Extraction observability: usage capture, live status payload, true abort (Wave 4)

Extraction is real spend and background work; the dock needs to see
and stop it. User decisions: persist all cost data (chat record),
per-stage usage granularity, and TRUE cancellation for abort.

USAGE CAPTURE (live + persisted):
- extraction.ts: per-call onStepFinish captures each billed step's
  usage (SDK LanguageModelUsage -> CallUsage: input/output/cache
  read+write/reasoning) into the registry's live per-stage usage
  (extractor/auditor; the merger is deterministic — no model call).
- /api/graph/status runs now carry usage (model + steps per stage);
  cost/context folds are the consumer's (core/prices.ts — nothing
  stores dollars).
- ChatRecord.extractions: append-only per-run usage log (mirrors the
  turns log): startedAt key, at, durationMs, merge stats when the
  merger ran, stages. Persisted on success AND failure — a failed run
  still spent money. Idempotent per startedAt; the list payload
  (ChatSummary) never leaks it.
- EmissionStats moved to contracts/graph.ts (its contract home);
  core/graph.ts re-exports for existing importers.
- Verified end-to-end against the real pipeline (backfill one chat):
  per-step token counts, reasoning tokens, and the auditor's growing
  prompt-cache reads captured and persisted.

TRUE ABORT (the dock's abort button, user decision):
- RunningExtraction owns one AbortController per run, shared across
  phases; abortExtraction(chatId) fires it and returns whether a run
  was aborted (idempotent no-op otherwise). The pending model call
  receives the signal — the provider cancels the request, spend
  stops. throwIfAborted() at phase boundaries ends runs aborted in
  sync gaps.
- Abort is a deliberate stop, not a failure: same ledger discipline
  (nothing merged, nothing checkpointed, partial usage persisted) but
  the run reports zero emissions instead of throwing. Exported via
  src/server/observability.ts for master's /api/activity/abort route.
- Tests: mid-run abort (hanging mock that rejects on the signal),
  live-accumulation + persisted-record assertions, store-seam
  idempotency, and the summary-payload leak guard.

src/agent/subagents/extraction.ts

@@ -1,7 +1,15 @@
 import { ToolLoopAgent, stepCountIs, tool, type LanguageModel, type UIMessage } from "ai";
 import { z } from "zod";
 import { modelFor } from "../models.ts";
-import type { AuditResult, ChatRecord, GraphNode, SessionFindings } from "../../core/contracts.ts";
+import type {
+	AuditResult,
+	CallUsage,
+	ChatRecord,
+	ExtractionRunUsage,
+	ExtractionStageUsage,
+	GraphNode,
+	SessionFindings,
+} from "../../core/contracts.ts";
 import { getGraph, mergeFindings, type EmissionStats, type GraphDeps } from "../../core/graph.ts";
 
 /**
@@ -211,12 +219,6 @@ function createExtractor(model: LanguageModel) {
 			}),
 		},
 		stopWhen: stepCountIs(4),
-		// One line per step: a background worker's progress must be legible
-		// from the server log (§5 observability baseline).
-		onStepFinish: (step) =>
-			console.info(
-				`[extraction] extractor step ${step.stepNumber}: ${step.finishReason}, tools: ${step.toolCalls.map((c) => c.toolName).join(", ") || "(none)"}`,
-			),
 	});
 }
 
@@ -300,10 +302,6 @@ function createAuditor(model: LanguageModel) {
 			}),
 		},
 		stopWhen: stepCountIs(4),
-		onStepFinish: (step) =>
-			console.info(
-				`[extraction] auditor step ${step.stepNumber}: ${step.finishReason}, tools: ${step.toolCalls.map((c) => c.toolName).join(", ") || "(none)"}`,
-			),
 	});
 }
 
@@ -312,11 +310,18 @@ function createAuditor(model: LanguageModel) {
 /** The pipeline phases, in order — what the home status endpoint shows. */
 export type ExtractionPhase = "extracting" | "auditing" | "merging";
 
