diff --git a/src/agent/subagents/extraction.ts b/src/agent/subagents/extraction.ts
index 3474bf8..2dd101b 100644
--- a/src/agent/subagents/extraction.ts
+++ b/src/agent/subagents/extraction.ts
@@ -28,7 +28,6 @@ import type { GraphStore } from "../../core/ports.ts";
 import { emit } from "../../core/events.ts";
 import { settleGraphLayout } from "../../core/layout-settle.ts";
 import { batchRuns, coverageOf, messageViewLines } from "../../core/coverage.ts";
-import { teacherProseBlocks } from "../../core/coverage.ts";
 import type { LhMessage } from "../../core/native-messages.ts";
 import { auditorGraphTools } from "../tools/graph.ts";
 import { runSubmitAgent, healStringifiedArrays } from "./submit-agent.ts";
@@ -42,10 +41,15 @@ import { runSubmitAgent, healStringifiedArrays } from "./submit-agent.ts";
  * gain; the extractor itself is the assembler now):
  *
  *   extractor (LLM)  the ONE stage that sees the raw source (a session
- *                    rendered as the teacher's prose, or a notes file
- *                    verbatim, walked in stretches) → submits NEW core
- *                    ideas + reasoning chains (owner redesign,
- *                    2026-09-30). DIGEST-AWARE (2026-09-30 evening):
+ *                    rendered as the teacher's prose — each passage
+ *                    labeled with its ACTUAL message id, "TEACHER [id]",
+ *                    owner 2026-10-13 — or a notes file verbatim, walked
+ *                    in stretches) → submits NEW core ideas + reasoning
+ *                    chains (owner redesign, 2026-09-30); a session
+ *                    submit additionally carries each proposition's
+ *                    messageId — the anchor the merger stamps into the
+ *                    node's message-granular provenance (2026-10-13).
+ *                    DIGEST-AWARE (2026-09-30 evening):
  *                    when the source already yielded material, the
  *                    prompt carries THE GRAPH SO FAR (that source's
  *                    propositions + chains, ids verbatim) and the
@@ -104,14 +108,16 @@ import { runSubmitAgent, healStringifiedArrays } from "./submit-agent.ts";
 
 /**
  * The extraction view: the session as TEACHER PROSE ONLY (owner ruling,
- * 2026-09-28 — supersedes the 2026-09-27 whole-session markdown view):
- * plain prose paragraphs under the session title. The shared markdown
- * engine (core/session-markdown.ts) keeps the full session format for
- * the future user-facing export; the extractor no longer uses it.
+ * 2026-09-28 — supersedes the 2026-09-27 whole-session markdown view),
+ * each passage labeled with its actual message id (2026-10-13). The
+ * shared markdown engine (core/session-markdown.ts) keeps the full session
+ * format for the future user-facing export; the extractor no longer uses
+ * it.
  */
 
 /** The whole-record view (used by callers that render a full session;
- *  the pipeline itself batches). TEACHER PROSE ONLY (owner, 2026-09-28).
+ *  the pipeline itself batches). TEACHER PROSE ONLY (owner, 2026-09-28),
+ *  passages labeled with their message ids (2026-10-13).
  */
 export function transcriptView(record: ChatRecord): string {
 	return proseView(record.messages, record.title);
@@ -119,13 +125,17 @@ export function transcriptView(record: ChatRecord): string {
 
 /** The extraction view under the teacher-prose ruling (owner, 2026-09-28):
  *  ONLY the teacher agent's text blocks — no learner messages, no
- *  thinking, no tool calls or results, no quiz blocks. Plain paragraphs
- *  under the session title; the shared markdown engine stays reserved for
- *  the future user-facing export. */
+ *  thinking, no tool calls or results, no quiz blocks — each labeled with
+ *  its ACTUAL message id (owner, 2026-10-13): the view lines ARE
+ *  core/coverage.ts messageViewLines ("TEACHER [id] text"), the exact
+ *  lines the coverage fingerprints hash, so the extractor can anchor
+ *  every proposition to the passage it came from (the session submit's
+ *  required messageId). The shared markdown engine stays reserved for the
+ *  future user-facing export. */
 function proseView(messages: ReadonlyArray<LhMessage>, title?: string): string {
-	const prose = teacherProseBlocks(messages);
+	const lines = messages.flatMap((message) => messageViewLines(message, message.id));
 	const head = title && title.length > 0 ? `# ${title}\n\n` : "";
-	return head + prose.join("\n\n");
+	return head + lines.join("\n\n");
 }
 
 // ─── the extractor ──────────────────────────────────────────────────────────
@@ -176,21 +186,45 @@ const chainSchema = Type.Object({
 // here + a ??-fill at the submit seam (fillFindings/fillAudit below) — same
 // contract on the wire (omission tolerated, empty never means "invalid"),
 // no zod left in the agent band.
-const findingsProps = {
+const propositionsDescription =
+	"Only the NEW core ideas this stretch contributes — ideas the prompt's THE GRAPH SO FAR already " +
+	"holds are referenced by id in chains, never restated here.";
+const chainsDescription =
+	"Every argument this stretch makes — including arguments that join new ideas to established " +
+	"ones; conclusions reusable by id as premises of later chains; bare ideas (no argument) ride " +
+	"the propositions list alone; pass [] when none — never omit the field.";
+
+const findingsSchema = Type.Object({
 	propositions: Type.Array(Type.Object(propositionProps), {
-		description:
-			"Only the NEW core ideas this stretch contributes — ideas the prompt's THE GRAPH SO FAR already " +
-			"holds are referenced by id in chains, never restated here.",
+		description: propositionsDescription,
 	}),
 	chains: Type.Array(chainSchema, {
+		description: chainsDescription,
+	}),
+});
+
+// THE SESSION EXTENSION (owner, 2026-10-13): every session proposition
+// carries a REQUIRED messageId — the anchor of the passage it came from,
+// copied from the view's "TEACHER [id]" label (validated at the submit
+// seam against the CURRENT batch). The NOTES door has no messages: its
+// schema stays the base shape above, prompt and wire unchanged.
+const sessionPropositionProps = {
+	...propositionProps,
+	messageId: Type.String({
 		description:
-			"Every argument this stretch makes — including arguments that join new ideas to established " +
-			"ones; conclusions reusable by id as premises of later chains; bare ideas (no argument) ride " +
-			"the propositions list alone; pass [] when none — never omit the field.",
+			"The message id of the ONE passage in this stretch that most directly states or explains this " +
+			'proposition — copy it EXACTLY from that passage\'s "TEACHER [id]" label.',
 	}),
 };
 
-const findingsSchema = Type.Object(findingsProps);
+const sessionFindingsSchema = Type.Object({
+	propositions: Type.Array(Type.Object(sessionPropositionProps), {
+		description: propositionsDescription,
+	}),
+	chains: Type.Array(chainSchema, {
+		description: chainsDescription,
+	}),
+});
 
 /** What the extractor SUBMITS (the redesign's wire shape) — propositions
  *  + chains. fillFindings normalizes it; validateFindingsChains checks
@@ -199,6 +233,10 @@ const findingsSchema = Type.Object(findingsProps);
  *  2026-09-30: no edge translation at any seam). */
 type FindingsSubmit = Static<typeof findingsSchema>;
 
+/** The SESSION wire — the notes shape plus the REQUIRED messageId anchor
+ *  on every proposition (owner, 2026-10-13). */
+type SessionFindingsSubmit = Static<typeof sessionFindingsSchema>;
+
 // VERDICTS-ONLY (owner, 2026-09-28): the auditor never alters the
 // extractor's findings, so it does not restate them — links are its
 // ENTIRE deliverable (owner, 2026-09-28 evening: the edges argument is
@@ -217,9 +255,11 @@ const auditSchema = Type.Object({
 	),
 });
 
-// The notes front door's shapes are IDENTICAL to the session shapes now
-// (the only difference was quiz attribution, which no longer exists):
-// one schema, one findings type, both front doors.
+// The notes front door's wire shape is the session shape MINUS the
+// messageId anchor (owner, 2026-10-13: only the SESSION door demands
+// passage anchors — notes have no messages, so their prompt and schema
+// stay exactly as they were): one base findings type for both doors,
+// the anchor riding as an optional field.
 type NotesFindings = SessionFindings;
 type NotesAuditResult = AuditVerdicts;
 
@@ -233,13 +273,30 @@ type NotesAuditResult = AuditVerdicts;
 // a pile of nodes with no structure). Only the per-item aliases stay
 // optional with a ??-fill.
 
