Graph redesign: true propositions, follows/supports, auditor-owned identity (vision §1 minimal implementation)

The minimal implementation of the 2026-09-02 graph vision (docs/vision.md §1):

- contracts/graph.ts: every node is a TRUE proposition (statement is both
  rendering label and identity key; required description; no kind, no name).
  Edges are follows (derivable) / supports (grounds without entailing) with
  message-granular provenance points {chatId, messageId}. Events reduce to
  correct/miss/dont-know plus observation (understanding notes); no taught
  events, no misconception kind.
- extraction.ts: extractor is TREE-BLIND (transcript only, no plan tree) and
  free-form; auditor sees findings + the current graph, owns faithfulness and
  identity (link-or-create verdict per proposition, recorded as linkTo);
  transcriptView tags every line with its message id (provenance anchors).
- core/graph.ts merger: applies verdicts deterministically — linkTo appends
  a link line (phrasings join aliases, provenance unions; reads merge by id),
  absent creates; NO string matching anywhere. Quiz events rebuilt from tool
  parts with attribution-only nodeId resolution; understanding notes become
  observation events (obs:<sourceId>); mapping lines are the verdict audit
  trail and make re-merges idempotent.
- deriveNodeStates: transitional — latest quiz event wins (known/missed/
  dont-know, else candidate); taught unreachable until the state-model
  ideation lands.
- graph-context.ts + 50-graph-context.md: follows chains, hotspot grouping,
  state vocabulary updated for the new event kinds.
- graph-view.tsx: node label is the statement; detail shows statement +
  description.
- tests: merger verdicts (link, no-string-match, cross-chat assertions),
  tree-blind pipeline end-to-end, follows vocabulary in context tests.
  276/276 green.

README.md

@@ -114,7 +114,7 @@ graph TB
     LEDG --> SNAP --> RGRAPH
 ```
 
-**Core invariant:** the extraction pipeline (extractor → auditor → merger) is the sole graph writer. The LLM stages propose and verify (propositions, edges, probe attribution — each with verbatim evidence); the deterministic merger owns every ledger append and rebuilds anything the model could silently mis-copy (event kinds, timestamps, idempotency refs) from the transcript. The teacher stays a teacher; everything below the ledgers is derived.
+**Core invariant:** the extraction pipeline (extractor → auditor → merger) is the sole graph writer — tree-blind and post-hoc. The LLM stages propose, verify, and judge identity (link-or-create against the current graph; each finding carries verbatim evidence and message-granular provenance); the deterministic merger owns every ledger append and rebuilds anything the model could silently mis-copy (event kinds, timestamps, idempotency refs, provenance) from the transcript. Every node is an objective, world-facing fact; the learner's relationship to it lives entirely in the event ledger. The teacher stays a teacher; everything below the ledgers is derived.
 
 ## Layout
 
@@ -165,7 +165,7 @@ data/                           chats/ · graph/ · jobs/ — runtime state, git
 
 **The async sub-agent protocol (ack-and-steer).** `research` / `demo` / `visual` are server-executed tools: the call resolves immediately mid-turn with a fire-and-forget ack and the teacher keeps teaching; a background runner works in parallel (the job store tracks a live activity line; the client polls `/api/jobs`). On completion the runner builds a **steer message** — a user-role `UIMessage` whose text part is the model-facing result (data parts are dropped by provider conversion) and whose `data-subagent-artifact` part carries the full result for the client — and the **wake pipeline** (`server/jobs.ts`) delivers it: a per-chat serialized queue waits for the turn to end and no question to be pending, then fires a server-side teacher turn that weaves the result into the lesson. The client adopts the wake turn through the same `turnInFlight` machinery as returning mid-stream (busy shimmer, composer gate) and renders steers as artifacts — never a bubble. Sub-agents **verify, never one-shot**: the demo-builder headlessly executes its HTML in system Chrome before delivery; the visual-maker renders each SVG and looks at it (needs a vision-capable model — `MODELS.visualMaker` in config.ts).
 
-**The knowledge graph (the two channels).** The write channel: the extraction pipeline — extractor (LLM: propositions, edges, probe attribution, each with verbatim evidence) → auditor (LLM: drops anything unbacked) → merger (`mergeFindings`, deterministic: exact/alias identity resolution, event rebuild from the transcript's tool parts, dedupe, checkpoint). Triggered once a chat accumulates `EXTRACTION.everyNQuizAnswers` (default 3, config.ts) new answered quizzes — a v1 placeholder trigger isolated in one seam (`turn-service.ts`), swappable without touching the pipeline. Failure checkpoints nothing; the next trigger re-runs. The read channel: the home view derives node states from the ledgers (`GET /api/graph` is a pure read — forceAtlas2 run-then-freeze, no idle simulation), and at session start the derived graph is rendered into a compact markdown block appended to the teacher's instructions (`buildGraphContext`) — whole graph while small, hotspots + 1-hop neighborhood past 150 nodes.
+**The knowledge graph (the two channels).** The write channel: the extraction pipeline — extractor (LLM, tree-blind: propositions as true statements + descriptions, follows/supports edges, quiz attribution, understanding notes) → auditor (LLM: drops anything unbacked, stamps each survivor with an identity verdict — link to an existing node or create) → merger (`mergeFindings`, deterministic: applies the verdicts, link-appends phrasings/provenance, event rebuild from the transcript's tool parts, dedupe, checkpoint). Triggered once a chat accumulates `EXTRACTION.everyNQuizAnswers` (default 3, config.ts) new answered quizzes — a v1 placeholder trigger isolated in one seam (`turn-service.ts`), swappable without touching the pipeline. Failure checkpoints nothing; the next trigger re-runs. The read channel: the home view derives node states from the ledgers (`GET /api/graph` is a pure read — forceAtlas2 run-then-freeze, no idle simulation), and at session start the derived graph is rendered into a compact markdown block appended to the teacher's instructions (`buildGraphContext`) — whole graph while small, hotspots + 1-hop neighborhood past 150 nodes.
 
 ## Testing