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.

components/graph-view.tsx

@@ -66,6 +66,7 @@ import Link from "next/link";
 import { FileTextIcon, Loader2Icon, SearchIcon, SettingsIcon, UploadIcon, WaypointsIcon } from "lucide-react";
 import { incrementalLayout, type GraphNode, type GraphSnapshot } from "@/src/core";
 import { GraphCanvasRenderer, type GraphRenderSettings } from "./graph-canvas.ts";
+import { GraphCoverageControl } from "./graph-coverage.tsx";
 import {
 	ARROW_LENGTH_RANGE,
 	CHARGE_RANGE,
@@ -843,11 +844,15 @@ export function GraphView() {
 			)}
 
 			{/* Legend + filters: search box and per-state toggle rows. */}
-			{/* Top-right controls — three separate floating containers (owner,
+			{/* Top-right controls — separate floating containers (owner,
 			    graph-view round 2): the search box, the settings gear (its own
-			    collapsible component), and the import button. */}
-			{!isEmpty && (
-				<div className="absolute right-3 top-3 z-10 flex items-center gap-2">
+			    collapsible component), the import button, and the coverage
+			    control. Coverage renders even when the graph is EMPTY — an
+			    empty graph with unextracted sessions is exactly when it
+			    matters (extract → the graph gains nodes). */}
+			<div className="absolute right-3 top-3 z-10 flex items-center gap-2">
+				{!isEmpty && (
+					<>
 					{/* Search — its own container (icon + input + no-match note). */}
 					<div className="w-56 rounded-xl border bg-card/85 p-1.5 shadow-lg backdrop-blur">
 						<div className="relative">
@@ -893,8 +898,12 @@ export function GraphView() {
 					    gear sits at the far right (owner, round 3) so its panel
 					    drops at the very right edge, over less of the graph. */}
 					<GraphSettingsControl settings={settings} changeSettings={changeSettings} />
-				</div>
-			)}
+					</>
+				)}
+				{/* Extraction coverage — own container, always present; the
+				    panel re-reads when background runs settle (refreshTick). */}
+				<GraphCoverageControl refreshKey={refreshTick} />
+			</div>
 
 			{/* Background pipeline status: what is currently running. */}
 			{pipelineRuns.length > 0 && (