-function fillFindings(raw: FindingsSubmit): FindingsSubmit {
+function fillFindings<T extends { propositions: Array<{ aliases?: string[] }>; chains: unknown }>(
+	raw: T,
+): T {
 	return {
+		...raw,
 		propositions: raw.propositions.map((p) => ({ ...p, aliases: p.aliases ?? [] })),
-		chains: raw.chains,
 	};
 }
 
+/** The notes fill: the shared alias ??-fill PLUS the door's boundary — a
+ *  stray messageId (the notes schema has none; extra properties pass
+ *  schema validation) is stripped so notes provenance stays chat-level
+ *  (the file is the anchor, owner 2026-09-13). */
+function fillNotesFindings(raw: FindingsSubmit): FindingsSubmit {
+	return fillFindings({
+		...raw,
+		propositions: raw.propositions.map((p) => {
+			const stripped = { ...p } as typeof p & { messageId?: unknown };
+			delete stripped.messageId;
+			return stripped;
+		}),
+	});
+}
+
 /** The chain laws (extractor redesign, 2026-09-30; digest-aware
  *  2026-09-30 evening) — the LOUD channel: runSubmitAgent turns a
  *  problem string into an error tool result and the model re-submits
@@ -266,12 +323,38 @@ function validateFindingsChains(value: FindingsSubmit, existingIds: ReadonlySet<
 	return null;
 }
 
+/** The SESSION anchor law (owner, 2026-10-13): every proposition names a
+ *  passage of the CURRENT batch — nonempty, and a teacher-prose message
+ *  id present in the stretch this extractor is reading (the same ids the
+ *  view's TEACHER [id] labels carry). Refused anchors ride the existing
+ *  error-back channel: no merge, no coverage checkpoint, until a valid
+ *  submit lands. The boundary is strict on purpose — an id from a LATER
+ *  or already-covered batch, another chat, or a learner/tool message is
+ *  refused even when it is a real message id of this chat. */
+function validateSessionAnchors(value: SessionFindingsSubmit, batchIds: ReadonlySet<string>): string | null {
+	for (const p of value.propositions) {
+		if (p.messageId.trim().length === 0) {
+			return `propositions: "${p.id}" is missing its messageId — copy the message id from the brackets of the passage (TEACHER [id]) that most directly states or explains it.`;
+		}
+		if (!batchIds.has(p.messageId)) {
+			return `propositions: "${p.id}" names messageId "${p.messageId}", which is not a passage of THIS stretch — copy the id from the brackets of one of this stretch's own TEACHER [id] passages.`;
+		}
+	}
+	return null;
+}
+
 /** (chains-primary, owner 2026-09-30) the wire IS the pipeline shape
  *  now: propositions + chains, no translation — the stores keep the
  *  chains and the derived edge view is recomputed on read. The fill
  *  already ran inside runSubmitAgent; this only re-asserts the
- *  aliases-filled type. */
-const asSessionFindings = (raw: FindingsSubmit): SessionFindings => ({
+ *  aliases-filled type (and preserves the session submit's messageId
+ *  anchor, 2026-10-13 — both doors lift through here). */
+const asSessionFindings = (
+	raw: {
+		propositions: Array<{ id: string; name: string; statement: string; aliases?: string[]; messageId?: string }>;
+		chains: Array<{ premises: string[]; conclusion: string }>;
+	},
+): SessionFindings => ({
 	propositions: raw.propositions.map((p) => ({ ...p, aliases: p.aliases ?? [] })),
 	chains: raw.chains,
 });
@@ -293,6 +376,14 @@ function fillAudit(raw: Static<typeof auditSchema>): AuditVerdicts {
 // describing Quiz/Recall-check/Question blocks was stale since the
 // 2026-09-28 teacher-prose ruling and is simply omitted.)
 
+/** The session-only anchor instruction (owner, 2026-10-13, verbatim):
+ *  passages arrive labeled "TEACHER [id]" and every proposition must
+ *  name the ONE passage it came from — the anchor the merger stamps
+ *  into message-granular provenance. Notes have no passages: their
+ *  contextualization stays untouched. */
+export const SESSION_MESSAGE_ID_RULE =
+	"For each new proposition, copy the message ID of the passage that most directly states or explains it into messageId.";
+
 export const SESSION_PREAMBLE =
 	"You are the extraction stage of a learning application. You read one stretch of a source — a teaching " +
 	"session, rendered as the teacher's prose in reading order — and report what it teaches as findings " +
@@ -337,7 +428,7 @@ reappear, by id, as a premise of later chains. A bare idea that no argument uses
 propositions list alone. Include every field even when empty — "chains": [] when the source makes no
 arguments. The tool's field descriptions carry the details.`;
 
-export const EXTRACTOR_INSTRUCTIONS = `${SESSION_PREAMBLE}\n\n${EXTRACTION_CORE}`;
+export const EXTRACTOR_INSTRUCTIONS = `${SESSION_PREAMBLE}\n\n${EXTRACTION_CORE}\n\n${SESSION_MESSAGE_ID_RULE}`;
 export const NOTES_EXTRACTOR_INSTRUCTIONS = `${NOTES_PREAMBLE}\n\n${EXTRACTION_CORE}`;
 
 // ── the same-source digest (owner, 2026-09-30 evening) ──
@@ -368,28 +459,33 @@ export function sourceDigest(graph: DerivedGraph, sourceId: string): string {
 	return lines.join("\n");
 }
 
-/** The extractor over ONE session transcript (the chat front door). */
+/** The extractor over ONE session transcript (the chat front door).
+ *  `batchIds` — the CURRENT batch's teacher-prose message ids — is the
+ *  anchor boundary: every submitted proposition's messageId must name
+ *  one of them (validateSessionAnchors at the submit seam). */
 function runExtractor(
 	engine: PiEngine | undefined,
 	sourceId: string,
 	prompt: string,
 	existingIds: ReadonlySet<string>,
+	batchIds: ReadonlySet<string>,
 	signal: AbortSignal | undefined,
 	onStep: (usage: Usage, model: string, step: number, finishReason: string, tools: string) => void,
 ): Promise<SessionFindings> {
 	// Chains in (the wire), chains out (the store) — no translation seam
 	// since chains-primary. Validation runs at the submit seam (error-back)
-	// over the MIXED namespace: local ids + existing graph ids.
-	return runSubmitAgent<FindingsSubmit>({
+	// over the MIXED namespace: local ids + existing graph ids, plus the
+	// session anchor law (messageId ∈ the current batch, 2026-10-13).
+	return runSubmitAgent<SessionFindingsSubmit>({
 		role: "extractor",
 		// Debug recorder key: the source id (the run's ledger key — the
 		// chat's chatId for chat runs, the src id for notes).
 		chatId: sourceId,
 		toolName: "submit_findings",
 		toolDescription: "Submit the session findings.",
-		parameters: findingsSchema,
+		parameters: sessionFindingsSchema,
 		fill: fillFindings,
-		validate: (value) => validateFindingsChains(value, existingIds),
+		validate: (value) => validateSessionAnchors(value, batchIds) ?? validateFindingsChains(value, existingIds),
 		systemPrompt: EXTRACTOR_INSTRUCTIONS,
 		prompt,
 		engine,
@@ -401,7 +497,9 @@ function runExtractor(
 }
 