-/** One in-flight pipeline run. Module-level: one process, one registry. */
-interface RunningExtraction {
+/** One in-flight pipeline run. Module-level: one process, one registry.
+ *  Exported for the status payload's consumer typing (the dock). */
+export interface RunningExtraction {
 	chatId: string;
 	phase: ExtractionPhase;
 	startedAt: number;
+	/** Live per-stage usage, accumulated as steps bill (the dock's cost /
+	 *  context-window blobs read this through /api/graph/status). */
+	usage: { extractor?: ExtractionStageUsage; auditor?: ExtractionStageUsage };
+	/** True-cancellation handle (the dock's abort button): one controller per
+	 *  run, shared across phases; abort() cancels the in-flight model call. */
+	controller: AbortController;
 }
 
 const runningExtractions = new Map<string, RunningExtraction>();
@@ -326,6 +331,18 @@ export function extractionStatuses(): RunningExtraction[] {
 	return [...runningExtractions.values()].sort((a, b) => a.startedAt - b.startedAt);
 }
 
+/** True cancellation of the in-flight run for a chat (the dock's abort
+ *  button): the pending model call receives the signal — the provider
+ *  cancels the request, spend stops — and the run ends like a failure:
+ *  nothing merged, nothing checkpointed, partial usage still persisted.
+ *  Returns false when no run is in flight (idempotent no-op). */
+export function abortExtraction(chatId: string): boolean {
+	const run = runningExtractions.get(chatId);
+	if (!run) return false;
+	run.controller.abort();
+	return true;
+}
+
 // ─── the pipeline ───────────────────────────────────────────────────────────
 
 export interface ExtractionModels {
@@ -350,21 +367,62 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 	const inFlight = new Set<string>();
 
 	function setPhase(chatId: string, phase: ExtractionPhase): void {
+		const prev = runningExtractions.get(chatId);
 		runningExtractions.set(chatId, {
 			chatId,
 			phase,
-			startedAt: runningExtractions.get(chatId)?.startedAt ?? Date.now(),
+			startedAt: prev?.startedAt ?? Date.now(),
+			usage: prev?.usage ?? {}, // phase changes never lose usage
+			controller: prev?.controller ?? new AbortController(),
 		});
 	}
 
+	/** Accumulate one billed step into the run's registry entry (live). */
+	function recordStep(chatId: string, stage: "extractor" | "auditor", usage: CallUsage, model: string): void {
+		const run = runningExtractions.get(chatId);
+		if (!run) return; // not running (tests driving stages directly)
+		run.usage[stage] ??= { model, steps: [] };
+		run.usage[stage]!.steps.push(usage);
+	}
+
+	/** The SDK's per-step usage, flattened to the persisted CallUsage fields
+	 *  (the money channel's capture shape, contracts/chat.ts). */
+	function callUsage(usage: {
+		inputTokens: number | undefined;
+		outputTokens: number | undefined;
+		inputTokenDetails?: { cacheReadTokens?: number; cacheWriteTokens?: number };
+		outputTokenDetails?: { reasoningTokens?: number };
+	}): CallUsage {
+		// Optional-chained: the SDK types the detail objects as required, but
+		// providers (and mocks) may leave them unset.
+		return {
+			inputTokens: usage.inputTokens,
+			outputTokens: usage.outputTokens,
+			cacheReadTokens: usage.inputTokenDetails?.cacheReadTokens,
+			cacheWriteTokens: usage.inputTokenDetails?.cacheWriteTokens,
+			reasoningTokens: usage.outputTokenDetails?.reasoningTokens,
+		};
+	}
+
 	async function extract(chatId: string): Promise<SessionFindings> {
 		const record = chatStore.getChat(chatId);
 		if (!record) throw new Error(`Chat not found: ${chatId}`);
+		const signal = runningExtractions.get(chatId)?.controller.signal;
+		signal?.throwIfAborted(); // an abort during a sync gap ends the run here
 		const view = transcriptView(record);
 		console.info(`[extraction ${chatId}] extractor starting (${view.split("\n").length} transcript lines)`);
 		const t0 = performance.now();
 
