref().filter(|_| app.delete_pending) {
+        return modal(root,column![text("Delete from model?").size(21),text(format!("{} and its owned elements will be removed. Incident relationships, occurrences and view placements are updated together. Counterparts in the other layer remain.",p.named(target.snapshot.request.object))).size(13),label("Undo restores the complete change. Use Hide for diagram-only removal."),row![action("Cancel",Message::CancelDelete),button("Delete from model").style(button::danger).padding(10).on_press(Message::ConfirmDelete(target.snapshot.token))].spacing(10)].spacing(16).into());
     }
     if app.pending.is_some() {
         return modal(root,column![text("Keep your changes?").size(21),text("Save the model and pending edits before continuing. Invalid drafts stay available for correction.").size(13),row![action("Cancel",Message::Cancel),action("Discard changes",Message::Discard),button("Save & continue").padding(10).on_press(Message::SaveAndContinue)].spacing(8)].spacing(16).into());
@@ -414,7 +414,7 @@ fn diagram(app: &App) -> View<'_, Message> {
     .align_y(iced::Center);
     if let Some(id) = app.active_diagram {
         chooser = chooser.push(action("View properties", Message::Select(id)));
-        controls = controls.push(action("Arrange", Message::Command(Command::Layout(id))));
+        controls = controls.push(action("Auto-layout", Message::Command(Command::Layout(id))));
     }
     let toolbar = column![chooser, controls].spacing(6);
     let projection = app
@@ -442,6 +442,7 @@ fn diagram(app: &App) -> View<'_, Message> {
     .align_y(iced::Center);
     let canvas: View<'_, Message> = if let Some(id) = app.active_diagram {
         let program = DiagramCanvas {
+            allocation: Some(app.allocation_capability()),
             project: app.project(),
             view_index: Some(app.document.view_index()),
             diagram: id,
@@ -458,18 +459,31 @@ fn diagram(app: &App) -> View<'_, Message> {
             connection: app.connection.as_ref(),
         };
         let mut scene = widget::stack![
-            widget::canvas(program).width(Fill).height(Fill),
+            crate::diagram::focus::wrap(
+                widget::canvas(program).width(Fill).height(Fill),
+                program.context,
+                crate::app::diagram_removal::enabled(app),
+                Message::DiagramTraverse
+            ),
             widget::canvas(crate::diagram::PortLabels(program))
                 .width(Fill)
                 .height(Fill),
+            widget::canvas(crate::diagram::WorkFeedback(program))
+                .width(Fill)
+                .height(Fill),
         ];
         if let Some(editor) = crate::app::architecture_authoring::inline_editor(app) {
             scene = scene.push(editor);
         }
         row![
-            widget::sensor(scene)
-                .on_show(Message::CanvasResized)
-                .on_resize(Message::CanvasResized),
+            widget::sensor(
+                container(scene)
+                    .id(crate::allocation_input::CANVAS_ID)
+                    .width(Fill)
+                    .height(Fill)
+            )
+            .on_show(Message::CanvasResized)
+            .on_resize(Message::CanvasResized),
             crate::app::architecture_authoring::palette(app)
         ]
         .height(Fill)
@@ -500,6 +514,27 @@ fn diagram(app: &App) -> View<'_, Message> {
     if app.active_diagram.is_some() {
         tools = tools.push(modes);
     }
+    if projection == Some(ProjectionKind::Allocation) {
+        tools = tools.push(
+            row![
+                action(
+                    &format!(
+                        "{} · {}",
+                        if app.allocation_drag.arrange_next {
+                            "Arrange next drag: armed"
+                        } else {
+                            "Arrange next drag"
+                        },
+                        crate::allocation_input::ARRANGE_SHORTCUT
+                    ),
+                    Message::WorkDrag(crate::app::allocation_drag::Event::ArrangeNext)
+                ),
+                label("Drag work into a performer to assign · out to remove assignment")
+            ]
+            .spacing(8)
+            .align_y(iced::Center),
+        );
+    }
     if let Some(diagram) = app.active_diagram {
         let view = oa_core::projection::project_view(app.project(), diagram);
         let edge = view.edges.iter().find(|edge| edge.id == app.selected);
@@ -511,7 +546,9 @@ fn diagram(app: &App) -> View<'_, Message> {
             )
             .is_some_and(|(source, target)| source != edge.source || target != edge.target)
         });
-        let hint = if let Some(session) = &app.connection {
+        let hint = if let Some(feedback) = &app.allocation_drag.feedback {
+            feedback.text.as_str()
+        } else if let Some(session) = &app.connection {
             if session.source.is_some() {
                 if session.candidates.is_empty() {
                     "No compatible targets are visible. Expand containers or show an endpoint · Esc cancels"
@@ -528,7 +565,9 @@ fn diagram(app: &App) -> View<'_, Message> {
         } else {
             "Right-click for actions · drag to arrange · scroll to zoom"
         };
-        tools = tools.push(container(label(hint)).height(30));
+        // Status is outside the measured canvas. Clipping prevents long text
+        // from painting over work headers or frozen target labels below it.
+        tools = tools.push(container(label(hint)).height(30).width(Fill).clip(true));
     }
     column![container(tools).padding(14), canvas].into()
 }

crates/oa-desktop/src/workflow.rs

@@ -19,7 +19,7 @@ mod transition_tests;
 
 #[derive(Debug, Clone)]
 pub enum Event {
-    Semantic(crate::semantic_review::Event),
+    Semantic(Box<crate::semantic_review::Event>),
     Port(crate::port_workflow::Event),
     ExchangeItem(Id, bool),
     Endpoint(bool, EndpointChoice),
@@ -41,6 +41,11 @@ pub enum Event {
     Resolve(Id, TransitionField, FieldDecision),
     Preview,
 }
+impl Event {
+    pub fn semantic(event: crate::semantic_review::Event) -> Self {
+        Self::Semantic(Box::new(event))
+    }
+}
 pub enum Workflow {
     Semantic(Box<crate::semantic_review::State>),
     Ports(Box<crate::port_workflow::State>),

crates/oa-server/tests/semantic_schema.py

@@ -2,7 +2,8 @@
 
 Run from any directory with Python 3: semantic_schema.py [--check] [--validate].
 --validate additionally runs source-7 structural fixtures with jsonschema.
-This generates documentation only, never runtime selectors or model mutations.
+The desktop stored-history editor reads the checked-in descriptor for field
+shapes. Core types and validation remain authoritative for model mutations.
 """
 import copy
 import json

docs/language.rst

@@ -2037,6 +2037,23 @@ will occur. Reparenting work must not silently change its performer. A computed
 parent summary must remain distinguishable from direct allocation. A collapse
 operation hides presentation detail without deleting the children.
 