 /** The extractor over ONE source of raw personal notes (the format-agnostic
- *  front door): same single-submit shape, notes-mode prompt + schema. */
+ *  front door): same single-submit shape, notes-mode prompt + schema —
+ *  the BASE wire (no messageId: notes have no passages, and a stray one
+ *  is stripped at the fill seam). */
 function runNotesExtractor(
 	engine: PiEngine | undefined,
 	sourceId: string,
@@ -417,7 +515,7 @@ function runNotesExtractor(
 		toolName: "submit_findings",
 		toolDescription: "Submit the notes findings.",
 		parameters: findingsSchema,
-		fill: fillFindings,
+		fill: fillNotesFindings,
 		validate: (value) => validateFindingsChains(value, existingIds),
 		systemPrompt: NOTES_EXTRACTOR_INSTRUCTIONS,
 		prompt,
@@ -793,7 +891,12 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 		}
 	}
 
-	async function extract(jobKey: string, sourceId: string, view: string): Promise<SessionFindings> {
+	async function extract(
+		jobKey: string,
+		sourceId: string,
+		view: string,
+		batchIds: ReadonlySet<string>,
+	): Promise<SessionFindings> {
 		const signal = runningExtractions.get(jobKey)?.controller.signal;
 		signal?.throwIfAborted(); // an abort during a sync gap ends the job here
 		// THE DIGEST (owner, 2026-09-30 evening): the extractor continues a
@@ -816,6 +919,7 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 			sourceId,
 			prompt,
 			new Set(graph.nodes.map((n) => n.id)),
+			batchIds,
 			signal,
 			(usage, model, step, finishReason, tools) => {
 				recordStep(jobKey, "extractor", callUsage(usage), model);
@@ -838,12 +942,26 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 
 		// The auditor NEVER sees the source (owner 2026-09-27): findings
 		// JSON + identity instructions, and the graph reached through
-		// exploration tools instead of an injected dump.
+		// exploration tools instead of an injected dump. The proposition
+		// projection omits messageId (2026-10-13): the auditor is
+		// IDENTITY-only and never sees the passages, so anchors are useless
+		// to it — they add cognitive load, not signal.
 		const auditResult = await runAuditor(
 			stageEngine("auditor", deps.auditor),
 			sourceId,
 			`Proposed findings from the extractor (the source itself is not available to you — the extractor is fully trusted; the propositions only — the reasoning chains are the merger's business, owner 2026-09-30):\n\n` +
-				`${JSON.stringify({ propositions: findings.propositions }, null, 2)}\n\n` +
+				`${JSON.stringify(
+					{
+						propositions: findings.propositions.map((p) => ({
+							id: p.id,
+							name: p.name,
+							statement: p.statement,
+							aliases: p.aliases,
+						})),
+					},
+					null,
+					2,
+				)}\n\n` +
 				`The current knowledge graph has ${graph.nodes.length} node(s). Explore it with your tools and link what links.`,
 			signal,
 			(usage, model, step, finishReason, tools) => {
@@ -1010,16 +1128,24 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 						status: "fulfilled",
 						value: await runJob({ id: chatId, kind: "chat", part }, async (jobKey) => {
 							// The batch's source view: TEACHER PROSE ONLY (owner,
-							// 2026-09-28) — plain paragraphs, same selection as the
-							// coverage fingerprints (messageViewLines parity).
-							const view = proseView(
-								batch.map((slot) => slot.message),
-								record.title,
+							// 2026-09-28), each passage labeled with its ACTUAL message
+							// id (2026-10-13) — the view lines ARE the coverage
+							// fingerprints' messageViewLines ("TEACHER [id] text"), one
+							// shared seam.
+							const messages = batch.map((slot) => slot.message);
+							const view = proseView(messages, record.title);
+							// The batch's teacher-prose ids — the ONLY anchors this
+							// job's submit may name (validateSessionAnchors at the
+							// submit seam refuses anything else: ids from other
+							// batches — even real ones of this chat — other chats,
+							// and non-prose messages).
+							const batchIds = new Set(
+								messages.filter((m) => messageViewLines(m, m.id).length > 0).map((m) => m.id),
 							);
 							setPhase(jobKey, "queued", "chat", undefined, part);
 							const findings = await withExtractSlot(jobKey, async () => {
 								setPhase(jobKey, "extracting", "chat", undefined, part);
-								return extract(jobKey, chatId, view);
+								return extract(jobKey, chatId, view, batchIds);
 							});
 							// SERIALIZED AUDIT (owner, 2026-09-28): audit + merge are the
 							// graph-mutating critical section — one job at a time,
diff --git a/src/core/contracts/graph.ts b/src/core/contracts/graph.ts
index 01b9eeb..d578276 100644
--- a/src/core/contracts/graph.ts
+++ b/src/core/contracts/graph.ts
@@ -231,11 +231,20 @@ export interface ExtractedProposition {
 	/** Verbatim phrasings the session used. */
 	aliases: string[];
 	/* Submit-schema slim (owner, 2026-09-28): `messages` and `evidence`
-	 * are GONE. Provenance is chat-level (the run's source key); the
-	 * verbatim-quote fields were never persisted and weak models burned
-	 * their retries on them ("propositions.0: must be object" — the
-	 * stringified-payload collapse). The extractor reports propositions
-	 * + structure, nothing else. */
+	 * are GONE. The verbatim-quote fields were never persisted and weak
+	 * models burned their retries on them ("propositions.0: must be
+	 * object" — the stringified-payload collapse). The extractor reports
+	 * propositions + structure, nothing else. */
+	/** OPTIONAL, SESSION PATH ONLY (owner, 2026-10-13): the message id of
+	 *  the ONE teacher passage this proposition came from — the extractor
+	 *  copies it from the view's "TEACHER [id]" label (core/coverage.ts
+	 *  messageViewLines) and the submit seam validates it against the
+	 *  CURRENT batch. The merger stamps it into the node's provenance
+	 *  point {chatId, messageId} (new nodes AND link-appends); chains
+	 *  stay chat-level. Notes imports and legacy/core callers have none:
+	 *  undefined → messageId "" (chat-level), so NO persisted shape or
+	 *  format version changes (GraphNode / ProvenancePoint untouched). */
+	messageId?: string;
 }
 
 /** One proposed argument (extractor redesign, 2026-09-30). Endpoints are
diff --git a/src/core/graph.ts b/src/core/graph.ts
index 7655901..39a1d41 100644
--- a/src/core/graph.ts
+++ b/src/core/graph.ts
@@ -11,8 +11,10 @@
  *                      same-source digest (digest-aware, 2026-09-30
  *                      evening: the extractor continues its own source,
  *                      references existing ids verbatim, assembles
- *                      cross-stretch itself). Fully trusted: no stage
- *                      re-checks it.
+ *                      cross-stretch itself). Session propositions carry
+ *                      their passage's messageId (2026-10-13) — the
+ *                      merger's provenance anchor. Fully trusted: no
+ *                      stage re-checks it.
  *   auditor (LLM)    → AuditVerdicts: identity links (local id → an existing
  *                      node, or create) via graph-exploration tools —
  *                      links ONLY (owner, 2026-09-28 evening: the auditor
@@ -109,11 +111,14 @@ export interface MergeSource {
 	coverage?: CoverageEntry[];
 }
 
