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-resolution.test.ts

@@ -42,7 +42,9 @@ describe("resolveSettings", () => {
 		assert.equal(eff.appearance.proseFontSize, 16);
 		assert.equal(eff.appearance.sessionNameSerif, true);
 		assert.equal(eff.appearance.mdRendering.headingWeight, 900);
-		assert.deepEqual(eff.graph, { enabled: true }); // wave 7 collapse: the master switch ONLY
+		// wave 7 collapse: the master switch ONLY + the redesign's chunk
+		// budget — absent record resolves the factory 4096 (the old config constant)
+		assert.deepEqual(eff.graph, { enabled: true, extractionChunkTokens: 4096 });
 	});
 
 	it("explicit record values win over every factory default", () => {
@@ -75,8 +77,12 @@ describe("resolveSettings", () => {
 		assert.equal(eff.appearance.mode, "light");
 		assert.equal(eff.appearance.proseFontSize, 20);
 		assert.equal(eff.appearance.mdRendering.headingWeight, 600);
-		// wave 7 collapse: the section IS the master switch.
-		assert.deepEqual(eff.graph, { enabled: false });
+		// wave 7 collapse: the section IS the master switch (absent budget
+		// field = factory 4096 — a pre-redesign record resolves cleanly).
+		assert.deepEqual(eff.graph, { enabled: false, extractionChunkTokens: 4096 });
+		// The chunk budget rides the same resolution: stored value wins.
+		const budgeted = resolveSettings({ version: 1, graph: { extractionChunkTokens: 2000 } });
+		assert.deepEqual(budgeted.graph, { enabled: true, extractionChunkTokens: 2000 });
 	});
 
 	it("partial role override: thinkingLevel alone borrows the SLOT's model (or nothing, without one)", () => {