+In an Allocation view, dragging an Activity or Function body MAY combine a
+performer change with diagram placement. The preview MUST identify the
+destination and preserve readable work and performer labels. A clean click
+selects without applying unrelated drafts. A refused work press with an unapplied
+property draft MUST preserve its text, caret and focused editor. An accepted drag is one atomic
+model/source/history transaction: semantic ownership and work identities are
+preserved; only leaf direct Allocation relations, their own retired routes and
+the affected view geometry change. Existing Allocation identities are retained on reassignment. Role
+realizations and assignments MUST NOT be silently changed. Uniform work groups
+may move their leaf responsibilities together; ambiguous or distributed groups
+and changes requiring collateral record edits MUST be refused with an explanation.
+Moving outside performer regions removes direct assignment only when the
+effective role responsibility is also absent. Releasing outside the viewport
+cancels the gesture. Explicit Arrange next drag applies geometry alone for one
+gesture. Refused and snapped no-op drops MUST NOT create history entries or
+discard Redo. Undo restores the exact source bundle and identities together.
+
 Applying a reachable source bundle is one model transaction. Graphical edits
 update its owning declarations through the source-preserving updater. Both
 paths validate their candidate and model/source equality before

docs/scope.md

@@ -22,7 +22,7 @@ Graphical and textual parity applies to the persistent fields of this profile. D
 
 - OA captures operational needs; SA defines the selected system contribution. SA contains no internal logical/physical components, and Studio does not decompose SA Actors. The System may be absent while authoring, with a completeness warning.
 - Work decomposition and performer allocation are independent. Only leaves have direct allocations. A parent drawn within one performer can be a computed leaf summary, not an additional allocation. Role sharing does not create several direct performers for one function.
-- Nesting expresses semantic containment or the selected allocation projection. Placement movement does not change ownership or allocation. Hide and delete have different effects.
+- Nesting expresses semantic containment or the selected allocation projection. A placement edit preserves ownership and allocation. In an Allocation view, a work-body drag previews and commits performer reassignment and placement as one transaction; Arrange next drag (Alt+A) keeps that gesture limited to geometry. Role responsibilities remain unchanged, and drops requiring ambiguous responsibility or collateral edits are refused. Hide and delete have different effects. Current verification and native limits are recorded in [issue 3](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/3).
 - Counterpart creation copies mapped typed content and required references. Existing-counterpart semantic review compares typed facts and prior observations, with explicit keep, take or final-value decisions for supported scalar, structural, constructor and individual collection-row changes. Reference mapping and candidate validation apply before an undoable transaction. Ordered collections have explicit final-order review with retained rejected drafts. Included trace rows can combine multiple source contributions into one validated model/history transaction; conflicting decisions and incompatible reference mappings remain explicit blockers. Existing Child/Incident attachment fields and artifact lifecycle review are implemented. Artifact creation reserves an explicit counterpart identity and requires all seven metadata decisions; identified source-owner absence can delete a link, while destination-only Take retains it. Owner moves and kept Presence must agree. Latest attachment/artifact native acceptance remains pending. Review does not automatically synchronize arbitrary structure or overwrite the other perspective. Creation scope follows ownership/reference dependencies, not every incident relationship.
 - Processes/chains use contributions and explicit sequence links; imported ordered exchange paths retain their implied order until topology conversion. Rich fragments belong to scenarios. Guards, expressions and state behavior text are descriptive; there is no execution engine. Mixed states and modes are permitted by this Studio profile.
 - OA Communication means connect Entities/Actors directly and can allocate Interactions whose actual performers match their endpoints and direction. Transition to SA requires explicit compatible boundary-port decisions; the tool does not guess system ports. Preserved OA boundary exchanges use Legacy ports. Capability grouping is containment; include, extend and generalization use separate typed relationships in OA and SA. Data/item references remain within their layer and can have explicit transitioned counterparts.

docs/source-cli.md

@@ -0,0 +1,66 @@
+# Source CLI
+
+Use `arcadia` to check or update local `.arcadia` projects without opening Studio
+or starting a server. Pass the entry file explicitly; its relative include paths
+resolve from their containing source files.
+
+Build with `cargo build --locked -p oa-cli --bin arcadia`. The resulting command
+is `target/debug/arcadia.exe` on Windows or `target/debug/arcadia` on Linux unless
+your Cargo configuration chooses another target directory. A workspace release
+build also includes it. Use the platform's usual executable path prefix when
+running these examples.
+
+```sh
+arcadia check project.arcadia
+arcadia check project.arcadia --json
+arcadia stabilize project.arcadia
+arcadia stabilize project.arcadia --write
+arcadia rename-alias project.arcadia old_alias new_alias
+arcadia rename-alias project.arcadia old_alias new_alias --write --json
+```
+
+`lint` is an alias for `check`. Checks accept incomplete engineering models with
+warnings; syntax errors and structural violations fail. Located diagnostics
+refer to the named file and coordinate space. Line and column numbers are
+one-based and columns count Unicode scalar values; byte ranges are half-open
+UTF-8 offsets.
+
+`stabilize` previews missing persistent identities and any supported source
+migration. `rename-alias` changes one existing global alias and its typed
+references while preserving comments, strings and unrelated source. Pass alias
+names without `@`. The command does not rename an element's display name.
+
+Both editing commands preview by default. Human output writes unified file
+diffs to stdout and diagnostics to stderr. `--json` writes one versioned report
+with diagnostics, migration information, exact before/after text for every
+changed file, diffs and the write result. Unchanged files are not included in
+that report. They are still checked for conflicts before a write.
+
+Add `--write` to save the candidate prepared by that invocation. Even an empty
+diff checks the captured files and pending-save state before returning. A failed
+write reports `written: false` and retains its proposed diff. This does not
+guarantee rollback; the reported conflict or recovery outcome determines the
+next step. A pending save
+requires explicit recovery through the existing project recovery workflow;
+the CLI does not recover it automatically.
+
+Missing IDs in a separate earlier preview remain provisional. A later command
+may allocate different IDs until you save them. This CLI does not persist a
+review plan for later application. It does not canonicalize the whole project
+or delete detached files. Source versions 3–7 use the core's supported migration
+rules; invalid source is not rewritten.
+
+| Exit code | Meaning |
+| --- | --- |
+| 0 | Valid check or successful preview/write; warnings may remain |
+| 1 | Invalid source or refused semantic alias change |
+| 2 | Invalid command arguments |
+| 3 | File/path, conflict, pending-save or output failure |
+
+Admission bounds match the desktop: 256 files, include depth 32, 1024 include
+edges, 64 MiB total UTF-8, 100,000 graph objects, 250,000 records and 500,000
+ordered references. `arcadia --help` lists the commands and bounds. These limits
+are not a claim of interactive performance at the maximum project size.
+
+For the notation itself, start with [the text-first examples](../examples/text-first/README.md)
+and the [language contract](language.rst).

harness/DECISIONS.md

@@ -278,3 +278,139 @@ This is a selected design under implementation, not a native acceptance claim.
 Native reverse scenario Apply selected a dependency and inserted five overlapping behavior placements into an unrelated architecture view. Core transition correctness did not make that presentation useful. Select the counterpart of the explicit request root and resolve its nearest scenario/process/chain/state owner. Without an explicit destination diagram, keep the exact core candidate and open Behavior; preserve unrelated architecture views. Retain ordinary architecture transition placement and honor explicit diagram choices.
 