-/** The run's chat-level provenance point (submit-schema slim, 2026-09-28:
- *  propositions no longer carry message ids — the model never reported
- *  them reliably anyway — so every birth from a run shares one point). */
-function pointOf(chatId: string): ProvenancePoint[] {
-	return [{ chatId, messageId: "" }];
+/** The run's provenance point. Chat-level by default (submit-schema slim,
+ *  2026-09-28 — the run's source key is the whole point); since the anchor
+ *  restore (owner, 2026-10-13) a SESSION birth may carry its passage's
+ *  message id — the extractor-copied messageId, validated at the submit
+ *  seam against the current batch. Chains, notes imports, and
+ *  legacy/core callers lacking an anchor keep "" (chat-level). */
+function pointOf(chatId: string, messageId?: string): ProvenancePoint[] {
+	return [{ chatId, messageId: messageId ?? "" }];
 }
 
 const samePoint = (a: ProvenancePoint, b: ProvenancePoint): boolean =>
@@ -166,7 +171,11 @@ export function mergeFindings(
 	// extractor's findings verbatim; the auditor's links join here by id.
 	for (const p of findings.propositions) {
 		if (mapping.has(p.id)) continue; // duplicate id WITHIN this submit — first resolution stands
-		const points = pointOf(chatId);
+		// The anchor (2026-10-13): a session proposition may carry its
+		// passage's messageId — it rides BOTH the create and the link-append
+		// line (each re-encounter anchors to ITS passage); absent (notes,
+		// legacy/core callers) → "", chat-level as before.
+		const points = pointOf(chatId, p.messageId);
 		const linkTo = linkOf.get(p.id);
 		let graphNodeId: string;
 		if (linkTo !== undefined && existingIds.has(linkTo)) {
diff --git a/src/core/settings.ts b/src/core/settings.ts
index 31eee28..4daece8 100644
--- a/src/core/settings.ts
+++ b/src/core/settings.ts
@@ -321,8 +321,11 @@ export interface GraphSettings {
 	 *  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).
+	 *  FACTORY DEFAULT 4096 (owner, 2026-10-13: halved back from the
+	 *  digest-era 8192 — the labeled passages + message anchors made
+	 *  smaller batches worth their overhead again; the pre-setting
+	 *  constant was 4096, vision-extraction-coverage.md, 2026-09-15).
+	 *  Only the FACTORY moves: an explicit user value always wins.
 	 *
 	 *  FLOOR 500 (EXTRACTION_CHUNK_TOKENS_FLOOR, the implementer's call
 	 *  per the owner's dispatch): every run pays the graph-carrying
@@ -402,7 +405,7 @@ export const FACTORY_SETTINGS: FactorySettings = {
 		sessionNameSerif: true,
 		mdRendering: { headingWeight: 900, boldColor: null, italicColor: null },
 	},
-	graph: { enabled: true, rendering: true, extractionChunkTokens: 8192 },
+	graph: { enabled: true, rendering: true, extractionChunkTokens: 4096 },
 	compaction: { thresholdTokens: 150_000 },
 };
 
diff --git a/tests/extraction.test.ts b/tests/extraction.test.ts
index 04aed81..ba22333 100644
--- a/tests/extraction.test.ts
+++ b/tests/extraction.test.ts
@@ -49,13 +49,14 @@ import {
 	sourceDigest,
 	EXTRACTION_CORE,
 	SESSION_PREAMBLE,
+	SESSION_MESSAGE_ID_RULE,
 	NOTES_PREAMBLE,
 	EXTRACTOR_INSTRUCTIONS,
 	NOTES_EXTRACTOR_INSTRUCTIONS,
 } from "../src/agent/subagents/extraction.ts";
-import { simplifyChains } from "../src/core/graph.ts";
+import { getGraph, simplifyChains } from "../src/core/graph.ts";
 import { ModelsNotConfiguredError, ProviderKeyMissingError, providerKeyMissing, type ModelSlotName } from "../src/core/settings.ts";
-import { coverageOf, messageViewLines } from "../src/core/coverage.ts";
+import { coverageOf, coverageSlots, messageViewLines } from "../src/core/coverage.ts";
 import { chatStore } from "../src/store/chats.ts";
 import { subscribe } from "../src/core/events.ts";
 import { PATHS } from "../config.ts";
@@ -232,7 +233,9 @@ after(() => {
 
 /** What the extractor SUBMITS for the fixture session (owner redesign,
  *  2026-09-30): propositions + REASONING CHAINS on the wire — one chain
- *  (p1 ⟹ p2), expanded to a follows-edge at the seam. */
+ *  (p1 ⟹ p2). Each proposition carries its passage anchor (2026-10-13):
+ *  the fixture's teacher-prose messages are a1 (chain rule prose) and a2
+ *  (derivative prose) — p1 anchors to a2, p2 to a1. */
 const FINDINGS = {
 	propositions: [
 		{
@@ -240,12 +243,14 @@ const FINDINGS = {
 			name: "Derivative",
 			statement: "The derivative measures how fast a function changes",
 			aliases: [],
+			messageId: "a2",
 		},
 		{
 			id: "p2",
 			name: "Chain rule",
 			statement: "The chain rule differentiates composed functions by multiplying local rates.",
 			aliases: [],
+			messageId: "a1",
 		},
 	],
 	chains: [
@@ -331,10 +336,22 @@ describe("transcriptView (pure — teacher prose only, owner 2026-09-28)", () =>
 		const view = transcriptView(record);
 
 		// The document header is the session title; the body is the
-		// teacher's text blocks as plain paragraphs.
+		// teacher's text blocks as labeled passages.
 		assert.match(view, /^# Extraction fixture$/m);
-		assert.match(view, /The chain rule composes rates of change along a path\./);
-		assert.match(view, /The derivative measures how fast a function changes\./);
+		assert.match(view, /^TEACHER \[a1\] The chain rule composes rates of change along a path\.$/m);
+		assert.match(view, /^TEACHER \[a2\] The derivative measures how fast a function changes\.$/m);
+
+		// MESSAGE-ID LABELS (owner, 2026-10-13): the passages carry their
+		// ACTUAL message ids, in exactly messageViewLines' shape — the same
+		// seam the coverage fingerprints hash. No label without prose: a3
+		// (quiz only) and the learner messages are not passages.
+		assert.doesNotMatch(view, /TEACHER \[a3\]/);
+		assert.doesNotMatch(view, /TEACHER \[u1\]/);
+		assert.equal(
+			view.slice(view.indexOf("TEACHER")),
+			record.messages.flatMap((m) => messageViewLines(m, m.id)).join("\n\n"),
+			"the view body IS the messageViewLines of the transcript — one shared seam",
+		);
 
 		// EVERYTHING else is gone: learner text, quiz blocks, tool notes,
 		// speaker headers — the ruling strips it all.
@@ -363,7 +380,7 @@ describe("transcriptView (pure — teacher prose only, owner 2026-09-28)", () =>
 			]),
 		].flat());
 		const view = transcriptView(chatStore.getChat(chat.id)!);
-		assert.match(view, /Prose survives\./);
+		assert.match(view, /^TEACHER \[a1\] Prose survives\.$/m, "the surviving passage is labeled with its real id");
 		assert.doesNotMatch(view, /research/);
 		assert.doesNotMatch(view, /long brief/);
 		assert.doesNotMatch(view, /### /);
@@ -479,6 +496,14 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
 			linkedLines.some((line) => line.provenance.some((pt) => pt.chatId === chatId)),
 			"the link-append unions provenance",
 		);
+		// ANCHORS (2026-10-13): both lines carry their proposition's passage
+		// id — p1's link-append anchors to a2 (its passage), p2's create to a1.
+		assert.ok(
+			linkedLines.some((line) => line.provenance.some((pt) => pt.chatId === chatId && pt.messageId === "a2")),
+			"the link-append line carries p1's passage id",
+		);
+		const created = ledgers.readNodes().find((n) => n.name === "Chain rule")!;
+		assert.deepEqual(created.provenance, [{ chatId, messageId: "a1" }], "the created node anchors to p2's passage");
 
 		// COVERAGE checkpointed per message (not a whole-chat checkpoint):
 		// one entry per transcript message, fingerprinted content each —
@@ -672,7 +697,8 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
 			chatStore,
 			graphStore: ledgers,
 			// 4096 budget: the fixture is sized to split in two (the factory
-			// default doubled to 8192, 2026-09-30).
+			// default again — halved back from the digest-era 8192, owner
+			// 2026-10-13).
 			getChunkTokens: () => 4096,
 			engineFor: (role) =>
 				role === "extractor"
@@ -725,7 +751,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
 		const ledgers = memoryLedgers();
 
 		const single = (id: string, name: string, statement: string) => ({
-			propositions: [{ id, name, statement, aliases: [], }],
+			propositions: [{ id, name, statement, aliases: [], messageId: "a1" }],
 			chains: [],
 		});
 		const findingsA = single("pa", "Alpha claim", "Alpha statement, full precision");
@@ -782,7 +808,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
 		const ledgers = memoryLedgers();
 
 		const single = (id: string, name: string, statement: string) => ({
-			propositions: [{ id, name, statement, aliases: [], }],
+			propositions: [{ id, name, statement, aliases: [], messageId: "a1" }],
 			chains: [],
 		});
 
