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.

app/api/chats/[id]/route.ts

@@ -1,4 +1,4 @@
-import { deleteChatSession, getChat, isTurnRunning, stores, type ChatDeleteMode } from "@/src/server";
+import { deleteChatSession, getChat, isTurnRunning, sessionCoverage, stores, type ChatDeleteMode } from "@/src/server";
 
 export async function GET(_req: Request, { params }: { params: Promise<{ id: string }> }) {
 	const { id } = await params;
@@ -6,7 +6,10 @@ export async function GET(_req: Request, { params }: { params: Promise<{ id: str
 	if (!chat) return Response.json({ error: "Not found" }, { status: 404 });
 	// turnInFlight lets a returning client re-attach to a running turn
 	// (chat-handler write-ahead + registry — see src/server/turn-liveness.ts).
-	return Response.json({ ...chat, turnInFlight: isTurnRunning(id) });
+	// coverage (extraction-UX redesign, 2026-09-24): the chat view's ring
+	// meter — one session's read of the same derivation /api/graph/coverage
+	// serves for all sessions. getChat already 404'd, so the block exists.
+	return Response.json({ ...chat, turnInFlight: isTurnRunning(id), coverage: sessionCoverage(id) });
 }
 
 /**

config.ts

@@ -59,17 +59,6 @@ export type ModelRole =
  * (server/turn-service.ts) so it can be swapped without touching the
  * pipeline.
  */
-/**
- * The extraction trigger (vision-extraction-coverage.md, 2026-09-15): a run
- * fires when a chat's UNCOVERED transcript tokens reach the chunk budget.
- * Runs are token-budgeted batches of the oldest uncovered messages — this
- * knob is the transcript share of the extractor's context (it also carries
- * the whole graph + instructions), so it bounds both cost and chunk size.
- * Replaces the old every-3-quiz-answers trigger, which never fired for
- * quiz-less sessions.
- */
-export const EXTRACTION = { chunkTokens: 4096 } as const;
-
 /**
  * The LIVE graph store (src/store/graph.ts) — owned by the app's extraction
  * pipeline. Line shapes: src/core/contracts.ts.

scripts/backfill-graph.ts

@@ -9,12 +9,18 @@ import { chatStore } from "../src/store/chats.ts";
 import { graphStore } from "../src/store/graph.ts";
 import { createExtractionPipeline } from "../src/agent/subagents/extraction.ts";
 import { getGraph } from "../src/core/graph.ts";
+import { effectiveSettings } from "../src/server/stores.ts";
 
 async function main() {
 	const only = process.argv[2]; // optional: extract just one chat id
 	const chats = only ? chatStore.listChats().filter((c) => c.id === only) : chatStore.listChats();
 	console.log(`[backfill] ${chats.length} chats to extract`);
-	const pipeline = createExtractionPipeline({ chatStore, graphStore });
+	const pipeline = createExtractionPipeline({
+		chatStore,
+		graphStore,
+		// Live budget: the graph section's setting, same as the app's trigger
+		getChunkTokens: () => effectiveSettings().graph.extractionChunkTokens,
+	});
 	for (const chat of chats) {
 		const t0 = Date.now();
 		try {

scripts/import-notes.ts

@@ -16,7 +16,7 @@ import * as fs from "node:fs";
 import * as path from "node:path";
 import { createExtractionPipeline } from "../src/agent/subagents/extraction.ts";
 import { getGraph } from "../src/core/graph.ts";
-import { stores } from "../src/server/stores.ts";
+import { effectiveSettings, stores } from "../src/server/stores.ts";
 
 async function main() {
 	const dir = process.argv[2] ?? "real-data-extraction/learn-sessions";
@@ -27,7 +27,11 @@ async function main() {
 		.sort();
 	console.log(`[import-notes] ${files.length} note files from ${dir} (concurrency ${limit})`);
 