 Automatically creating another architecture view would retain the wrong editing workspace and introduce unrequested model state. Merely navigating to Behavior after adding placements would conceal the presentation damage. Both alternatives are rejected. The selected correction retains one source transaction and Undo operation and guards stale canvas events. Revisit if mixed-root requests or realistic explicit destination workflows require a separate user choice; do not infer such a choice from dependency ordering. Test/build/native acceptance is recorded separately in release-behavior-transition-context-20260906.md.
+
+## Property baselines and explicit alternative cases — 2026-09-11
+
+Problem: complete independent bindings repeat shared engineering assumptions in
+every ordinary study case. The user requires practical text-only development and
+reduced cognitive load for small and large models. Evaluator implementation
+simplicity alone cannot justify that authoring cost.
+
+Select property-owned base values/formulas and one-level case overrides as the next
+active-study contract to formalize. Every evaluator caller explicitly requests
+ModelBaseline or a particular Case identity; no active UI selection, unnamed
+default case or case-to-case inheritance determines meaning. The baseline is the
+model's explicit property values, not a mandatory extra record for entering the
+first value. Inherited formulas read the requested effective case. An explicit
+Unbound override shadows a known base; clearing an override uses the base.
+
+The [executed comparison](release-analysis-context-experiment-20260911.md) passed
+218 assertions. Twenty cases with20 fixed/two varying inputs used62 binding rows
+under B versus480 under D, with identical results. Updating one shared assumption
+required one B binding versus20 D bindings. Reusable predicates eliminated D's
+threshold-edit disadvantage, so repeated formulas are not the reason for selection.
+
+Retain an explicit complete independent freeze/export for intentionally separate
+assumptions. It must capture effective values/formulas and the full exact definition
+environment, including package pins; copying only case rows leaves hidden live
+dependencies. Captured revisions and per-input origins must make propagation
+visible. Effective dependency/cycle validation and stale result handling must cover
+the whole requested context.
+
+Reject compulsory complete cases for ordinary shared-assumption modeling; retain
+their useful isolation as an explicit independent snapshot. Reject arbitrary
+inheritance and UI-dependent evaluation. Do not import the tiny experiment
+interpreter as production architecture. Exact check identity, type/operator
+algebra, source syntax, library closure/compatibility, transitions and public
+snapshot formats still require the coordinated precise contract. Current source7
+does not implement this decision.
+
+Revisit if complete text/native tasks expose unacceptable hidden propagation,
+wrong-context edits or inability to preserve reproducible independent studies.
+The comparison establishes semantic/text maintenance evidence, not human task
+timings or full quantity/library integration acceptance.
+
+## Analysis and library contract convergence — 2026-09-11
+
+Root Codex-956atf read the complete [baseline refinement](release-analysis-baseline-contract-20260911.md),
+[library refinement](release-library-compatibility-contract-20260911.md), their
+complete fixtures and [independent review](release-refined-contracts-review-20260911.md).
+Select the following architecture for production implementation:
+
+- Required property-owned Binding values, explicit ModelBaseline/Case selection,
+  one level of complete-case override maps and shared root checks. Clear removes
+  an override; Unbound masks the base. Inherited formulas evaluate dependencies
+  in the requested context. Pure calculations see only explicit parameters.
+- Same-layer property dependencies and case targets, with explicit analysis
+  selection for transitions and exports. Check/case subjects may be absent;
+  architectural containment must not infer their selection. Validate every
+  effective dependency graph, including statically referenced unused branches.
+- The refined R6 closed algebra, exact rational R7 literal/AST preservation,
+  affine point/difference distinction and declared-output kind anchoring.
+  Strict expression operands gather actual missing/failure causes; Boolean
+  control flow evaluates only the selected branch. Supported domain failures
+  are distinct from violated predicates and missing values.
+- Whole accepted PortableDocument freeze with exact SourceBundle, local
+  definitions, all imported package contents/pins and validated provenance.
+  Replay resolves only that immutable private capture. A result report, shallow
+  case copy or current cache is not a reproducible freeze.
+- Exact archive/reference/history identity alongside verified same-origin
+  typed-contract equivalence. Different nominal origins remain distinct.
+  Compatibility supplies a scoped expected/actual field-path and operation
+  correspondence; it never advances a pin or rewrites outside record identities.
+  Keep qualified neutral definitions, immutable mapped layered definitions and
+  ordinary editable pattern instances for the first coherent implementation.
+- Explicit source preparation/acceptance with complete version-controlled
+  package/base/map/lineage state, recomputed admission and stale-input rejection.
+  Exact three-way facets retain independent local edits. Mounted OA/SA transfer
+  requires a verified exact target-layer export or an explicitly independent
+  editable local derivative; no relabeling or silent mutation of a mount.
+
+These are architecture decisions, not claims that the proposed schema8 examples
+are admitted by current source7. Before real consumer integration, enumerate and
+implement the class-specific canonical contract over all interpretation-bearing
+fields and use sites, exact transitive archive closure and full source/history
+boundaries. Retain the frozen120-assertion prototype with its documented C2
+threshold-unit coverage gap; production typing must check every operand.
+
+Close independent C1 before evaluator expansion: a request-local, profile-versioned
+logical work meter must bound dynamic expression visits, calls, list traversal
+and exact-number work. Static acyclicity/depth/node limits do not bound expanded
+execution. Cache warmth must not change outcomes; terminal exhaustion stops
+further traversal and marks collected causes as incomplete. Numeric ceilings and
+the precise charging table require measured foundation implementation before
+publishing the profile. The333-node/31-level counterexample and a nearby successful
+case are mandatory tests across direct/API/frozen replay.
+
+The exact numeric foundation is the next bounded core implementation. Ordinary
+engineering approximations, a complete low-noise text workflow, two-project
+library maintenance and native/API/source parity remain required release work.
+An exact-only slice cannot complete the user's first release.
+
+## Analysis production staging — 2026-09-11
+
+Root accepts the concrete [production integration sequence](release-analysis-production-integration-plan-20260911.md).
+Allocate schema8 to the next coherent production analysis integration. Start with
+the actual Project's neutral definition catalog, three analysis element kinds,
+typed expressions and a closed Local definition-reference environment. Imported
+references will be admitted only with the real package environment; no placeholder
+resolver, guessed pin, implicit type compatibility or competing package format.
+This stages implementation and does not defer the required maintained libraries.
+
+The first useful gate is the complete persisted/source-authored response budget,
+shared two-parameter calculation and check: baseline7/4 seconds versus degraded9/4,
+with explicit request context and the same core result through CLI and REST.
+Required property fields cannot come from generic factory guesses. Existing
+descriptive expressions/unit labels retain their exact old meaning and bytes.
+Freeze older top-level wire DTOs before making definitions required in schema8;
+reject new fields/constructors in older versions instead of silently dropping them.
+Global, scoped parameter, imported and historical identities remain distinct.
+
+Implement pure static numeric type helpers once and reuse them for admission and
+runtime. Validate every effective case graph and unused branch before accepting a
+candidate; deleting dependencies requires explicit same-batch repair. Numeric
+domain failure is not a static type failure. Full evaluator traversal and actual
+C1 input, provenance, terminal incomplete causes and immutable replay are required
+before claiming evaluated engineering behavior. Until explicit analysis review/
+transition facets exist, those entry points must reject unsupported analysis with
+a clear capability error, including manual-trace paths that could otherwise appear
+to reconcile headers alone.
+
+Logical expression depth128 must be reconciled with bounded actual JSON/source
+decoding; do not simply disable recursion limits. Raw byte, decoded string and
+aggregate literal/graph/case-admission limits are separate from evaluation fuel.
+Concrete decoder/admission ceilings remain subject to bounded boundary and timing
+experiments; the implementer must surface those choices before locking the profile.
+The current local numeric gate runs against frozen root source. New core contract
+work proceeds in an isolated checkout, preserving root's Cargo/native leases and
+the other hosts' CLI, staged-source and B4 ownership.