@@ -1016,6 +1042,185 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
 	});
 });
 
+// ─── message anchors (messageId — owner, 2026-10-13) ────────────────────────
+
+describe("message anchors (session propositions carry their passage's id)", () => {
+	/** A single-proposition submit with an explicit anchor. */
+	const anchored = (messageId: string) => ({
+		propositions: [
+			{ id: "p1", name: "Anchor claim", statement: "Anchor claim, full precision.", aliases: [], messageId },
+		],
+		chains: [],
+	});
+
+	/** One scripted extractor turn: a submit_findings tool call. */
+	const submitStep = (payload: unknown): FauxResponseStep => () =>
+		fauxAssistantMessage(
+			[fauxToolCall("submit_findings", payload as ToolCall["arguments"], { id: "anchor-call" })],
+			{ stopReason: "toolUse" },
+		);
+
+	it("a submit MISSING messageId never passes: the schema rejects every turn — nothing merges, nothing checkpoints", async () => {
+		const { chatId } = fixtureChat();
+		const ledgers = memoryLedgers();
+		// The degraded shape: propositions without anchors, chains present —
+		// only the REQUIRED field is missing, and the schema refuses it on
+		// every turn until the budget is gone (the required-field doctrine,
+		// 2026-09-28, now covering the anchor too).
+		const bare = () =>
+			fauxEngine(
+				Array.from({ length: 4 }, () =>
+					submitStep({
+						propositions: [{ id: "p1", name: "Anchor claim", statement: "Anchor claim, full precision.", aliases: [] }],
+						chains: [],
+					}),
+				),
+			);
+		const pipeline = createExtractionPipeline({
+			chatStore,
+			graphStore: ledgers,
+			engineFor: (role) => (role === "extractor" ? bare() : submitModel("submit_review", { links: [] })),
+		});
+		assert.deepEqual(await pipeline.runExtraction(chatId), { nodes: 0, chains: 0 });
+		assert.equal(ledgers.readNodes().length, 0, "nothing merged");
+		assert.equal(ledgers.readCoverage().length, 0, "nothing checkpointed — the batch stays re-runnable");
+	});
+
+	it("an EMPTY or UNKNOWN anchor rides the error-back channel: refused, the model re-anchors clean, then merges", async () => {
+		const { chatId } = fixtureChat();
+		const ledgers = memoryLedgers();
+		// Three bad anchors, all schema-valid (messageId is a string) — only
+		// the anchor law refuses them: empty, a LEARNER message of this very
+		// chat (real id, not a teacher passage), and pure fiction.
+		const extractor = fauxEngine([
+			submitStep(anchored("")),
+			submitStep(anchored("u1")),
+			submitStep(anchored("made_up")),
+			submitStep(anchored("a2")),
+		]);
+		const pipeline = createExtractionPipeline({
+			chatStore,
+			graphStore: ledgers,
+			extractor,
+			auditor: submitModel("submit_review", { links: [] }),
+		});
+		assert.deepEqual(await pipeline.runExtraction(chatId), { nodes: 1, chains: 0 }, "the retry anchored and merged");
+		const node = ledgers.readNodes()[0]!;
+		assert.deepEqual(node.provenance, [{ chatId, messageId: "a2" }], "the node anchors to its passage");
+	});
+
+	it("the boundary is the CURRENT BATCH: a real teacher message id from another batch is refused, the in-batch retry merges", async () => {
+		const { chatId } = chunkyChat(); // deterministic batches [a1,a2,a3] + [a4,a5] at the 4096 budget
+		const ledgers = memoryLedgers();
+		// Batch 1: "a5" is a REAL teacher-prose id of this very chat — but it
+		// lives in batch 2, so this stretch refuses it; the re-anchor to "a2"
+		// merges. Batch 2 anchors to its own "a4".
+		const extractor = fauxEngine([
+			submitStep(anchored("a5")),
+			submitStep(anchored("a2")),
+			submitStep(anchored("a4")),
+		]);
+		const pipeline = createExtractionPipeline({
+			chatStore,
+			graphStore: ledgers,
+			getChunkTokens: () => 4096,
+			extractor,
+			// One review per batch job (the retry lives in the extractor's
+			// own turn budget, not the auditor's).
+			auditor: fauxEngine([passThroughAuditStep(), passThroughAuditStep()]),
+		});
+		assert.deepEqual(await pipeline.runExtraction(chatId), { nodes: 2, chains: 0 });
+		const anchors = ledgers.readNodes().map((n) => n.provenance[0]!.messageId).sort();
+		assert.deepEqual(anchors, ["a2", "a4"], "each job's node anchors INSIDE its own batch — never a5");
+		assert.equal(ledgers.readCoverage().length, 5, "both batches checkpointed");
+	});
+
+	it("a LINK-APPEND carries its proposition's anchor into the existing node's provenance", async () => {
+		const { chatId } = fixtureChat();
+		const ledgers = memoryLedgers();
+		const existingId = "n_anchor_existing";
+		ledgers.appendNode({
+			id: existingId,
+			name: "Derivative",
+			statement: "Derivatives measure rates of change",
+			aliases: [],
+			createdAt: "2026-08-01T00:00:00.000Z",
+			provenance: [],
+		});
+		const pipeline = createExtractionPipeline({
+			chatStore,
+			graphStore: ledgers,
+			extractor: submitModel("submit_findings", anchored("a2")),
+			auditor: submitModel("submit_review", { links: [{ id: "p1", linkTo: existingId }] }),
+		});
+		await pipeline.runExtraction(chatId);
+		// The link-append line — the re-encounter — carries the passage id.
+		const appended = ledgers
+			.readNodes()
+			.filter((n) => n.id === existingId)
+			.find((line) => line.provenance.some((pt) => pt.chatId === chatId))!;
+		assert.deepEqual(appended.provenance, [{ chatId, messageId: "a2" }]);
+		// And the derived graph unions it under the same point identity.
+		const merged = getGraph(ledgers).nodes.find((n) => n.id === existingId)!;
+		assert.ok(merged.provenance.some((pt) => pt.chatId === chatId && pt.messageId === "a2"));
+	});
+
+	it("the notes door stays anchor-free: no messageId required — and a stray one never reaches provenance", async () => {
+		const ledgers = memoryLedgers();
+		const pipeline = createExtractionPipeline({
+			chatStore,
+			graphStore: ledgers,
+			// NOTES_FINDINGS carries no messageId (the notes schema never
+			// asks for one) — the submit validates exactly as before.
+			extractor: submitModel("submit_findings", NOTES_FINDINGS),
+			auditor: submitModel("submit_review", { links: [] }),
+		});
+		assert.deepEqual(await pipeline.importNotes({ filePath: "/vault/anchor-free.md", text: NOTES_TEXT }), { nodes: 1, chains: 0 });
+		assert.deepEqual(
+			ledgers.readNodes()[0]!.provenance,
+			[{ chatId: ledgers.readSources()[0]!.id, messageId: "" }],
+			"notes provenance stays chat-level — the file is the anchor",
+		);
+
+		// The boundary: even a hallucinated messageId (extra properties pass
+		// schema validation) is stripped at the notes fill seam.
+		const stray = {
+			propositions: [{ ...NOTES_FINDINGS.propositions[0], messageId: "made_up" }],
+			chains: [],
+		};
+		const second = createExtractionPipeline({
+			chatStore,
+			graphStore: ledgers,
+			extractor: submitModel("submit_findings", stray),
+			auditor: submitModel("submit_review", { links: [] }),
+		});
+		assert.deepEqual(await second.importNotes({ filePath: "/vault/stray-anchor.md", text: NOTES_TEXT }), { nodes: 1, chains: 0 });
+		const secondSource = ledgers.readSources()[1]!;
+		const strayNode = ledgers.readNodes().find((n) => n.provenance.some((pt) => pt.chatId === secondSource.id))!;
+		assert.deepEqual(strayNode.provenance, [{ chatId: secondSource.id, messageId: "" }], "the stray anchor was stripped before the merger");
+	});
+
+	it("coverage fingerprints are UNCHANGED by the anchors: the stored fps equal the plain coverage-slot hashes", async () => {
+		const { chatId, record } = chunkyChat();
+		const ledgers = memoryLedgers();
+		const pipeline = createExtractionPipeline({
+			chatStore,
+			graphStore: ledgers,
+			getChunkTokens: () => 4096,
+			extractor: fauxEngine([findingsStep(), findingsStep()]),
+			auditor: fauxEngine([passThroughAuditStep(), passThroughAuditStep()]),
+		});
+		await pipeline.runExtraction(chatId);
+		// The labeled view reuses messageViewLines; the fingerprint seam is
+		// the same lines it always was — same hashes, same coverage.
+		assert.deepEqual(
+			ledgers.readCoverage().map((c) => c.fp).sort(),
+			coverageSlots(record.messages).map((slot) => slot.fp).sort(),
+		);
+		assert.equal(coverageOf(record.messages, ledgers.readCoverage(), chatId).uncoveredCount, 0);
+	});
+});
+
 // ── the notes front door (format-agnostic import) ────────────────────────────
 