-	const pipeline = createExtractionPipeline(stores);
+	const pipeline = createExtractionPipeline({
+		...stores,
+		// Live budget: the graph section's setting, same as the app's trigger
+		getChunkTokens: () => effectiveSettings().graph.extractionChunkTokens,
+	});
 	const queue = [...files];
 	const totals = { nodes: 0, edges: 0, events: 0, failed: 0 };
 	const workers = Array.from({ length: Math.min(limit, files.length) }, async () => {

src/agent/subagents/extraction.ts

@@ -4,7 +4,7 @@ import type { Usage } from "@earendil-works/pi-ai";
 import { z } from "zod";
 import { lhTool, toPiTools } from "../lh-tool.ts";
 import type { ModelRole } from "../../../config.ts";
-import { ModelsNotConfiguredError, ROLE_SLOT, type ModelSlotName } from "../../core/settings.ts";
+import { FACTORY_SETTINGS, ModelsNotConfiguredError, ROLE_SLOT, type ModelSlotName } from "../../core/settings.ts";
 import type { PiEngine } from "../models.ts";
 import { runSubagent } from "./pi-run.ts";
 import type {
@@ -20,7 +20,6 @@ import { getGraph, mergeFindings, type EmissionStats, type GraphDeps } from "../
 import type { GraphStore } from "../../core/ports.ts";
 import { settleGraphLayout } from "../../core/layout-settle.ts";
 import { batchRuns, batchTag, coverageOf, messageViewLines } from "../../core/coverage.ts";
-import { EXTRACTION } from "../../../config.ts";
 
 /**
  * The extraction pipeline (vision §1 construction, 2026-09-02 redesign) — the
@@ -569,7 +568,15 @@ export interface ExtractionModels {
 	engineFor?: (role: ModelRole) => PiEngine | undefined;
 }
 
-export interface ExtractionPipelineDeps extends GraphDeps, ExtractionModels {}
+export interface ExtractionPipelineDeps extends GraphDeps, ExtractionModels {
+	/** The chunk budget — the transcript-token share of the extractor's
+	 *  context; batches fill to it (the trigger fires on the same number,
+	 *  read fresh per turn by the composition root). OPTIONAL with the
+	 *  factory default (4096) so test fixtures stay minimal; the server
+	 *  callers wire the live effective settings (extraction-UX redesign,
+	 *  2026-09-24). */
+	getChunkTokens?: () => number;
+}
 
 export interface NotesImportInput {
 	/** The source's file path — its identity (deterministic src id) AND its
@@ -760,10 +767,11 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 				console.info(`[extraction ${chatId}] nothing uncovered — no-op`);
 				return { nodes: 0, edges: 0, events: 0 };
 			}
-			const batches = batchRuns(covered.uncovered, EXTRACTION.chunkTokens);
+			const chunkTokens = deps.getChunkTokens?.() ?? FACTORY_SETTINGS.graph.extractionChunkTokens;
+			const batches = batchRuns(covered.uncovered, chunkTokens);
 			console.info(
 				`[extraction ${chatId}] pipeline start — ${covered.uncoveredTokens} uncovered tok, ` +
-					`${covered.uncoveredCount} messages, ${batches.length} batch(es) of ≤${EXTRACTION.chunkTokens} tok`,
+					`${covered.uncoveredCount} messages, ${batches.length} batch(es) of ≤${chunkTokens} tok`,
 			);
 			for (const batch of batches) {
 				// The batch's prompt view: SESSION header + the batch's lines,

src/core/settings-resolution.ts

@@ -205,6 +205,10 @@ export function resolveSettings(record: UserSettings | null): EffectiveSettings
 			// the embedding/clustering/labeling rungs and the BYOK embeddingModel
 			// are gone (stale record keys are simply never read here).
 			enabled: graph.enabled ?? FACTORY_SETTINGS.graph.enabled,
+			// The chunk budget (extraction-UX redesign, 2026-09-24): absent
+			// (pre-redesign record, fresh install) resolves to the factory
+			// 4096; the sanitizer has already clamped/floored any stored value.
+			extractionChunkTokens: graph.extractionChunkTokens ?? FACTORY_SETTINGS.graph.extractionChunkTokens,
 		},
 	};
 }
@@ -216,7 +220,7 @@ export function resolveSettings(record: UserSettings | null): EffectiveSettings
  * switch. Used by the chat-handler's post-turn trigger. (Wave 7: the master
  * switch is the ONLY graph setting left — the section collapsed.)
  */
-export function extractionEnabled(graph: Required<GraphSettings>): boolean {
+export function extractionEnabled(graph: { enabled: boolean }): boolean {
 	return graph.enabled;
 }
 