-		const extraction = await extractorAgent.generate({ prompt: `Transcript:\n\n${view}` });
+		const extraction = await extractorAgent.generate({
+			prompt: `Transcript:\n\n${view}`,
+			abortSignal: signal,
+			onStepFinish: (step) => {
+				recordStep(chatId, "extractor", callUsage(step.usage), step.model.modelId);
+				console.info(
+					`[extraction] extractor step ${step.stepNumber}: ${step.finishReason}, tools: ${step.toolCalls.map((c) => c.toolName).join(", ") || "(none)"}`,
+				);
+			},
+		});
 		for (const part of extraction.content) {
 			if (part.type === "tool-result" && part.toolName === "submit_findings") {
 				console.info(`[extraction ${chatId}] extractor done in ${Math.round(performance.now() - t0)}ms`);
@@ -377,6 +435,8 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 	async function audit(chatId: string, findings: SessionFindings): Promise<AuditResult> {
 		const record = chatStore.getChat(chatId);
 		if (!record) throw new Error(`Chat not found: ${chatId}`);
+		const signal = runningExtractions.get(chatId)?.controller.signal;
+		signal?.throwIfAborted(); // an abort during the extract→audit gap ends here
 		const view = transcriptView(record);
 		const graph = getGraph(graphStore);
 		console.info(
@@ -389,6 +449,13 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 			prompt:
 				`Transcript:\n\n${view}\n\nProposed findings:\n\n${JSON.stringify(findings, null, 2)}\n\n` +
 				`Current knowledge graph (${graph.nodes.length} nodes):\n\n${graphView(graph.nodes)}`,
+			abortSignal: signal,
+			onStepFinish: (step) => {
+				recordStep(chatId, "auditor", callUsage(step.usage), step.model.modelId);
+				console.info(
+					`[extraction] auditor step ${step.stepNumber}: ${step.finishReason}, tools: ${step.toolCalls.map((c) => c.toolName).join(", ") || "(none)"}`,
+				);
+			},
 		});
 		let auditResult: AuditResult | null = null;
 		for (const part of review.content) {
@@ -412,6 +479,25 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 		return auditResult;
 	}
 
+	/** Append the run's usage record to the chat's extractions log — success
+	 *  or failure: a failed run still spent money, and its partial usage is
+	 *  exactly what the record should show (stats absent = never merged).
+	 *  Idempotent per startedAt (the store dedupes). */
+	function persistRunUsage(chatId: string, durationMs: number, stats: EmissionStats | undefined): void {
+		const run = runningExtractions.get(chatId);
+		if (!run) return;
+		chatStore.appendExtractionUsage(chatId, {
+			startedAt: run.startedAt,
+			at: new Date().toISOString(),
+			durationMs,
+			stats,
+			stages: {
+				extractor: run.usage.extractor ?? { model: "unknown", steps: [] },
+				auditor: run.usage.auditor ?? { model: "unknown", steps: [] },
+			},
+		});
+	}
+
 	async function runExtraction(chatId: string): Promise<EmissionStats> {
 		if (inFlight.has(chatId)) return { nodes: 0, edges: 0, events: 0 };
 		inFlight.add(chatId);
@@ -426,12 +512,22 @@ export function createExtractionPipeline(deps: ExtractionPipelineDeps): Extracti
 			// The merger re-reads the chat record itself — events are rebuilt
 			// from the transcript, never from stale copies.
 			const stats = mergeFindings(chatId, auditResult, { chatStore, graphStore });
+			persistRunUsage(chatId, Math.round(performance.now() - t0), stats);
 			console.info(
 				`[extraction ${chatId}] merged: ${stats.nodes} nodes, ${stats.edges} edges, ${stats.events} events ` +
 					`(${Math.round(performance.now() - t0)}ms total)`,
 			);
 			return stats;
 		} catch (err) {
+			persistRunUsage(chatId, Math.round(performance.now() - t0), undefined);
+			// Aborted (the dock's abort button): a deliberate stop, not a
+			// failure — same ledger discipline as a failure (nothing merged,
+			// nothing checkpointed, partial usage persisted), but the run
+			// reports zero emissions instead of throwing.
+			if (err instanceof Error && err.name === "AbortError") {
+				console.info(`[extraction ${chatId}] aborted (${Math.round(performance.now() - t0)}ms) — nothing merged, nothing checkpointed`);
+				return { nodes: 0, edges: 0, events: 0 };
+			}
 			// The throw travels to the caller; this line is what makes the
 			// run's log legible end-to-end (no hanging "pipeline start").
 			console.error(`[extraction ${chatId}] pipeline failed (${Math.round(performance.now() - t0)}ms):`, err);

