Storage ports: ChatStore/GraphStore/JobStore + adapters + core inversion (stage 3)

Per-entity semantic ports (src/core/ports.ts), one adapter family
(src/store/*, fs JSON/JSONL), exactly one composition point
(src/server/stores.ts). Dependency direction is now machine-checked:
adapters implement core interfaces; core never imports an adapter.

The inversion:
- core/graph.ts (emitChat/getGraph/graphSnapshot/foldStaleChats) is now
  pure — it takes the storage ports as explicit parameters (GraphDeps).
  No store imports; newGraphNodeId is local; node id format unchanged.
- core/graph-context.ts buildGraphContext() no longer defaults to the
  live ledgers: the chat-handler hands in getGraph(graphStore) per turn.
- store adapters export exactly one object each implementing their port
  (chatStore/graphStore/jobStore); bodies otherwise verbatim.
  NodeMapping + SessionCheckpoint moved store/graph -> core/contracts
  (they ARE contract shapes); CreateJobInit/JobPatch live in ports.
- titleFromPrompt moved store/chats -> core/contracts (pure helper,
  planNodeStatus precedent). Store modules now contain persistence only.
- server/stores.ts is the composition root; server/{chats,graph,jobs}.ts
  and chat-handler wire from it; agent (plan tools, sub-agent runner)
  call the port objects. The shell surface (@/src/server exports) is
  unchanged.

Lint law extended: the whole of src/core is now a purity zone (was a
file glob with a graph/graph-context exemption). Verified it fires on
core->store imports; tsc clean, 190/190 tests, eslint clean, prod build
clean (prerender 6/6). Tests pass deps explicitly — graph.test uses the
same fs-adapter pair stores.ts wires in production; graph-context.test
keeps its in-memory ledgers as a GraphStore implementation.

src/store/jobs.ts

@@ -1,18 +1,19 @@
+/**
+ * JobStore — the fs JSON adapter: one file per background sub-agent job in
+ * data/jobs/ (contracts.ts "THE ASYNC PROTOCOL"). Keyed by toolCallId for
+ * dedup: the chat-handler spawn hook never creates two jobs for the same
+ * tool part. Implements core/ports.ts JobStore. Idioms: sync fs, id-guarded
+ * filenames, JSON with tab indentation. Writes are small and rare (activity
+ * line updates); the read-modify-write sections in the runner contain no
+ * awaits, so they are atomic within the single-threaded event loop.
+ */
+
 import * as fs from "node:fs";
 import * as path from "node:path";
 import { PATHS } from "../../config.ts";
-import type { JobKind, JobRecord } from "../core/contracts.ts";
-
-/**
- * Job store — one JSON file per background sub-agent job in data/jobs/
- * (contracts.ts "THE ASYNC PROTOCOL"). Keyed by toolCallId for dedup: the
- * chat-handler spawn hook never creates two jobs for the same tool part.
- *
- * Follows src/store/chats.ts idioms: sync fs, id-guarded filenames, JSON
- * with tab indentation. Writes are small and rare (activity line updates);
- * the read-modify-write sections in the runner contain no awaits, so they
- * are atomic within the single-threaded event loop.
- */
+import type { JobStore } from "../core/ports.ts";
+import type { CreateJobInit, JobPatch } from "../core/ports.ts";
+import type { JobRecord } from "../core/contracts.ts";
 
 /** Background jobs (data/jobs). Not in config.ts PATHS (orchestrator-owned). */
 const JOBS_DIR = path.join(PATHS.data, "jobs");
@@ -22,15 +23,7 @@ function jobFile(id: string): string {
 	return path.join(JOBS_DIR, `${id}.json`);
 }
 
-export interface CreateJobInit {
-	kind: JobKind;
-	chatId: string;
-	toolCallId: string;
-	/** First activity line (defaults to "starting"). */
-	activity?: string;
-}
-
-export function createJob(init: CreateJobInit): JobRecord {
+function createJob(init: CreateJobInit): JobRecord {
 	const now = new Date().toISOString();
 	const record: JobRecord = {
 		id: `job_${Date.now().toString(36)}_${crypto.randomUUID().slice(0, 8)}`,
@@ -47,7 +40,7 @@ export function createJob(init: CreateJobInit): JobRecord {
 	return record;
 }
 
-export function getJob(id: string): JobRecord | null {
+function getJob(id: string): JobRecord | null {
 	try {
 		return JSON.parse(fs.readFileSync(jobFile(id), "utf-8")) as JobRecord;
 	} catch {
@@ -56,10 +49,7 @@ export function getJob(id: string): JobRecord | null {
 }
 
 /** Merge a partial patch into the record (identity fields are immutable). */
-export function updateJob(
-	id: string,
-	patch: Partial<Omit<JobRecord, "id" | "kind" | "chatId" | "toolCallId" | "createdAt">>,
-): JobRecord | null {
+function updateJob(id: string, patch: JobPatch): JobRecord | null {
 	const record = getJob(id);
 	if (!record) return null;
 	const next: JobRecord = { ...record, ...patch, updatedAt: new Date().toISOString() };
@@ -68,7 +58,7 @@ export function updateJob(
 }
 
 /** All jobs for a chat, newest activity first. */
-export function listJobs(chatId: string): JobRecord[] {
+function listJobs(chatId: string): JobRecord[] {
 	try {
 		fs.mkdirSync(JOBS_DIR, { recursive: true });
 		return fs
@@ -83,6 +73,14 @@ export function listJobs(chatId: string): JobRecord[] {
 }
 
 /** The job fulfilling a given tool part, if any (spawn-hook dedup). */
-export function findJobByToolCallId(chatId: string, toolCallId: string): JobRecord | null {
+function findJobByToolCallId(chatId: string, toolCallId: string): JobRecord | null {
 	return listJobs(chatId).find((j) => j.toolCallId === toolCallId) ?? null;
 }
+
+export const jobStore: JobStore = {
+	createJob,
+	getJob,
+	updateJob,
+	listJobs,
+	findJobByToolCallId,
+};