Checkpoint source 7 workflows and in-progress diagram authoring redesign

Preserve current core, source, REST, desktop, recovery, documentation and validation work, including AGENTS.md and the development summary. This is a work-in-progress checkpoint: the new compact palette has outstanding compilation errors and native acceptance; earlier passing gates retain their documented scope.

harness/fixtures/source7-native/README.md

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+# Source7 native acceptance fixture
+
+This is the frozen baseline for separately scoped native cases. Current passes
+and remaining rendering/workflow gates are recorded in the
+[native acceptance report](../../release-source7-native-acceptance-20260907.md);
+fixture generation alone is not native acceptance. `base/project.arcadia` and its included
+`rationale.arcadia` contain43elements and9relations: OA and SA callers each reuse
+an A→B→C procedure twice and through one nested wrapper. A direct X contribution
+allows a caller link specifically into B. The SA boundary has two parameterless
+operations and a correlated Reply. All identities are deterministic.
+
+Copy the complete `base` directory into a fresh working directory per case. Keep
+the baseline unchanged. `harness/source7-native-contract.rs` generates it and
+checks actual saved results against an independently constructed complete model
+and source update. It refuses migration, UUID stabilization or whitespace
+normalization. Current exact baseline generation and comparison passed against
+the source7 core; this does not constitute UI acceptance.
+
+Cases for the actual compiled desktop:
+
+- `operation-reset`: edit the first existing Call (`@operation_probe_43`) to
+  select Reset's exact allocation (`@operation_probe_30`). Reply remains
+  independently identified and derives this Call's operation. No new model
+  records are expected.
+- `operation-status`: on a separate baseline copy, select ReadStatus's allocation
+  (`@operation_probe_31`) on the same Call. Its authored message name is retained.
+- `oa-link` / `sa-link`: in the appropriate `@oa_caller` / `@sa_caller`, create
+  one contextual Precedence from direct `@oa_x` / `@sa_x` into B through the first
+  reference R1. Enter name `First assessment gate` and guard `Check accepted`.
+  Repeated reference R2 and the procedure definition must remain unchanged.
+- `oa-nested` / `sa-nested`: target B through R3 and its Inner assessment reference.
+  The exact two-component instance path is required.
+- `baseline`: Undo the one accepted edit, save, and compare all model/source
+  bytes. Redo and saved reopen must return the same accepted identity and fields.
+
+For creation checks, exactly one newly allocated v4 relation UUID is permitted.
+Only that fresh nonce is read from the native result; every authored field,
+alias, owner, path, purpose, dependency and complete source update is predicted.
+No existing identity or unrelated record is excluded from comparison. Preserve
+the accepted files/hashes to prove that Redo/reopen retain this allocated UUID.
+
+Build the checker using the current source7 core library and matching serde_json
+library, then run `CHECKER generate NEW_DIRECTORY` or
+`CHECKER check MODE WORKING_DIRECTORY/project.arcadia`. Source6 teaching and
+historical recovery oracles remain in their separate fixture directories.
+
+## Additional purpose cases: validated oracles, native pending
+
+New source in `harness/source7-native-contract.rs` adds two independent incidence
+oracles. Direct-rustc `-D warnings` compilation passed in4.05s during a coordinated
+brief lease; both purpose self-checks passed. Existing base bytes and its manifest
+remain unchanged. Native purpose authoring/history is not yet accepted.
+
+Validated checker: `.local/native-qa/source7-native-contract-incidence.exe`, SHA256
+`16994DC437F5CCC5E5F6FBB4212C03449F2389AE4615FA98B2930B3637468EE3`.
+The original checker remains unchanged at SHA256
+`4AC615A099F23A78F111BAD3966A3CCB808FCA1C5FC46FBAC9A947508A568600`.
+Logs: `.local/native-qa/source7-incidence-{build,selfcheck,generation}.log`.
+Generated separate fixture `.local/native-qa/source7-incidence-base` passed the
+complete baseline check; entry SHA256
+`77C26FD2DD71514AB89C0FA71113825AC8F3DBD8F71A56EFAE8E5430C92D99B8`.
+Regenerated original baseline matched all three manifest hashes; preserved native
+OA-link and operation-Reset accepted cases also passed the extended checker.
+
+To reproduce, build the checker against matching current core/serde libraries, preserving the
+old checker executable, and first run `CHECKER verify-incidence-contract`. This
+constructs expected typed commands, proves complete core analysis with exactly
+one assembly record and unchanged precedence/entries/exits, checks invalid
+direction/work counterfactuals, and checks stable source updates. Native check
+modes predict the entire Project and two-file source bundle; only the new link's
+v4 nonce is taken from actual output, never its name, endpoints, purpose or evidence.
+
+### OA Exchange assembly
+
+Run `CHECKER generate-incidence NEW_DIRECTORY`; this separate deterministic variant
+adds one Interaction, `@oa_assessment_handoff`, **Assessment handoff X to B**,
+from `@oa_work_x` to `@oa_work_b`. It contains43elements/10relations/two sources.
+Do not replace `base` with this variant. Check the clean copy with
+`CHECKER check incidence-baseline NEW_DIRECTORY/project.arcadia`.
+
+In OA caller, choose **Tools → Qualified link / assembly…**. Set source to direct
+X (`[]/oa_x`); Choose target → Enter First assessment → B (`[oa_r1]/oa_b`). Enter
+name **Caller assessment handoff**. Choose **Exchange assembly** and first leave
+evidence empty: Apply must refuse. Then select the exact **Assessment handoff X to B**
+Interaction; Apply should become available. Apply once and Save a fresh copy.
+
+Run `CHECKER check oa-exchange-assembly SAVED/project.arcadia`. Undo/Save uses
+`incidence-baseline`; Redo/Save uses `oa-exchange-assembly` and must preserve the
+same accepted UUID/bytes. The link is incidence: no precedence arrow/guard or
+merged execution is inferred. Core proof checks its exchange contributes to this
+caller’s behavior coverage, not the shared procedure’s global coverage. The
+reversed contextual endpoint counterfactual must be rejected; deleting the
+evidence exchange removes its dependent incidence link (automated oracle only).
+
+### SA Common work incidence
+
+Use a fresh copy of the original unchanged `base`, not the exchange variant.
+In SA caller, choose **Tools → Qualified link / assembly…**. For source Enter
+First assessment → B (`[sa_r1]/sa_b`); for target return Root then Enter Second
+assessment → B (`[sa_r2]/sa_b`). Enter name **Shared assessment work** and select
+**Common work incidence**. Choosing **X · Check authorization** (`@sa_work_x`)
+as evidence must reject; repair to exact **B · Review assessment** (`@sa_work_b`).
+Both full reference paths must remain distinct while the shared work identity is
+the same. Apply once and Save a fresh copy.
+
+Run `CHECKER check sa-common-work SAVED/project.arcadia`. Undo/Save uses `baseline`;
+Redo/Save uses `sa-common-work` and exact accepted UUID/byte comparison. This records
+shared identity; it neither fuses the two occurrences nor creates execution order.
+The complete-model oracle rejects renamed/duplicated work, collapsed instance
+paths, wrong evidence or unrelated record changes.
+
+After compiling, also regenerate original `generate` into a fresh scratch folder
+and compare its three hashes with the existing manifest, then rerun a preserved
+old accepted case. These checks establish that extending the checker did not alter
+the already-measured baseline or existing expected results.