src/core/contracts/chat.ts

@@ -9,6 +9,7 @@
 import type { UIMessage } from "ai";
 import type { Phase3 } from "../phases.ts";
 import type { PlanNodeStatus, PlanTree } from "./plan.ts";
+import type { EmissionStats } from "./graph.ts";
 
 // ─── Chat records (the session store's on-disk format) ───────────────────────
 
@@ -32,6 +33,41 @@ export interface ChatRecord {
 	 * each entry onto its message; aggregates are folds over this log
 	 * (core/prices.ts). */
 	turns?: TurnUsage[];
+	/** Append-only background-extraction usage log (2026-09 observability):
+	 *  one entry per finished pipeline run on THIS chat — extraction is real
+	 *  spend too. Same parallel-log discipline as `turns` (nothing rides
+	 *  inside messages). Keyed by startedAt; idempotent appends. */
+	extractions?: ExtractionRunUsage[];
+}
+
+// ─── Background-extraction usage (the money channel, extraction side) ────────
+
+/** One pipeline stage's model usage — the stage's model + every step it
+ *  billed (CallUsage per agent step). Steps, not a sum: cost and context
+ *  folds happen at read time (core/prices.ts). */
+export interface ExtractionStageUsage {
+	/** The OpenRouter model id that ran this stage. */
+	model: string;
+	steps: CallUsage[];
+}
+
+/** One finished (or failed mid-flight) extraction run's usage record.
+ *  Appended to the chat's `extractions` log when the run ends — success or
+ *  failure, because money was spent either way; `stats` is present only
+ *  when the merger actually ran. */
+export interface ExtractionRunUsage {
+	/** The run's registry startedAt (ms) — the idempotency key. */
+	startedAt: number;
+	at: string;
+	durationMs: number;
+	/** What the run merged into the graph; absent when it failed first. */
+	stats?: EmissionStats;
+	/** Model usage per stage, in pipeline order (merger is deterministic —
+	 *  no model call, no entry). */
+	stages: {
+		extractor: ExtractionStageUsage;
+		auditor: ExtractionStageUsage;
+	};
 }
 
 // ─── Usage accounting (the money channel) ─────────────────────────────────────

src/core/contracts/graph.ts

@@ -22,6 +22,17 @@
  *  strength — strength is derived at read time from topology. */
 export type EdgeType = "follows" | "supports";
 
+/** What one extraction run merged into the graph ledgers — the merger's
+ *  output, also persisted in extraction-run usage records (contracts/chat). */
+export interface EmissionStats {
+	/** New graph nodes appended. */
+	nodes: number;
+	/** New edge assertions appended. */
+	edges: number;
+	/** Ledger events rebuilt (quiz outcomes + observations). */
+	events: number;
+}
+
 /** One provenance point — message-granular (DECIDED 2026-09-02): nodes and
  *  edges record every (chat, message) where they came up, deep-linkable to
  *  the exact transcript point. */

src/core/graph.ts

@@ -42,6 +42,7 @@ import { randomBytes } from "node:crypto";
 import { isToolUIPart, type UIMessage } from "ai";
 import type {
 	AuditResult,
+	EmissionStats,
 	GraphEdge,
 	GraphNode,
 	ProvenancePoint,
@@ -108,15 +109,6 @@ const samePoint = (a: ProvenancePoint, b: ProvenancePoint): boolean =>
 