@@ -228,7 +232,7 @@ export function extractionEnabled(graph: Required<GraphSettings>): boolean {
  * Teacher's tool factories consume this at registration time.
  */
 export function graphToolsEnabled(effective: {
-	graph: Required<GraphSettings>;
+	graph: { enabled: boolean };
 	agent: { graphTools: { enabled?: boolean } };
 }): boolean {
 	return effective.graph.enabled && (effective.agent.graphTools.enabled ?? true);

src/core/settings.ts

@@ -255,6 +255,26 @@ export interface GraphSettings {
 	 *  names, and the prober graph tools read the ledgers directly — there
 	 *  is nothing left to configure. Data stays stored either way. */
 	enabled?: boolean;
+	/** The chunk budget (extraction-UX redesign, owner 2026-09-24): the
+	 *  transcript-token share of the extractor's context — a run fires
+	 *  when a chat's UNCOVERED tokens reach it, and the run batches the
+	 *  oldest uncovered messages into runs of ≤ this many tokens. It
+	 *  bounds both cost and chunk size (the extractor prompt also
+	 *  carries the whole graph + instructions, so a smaller budget means
+	 *  more, smaller runs — each paying that fixed overhead).
+	 *
+	 *  FACTORY DEFAULT 4096 (the pre-setting constant, config.ts's
+	 *  EXTRACTION.chunkTokens — vision-extraction-coverage.md, 2026-09-15).
+	 *
+	 *  FLOOR 500 (EXTRACTION_CHUNK_TOKENS_FLOOR, the implementer's call
+	 *  per the owner's dispatch): every run pays the graph-carrying
+	 *  prompt overhead out of the write channel's money — a budget below
+	 *  ~500 tokens would fire penny-batches that cost more per extracted
+	 *  token than the content is worth, so the sanitizer clamps and the
+	 *  PUT rejects below it. NO CEILING on purpose: a large budget just
+	 *  delays extraction — the user's stated cost/thoroughness tradeoff,
+	 *  not a misconfiguration to police. */
+	extractionChunkTokens?: number;
 }
 
 /** THE record. Every section optional (delta); unknown top-level keys are
@@ -307,9 +327,14 @@ export const FACTORY_SETTINGS: FactorySettings = {
 		sessionNameSerif: true,
 		mdRendering: { headingWeight: 900, boldColor: null, italicColor: null },
 	},
-	graph: { enabled: true },
+	graph: { enabled: true, extractionChunkTokens: 4096 },
 };
 
+/** The chunk budget's validated floor (GraphSettings.extractionChunkTokens
+ *  — see its doc for the penny-batch rationale; the settings PUT names this
+ *  in its rejection, the sanitizer clamps to it). */
+export const EXTRACTION_CHUNK_TOKENS_FLOOR = 500;
+
 // ─── Sanitizer ─────────────────────────────────────────────────────────────
 
 const PROSE_FONT_MIN = 12;
@@ -462,9 +487,20 @@ function sanitizeGraph(raw: Record<string, unknown>): GraphSettings {
 	// this reconstruction — the migration story: the next graph-section
 	// write (PUT is replace-whole) persists the collapsed shape, and no
 	// active code ever looks at the stale fields.
+	//
+	// extractionChunkTokens (extraction-UX redesign, 2026-09-24): the chunk
+	// budget — clamp-never-reject (the bd68486 discipline): a finite
+	// positive number floors to EXTRACTION_CHUNK_TOKENS_FLOOR (fractions
+	// floor to integers), anything else drops to the factory default at
+	// resolution. A disk record below the floor (older app, hand edit)
+	// clamps UP — the floor is a cost protection, not data to honor.
 	const out: GraphSettings = {};
 	const enabled = boolOrDrop(raw.enabled);
 	if (enabled !== undefined) out.enabled = enabled;
+	const rawTokens = raw.extractionChunkTokens;
+	if (typeof rawTokens === "number" && Number.isFinite(rawTokens) && rawTokens > 0) {
+		out.extractionChunkTokens = Math.max(EXTRACTION_CHUNK_TOKENS_FLOOR, Math.floor(rawTokens));
+	}
 	return out;
 }
 

src/server/chat-handler.ts

@@ -317,7 +317,10 @@ export async function handleChatRequest(
 				// pipeline knobs — embedding/clustering/labeling — gate inside the
 				// pipeline and its consumers, later waves, via the same resolved view.)
 				if (extractionEnabled(effective.graph)) {
-					triggerExtraction(stores, extraction, chatId);
+					// Fresh per-turn read of the graph section's chunk budget
+					// (extraction-UX redesign, 2026-09-24): the trigger compares
+					// against it and the pipeline's batches share it.
+					triggerExtraction(stores, extraction, chatId, effective.graph.extractionChunkTokens);
 				}
 				// LAST: a poller that sees not-in-flight must read an already-persisted
 				// record — endTurn only after persistTurn has done its job.