harness/PLAN.md

@@ -1,83 +1,16 @@
-# First release execution plan
+# Historical execution plan — superseded
 
-Updated 2026-09-11, Codex-9e8r6t `/root`.
-[PROJECT_GOAL.md](../PROJECT_GOAL.md) defines the outcome;
-[TASK_LEDGER.md](TASK_LEDGER.md) separates evidence from assumptions;
-[STATE.md](STATE.md) owns active leases and results.
+Live plans, ownership, dependencies and handoffs moved once to
+[Gitea issue1 comment412](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/1#issuecomment-412)
+and the linked canvas issue on2026-09-11, following the shared working agreement.
+This document is retained as a stable navigation target, not a live ledger.
 
-## Immediate implementation and acceptance
+The [complete original PLAN.md](history/2026-09-11-ledgers-before-gitea-migration/PLAN.md)
+is byte-preserved with the [archive manifest](history/2026-09-11-ledgers-before-gitea-migration/manifest.json).
+Its decisions, rationale, examples and historical evidence remain available;
+relative links inside it resolve from the original `harness/` directory.
 
-1. Preserve the verified creation integration and matching GUI stage, committed
-   as 4bb4aaf and transferred with independent anonymous readback/hash verification. Final immutable
-   desktop653/653 passed after creation ancestry/guide changes, alongside focused
-   creation21/guide3. StrictClippy/fmt pass after a behavior-equivalent history
-   rewrite; affected history63 and GUI build also pass. Preserve exact artifact
-   scopes and serialize future Cargo/source leases.
-2. Named process/scenario/machine creation, exact Undo/Redo and nine-file reopen
-   have passed at actual minimum size. Wide/minimum cancellation passed; SA draft
-   crash recovery is active. Address observed blank canvases and prerequisite
-   creation detours through the staged-source plan: source subform retains the
-   parent draft and final adoption atomically creates prerequisite and consumer.
-   First slice covers Lifeline, process Work and machine owner, with semantic
-   first-action prompts. Independent review precedes final integration/native QA.
-3. Operate the rebuilt app at minimum/normal sizes. Complete the saved basic
-   supplementary move/camera/invalid-draft and minimum-size story; the main basic
-   model and explicit transition passed full Project+SourceBundle, Undo/Redo and
-   reopen on candidate3 at wide size. Exercise new
-   scenario workspace, creation and caller return with real inputs and saved
-   model evidence, then correct and reverify concrete defects.
-4. Integrate standalone B4 scenario lifetimes and the external independent
-   scenario contract without overwriting local layout work. Resolve source-derived
-   lifetime versus insertion bounds, activation-after-Delete and lane-map issues.
-   Close remaining
-   contextual operand, missing-source and state-naming workflow gaps identified
-   by the current behavior audit and native study.
-
-## Foundational semantic additions
-
-The updated objective explicitly requires functional constraints/calculations,
-quantities/units and maintained model libraries. Current metadata/includes are
-insufficient. This work runs independently of useful behavior improvements.
-
-The newest objective also requires complete uncluttered text-only workflows.
-Combine the local three-task usability audit with the other host's language/
-identity/API design. Two concise current-grammar recipes now pass their bounded
-REST identity/source/persistence experiment. Next evaluate
-cross-file definitions/references, safe alias rename and identity-preserving
-patch preview on repeated-name modular models. Do not equate shorter examples
-or parser throughput with task usability, and do not silently change omissions.
-
-- Compare real candidate semantics before large changes. Use primary Capella,
-  SysML and quantity/unit evidence, with explicit compatibility limits.
-- Falsify candidates through mass/power/latency budgets, mixed/affine units,
-  unknown/error/false results, dependency cycles, reference identity and bounded
-  evaluation. Separate descriptive existing text from executable declarations.
-- Probe libraries through two projects/two instances, pinned offline content,
-  exports/dependency closure, bindings, distinct origin/local identities, updates
-  with local divergence, detachment and exact transactional rollback.
-- Run a small pure-core experiment for the selected candidate. Independent
-  criticism must precede broad schema/source/API migration. Retain current typed
-  Project, Command and source-writer boundaries unless evidence requires change.
-- Implement the ratified contracts across validation, visitors, deletion,
-  identity, OA/SA transitions, source/reST, schema/REST, ergonomic graphical
-  authoring and help. Add real examples and independent parity acceptance.
-
-## Integration and release
-
-- Publish coherent commits and verified bundle transfers through Gitea; keep
-  concise host-scoped handoffs and Wiki. Do not overwrite another host's branch.
-- Refresh relevant source/schema/example/doc gates and run current core,
-  desktop/server and real REST transport/restart/ETag/draft-conflict workflows.
-- Build matching optimized desktop/server packages. Regenerate complete notices
-  for actual inputs and verify archive contents, hashes and clean-runtime launch.
-  Historical ELF fixtures and build preparation do not replace execution.
-- Obtain a viable Linux environment and run current GUI/server workflows there.
-  Supported WSL2 failed; no repeated rejected workaround. Continue independent
-  work while the environment question is pending.
-- Conduct fresh independent requirements, semantic, usability, architecture,
-  correctness, runtime and documentation reviews. Resolve all material findings,
-  reverify affected behavior and only then declare release completion.
-
-Historical milestones and evidence remain intact in
-[the dated plan archive](history/2026-09-10-ledgers-before-second-consolidation/PLAN.md).
-They do not supersede current user scope or imply current-tree acceptance.
+Use [STATE.md](STATE.md) for the verified branch checkpoint,
+[DECISIONS.md](DECISIONS.md) for durable decisions, and
+[PROJECT_GOAL.md](../PROJECT_GOAL.md) for the unchanged user requirements.
+Do not repeat the migration or revive the duplicated live ledger.

