delete the mappings ledger — per-job in-memory resolution + notes fingerprint guard

The persisted (chatId, sourceId)→node table was a shared namespace across
independent chunk/batch jobs: each chunk's extractor mints local ids fresh
(p1..pN), so later chunks collided with earlier ones — propositions silently
skipped as 'already resolved' (coverage checkpointed anyway: permanent silent
loss) and edges resolved onto the wrong nodes (the 'everything links to
everything' mush). Owner ruling 2026-09-29: mergeFindings resolves THIS job's
ids in memory, nothing persists between jobs; cross-job identity is the
auditor's linkTo verdicts alone.

- contracts: NodeMapping dies; NotesSource.contentFp — sha256 of the text at
  the last run, the re-import guard (unchanged re-import = TRUE no-op, no
  model calls, no usage; changed text re-runs; legacy unstamped sources
  re-run once)
- merger: job-local resolution map, in-submit duplicate ids skip once,
  edges resolve extractor-local ids only
- ports/store: appendMapping/readMappings, LEDGER_FILES.mappings,
  rewriteLedgers.mappings gone (stale data/graph/mappings.jsonl just stops
  being read)
- session-clusters: birthSessionOf is provenance-only — the legacy
  mapping-line fallback for provenance-empty notes nodes dies
- deletion: no mapping rows to strip; stats lose mappingsRemoved
- replay-layout batches nodes by first provenance point
- graph.test pins the new independence semantics (re-merge re-creates;
  duplicate ids within one submit resolve once); extraction tests pin
  per-chunk merges + the fingerprint guard