src/server/chats.ts

@@ -1,6 +1,8 @@
 import { abortExtraction, extractionStatuses } from "../agent/subagents/extraction.ts";
+import { coverageOf } from "../core/coverage.ts";
 import { deleteChatTraces, type ChatDeleteMode, type ChatDeletionStats } from "../core/graph-deletion.ts";
 import { titleFromPrompt } from "../core/contracts.ts";
+import type { UIMessage } from "ai";
 import { graphRevision } from "./graph.ts";
 import { stores } from "./stores.ts";
 import { isTurnRunning } from "./turn-liveness.ts";
@@ -110,3 +112,47 @@ export async function deleteChatSession(chatId: string, mode: ChatDeleteMode): P
 	stores.chatStore.deleteChat(chatId);
 	return { ok: true, mode, stats, jobsRemoved, graphRevision: graphRevision() };
 }
+
+/** One session's coverage read (extraction-UX redesign, owner dispatch
+ *  2026-09-24): the chat view's ring meter + popover data — the same
+ *  derivation the all-sessions list serves (/api/graph/coverage), scoped
+ *  to one chat. "Uncovered" stays DERIVED per request (fingerprint the
+ *  transcript, diff the coverage ledger — never dual-tracked).
+ *
+ *  lastFoldedAt: the newest coverage row's fold timestamp — a cheap single
+ *  pass over the chat's ledger rows (the ring popover's "last extraction"
+ *  line); null before the session's first fold. */
+export interface SessionCoverage {
+	totalMessages: number;
+	coveredCount: number;
+	uncoveredCount: number;
+	coveredTokens: number;
+	uncoveredTokens: number;
+	/** True while a chat-kind extraction run is registered for this session. */
+	running: boolean;
+	/** ISO of the newest fold in this session's coverage rows; null before any. */
+	lastFoldedAt: string | null;
+}
+
+/** The per-session coverage block (see SessionCoverage). Null when the
+ *  chat doesn't exist — callers own the 404. */
+export function sessionCoverage(chatId: string): SessionCoverage | null {
+	const record = stores.chatStore.getChat(chatId);
+	if (!record) return null;
+	const entries = stores.graphStore.readCoverage();
+	const cov = coverageOf(record.messages as UIMessage[], entries, chatId);
+	let lastFoldedAt: string | null = null;
+	for (const entry of entries) {
+		if (entry.chatId !== chatId) continue;
+		if (lastFoldedAt === null || entry.foldedAt > lastFoldedAt) lastFoldedAt = entry.foldedAt;
+	}
+	return {
+		totalMessages: cov.slots.length,
+		coveredCount: cov.coveredCount,
+		uncoveredCount: cov.uncoveredCount,
+		coveredTokens: cov.coveredTokens,
+		uncoveredTokens: cov.uncoveredTokens,
+		running: extractionStatuses().some((run) => run.kind === "chat" && run.chatId === chatId),
+		lastFoldedAt,
+	};
+}

src/server/settings-body.ts

@@ -22,7 +22,7 @@ import type {
 	ModelsSettings,
 	RoleModelOverride,
 } from "../core/settings.ts";
-import { BACKGROUND_MODEL_ROLES, MODEL_SLOTS } from "../core/settings.ts";
+import { BACKGROUND_MODEL_ROLES, EXTRACTION_CHUNK_TOKENS_FLOOR, MODEL_SLOTS } from "../core/settings.ts";
 import { TOGGLEABLE_TOOLS } from "../core/pending.ts";
 