 // ─── the merger (extraction pipeline stage 3 — deterministic) ────────────────
 
-export interface EmissionStats {
-	/** New graph nodes appended. */
-	nodes: number;
-	/** New edge assertions appended. */
-	edges: number;
-	/** New ledger events appended. */
-	events: number;
-}
-
 /**
  * Merge one chat's audited findings into the graph ledgers — the pipeline's
  * apply stage. Deterministic + idempotent: re-merging the same verdicts (or
@@ -470,3 +462,6 @@ export function graphSnapshot(deps: GraphDeps): GraphSnapshot {
 
 	return { nodes, edges, sessions, nodeSessions, nodeObservations };
 }
+
+// Re-export: the contract owns the shape; legacy importers still reach it.
+export type { EmissionStats };

src/core/ports.ts

@@ -18,6 +18,7 @@ import type {
 	JobKind,
 	JobRecord,
 	LedgerEvent,
+	ExtractionRunUsage,
 	NodeMapping,
 	PlanTree,
 	SessionCheckpoint,
@@ -41,6 +42,8 @@ export interface ChatStore {
 	 * 2026-09): idempotent per messageId — a turn persisted twice (abort
 	 * replays, wake-turn retries) appends exactly once. */
 	appendTurnUsage(id: string, entry: TurnUsage): void;
+	/** Append one extraction-run usage entry — idempotent per startedAt. */
+	appendExtractionUsage(id: string, entry: ExtractionRunUsage): void;
 }
 
 // ─── GraphStore — the append-only evidence ledgers (data/graph) ──────────────

src/server/observability.ts

@@ -8,5 +8,5 @@
  * this file is where the deep imports surface, so routes stay clean.
  */
 
-export { extractionStatuses, type ExtractionPhase } from "../agent/subagents/extraction.ts";
+export { abortExtraction, extractionStatuses, type ExtractionPhase, type RunningExtraction } from "../agent/subagents/extraction.ts";
 export { chatStore } from "../store/chats.ts";

src/store/chats.ts

@@ -11,7 +11,7 @@ import * as fs from "node:fs";
 import * as path from "node:path";
 import { PATHS } from "../../config.ts";
 import type { ChatStore } from "../core/ports.ts";
-import type { ChatRecord, ChatSummary, PlanTree, TurnUsage } from "../core/contracts.ts";
+import type { ChatRecord, ChatSummary, ExtractionRunUsage, PlanTree, TurnUsage } from "../core/contracts.ts";
 import type { UIMessage } from "ai";
 import { findPendingToolCall } from "../core/pending.ts";
 import { phaseOfTree } from "../core/phases.ts";
@@ -51,9 +51,10 @@ function listChats(): ChatSummary[] {
 			.filter((f) => f.endsWith(".json"))
 			.map((f) => getChat(f.slice(0, -5)))
 			.filter((r): r is ChatRecord => r !== null)
-			.map(({ messages, tree, turns, ...summary }) => ({
-				// turns stay out of the list payload (list = summaries; usage
-				// aggregates ride the full record, the picker never needs them).
+			.map(({ messages, tree, turns, extractions, ...summary }) => ({
+				// turns and extractions stay out of the list payload (list =
+				// summaries; usage aggregates ride the full record, the picker
+				// never needs them).
 				...summary,
 				messageCount: messages.length,
 				// Record-derived status for the session picker: phase from the
@@ -90,6 +91,18 @@ function appendTurnUsage(id: string, entry: TurnUsage): void {
 	fs.writeFileSync(chatFile(id), JSON.stringify(record, null, "\t"), "utf-8");
 }
 
+/** Append one extraction-run usage entry to the record's extractions
+ * log — idempotent per startedAt: a retry that reaches the append twice
+ * (abort replays) does not double-count spend. */
+function appendExtractionUsage(id: string, entry: ExtractionRunUsage): void {
+	const record = getChat(id);
+	if (!record) throw new Error(`Chat not found: ${id}`);
+	record.extractions = record.extractions?.some((r) => r.startedAt === entry.startedAt)
+		? record.extractions
+		: [...(record.extractions ?? []), entry];
+	fs.writeFileSync(chatFile(id), JSON.stringify(record, null, "\t"), "utf-8");
+}
+
 /** Persist the session plan tree (plan tools call this in execute). */
 function saveTree(id: string, tree: PlanTree): void {
 	const record = getChat(id);
@@ -107,4 +120,5 @@ export const chatStore: ChatStore = {
 	saveMessages,
 	saveTree,
 	appendTurnUsage,
+	appendExtractionUsage,
 };