 /** Raw personal notes — arbitrary format, no session, no message ids. */
@@ -1069,9 +1274,9 @@ describe("the extractor redesign (owner, 2026-09-30): chains are the deliverable
 		const ledgers = memoryLedgers();
 		const extractor = submitModel("submit_findings", {
 			propositions: [
-				{ id: "p1", name: "A", statement: "A holds.", aliases: [] },
-				{ id: "p2", name: "B", statement: "B holds.", aliases: [] },
-				{ id: "p3", name: "C", statement: "A and B together entail C.", aliases: [] },
+				{ id: "p1", name: "A", statement: "A holds.", aliases: [], messageId: "a1" },
+				{ id: "p2", name: "B", statement: "B holds.", aliases: [], messageId: "a2" },
+				{ id: "p3", name: "C", statement: "A and B together entail C.", aliases: [], messageId: "a1" },
 			],
 			chains: [{ premises: ["p1", "p2"], conclusion: "p3" }],
 		});
@@ -1100,10 +1305,10 @@ describe("the extractor redesign (owner, 2026-09-30): chains are the deliverable
 		const ledgers = memoryLedgers();
 		const extractor = submitModel("submit_findings", {
 			propositions: [
-				{ id: "p1", name: "A", statement: "A holds.", aliases: [] },
-				{ id: "p2", name: "B", statement: "B holds.", aliases: [] },
-				{ id: "p3", name: "C", statement: "C follows.", aliases: [] },
-				{ id: "p4", name: "Lonely", statement: "A bare proposition no argument uses.", aliases: [] },
+				{ id: "p1", name: "A", statement: "A holds.", aliases: [], messageId: "a1" },
+				{ id: "p2", name: "B", statement: "B holds.", aliases: [], messageId: "a2" },
+				{ id: "p3", name: "C", statement: "C follows.", aliases: [], messageId: "a1" },
+				{ id: "p4", name: "Lonely", statement: "A bare proposition no argument uses.", aliases: [], messageId: "a2" },
 			],
 			chains: [
 				{ premises: ["p1"], conclusion: "p3" },
@@ -1238,6 +1443,16 @@ describe("the extractor redesign (owner, 2026-09-30): chains are the deliverable
 		assert.ok(NOTES_EXTRACTOR_INSTRUCTIONS.startsWith(NOTES_PREAMBLE));
 		assert.ok(NOTES_EXTRACTOR_INSTRUCTIONS.includes(EXTRACTION_CORE), "the notes extractor shares the core by construction");
 
+		// THE ANCHOR RULE (owner, 2026-10-13) is SESSION-ONLY: the exact
+		// sentence rides the session instructions; the notes
+		// contextualization never mentions message ids at all.
+		assert.equal(
+			SESSION_MESSAGE_ID_RULE,
+			"For each new proposition, copy the message ID of the passage that most directly states or explains it into messageId.",
+		);
+		assert.ok(EXTRACTOR_INSTRUCTIONS.includes(SESSION_MESSAGE_ID_RULE), "the session instructions carry the rule");
+		assert.ok(!NOTES_EXTRACTOR_INSTRUCTIONS.includes("messageId"), "the notes prompt never mentions message ids");
+
 		// The preambles differ in exactly their source description.
 		assert.notEqual(SESSION_PREAMBLE, NOTES_PREAMBLE);
 		assert.match(SESSION_PREAMBLE, /a teaching\s+session, rendered as the teacher's prose in reading order/);
@@ -1431,12 +1646,22 @@ function capturedView(context: unknown): string {
 	return typeof last?.content === "string" ? last.content : "";
 }
 
-/** An extractor step that submits FINDINGS, optionally capturing its view. */
+/** An extractor step that submits FINDINGS, optionally capturing its view.
+ *  The step plays by the anchor law it runs under (2026-10-13): every
+ *  proposition's messageId is copied from a TEACHER [id] label of the
+ *  CURRENT stretch, so multi-batch fixtures reuse this step across batches
+ *  without ever naming a passage their batch does not hold. */
 function findingsStep(capture?: (view: string) => void): FauxResponseStep {
 	return (context) => {
-		capture?.(capturedView(context));
+		const view = capturedView(context);
+		capture?.(view);
+		const anchor = /TEACHER \[([^\]]+)\]/.exec(view)?.[1] ?? "a1";
+		const submit = {
+			...FINDINGS,
+			propositions: FINDINGS.propositions.map((p) => ({ ...p, messageId: anchor })),
+		};
 		return fauxAssistantMessage(
-			[fauxToolCall("submit_findings", FINDINGS as unknown as ToolCall["arguments"], { id: "findings-call" })],
+			[fauxToolCall("submit_findings", submit as unknown as ToolCall["arguments"], { id: "findings-call" })],
 			{ stopReason: "toolUse" },
 		);
 	};
@@ -1487,7 +1712,8 @@ describe("the chunked pipeline (extraction coverage)", () => {
 			chatStore,
 			graphStore: ledgers,
 			// 4096 budget: the fixture is sized to split in two (the factory
-			// default doubled to 8192, 2026-09-30).
+			// default again — halved back from the digest-era 8192, owner
+			// 2026-10-13).
 			getChunkTokens: () => 4096,
 			extractor: fauxEngine([findingsStep((v) => views.push(v)), findingsStep((v) => views.push(v))]),
 			auditor: fauxEngine([passThroughAuditStep(), passThroughAuditStep()]),
@@ -1501,9 +1727,17 @@ describe("the chunked pipeline (extraction coverage)", () => {
 		assert.ok(!views[0]!.includes("topic 4:"), "the batch stops at the token budget");
 		assert.ok(views[1]!.includes("topic 4:") && views[1]!.includes("topic 5:"));
 		assert.ok(!views[1]!.includes("topic 3:"));
-		assert.doesNotMatch(views[0]!, /### /, "plain paragraphs — no speaker headers");
+		assert.doesNotMatch(views[0]!, /### /, "no speaker headers — passages are TEACHER [id] lines");
 		// The document header is the session title.
 		assert.ok(views[0]!.startsWith("# Chunky coverage fixture"));
+		// MESSAGE-ID LABELS (2026-10-13): every passage carries its REAL
+		// message id — batch 1 holds a1-a3, batch 2 a4-a5, and the labels
+		// follow the split exactly.
+		assert.match(views[0]!, /^TEACHER \[a1\] topic 1:/m);
+		assert.match(views[0]!, /^TEACHER \[a3\] topic 3:/m);
+		assert.doesNotMatch(views[0]!, /TEACHER \[a4\]/);
+		assert.match(views[1]!, /^TEACHER \[a4\] topic 4:/m);
+		assert.match(views[1]!, /^TEACHER \[a5\] topic 5:/m);
 