harness/REBOOT_HANDOFF_20260911.md

@@ -0,0 +1,121 @@
+# User-requested reboot checkpoint — 2026-09-11
+
+Codex-956atf `/root`. The user will install Ubuntu26.04 in WSL2 and reboot, and
+explicitly requested progress preservation and a safe-reboot signal. Work is
+**paused**, not completed. Resume only after the user returns. All three local
+agents stopped and saved their work; root stopped its sole Cargo build. No machine
+restart, installation, Windows feature change or credential change was performed.
+
+## Saved source and ownership
+
+- Main checkout `codex/behavior-authoring-20260910`: numeric foundation7d14bd0,
+  CLIbc311bc, corrected external evidence dc0f2e1, instructions ancestryc7ed894,
+  chooser/workspace7f081ad, staged prerequisites c0e66f9 (externaldf6f595), numeric
+  evidence/decoder review03d20ec, followed by this reboot checkpoint. Remote branch
+  is `codex/release1-956atf`. New desktop source is **uncompiled/unaccepted**.
+- Isolated `.local/analysis-core-worktree-20260911/`, local branch
+  `codex/analysis-core-20260911`, remote `codex/analysis-core-956atf-20260911`:
+  Checkpoint `b96ff3935ab3f36b7144566e46559a05a29292a5`: WIP actual schema8
+  definitions/Expr/records, commands/references/migration and
+  static admission, based at7d14bd0. Its
+  `harness/release-analysis-core-schema8-wip-20260911.md` inventories20 code/test
+  paths and22 prepared, unexecuted tests. No source8/evaluator/transport closure.
+- Isolated `.local/behavior-canvas-worktree-20260911/`, local branch
+  `codex/behavior-canvas-20260911`, remote `codex/behavior-canvas-956atf-20260911`:
+  WIP shared camera/viewport, based atc0e66f9. Checkpoint
+  `e511c4153fb5bb484652434340e0e4c7000c93d0` is deliberately
+  not compile-coherent: missing test module, missing App Camera handlers and old
+  production Scrollables still active. Its
+  `harness/release-behavior-canvas-reboot-handoff-20260911.md` lists exact paths
+  and ten remaining steps. Do not merge it as a finished canvas implementation.
+
+Both WIP branches are independent of the main branch. Preserve them, finish their
+bounded slices and review before integration. No worker may run Cargo/native or
+edit the root checkout without a new root lease. Separate-host9e8r6t owns incoming
+prerequisite-form refinements; ytr83r owns B4/lifecycle/Linux work. Re-read Gitea
+issues1/2 and current Wiki before resuming; their progress may have changed.
+
+## Verified gates and interrupted build
+
+- Numeric26/26 at7d14bd0,0.29s execution; strict core all-target Clippy with
+  warnings denied passes11m49s. Exact162-input/binary/log provenance is in
+  [the numeric gate](release-analysis-numeric-gate-20260911.md).
+- Local `cargo test --locked -p oa-cli -- --test-threads=1`:12/12 integration
+  tests, zero failures/ignored,3.00s execution after42.86s compile. The initial
+  `--bin arcadia` invocation ran zero tests and counts only as compilation.
+  Full log: `.local/logs/source-cli-full-local-20260911.log`.
+- Previous desktop676/676, formatting and strict Clippy passed at2cc4d11.
+  No acceptance transfers to new7f081ad/c0e66f9 source.
+- `cargo test --locked -p oa-desktop --bin arcadia-studio --no-run` was deliberately
+  stopped for this reboot while compiling oa-core after renderer dependencies.
+  Cargo exit101 follows the explicitly stopped owned rustc process (`0xffffffff`);
+  no source diagnostic or test failure was reported, and no desktop tests ran.
+  Preserve `.local/logs/desktop-chooser-contextual-first-20260911.log`. Root
+  verified no Cargo/rustc/Clippy processes remained after stopping its process tree.
+
+## Two new focus findings to fix first
+
+[Paused independent integration review](release-chooser-contextual-integration-review-20260911.md)
+contains16 source hashes and two source-derived, unexecuted P2 findings:
+
+1. Initial parent FormShown consumes its one-time focus. Child source Open removes
+   that parent widget tree; Back/Use remounts it without a new focus intent.
+2. FormShown validates context before creating a global NAME_INPUT focus Task,
+   but the delayed operation is not bound to the still-current mount/session.
+   It can act on a replacement parent or clear current child/Review input focus.
+
+Implement a live-session/mount-scoped focus operation covering initial mount and
+source→parent return. Add actual mounted regressions for Open→Back/Use, changed
+document/owner/modal/session between Task creation and execution, raw/source/history
+preservation, and then continue the combined compile/focused/full/Clippy/native
+gates. Do not misstate the popup search-input counterexample: the root Popup
+operation traverses its ordinary content; the separate picker input is excluded.
+
+## Native session and exact private backup
+
+Immutable GUI80cf197 remains the native test binary; SHA256
+`A5ED6DF334B1BFB620425AFDF3E863F0B522990E6FB47C6C401A71CF4443954A`.
+All four OA create/history checkpoints and final reopen pass. Separate SA Action
+Save/Undo/Redo passes, with63 accepted objects. Working entry:
+`.local/native-qa/scenario-20260911/sa/project.arcadia`.
+
+The current **unapplied** State draft has literal name `SA native state`, captured
+by clicking SA A inspector at the inner chosen operand before SA Inner anchor.
+Its lifeline is preselected, but SA Ready is not chosen and Create was not pressed.
+It must not be described as a passed SA State checkpoint. Old GUI again required
+scrolling its new form back upward to find Name; new fixes have not run natively.
+
+Private backup `.local/reboot-20260911-1344/` contains the complete accepted SA
+source directory, exact64,935-byte recovery JSON, build/CLI logs and hash manifest.
+Recovery id `30511014-b831-47e3-afd2-6c4e44835a8f`; copied recovery SHA256
+`5C7B90BE613AF35463C563B9AA85A7AB1F8D48561EA935ABC6FC1E79549DF0E8`.
+Root verified its project/origin and raw draft name before copying. The original
+checkpoint remains under `%LOCALAPPDATA%/ArcadiaStudio/recovery/`. The saved-model
+backup passes `check sa-action` and exact `same` against sa-action-verified.
+No private recovery data is committed or sent to Gitea.
+
+After reboot prefer the application's Home recovery entry to resume this raw draft.
+If needed, preserve any newer checkpoint before restoring the exact private backup
+to that same recovery directory. Use the independent scenario oracle for subsequent
+State/Reuse/Fragment/history/reopen checks. Old window handles/screenshot ids and
+process ids are invalid after reboot; select the actual returned Studio window.
+
+## Linux and resumption
+
+Before installation, this account had WSL2.7.13/kernel6.18.33.2-2 and default2 but
+no registered distribution or Ubuntu Appx package. VirtualMachinePlatform was
+enabled, hypervisor present, common reboot flags absent; elevated feature detail
+was unavailable. No Linux startup/build pass follows from those checks.
+
+On return, inspect `wsl --list --verbose` and actually execute `uname -sr` inside
+the installed Ubuntu. Verify the user's installed distribution/version, then set
+up the project's Linux dependencies and perform real Linux build/test/runtime
+gates. Keep Windows compilation serialized using `.local/toolchain/env.ps1`.
+The isolated core's first proposed gate is its22 prepared analysis tests, plus
+numeric regressions, after review of its WIP handoff. Full depth128 JSON decoding,
+allocation/lifecycle/output caps and exact save/readback remain required; see
+[the decoder review](release-analysis-decoder-review-20260911.md).
+
+Continue the original complete OA/SA release goal, preserving issue2's modern
+canvas requirement and analysis/library/source/REST/GUI parity. This reboot pause
+does not alter completion criteria or authorize marking the project complete.

