feat: extraction coverage — message-granular ledger + token-batched runs (d132373 vision)

THE MESSAGE IS THE UNIT OF COVERAGE (vision-extraction-coverage.md): a
per-chat append-only ledger (coverage.jsonl) records which messages the
pipeline has extracted, by content fingerprint over exactly what the
extraction view sees (one shared line builder — core/coverage.ts); the
uncovered remainder is DERIVED at read time, never dual-tracked. A quiz
answer merging into the asking message re-opens only that message;
plan-block data-part attach never re-opens anything.

- The trigger (turn-service) replaces every-3-quiz-answers with
  uncovered-tokens >= EXTRACTION.chunkTokens (4096) — quiz-less sessions
  extract too, content size is the honest signal.
- runExtraction is now chunked: token-budgeted batches of the oldest
  uncovered consecutive messages (a tool call + result never split), each
  merged batch checkpointing its messages' coverage atomically — an abort
  or error loses at most the in-flight batch; merged batches stay covered.
- Observation refs are batch-tagged (obs:<batchTag>:<sourceId>): re-runs
  of the same batch dedupe; a re-opened message's fresh understanding
  lands as a new event. Fixes the old obs:p1 position-collision.
- New API: GET /api/graph/coverage (exact per-session derived coverage +
  running flags, most-uncovered first) and POST /api/graph/coverage/extract
  (manual run for one session, 409 while in flight).
- Graph view chrome: the coverage button opens a panel with every
  session's covered/uncovered tokens and a per-session Extract button —
  the manual answer to aborted runs, errors, and dormant tails. Renders
  even when the graph is empty: an empty graph with uncovered sessions is
  exactly when it matters. Polls only while open.
- Notes imports keep the whole-file checkpoint path (coverage undefined).
- Tests: pure-core coverage suite (11), chunked-pipeline suite (3:
  multi-batch + no-op, abort-keeps-earlier-batches + remainder re-run,
  re-open alone + data-part invisibility), panel render suite (5);
  pendingQuizAnswers and its tests deleted as dead code. 486/486.

Live-smoked on real GLM: manual extract of "teach me modal realism" ran
one batch, wrote 4 coverage entries, panel flipped to "1.3k covered ·
complete" with the button disabled, graph refetched (nodes 11), usage
persisted with real stats.

tests/graph.test.ts

@@ -20,7 +20,7 @@ import { after, describe, it } from "node:test";
 import type { UIMessage } from "ai";
 import type { AuditResult } from "../src/core/contracts.ts";
 import type { QuestionAnswerData } from "../src/core/question-core.ts";
-import { clusterContentId, getGraph, graphSnapshot, mergeFindings, pendingQuizAnswers, type GraphDeps } from "../src/core/graph.ts";
+import { clusterContentId, getGraph, graphSnapshot, mergeFindings, type GraphDeps } from "../src/core/graph.ts";
 import { graphStore } from "../src/store/graph.ts";
 import { chatStore } from "../src/store/chats.ts";
 import { LEDGER_FILES, PATHS, SOURCES_FILE, EMBEDDINGS_FILE } from "../config.ts";
@@ -564,55 +564,6 @@ describe("the merger (mergeFindings)", () => {
 	});
 });
 
-// ─── the trigger helper ──────────────────────────────────────────────────────
-
-describe("the trigger helper (pendingQuizAnswers)", () => {
-	it("counts answered quizzes not yet in the ledger — dismissed/ask never count", () => {
-		const chat = fixtureChat("Trigger fixture", [
-			user("u1", "go"),
-			assistant("a1", [
-				quizPart(
-					"call-s",
-					{ question: "QS", options: [{ label: "a" }, { label: "b" }], correctAnswer: "a", explanation: "e" },
-					answer({ questionId: "call-s", questionText: "QS text", correct: true, answeredAt: "2026-08-22T03:00:00.000Z" }),
-				),
-				quizPart(
-					"call-s2",
-					{ question: "QS2", options: [{ label: "a" }, { label: "b" }], correctAnswer: "a", explanation: "e" },
-					answer({ questionId: "call-s2", questionText: "QS2 text", dismissed: true }),
-				),
-				{
-					type: "tool-ask_user_question",
-					toolCallId: "call-s3",
-					state: "output-available",
-					input: { question: "free?" },
-					output: answer({ questionId: "call-s3", kind: "ask", questionText: "free?", text: "y" }),
-				},
-			]),
-		]);
-
-		assert.equal(pendingQuizAnswers(chat.id, graphDeps), 1, "one answered quiz pending");
-		assert.equal(pendingQuizAnswers("chat_does_not_exist", graphDeps), 0);
-
-		mergeFindings(chat.id, fixtureAudit(), graphDeps, sessionSource(chat.id));
-		// call-s is unattributed here (fixtureAudit has no call-s attribution)
-		// — but it still becomes an event, so nothing stays pending.
-		assert.equal(pendingQuizAnswers(chat.id, graphDeps), 0, "extracted → nothing pending");
-
-		// A NEW answered quiz raises the count again (the re-trigger path).
-		chatStore.saveMessages(chat.id, [
-			...chatStore.getChat(chat.id)!.messages,
-			assistant("a3", [
-				quizPart(
-					"call-s4",
-					{ question: "QS4", options: [{ label: "a" }, { label: "b" }], correctAnswer: "a", explanation: "e" },
-					answer({ questionId: "call-s4", questionText: "QS4 text", correct: false, answeredAt: "2026-08-22T03:01:00.000Z" }),
-				),
-			]),
-		]);
-		assert.equal(pendingQuizAnswers(chat.id, graphDeps), 1);
-	});
-});
 
 // ─── store primitives ────────────────────────────────────────────────────────