 		// Batch 1 merged the full findings (verdicts-only: the extractor's
 		// output always fully merges); batch 2's identical ids are a
@@ -1538,7 +1772,8 @@ describe("the chunked pipeline (extraction coverage)", () => {
 			chatStore,
 			graphStore: ledgers,
 			// 4096 budget: the fixture is sized to split in two (the factory
-			// default doubled to 8192, 2026-09-30).
+			// default again — halved back from the digest-era 8192, owner
+			// 2026-10-13).
 			getChunkTokens: () => 4096,
 			// Batch 1 submits and merges; batch 2's extractor call HANGS
 			// until the abort fires — the dock's abort button, mid-run.
@@ -1859,7 +2094,7 @@ describe("digest-aware serialized extraction (the extractor is the assembler)",
 		});
 		ledgers.appendNode(seed("n_a", "Self-ownership"));
 		const FINDINGS_B: SessionFindings = {
-			propositions: [{ id: "p1", name: "Appropriation axiom", statement: "c", aliases: [] }],
+			propositions: [{ id: "p1", name: "Appropriation axiom", statement: "c", aliases: [], messageId: "a1" }],
 			chains: [{ premises: ["n_a", "p1"], conclusion: "p1", }].slice(0, 0), // chains live in the engine below
 		};
 		const views: string[] = [];
@@ -1871,7 +2106,7 @@ describe("digest-aware serialized extraction (the extractor is the assembler)",
 					chains: [{ premises: ["n_a", "p1"], conclusion: "p1b" }],
 				};
 				// conclusion p1b must exist — real submit:
-				submit.propositions.push({ id: "p1b", name: "Property rights", statement: "d", aliases: [] });
+				submit.propositions.push({ id: "p1b", name: "Property rights", statement: "d", aliases: [], messageId: "a2" });
 				return fauxAssistantMessage([fauxToolCall("submit_findings", submit as unknown as ToolCall["arguments"], { id: "f1" })], { stopReason: "toolUse" });
 			},
 		]);
@@ -1918,7 +2153,7 @@ describe("digest-aware serialized extraction (the extractor is the assembler)",
 						fauxToolCall(
 							"submit_findings",
 							{
-								propositions: [{ id: "p1", name: "Axiom", statement: "s", aliases: [] }],
+								propositions: [{ id: "p1", name: "Axiom", statement: "s", aliases: [], messageId: "a1" }],
 								chains: [],
 							} as unknown as ToolCall["arguments"],
 							{ id: "good" },
@@ -1944,11 +2179,18 @@ describe("digest-aware serialized extraction (the extractor is the assembler)",
 		let extractCalls = 0;
 		let auditCalls = 0;
 		// One step per engine call (faux engines consume steps): two batches.
-		const extractStep = (): FauxResponseStep => () => {
+		const extractStep = (): FauxResponseStep => (context) => {
 			extractCalls++;
 			events.push(`extract${extractCalls}`);
+			// The anchor is copied from the CURRENT stretch's first TEACHER
+			// label (a1 in batch 1, a4 in batch 2) — batch-local by construction.
+			const anchor = /TEACHER \[([^\]]+)\]/.exec(capturedView(context))?.[1] ?? "a1";
+			const submit = {
+				...FINDINGS,
+				propositions: FINDINGS.propositions.map((p) => ({ ...p, messageId: anchor })),
+			};
 			return fauxAssistantMessage(
-				[fauxToolCall("submit_findings", FINDINGS as unknown as ToolCall["arguments"], { id: `f${extractCalls}` })],
+				[fauxToolCall("submit_findings", submit as unknown as ToolCall["arguments"], { id: `f${extractCalls}` })],
 				{ stopReason: "toolUse" },
 			);
 		};
@@ -1967,7 +2209,7 @@ describe("digest-aware serialized extraction (the extractor is the assembler)",
 			graphStore: ledgers,
 			extractor,
 			auditor,
-			getChunkTokens: () => 4096, // two batches over the chunky fixture (factory default doubled to 8192, 2026-09-30)
+			getChunkTokens: () => 4096, // two batches over the chunky fixture (the factory default, 4096 — halved back 2026-10-13)
 		});
 		const stats = await pipeline.runExtraction(chatId);
 		assert.deepEqual(events, ["extract1", "audit1", "extract2", "audit2"], "strict per-source order: extract → audit → merge → NEXT extract");
diff --git a/tests/graph.test.ts b/tests/graph.test.ts
index 877a154..e21203c 100644
--- a/tests/graph.test.ts
+++ b/tests/graph.test.ts
@@ -290,9 +290,10 @@ describe("the merger (mergeFindings)", () => {
 			assert.equal("kind" in node, false, "no kind field");
 			assert.ok(Array.isArray(node.provenance), "provenance attached");
 		}
-		// Provenance is CHAT-LEVEL (submit-schema slim, 2026-09-28):
-		// propositions no longer carry message ids — the run's source key
-		// is the whole provenance.
+		// Provenance without an anchor stays CHAT-LEVEL: this caller submits
+		// no messageId (the legacy/core + notes shape — anchors are the
+		// session door's alone, 2026-10-13), so the run's source key is the
+		// whole provenance point.
 		const alpha = graph.nodes.find((n) => n.statement === "Alpha intuition")!;
 		assert.deepEqual(alpha.provenance, [{ chatId: chat1.id, messageId: "" }]);
 
@@ -306,6 +307,60 @@ describe("the merger (mergeFindings)", () => {
 
 	});
 