harness/STATE.md

@@ -1,202 +1,91 @@
-# Progress Ledger — first release
+# Verified branch checkpoint — 2026-09-12
 
-Updated 2026-09-11, Codex-9e8r6t `/root`, Windows host.
-**Release remains unaccepted; meaningful product and integration work is active.**
+This checkpoint describes Codex-956atf's contribution, not a combined release.
+[PROJECT_GOAL.md](../PROJECT_GOAL.md) remains authoritative; the complete OA/SA
+release is unfinished. Current user guidance emphasizes close study of Capella
+semantics and practical, ergonomic engineering workflows.
 
-## Objective and current source
+**Linux/WSL builds and all checks are paused until the user explicitly reports
+networking resolved.** No guest diagnosis, restart or cache transfer is active.
+Completed Linux evidence remains historical; the VPN remains untouched.
 
-Deliver the complete OA/SA first release in [PROJECT_GOAL.md](../PROJECT_GOAL.md).
-The latest authoritative attachment is
-`815ff7b9-73c4-41a2-a809-635ecf8389d6/goal-objective.md`, read in full and preserved
-in that file. It requires constraints/calculations, quantities/units and reusable
-libraries, plus uncluttered human/AI text-only modeling at small and large scale.
-Long homogeneous lists and poor behavior editing remain explicit concerns.
+## Verified implementation
 
-Local branch: `codex/release1-9e8r6t`, base `1797516`, committed head `4bb4aaf`.
-Named behavior creation, its guide and independent oracle, concise text-first
-examples and prior integration evidence are committed and remotely transferred.
-Its final ancestry/guide correction passed full653; post-lint history63, strict
-Clippy/fmt and matching GUI build passed. Current uncommitted work corrects the
-oracle's retained-file rule, clarifies source-7 constructor defaults, records
-native creation and implements contextual prerequisite creation. Preserve all
-workers' edits. No open Gitea PRs at the latest read, comments through138.
+Previous native acceptance uses source **3c9e6eeb64ce3efc03b29890b82199a42c21f335** on
+`codex/behavior-authoring-20260910`. It passes 720/720 Windows desktop tests and strict
+all-target desktop Clippy. It includes direct scenario/process authoring,
+parent-focus and editing-session/chooser corrections, and boxed workflow events.
+Evidence checkpoint e7491fb preserves exact logs. Instruction-only merge828c50c
+retains the incoming user-owned AGENTS/PROJECT_GOAL files unchanged. The actual
+remote default branch `main` was checked after that merge; its current guidance
+was read without overwriting the user's local specification.
 
-## Completed work and scoped evidence
+The matching GUI built warning-free and passed recovered SA State, clicked Reuse,
+and ALT Fragment creation with exact Save/Undo/Redo and final native Open/Save at
+the 1100x700 client minimum. The whole Project, all identities and both source files
+match every required history checkpoint. The native session is closed.
 