 /** Parsed-or-rejected — `ok: false` carries the 400's error message. */
@@ -283,15 +283,33 @@ export function parseAppearanceSettingsBody(body: unknown): SettingsBodyResult<A
 export function parseGraphSettingsBody(body: unknown): SettingsBodyResult<GraphSettings> {
 	const raw = asRecord(body);
 	if (!raw) return { ok: false, error: "Invalid JSON body" };
-	// Wave 7 collapse (owner ruling 2026-09-23): the section is the master
+	// Wave 7 collapse (owner ruling 2026-09-23) + the extraction-UX
-	// switch ONLY. PUT is replace-whole — a body like {enabled: true} IS the
+	// redesign (2026-09-24): the section is the master switch and the
-	// whole section now; the dead rungs' keys in old records are unread
+	// chunk budget. PUT is replace-whole — a body like {enabled: true} IS
-	// (the sanitizer drops them; see sanitizeGraph).
+	// the whole section (extractionChunkTokens absent = factory default at
+	// resolution); the dead rungs' keys in old records are unread (the
+	// sanitizer drops them; see sanitizeGraph).
 	const settings: GraphSettings = {};
 	if (raw.enabled !== undefined) {
 		if (typeof raw.enabled !== "boolean") return { ok: false, error: "enabled must be a boolean" };
 		settings.enabled = raw.enabled;
 	}
+	if (raw.extractionChunkTokens !== undefined) {
+		if (typeof raw.extractionChunkTokens !== "number" || !Number.isFinite(raw.extractionChunkTokens)) {
+			return { ok: false, error: "extractionChunkTokens must be a number" };
+		}
+		const floored = Math.floor(raw.extractionChunkTokens);
+		if (floored < EXTRACTION_CHUNK_TOKENS_FLOOR) {
+			// the floor's rationale lives on GraphSettings.extractionChunkTokens:
+			// every run pays the graph-carrying prompt overhead — penny-batches
+			// cost more per extracted token than the content is worth.
+			return {
+				ok: false,
+				error: `extractionChunkTokens must be at least ${EXTRACTION_CHUNK_TOKENS_FLOOR} (smaller batches waste the per-run graph overhead)`,
+			};
+		}
+		settings.extractionChunkTokens = floored;
+	}
 	return { ok: true, settings };
 }
 

src/server/turn-service.ts

@@ -19,7 +19,6 @@ import type { UIMessage } from "ai";
 import { withPlanBlocks } from "../core/plan-blocks.ts";
 import { coverageOf } from "../core/coverage.ts";
 import type { ChatStore, GraphStore } from "../core/ports.ts";
-import { EXTRACTION } from "../../config.ts";
 import type { ExtractionPipeline } from "../agent/subagents/extraction.ts";
 import { ModelsNotConfiguredError } from "../core/settings.ts";
 
@@ -74,11 +73,14 @@ export function persistTurn(chatStore: ChatStore, chatId: string, messages: UIMe
 /**
  * The graph write channel (vision §1 construction): the extraction pipeline
  * (extractor → auditor → merger — the sole graph writer) runs ASYNC once a
- * chat's UNCOVERED transcript tokens reach EXTRACTION.chunkTokens
+ * chat's UNCOVERED transcript tokens reach the chunk budget
  * (vision-extraction-coverage.md, 2026-09-15 — replacing the old
  * every-3-quiz-answers count: content size is the honest signal, and
- * quiz-less sessions extract too). The pipeline itself extracts only the
+ * quiz-less sessions extract too). The budget is the graph section's
- * uncovered batches. Fire-and-forget — never blocks the turn; failures are
+ * extractionChunkTokens setting (extraction-UX redesign, 2026-09-24) —
+ * the composition root passes the per-turn effective read (chat-handler
+ * resolves fresh per turn, same as every other gate). The pipeline
+ * itself extracts only the uncovered batches. Fire-and-forget — never blocks the turn; failures are
  * logged by the pipeline and leave coverage untouched, so the next trigger
  * (or the manual extract button) re-runs what's left.
  *
@@ -90,13 +92,14 @@ export function triggerExtraction(
 	deps: { chatStore: ChatStore; graphStore: GraphStore },
 	extraction: ExtractionPipeline,
 	chatId: string,
+	chunkTokens: number,
 ): void {
 	if (process.env.NODE_ENV === "test") return;
 	try {
 		const record = deps.chatStore.getChat(chatId);
 		if (!record) return;
 		const covered = coverageOf(record.messages as UIMessage[], deps.graphStore.readCoverage(), chatId);
-		if (covered.uncoveredTokens < EXTRACTION.chunkTokens) return;
+		if (covered.uncoveredTokens < chunkTokens) return;
 		void extraction.runExtraction(chatId).catch((err) => {
 			// BYOK (owner, 2026-09-22): an unconfigured write channel SKIPS
 			// (the coverage ledger keeps the messages uncovered — the next