docs/architecture.md

@@ -329,7 +329,7 @@ Sub-agents **verify, never one-shot**: the demo-builder headlessly executes its
 ```mermaid
 flowchart TB
     TRIG["trigger seam (turn-service): coverageOf(record, coverageLedger)<br/>— uncovered tokens ≥ graph.extractionChunkTokens (settings)?"] -->|"yes, single-flight per source"| RUN["extraction.runExtraction(chatId)"]
-    IMPORT["POST /api/graph/import (notes front door)<br/>deterministic src id = sha256(path) — idempotent re-imports"] -->|"importNotes: shared pipeline, second extractor prompt"| RUN
+    IMPORT["POST /api/graph/import (notes front door)<br/>deterministic src id = sha256(path); content-fp guard skips unchanged re-imports"] -->|"importNotes: shared pipeline, second extractor prompt"| RUN
     RUN --> BATCH["batchRuns — greedy token-budgeted batches of oldest uncovered TEACHER-PROSE messages"]
     BATCH --> EXT["EXTRACTOR (LLM) — sees ONLY the session markdown view<br/>(tree-blind, graph-blind; shared engine: core/session-markdown.ts)"]
     EXT --> AUD["AUDITOR (LLM, agentic loop) — sees findings ONLY, never the source;<br/>explores the graph via find / list_sessions / list_propositions tools,<br/>judges identity ONLY (link-or-create, equivalence bias) — never mints edges"]
@@ -342,11 +342,11 @@ flowchart TB
 
 **Serialized audit, parallel extracts — per-chunk jobs** (owner ruling 2026-09-28): every chunk (notes file) and every batch (chat coverage) is its own JOB — registry row, usage record, failure domain. Extracts fan out in parallel across all jobs and sources, throttled by a process-wide 3-permit extract semaphore on `globalThis` (the provider-facing rate stance; a job waiting for a permit shows `queued`). The audit→merge section remains a process-wide FIFO critical section — a mutex on `globalThis` (the same module-instance idiom as the run registries): before any auditor LLM call or graph read, a job waits (`waiting` phase) until every earlier job's merge has landed, so each auditor explores the graph as it actually stands — two concurrent audits would each link into a graph the other is about to change, the structural mint of duplicate nodes. Failure isolation: one job failing (bad chunk, degraded model output) is absorbed at the fan-out — its messages stay uncovered and honestly re-runnable while its siblings still merge; the run returns what actually merged. Abort is source-wide: every job of a source's fan-out dies together, and merged jobs keep their checkpoints. The status feed shows one row per job (`file.md · 2/5` suffixes for chunked sources), and each job persists its own usage record (failed jobs bill their partial spend too).
 
-**Division of trust** (the pipeline's core rule): the extractor is fully trusted and is the only stage that ever sees the source. The auditor never sees the transcript — it receives the findings JSON alone and explores the existing graph through read-only tools (`find`, `list_sessions`, `list_propositions` — statement text included, no timestamps) to reach its verdicts. VERDICTS-ONLY (owner ruling 2026-09-28): the auditor's submit is `{ links }` — identity links only (which findings propositions ARE existing nodes). The edges argument is GONE (owner, same evening): the auditor never mints edges — cross-source connection happens solely through identified equivalences, and relations between propositions come from the extractor alone. It never restates the findings; the merger joins findings + verdicts, so an order of magnitude less is emitted and there is no structural way for the auditor to alter or drop extractor output. Equivalence bias (owner ruling 2026-09-27): paraphrases, rewordings, and compressions of the same claim MERGE; only genuinely distinct propositions stay apart. The deterministic merger validates and appends: link resolution, dedupe by `(from, to, type)`, coverage checkpoints. There is no drop channel — nothing rejects the extractor's output.
+**Division of trust** (the pipeline's core rule): the extractor is fully trusted and is the only stage that ever sees the source. The auditor never sees the transcript — it receives the findings JSON alone and explores the existing graph through read-only tools (`find`, `list_sessions`, `list_propositions` — statement text included, no timestamps) to reach its verdicts. VERDICTS-ONLY (owner ruling 2026-09-28): the auditor's submit is `{ links }` — identity links only (which findings propositions ARE existing nodes). The edges argument is GONE (owner, same evening): the auditor never mints edges — cross-source connection happens solely through identified equivalences, and relations between propositions come from the extractor alone. It never restates the findings; the merger joins findings + verdicts, so an order of magnitude less is emitted and there is no structural way for the auditor to alter or drop extractor output. Equivalence bias (owner ruling 2026-09-27): paraphrases, rewordings, and compressions of the same claim MERGE; only genuinely distinct propositions stay apart. The deterministic merger validates and appends: link resolution, edge dedupe by `(from, to, type)`, coverage checkpoints. There is no drop channel — nothing rejects the extractor's output. **Per-job in-memory resolution** (owner, 2026-09-29): the mappings ledger is deleted — each job resolves its own proposition ids against the graph in memory and merges independently, so no job can see or collide with another's ids (the persisted table once silently dropped same-id propositions across chunks and welded wrong edges). Cross-job and cross-run identity is the auditor's links alone, plus the coverage ledger (nothing re-extracts) and the notes content-fingerprint guard.
 
 **Coverage, not quiz-counting** (supersedes the v1 every-N-quiz-answers trigger): each message's *view* (the compact line format `core/coverage.ts` has always hashed) is hashed into a per-chat fingerprint ledger (`coverage.jsonl`); "covered" means exactly "a run committed on this content." The prompt view is the richer markdown document — a deliberate 2026-09-27 split: re-formatting presentation never re-opens covered history. Uncovered = fingerprint diff, never dual-tracked; runs are greedy token-budgeted batches (`graph.extractionChunkTokens` — a settings knob, default 4096, floor 500, read fresh each turn) of the oldest uncovered messages — quiz-less sessions extract too. A coarse `sessions.jsonl` checkpoint still marks each merged run. The trigger seam (`turn-service.ts`) is trigger-agnostic from the pipeline's side: when a better mechanism lands (session end, idle, explicit flush), only the seam changes. Single-flight per source; the run registry powers the coverage UI and true abort.
 
-**Two front doors, one pipeline**: chat transcripts (quiz-triggered) and raw personal notes (`POST /api/graph/import` — each file becomes a `NotesSource` playing the `chatId` role, deterministic id from the path hash). Notes chunk like chats (owner, 2026-09-28): large files split at line boundaries under the same token budget, and each chunk/batch fans out as its own job exactly like a chat run — parallel extracts under the semaphore, serialized audits under the gate. No single model call carries a whole file. Both submit tools require their top-level fields (`edges`/`links` present even when empty): a payload missing them fails validation rather than silently merging structure-less nodes.
+**Two front doors, one pipeline**: chat transcripts (quiz-triggered) and raw personal notes (`POST /api/graph/import` — each file becomes a `NotesSource` playing the `chatId` role, deterministic id from the path hash; a content-fingerprint stamp makes an unchanged re-import a TRUE no-op — no model calls, no usage — while changed text re-runs the whole file, owner 2026-09-29). Notes chunk like chats (owner, 2026-09-28): large files split at line boundaries under the same token budget, and each chunk/batch fans out as its own job exactly like a chat run — parallel extracts under the semaphore, serialized audits under the gate. No single model call carries a whole file. Both submit tools require their top-level fields (`edges`/`links` present even when empty): a payload missing them fails validation rather than silently merging structure-less nodes.
 
 **The read channel is pure derivation.** `GET /api/graph` reads the ledgers (`graphSnapshot`: merged nodes/edges, birth-session clusters, positions) — the home view never triggers a write. Node detail cards show a node's edges — outgoing under "What follows from this" / "What this supports", incoming under "Follows from" / "Supported by" (an edge A→B means A implies or supports B, owner semantics 2026-09-28) — and its birth sessions.
 
@@ -409,7 +409,7 @@ The Electron main is a launcher + security guard, never a host for app logic: si
 | **One writer per ledger** — the merger is the sole graph writer; chat records written only by the turn pipeline; job records only by the runner; positions PUT is the only sanctioned graph-adjacent exception |
 | **The store never decides** — adapters persist and shape-guard; merge/dedup/derivation semantics are reader-side, in core |
 | **Derived, never dual-tracked** — append-only evidence; every state recomputed at read (snapshot, plan statuses, phases, costs, coverage) |
-| **Idempotency via deterministic keys** — steer ids, ledger refs, coverage fingerprints, mapping `(chatId, sourceId)`, cluster content hashes; re-running anything converges |
+| **Idempotency via deterministic keys** — steer ids, ledger refs, coverage fingerprints, source content fingerprints, cluster content hashes; re-running anything converges |
 | **LLMs judge; code mechanizes** — grading, merging, fingerprints, layout are deterministic; a failed LLM stage checkpoints nothing |
 | **The persisted record is the only source of truth** — agents are stateless per-turn rebuilds; no unanswered tool call reaches a provider |
 | **Failure containment** — side channels (context, extraction, usage, naming) are fire-and-forget behind try/catch seams; a side-channel failure never touches the response or the persist; the turn registry clears on every path |