-- Palette inline naming and focused Escape: `7d1df4f`, independently published as
-  `codex/palette-authoring-20260910`. Candidate 2 focused tests, GUI build and
-  strict desktop Clippy passed. Its native F2 rename/Save/Undo/Redo matched exact
-  three-file expectations; Entity creation matched the complete independent
-  model/source oracle. Candidate3 completed ordinary Activity, existing placement,
-  allocation, direct Interaction and F2: complete basic model/four sources PASS.
-  Explicit SA actor/destination transition passed complete model/six sources;
-  Undo four-source baseline, Redo six-source result and reopen all passed. Six
-  physical files are byte-identical across reopen/reuse-preview Cancel/Save.
-  Immutable checkpoints/logs: `.local/native-qa/palette-20260910-v3/`.
-- Recovery naming autofocus: `31b7dc3`, 13 focused checkpoint tests passed after
-  integrated compilation. Its new autofocus behavior still needs native check.
-- Other-host behavior/topology/scenario/history: original `01bb52a` integrated
-  as `057eddd`; constructor cache fix `b6b76ef` integrated as `a70de55`; explicit
-  history seed fix `4ecad78` cherry-picked as `81668f9`.
-- Corrected immutable desktop artifact completed **631/631 passed**,408.18s,
-  exit0; all three prior618-artifact failures are fixed. Exact artifact/logs in
-  `.local/scenario-workspace-20260910/tests-81668f9/`. It covers3978bbe workspace,
-  Back/OpenUse guards and both history fixes, but not later Sensor/creation work.
-- A real same-size owner/document Sensor regression led to `d114a27`; affected
-  scenario53/53 passed. Current native candidate3 predates that correction.
-  Mounted workspace tests cover500×570 and wide geometry; native current-build
-  scenario acceptance remains pending.
-- Named local creation passed final21/21 and guide3/3 after ancestry-label
-  correction. The matching immutable desktop suite passed **653/653**,362.83s,
-  zero failures/ignored; exact artifact864B0F…E86/log/result under
-  `.local/behavior-creation-20260911/tests-final`. Independent integration review
-  found no additional correctness blocker. StrictClippy/all-targets/-Dwarnings
-  and workspacefmt pass after one behavior-equivalent history_fields let-chain
-  correction; affected history63/63 and matching GUI rebuild pass. Current native
-  GUI is `gui-verified` SHA D4D9C2BD…B20C31. At actual 1100×700 client size,
-  named OA Process, explicit ParticipantInteraction Scenario with capability
-  context and SA owner-linked State machine plus requested first view passed
-  complete independent Project/SourceBundle checks at 7/8/9 files. Each single
-  Undo/Redo preserved exact expected semantics, sources and role identities.
-  Reopen/Save retained all nine physical source files byte-for-byte. Wide/minimum
-  draft cancellations retained the initial six files exactly. Detailed report:
-  [native creation](release-behavior-creation-native-20260911.md).
-- Independent creation oracle v2 corrects a harness assumption: Save retains
-  known detached source files after Undo. Full Project and reachable source
-  equality remain mandatory; the complete physical inventory must equal the
-  explicit pre-Undo checkpoint overlaid with expected reachable bytes. Unknown,
-  changed or missing retained files fail. No product defect was hidden by this
-  correction; see [oracle review](release-behavior-creation-oracle-20260911.md).
-- Fresh source-7 constructor probes passed 54 explicit/omitted comparisons and
-  12 required-field refusals across OA/SA, with complete typed models, canonical
-  reparse and exact authored no-op/name-edit retention. Constructor and Scenario
-  default wording now describes current behavior; strict HTML regeneration
-  passed. Other constructor families are explicitly outside this evidence.
-  See [default review](release-constructor-defaults-review-20260911.md).
-- Source schema checks passed: 72 fixtures, 204 schemas, 14 families, 90 scalar
-  leaves. API/language reST rendered with strict docutils without warnings.
-- Packaging committed `b98f135`: portable Linux adapter, shared package checks,
-  Docker input validation and exact upstream notices. Independent review found
-  and fixed five concrete defects. Python 11/11 and PowerShell contracts pass.
-  Historical Windows-input ZIP has 557 files; real Linux notices close over
-  339 packages/681 files. Linux archive adapter used inert ELF fixtures, not
-  actual current application binaries. Exact Fira/Cantarell notice Git bytes
-  were independently verified. Current-source notices need regeneration.
-- Independent native Capella creation study completed, saved and closed cleanly;
-  report `release-capella-creation-study-20260910.md` is complete. Viewpoint-first
-  naming and distinct local create/existing selection inform the implementation.
-- Textual usability audit completed three static tasks and example counts. The
-  existing grammar already permits omitted initial IDs/defaults; key gaps are
-  cross-file reference context, safe alias refactoring and reviewed patches.
-  Source7 EBNF/schema documentation and viewpoint omission guidance are corrected;
-  generated language HTML passed strict docutils. Both concise snippets passed
-  26 real REST requests: identity-only stabilization, exact no-op/name edit,
-  stale/invalid nonmutation and restart persistence. All120 current core/server
-  files match the preserved source7 binary's documented snapshot. This closes
-  the bounded recipe gap, not large-model or native text-editor acceptance. The
-  verified recipe is now `examples/text-first` and in the language reference.
+- [Windows regression/lint evidence](release-chooser-correction-gate-20260911.md)
+- [Previous native SA evidence](release-scenario-native-3c9e6ee-20260911.md)
+- [Earlier native OA/SA Action evidence, scoped to 80cf197](release-scenario-native-20260911.md)
+- [Scenario oracle and reproducible procedure](fixtures/scenario-authoring/README.md)
 
-Detailed evidence: [integrated gates](release-integrated-gates-20260910.md),
-[palette native](release-palette-native-20260910.md),
-[scenario workspace](release-scenario-workspace-20260910.md),
-[creation design](release-local-behavior-creation-20260910.md),
-[packaging implementation](release-packaging-implementation-20260910.md),
-[independent packaging review](release-packaging-independent-review-20260910.md).
+## Isolated contributions and material limits
 
-## Active ownership and execution
+Core candidate **847b1caa7e75bb82f6ce5193c45bcfc45973ad1a** is on the separate
+`codex/analysis-core-956atf-20260911` publication branch. Windows execution passes
+the 128 KiB-thread lifecycle subprocess, all 6 codec tests, 28 analysis tests, 26 numeric
+tests and strict all-target core Clippy. These counts are separate scopes; the
+subprocess driver is included in the 6. Production `DEPTH_128_VALIDATED` remains
+false. Legacy/migration/save integration, release memory measurements and complete
+source8/transport/evaluator acceptance remain open.
+[Windows codec evidence](release-analysis-codec-windows-gate-20260911.md).
 
-- Root: integration, common ledgers, source/API checks and exclusive native input.
-  Full653 is terminal PASS. V4 creation/Undo/Redo/reopen is complete; actual SA
-  pending-draft crash recovery is active on the same verified GUI. The forced
-  interruption targeted only isolated QA PID5184 after checkpoint persistence;
-  restarted PID1284/window6161106 uses the same private profile and runtime.
-  Recovery is now terminal PASS: full draft fields/IDs retained, autofocus,
-  first Escape and a fresh Save As preserve the complete nine-file model. The
-  current wide GUI is saved on `checkpoint-recovery-cancel/project.arcadia`;
-  treat that checkpoint as immutable and reopen a work copy before editing.
-- `release_audit`: prior creation and constructor reports frozen. Now owns the
-  staged prerequisite creation implementation for Scenario Lifeline/process Work/
-  New machine owner, semantic first-action prompts, relevant App/recovery/guide
-  wiring and focused tests. Cargo writer is reserved to this worker when needed;
-  freeze source during tests and request independent review before integration.
-- `behavior_audit`: v2 native oracle frozen, warnings-denied compilation and
-  falsifiers pass, executable056EEFD…F6A36. Now independently challenges staged
-  source semantics and expected behavior; no production/Cargo/native ownership.
-- `palette_finish`: native report/evidence frozen: 13 creation oracle commands
-  and 19 separate recovery checks pass. Now owns new `crates/oa-cli` for local
-  source check/lint, preview/explicit-write stabilization and alias rename/diff.
-  Uses existing source-file diagnostics/expectations/journal writer, no grammar
-  or core changes. Root owns workspace/lock integration; serialize Cargo with
-  release_audit. Preview UUIDs remain candidates until that invocation writes.
-- Separate host Codex-956atf: standalone scenario lifetime projection, independent
-  native scenario oracle, quantity/calculation design and library design. It has
-  its own cold toolchain/results. Its source-only reviews are not local passes.
+The cleaned R123 canvas at **a31b40d0f8551ed87c8cd66250b9afb4809b3a79** passes
+729/729 Windows desktop tests, strict all-target Clippy and the matching GUI build.
+All 518 input identities agree with Git and the closed receipts. Actual minimum-size
+OA action, nested state, bound reuse and ALT creation passed Save and exact one-step
+Undo/Redo Project/SourceBundle comparisons. All 85 archived files match their Git
+index bytes. Reopen was interrupted by physical Escape and remains unverified;
+Computer Use remains paused. [Exact gates and bounded native evidence](release-behavior-canvas-a31b40d-native-20260911.md)
+supersede the earlier pre-cleanup gate as this source's checkpoint.
 