tests/extraction.test.ts

@@ -890,7 +890,7 @@ function passThroughAuditStep(): FauxResponseStep {
 }
 
 /** A session with UNCOVERED-multiple-batch mass: five long distinct messages
- *  (~1200 tok each — 3600+1200 > EXTRACTION.chunkTokens 4096 → batches of
+ *  (~1200 tok each — 3600+1200 > the factory chunk budget 4096 → batches of
  *  [m1,m2,m3] and [m4,m5]). */
 function chunkyChat() {
 	const chat = chatStore.createChat("Chunky coverage fixture");

tests/graph.test.ts

@@ -21,6 +21,7 @@ import type { UIMessage } from "ai";
 import type { AuditResult, NamingRunUsage } from "../src/core/contracts.ts";
 import type { QuestionAnswerData } from "../src/core/question-core.ts";
 import { getGraph, graphSnapshot, mergeFindings, type GraphDeps } from "../src/core/graph.ts";
+import { coverageSlots } from "../src/core/coverage.ts";
 import { graphStore } from "../src/store/graph.ts";
 import { chatStore } from "../src/store/chats.ts";
 import { LEDGER_FILES, PATHS, SOURCES_FILE } from "../config.ts";
@@ -618,7 +619,7 @@ describe("graph ledger store", () => {
 // ─── session deletion (wave 6 — the first destructive ledger operation) ─────
 
 import { deleteChatTraces, type ChatDeletionStats } from "../src/core/graph-deletion.ts";
-import { deleteChatSession } from "../src/server/chats.ts";
+import { deleteChatSession, sessionCoverage } from "../src/server/chats.ts";
 import { beginTurn, endTurn } from "../src/server/turn-liveness.ts";
 import { jobStore } from "../src/store/jobs.ts";
 import {
@@ -989,3 +990,71 @@ describe("single-node deletion (deleteNodeTraces + deleteGraphNode, node interlu
 		assert.deepEqual(deleteGraphNode("n_orch"), { ok: false, status: 404, code: "not_found", error: "No such node" });
 	});
 });
+
+describe("session coverage read (extraction-UX redesign, 2026-09-24)", () => {
+	it("one session's block: derived uncovered, the newest fold, honest nulls", () => {
+		// Empty coverage: everything uncovered, no fold yet, not running.
+		const chat = fixtureChat("coverage read", [
+			user("cov_u1", "tell me about coverage reads"),
+			user("cov_u2", "and about per-session blocks"),
+			user("cov_u3", "a third distinct message"),
+		]);
+		const empty = sessionCoverage(chat.id)!;
+		assert.ok(empty);
+		assert.equal(empty.totalMessages, 3);
+		assert.equal(empty.coveredCount, 0);
+		assert.equal(empty.uncoveredCount, 3);
+		assert.equal(empty.coveredTokens, 0);
+		assert.ok(empty.uncoveredTokens > 0);
+		assert.equal(empty.running, false);
+		assert.equal(empty.lastFoldedAt, null, "no fold yet");
+
+		// Fold the first two messages: the read derives the split + the
+		// newest fold timestamp from the ledger rows.
+		const slots = coverageSlots(chatStore.getChat(chat.id)!.messages as UIMessage[]);
+		graphStore.appendCoverage({ chatId: chat.id, fp: slots[0]!.fp, tokens: slots[0]!.tokens, foldedAt: "2026-09-24T10:00:00.000Z" });
+		graphStore.appendCoverage({ chatId: chat.id, fp: slots[1]!.fp, tokens: slots[1]!.tokens, foldedAt: "2026-09-24T11:30:00.000Z" });
+		// Another session's row must not leak into this read.
+		graphStore.appendCoverage({ chatId: "chat_other", fp: slots[2]!.fp, tokens: slots[2]!.tokens, foldedAt: "2026-09-24T23:00:00.000Z" });
+
+		const cov = sessionCoverage(chat.id)!;
+		assert.equal(cov.totalMessages, 3);
+		assert.equal(cov.coveredCount, 2);
+		assert.equal(cov.uncoveredCount, 1);
+		assert.equal(cov.coveredTokens, slots[0]!.tokens + slots[1]!.tokens);
+		assert.equal(cov.uncoveredTokens, slots[2]!.tokens);
+		assert.equal(cov.lastFoldedAt, "2026-09-24T11:30:00.000Z", "the NEWEST fold, and scoped to this session's rows");
+	});
+
+	it("running: true only for THIS session's chat-kind run (the registry pin)", () => {
+		const chat = fixtureChat("coverage running", [user("cov_r1", "running pin")]);
+		const g = globalThis as { __lhExtractionRuns?: unknown };
+		const realRuns = g.__lhExtractionRuns;
+		try {
+			g.__lhExtractionRuns = {
+				running: new Map([
+					// a notes run for the same id is NOT this session's chat run
+					["src_notes", { chatId: "src_notes", kind: "notes", phase: "extracting", startedAt: 1, usage: {}, controller: new AbortController() }],
+					["other_chat", { chatId: "other_chat", kind: "chat", phase: "auditing", startedAt: 2, usage: {}, controller: new AbortController() }],
+				]),
+				inFlight: new Set(),
+				lastStartedAt: 0,
+			};
+			assert.equal(sessionCoverage(chat.id)!.running, false, "no chat-kind run for this id");
+			g.__lhExtractionRuns = {
+				running: new Map([
+					[chat.id, { chatId: chat.id, kind: "chat", phase: "extracting", startedAt: 3, usage: {}, controller: new AbortController() }],
+				]),
+				inFlight: new Set(),
+				lastStartedAt: 0,
+			};
+			assert.equal(sessionCoverage(chat.id)!.running, true);
+		} finally {
+			g.__lhExtractionRuns = realRuns;
+		}
+	});
+
+	it("unknown chat → null (the caller owns the 404)", () => {
+		assert.equal(sessionCoverage("chat_never_was"), null);
+	});
+});