+	it("messageId anchors (2026-10-13): creates AND link-appends stamp the passage id; chains stay chat-level", () => {
+		// The session submit's anchor (owner, 2026-10-13): a proposition may
+		// carry its passage's message id — the merger stamps it into the
+		// node's provenance point for BOTH births and re-encounters. A
+		// caller without one (notes, legacy/core — pinned above) keeps "".
+		const chat = fixtureChat(
+			"Anchor fixture",
+			[
+				...user("u1", "teach anchors"),
+				...teacher("t1", "First anchored passage."),
+				...teacher("t2", "Second anchored passage."),
+			].flat(),
+		);
+		const first = mergeFindings(
+			chat.id,
+			{
+				propositions: [{ id: "p1", name: "Anchored", statement: "Anchored statement", aliases: [], messageId: "t1" }],
+				chains: [],
+			},
+			{ links: [] },
+			graphDeps,
+			sessionSource(chat.id),
+		);
+		assert.equal(first.nodes, 1);
+		const created = scopedGraph([chat.id]).nodes.find((n) => n.statement === "Anchored statement")!;
+		assert.deepEqual(created.provenance, [{ chatId: chat.id, messageId: "t1" }], "the created node anchors to its passage");
+
+		// The re-encounter: link-appended, anchored to ITS passage — while
+		// the chain the same job asserts stays chat-level.
+		const second = mergeFindings(
+			chat.id,
+			{
+				propositions: [
+					{ id: "q1", name: "Anchored again", statement: "Anchored statement, rephrased", aliases: [], messageId: "t2" },
+					{ id: "q2", name: "Follows", statement: "Follows the anchored claim", aliases: [], messageId: "t2" },
+				],
+				chains: [{ premises: ["q1"], conclusion: "q2" }],
+			},
+			{ links: [{ id: "q1", linkTo: created.id }] },
+			graphDeps,
+			sessionSource(chat.id),
+		);
+		assert.equal(second.nodes, 1, "q1 linked (no create), q2 created");
+		const linkLine = graphStore
+			.readNodes()
+			.filter((n) => n.id === created.id)
+			.find((line) => line.provenance.some((pt) => pt.chatId === chat.id && pt.messageId === "t2"));
+		assert.ok(linkLine, "the link-append line carries the re-encounter's passage id");
+		assert.equal(linkLine!.name, "Anchored again", "the appended line is the re-encounter (reads merge it into aliases)");
+		const chains = graphStore.readChains().filter((c) => c.provenance.some((pt) => pt.chatId === chat.id));
+		assert.equal(chains.length, 1);
+		assert.deepEqual(chains[0]!.provenance, [{ chatId: chat.id, messageId: "" }], "chains stay chat-level — never anchored");
+	});
+
 	it("merges INDEPENDENTLY per call — no cross-run identity (owner, 2026-09-29)", () => {
 		// The mappings ledger is gone: resolution is a job-local in-memory
 		// map, so a second merge of the same verdicts knows nothing of the
diff --git a/tests/render-extraction-coverage.test.tsx b/tests/render-extraction-coverage.test.tsx
index ed933dd..fbbfab1 100644
--- a/tests/render-extraction-coverage.test.tsx
+++ b/tests/render-extraction-coverage.test.tsx
@@ -40,8 +40,10 @@ describe("fetchGraphRead — one truth with the extraction trigger (2026-10-02)"
 	// effectiveSettings gate waits for. The old hand-rolled fallback
 	// read the raw delta and guessed `?? 4096` — a stale pre-setting-era
 	// constant — so an unset budget filled the ring at half the truth
-	// (owner repro: 6k shown full, extraction correctly silent at 8192).
-	// Now the raw delta resolves through the SAME core resolver.
+	// (owner repro: 6k shown full, extraction correctly silent at the then-
+	// factory 8192). The 2026-10-13 ruling restored the factory to 4096 (more
+	// frequent graph updates); the LAW is unchanged — the denominator is the
+	// factory the same core resolver serves, never a hand-rolled constant.
 	const stub = (payload: unknown, ok = true) => {
 		const real = globalThis.fetch;
 		globalThis.fetch = (async () =>
@@ -51,25 +53,25 @@ describe("fetchGraphRead — one truth with the extraction trigger (2026-10-02)"
 		};
 	};
 
-	it("an absent graph section denominates at the factory 8192 — never 4096, never a missing ring", async () => {
+	it("an absent graph section denominates at the factory 4096 — never a hand-rolled constant, never a missing ring", async () => {
 		const restore = stub({ settings: { version: 1 } });
 		const read = await fetchGraphRead();
 		restore();
-		assert.deepEqual(read, { enabled: true, chunkTokens: 8192 });
+		assert.deepEqual(read, { enabled: true, chunkTokens: 4096 });
 	});
 
-	it("the owner repro shape — graph section present, budget never written — is 8192", async () => {
+	it("the owner repro shape — graph section present, budget never written — is the factory", async () => {
 		const restore = stub({ settings: { version: 1, graph: { enabled: true } } });
 		const read = await fetchGraphRead();
 		restore();
-		assert.equal(read?.chunkTokens, 8192, "the record lacks the key: factory, not the stale 4096");
+		assert.equal(read?.chunkTokens, 4096, "the record lacks the key: factory, not a stale constant");
 	});
 
 	it("first boot (settings null) resolves factory — the ring shows, at the true budget", async () => {
 		const restore = stub({ settings: null });
 		const read = await fetchGraphRead();
 		restore();
-		assert.deepEqual(read, { enabled: true, chunkTokens: 8192 });
+		assert.deepEqual(read, { enabled: true, chunkTokens: 4096 });
 	});
 
 	it("a custom budget rides through verbatim", async () => {
diff --git a/tests/render-settings.test.tsx b/tests/render-settings.test.tsx
index b3ed9b3..dcb235a 100644
--- a/tests/render-settings.test.tsx
+++ b/tests/render-settings.test.tsx
@@ -203,9 +203,9 @@ describe("GraphSection — master switch + chunk budget (wave 7 + 2026-10-02)",
 	it("the chunk-budget row: unset shows EMPTY with the factory placeholder + hint — one truth with the trigger", () => {
 		const html = renderToStaticMarkup(<GraphSection graph={undefined} onSectionChange={() => {}} />);
 		const input = tagOf(html, "input-chunk-tokens");
-		assert.ok(input.includes('placeholder="8192"'), "the placeholder IS the resolved factory default");
-		assert.ok(!/value="\d/.test(input), "unset renders EMPTY, not a materialized 8192");
-		assert.ok(html.includes(">8192 tok</"), "the hint reports the resolved truth");
+		assert.ok(input.includes('placeholder="4096"'), "the placeholder IS the resolved factory default");
+		assert.ok(!/value="\d/.test(input), "unset renders EMPTY, not a materialized 4096");
+		assert.ok(html.includes(">4096 tok</"), "the hint reports the resolved truth");
 	});
 
 	it("a stored budget shows its value and denominates the hint", () => {
diff --git a/tests/settings-resolution.test.ts b/tests/settings-resolution.test.ts
index 3bca067..9297e54 100644
--- a/tests/settings-resolution.test.ts
+++ b/tests/settings-resolution.test.ts
@@ -43,8 +43,9 @@ describe("resolveSettings", () => {
 		assert.equal(eff.appearance.sessionNameSerif, true);
 		assert.equal(eff.appearance.mdRendering.headingWeight, 900);
 		// wave 7 collapse: the master switch ONLY + the redesign's chunk
-		// budget — absent record resolves the factory 8192 (the 2026-09-30 bump)
-		assert.deepEqual(eff.graph, { enabled: true, rendering: true, extractionChunkTokens: 8192 });
+		// budget — absent record resolves the factory 4096 (halved back
+		// from the digest-era 8192, owner, 2026-10-13)
+		assert.deepEqual(eff.graph, { enabled: true, rendering: true, extractionChunkTokens: 4096 });
 	});
 
 	it("explicit record values win over every factory default", () => {
@@ -76,8 +77,8 @@ describe("resolveSettings", () => {
 		assert.equal(eff.appearance.proseFontSize, 20);
 		assert.equal(eff.appearance.mdRendering.headingWeight, 600);
 		// wave 7 collapse: the section IS the master switch (absent budget
-		// field = factory 8192 — a pre-redesign record resolves cleanly).
-		assert.deepEqual(eff.graph, { enabled: false, rendering: true, extractionChunkTokens: 8192 });
+		// field = factory 4096 — a pre-redesign record resolves cleanly).
+		assert.deepEqual(eff.graph, { enabled: false, rendering: true, extractionChunkTokens: 4096 });
 		// The DISPLAY split (owner, 2026-10-06): extraction off leaves the
 		// rendering switch ON — the data channel and the view are separate.
 		assert.equal(renderingEnabled(eff.graph), true);
diff --git a/tests/settings.test.ts b/tests/settings.test.ts
index 5ba376e..35111de 100644
--- a/tests/settings.test.ts
+++ b/tests/settings.test.ts
@@ -22,9 +22,10 @@ describe("FACTORY_SETTINGS (the compiled factory layer)", () => {
 		assert.equal(CURRENT_SETTINGS_VERSION, 1);
 		assert.deepEqual(FACTORY_SETTINGS.general, { autoUpdate: true });
 		// wave 7 collapse: the master switch ONLY + the extraction-UX
-		// redesign's chunk budget (2024-09-24); default doubled 8192 with
-		// the digest-aware redesign (owner, 2026-09-30)
-		assert.deepEqual(FACTORY_SETTINGS.graph, { enabled: true, rendering: true, extractionChunkTokens: 8192 });
+		// redesign's chunk budget (2026-09-24); doubled to 8192 with the
+		// digest-aware redesign (2026-09-30), then HALVED BACK to 4096
+		// with the message anchors (owner, 2026-10-13)
+		assert.deepEqual(FACTORY_SETTINGS.graph, { enabled: true, rendering: 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