-Verified bundles for eb5161b and 4ecad78 are retained in
-`.local/integration-20260910`. Local refs `codex/behavior-snapshot-eb5161b` and
-`codex/history-seed-20260910` preserve exact commits. B4 lifetime projection and
-its guide delta are not integrated yet; coordinate shared scene wiring. Review
-found insertion versus lifetime bounds, activation after branch-local Delete and
-unassigned-lane map differences that must be addressed before acceptance.
+Allocation candidate **f52d81c1b96a34bb78b8ada27b7761dc0b009f5d** preserves the
+canvas source and passes its first 54 focused Windows planner/App/widget tests,
+including four actual App-tree focus/keyboard/render cases; all 525 inputs remained
+unchanged. This is not a full-suite, strict-lint, native or release gate. Independent
+review found a frozen performer label can still obscure the dragged work header;
+that repair and broader integration remain unverified. [Issue 3](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/3)
+owns its live work. Parent/child native focus, complete direct manipulation,
+persistent process placement/lanes and coherent peer integration remain open.
 
-## Unresolved requirements and gates
+The combined allocation/saved-destination repair baseline **d9b3f0dc91e8882e6efc262c2e8d971998d2694e**
+passes 792/792 Windows desktop tests with all 526 source inputs unchanged.
+[Exact baseline evidence and independent review](release-allocation-d9b3f0d-windows-20260912.md).
+Review found the fixed-label overlap refusal makes a collapsed long-name target
+unreachable with an ordinary grab offset. The [feedback decision](release-allocation-feedback-decision-20260912.md)
+replaces duplicate canvas labels with a dedicated toolbar identity; that correction
+and current strict-lint/native acceptance remain unverified.
 
-1. Finish native basic supplementary move/camera/focus/minimum matrix and current
-   scenario/process/state tasks. Main basic/transition/history/reopen passed at
-   wide size. Check raw drafts, recovery, exact source and real task completion.
-2. Implement/review/natively verify contextual
-   missing-source and first-action flows. Named creation/history/reopen passed;
-   operand-editing and qualified Action allocation remain separate open work.
-3. Constraints/calculations and quantity compatibility are currently descriptive
-   metadata; same-project includes are not maintained cross-project libraries.
-   Independent semantic designs and falsification are active before broad schema
-   changes. See [library review brief](release-library-candidate-review-20260910.md).
-   Other-host proposals expose cosmetic package revision/type compatibility,
-   subjectless analysis closure and text-only instance normalization decisions;
-   full reports and paired criticism are now available from verified c6d296a.
-   Its 218-assertion maintenance experiment supports explicit baseline values
-   with one-level Case overrides; complete freeze and effective-case evaluation
-   are required. Refined baseline/library contracts remain active externally.
-4. Implement and evaluate the source-only CLI baseline, then compare language
-   improvements using both local usability and complete other-host proposals.
-   Current grammar+tooling, domain syntax, namespaces and portable identity
-   modules remain distinct candidates. Concise examples/CLI alone do not prove
-   uncluttered modular engineering authoring or safe large-model changes.
-5. Run coherent current desktop/core/server, specification, examples, REST and
-   optimized packaging gates after integration. Prior passes remain scoped.
-6. Current Linux runtime requires a viable environment: supported WSL2 import
-   failed once with HCS_E_HYPERV_NOT_INSTALLED; no distro registered. The user
-   has a pending environment question. No repeated denied QEMU workaround.
-7. Fresh independent cross-disciplinary release review remains required after
-   actual workflow and semantic acceptance, with all material findings resolved.
+Complete quantities/calculations/constraints, maintained libraries, graphical/
+source/REST parity, transitions and engineering-task usability, aligned reST/help,
+optimized packages and final independent acceptance remain required. Finite
+prototypes and published previews are intermediate results.
 
-## Handoff and publication
+## Authoritative records
 
-Use Gitea issue #1 and current Wiki to coordinate as **Codex-9e8r6t**. Read before
-resuming; preserve the other host's work. Direct Git push now fails authentication;
-anonymous fetch and Gitea MCP still work. Integration3978bbe was published and
-independently fetched/hash-verified as a Git bundle on
-`codex/integration-transfer-20260910`; Wiki `Integration3978bbe` and issue#97 own
-exact transfer instructions. Other host has integrated it and an equivalent
-Sensor fix. Creation4bb4aaf was likewise published on
-`codex/integration-transfer-20260911`, file
-`harness/transfers/creation-4bb4aaf.bundle.b64`: decoded105022 bytes,
-SHA256 `0DEFAE91A56430076C432758F923BC0675911DA9FA7588C9961FF15F47EAEBF6`,
-prerequisite3978bbe. Anonymous Git readback, strict base64 length/hash check and
-`git bundle verify` passed; issue#128 gives selective integration instructions.
-Publish subsequent corrected oracle/native/default evidence similarly; preserve
-the other host's later B4/reference chooser/design work and avoid duplicates.
+- [Project overview and historical coordination](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/1)
+- [Direct process/scenario canvas work](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/2)
+- [Activity allocation drag](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/3)
+- [Analysis, codec and source/API integration](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/7)
+- [Maintained reusable libraries](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/8)
+- [Decisions and reusable evidence](DECISIONS.md)
+- [Shared overview](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/wiki/BehaviorAuthoring20260911)
+- [Published milestones and their exact limitations](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/releases)
+- [Historical Linux gate before deferral](release-linux-core-cli-gate-956atf-20260911.md)
 
-Other-host c6d296a transfer is verified and imported as local
-`codex/behavior-snapshot-c6d296a`: 334830 bytes,
-SHA256 `526A80E2D32ED0E57A7B2372B5F02D4652E8751DFEBA81953C4F045225D6AACB`,
-prerequisite1797516, from `codex/behavior-transfer-20260910` file
-`harness/transfers/behavior-c6d296a.bundle.b64`. Selected analysis/library/text
-reports, criticism, experiments and independent scenario oracle are restored;
-51 evidence files compare byte-for-byte with Git blobs. No source/ledger merge.
-Issue#136/#143 and refreshed Wiki Authoring20260911 record the handoff.
-
-The old ledgers, including all historical platform and native evidence, were
-archived byte-for-byte before this consolidation in
-[history/2026-09-10-ledgers-before-second-consolidation](history/2026-09-10-ledgers-before-second-consolidation/STATE.md),
-with hashes.json. Their historical-current wording does not supersede this file.
+The duplicated live ledgers were migrated once into Gitea comment412. Their
+[complete original bytes and manifest](history/2026-09-11-ledgers-before-gitea-migration/manifest.json)
+preserve historical assumptions, decisions, experiments, limitations and links.
+Links inside the archived documents retain their original `harness/` base.
+Do not maintain live plans in this checkpoint or repeat that migration.