tests/settings-body.test.ts

@@ -162,6 +162,28 @@ describe("parseGraphSettingsBody", () => {
 		assert.equal(parseGraphSettingsBody("nope").ok, false);
 	});
 
+	it("extractionChunkTokens: whole tokens ≥ the 500 floor (extraction-UX redesign, 2026-09-24)", () => {
+		const ok = parseGraphSettingsBody({ enabled: true, extractionChunkTokens: 2048 });
+		assert.ok(ok.ok);
+		assert.deepEqual(ok.settings, { enabled: true, extractionChunkTokens: 2048 });
+		// absent = unset — replace-whole keeps the factory default at resolution
+		const absent = parseGraphSettingsBody({ enabled: true });
+		assert.ok(absent.ok);
+		assert.deepEqual(absent.settings, { enabled: true });
+		// fractions floor to whole tokens
+		const fraction = parseGraphSettingsBody({ extractionChunkTokens: 1024.9 });
+		assert.ok(fraction.ok);
+		assert.equal(fraction.settings.extractionChunkTokens, 1024);
+		// below the cost floor: 400 with the floor named (penny-batches)
+		const tiny = parseGraphSettingsBody({ extractionChunkTokens: 100 });
+		assert.equal(tiny.ok, false, "below-floor rejected");
+		assert.match(tiny.ok === false ? tiny.error : "", /at least 500/);
+		// junk shapes: 400
+		assert.equal(parseGraphSettingsBody({ extractionChunkTokens: "4096" }).ok, false);
+		assert.equal(parseGraphSettingsBody({ extractionChunkTokens: NaN }).ok, false);
+		assert.equal(parseGraphSettingsBody({ extractionChunkTokens: null }).ok, false);
+	});
+
 	it("the dead wave-6 rungs in a body are ignored — the section collapses on write", () => {
 		// Old clients may still send {embedding: true, embeddingModel: …};
 		// the parser reads ONLY the master switch — the dead keys are not

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.
+		// wave 7 collapse: the section IS the master switch (absent budget
-		assert.deepEqual(eff.graph, { enabled: false });
+		// 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)", () => {

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)", () => {