Extraction-UX data layer: the chunk budget becomes a graph setting; the chat view gets a per-session coverage read

Owner-locked extraction-UX redesign (dispatch 2026-09-24), part 1 (data
layer; the UI chunk follows).

THRESHOLD -> SETTING
- config.ts's EXTRACTION.chunkTokens dies; the default moves into
  FACTORY_SETTINGS.graph.extractionChunkTokens (4096, the old constant's
  value). GraphSettings gains the optional field, Required at resolution
  via the standard ?? FACTORY pattern — pre-redesign records resolve the
  default cleanly.
- FLOOR 500 (the implementer's call, documented on the field): every run
  pays the graph-carrying prompt overhead out of the write channel's
  money — a smaller budget fires penny-batches that cost more per
  extracted token than the content is worth. The sanitizer CLAMPS up
  (bd68486 clamp-never-reject discipline: fractions floor, junk drops);
  the settings PUT REJECTS below-floor with the rationale in the message.
  No ceiling: a large budget just delays extraction — the user's stated
  cost/thoroughness tradeoff, not a misconfiguration to police.
- The trigger (turn-service.triggerExtraction) takes the budget as a
  parameter — chat-handler passes effective.graph.extractionChunkTokens,
  the fresh per-turn read, same as every other gate.
- The pipeline's BATCH side threads through the same number:
  ExtractionPipelineDeps gains an OPTIONAL getChunkTokens getter with the
  factory default (Teacher's 24 test fixtures stay untouched; the two
  call-site lines inside extraction.ts are the only cross-band edits,
  flagged). chat-handler + backfill/import-notes wire the live
  effectiveSettings — trigger and batches share one budget, always.

PER-SESSION COVERAGE READ
- sessionCoverage(chatId) (server/chats.ts): the chat view's ring-meter
  block — totalMessages/coveredCount/uncoveredCount/coveredTokens/
  uncoveredTokens (the same coverageOf derivation /api/graph/coverage
  serves, scoped to one chat), running (chat-kind extraction registered
  for this id), and lastFoldedAt (the chat's newest coverage row's fold
  — a cheap single pass; null before any fold). GET /api/chats/[id]
  carries it as coverage: {...}; unknown chat -> null (the route 404s
  first).
- /api/graph/coverage (the all-sessions list) compiles untouched — the
  per-session read is a scoping of it, not a supersession; the UI's
  sidebar/ring chunk decides which surface it consumes.

Tests: factory/sanitizer pins (clamp-up, fraction-floor, junk-drop),
resolution pins (absent -> 4096, stored 2000 wins), settings-body pins
(valid/absent/fraction/below-floor 400/junk 400), sessionCoverage pins
(derived split, newest-fold scoping, cross-session isolation, running via
the registry, null on unknown chat). 893/893.

tests/settings.test.ts

@@ -21,7 +21,9 @@ describe("FACTORY_SETTINGS (the compiled factory layer)", () => {
 	it("pins the owner-decided defaults", () => {
 		assert.equal(CURRENT_SETTINGS_VERSION, 1);
 		assert.deepEqual(FACTORY_SETTINGS.general, { autoUpdate: true });
-		assert.deepEqual(FACTORY_SETTINGS.graph, { enabled: true }); // wave 7 collapse: the master switch ONLY
+		// wave 7 collapse: the master switch ONLY + the extraction-UX
+		// redesign's chunk budget (2026-09-24) — default = the old config constant
+		assert.deepEqual(FACTORY_SETTINGS.graph, { enabled: true, extractionChunkTokens: 4096 });
 		const a = FACTORY_SETTINGS.appearance;
 		assert.equal(a.mode, "dark");
 		assert.equal(a.background, null); // the mode's own default, not a factory hex
@@ -106,6 +108,21 @@ describe("sanitizeUserSettings", () => {
 		assert.deepEqual(out.agent, {});
 		assert.deepEqual(out.appearance, {});
 		assert.deepEqual(out.graph, {});
+
+		// extractionChunkTokens (extraction-UX redesign, 2026-09-24):
+		// clamp-never-reject — a finite positive value survives (fractions
+		// floor), below-floor values clamp UP to the cost floor, junk drops
+		// (the factory default resolves at read time).
+		const budget = sanitizeUserSettings({ version: 1, graph: { enabled: true, extractionChunkTokens: 2048 } });
+		assert.deepEqual(budget?.graph, { enabled: true, extractionChunkTokens: 2048 });
+		const fraction = sanitizeUserSettings({ version: 1, graph: { extractionChunkTokens: 1024.9 } });
+		assert.equal(fraction?.graph?.extractionChunkTokens, 1024, "fractions floor to whole tokens");
+		const tiny = sanitizeUserSettings({ version: 1, graph: { extractionChunkTokens: 10 } });
+		assert.equal(tiny?.graph?.extractionChunkTokens, 500, "below the floor clamps UP — penny-batches are a cost bug, not a preference");
+		for (const junk of [0, -1000, NaN, Infinity, "4096", null, true]) {
+			const dropped = sanitizeUserSettings({ version: 1, graph: { extractionChunkTokens: junk } });
+			assert.equal(dropped?.graph?.extractionChunkTokens, undefined, `junk ${String(junk)} drops`);
+		}
 	});
 
 	it("out-of-range numbers CLAMP (proseFontSize, headingWeight)", () => {