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/core/contracts.ts

@@ -1,7 +1,7 @@
 /**
  * Shared contracts — the single source of truth every component codes against.
- * Pure types + protocol docs; no runtime code, type-only imports (safe
- * everywhere: server, client, tests). See docs/vision.md (§ refs).
+ * Pure types + protocol docs + tiny pure helpers; type-only imports of "ai"
+ * (safe everywhere: server, client, tests). See docs/vision.md (§ refs).
  */
 
 import type { UIMessage } from "ai";
@@ -83,6 +83,23 @@ export interface GraphEdge {
 	provenance: string[];
 }
 
+/** mappings.jsonl line — the naive-union identity map: a chat's tree node →
+ * the graph node it folded into (the merge audit trail; v1 never merges two
+ * sessions' tree nodes — W8 exact-title match aside). */
+export interface NodeMapping {
+	chatId: string;
+	treeNodeId: string;
+	graphNodeId: string;
+}
+
+/** sessions.jsonl line — the emission checkpoint for one chat (which chats
+ *  have been folded, and through which updatedAt — never fold twice). */
+export interface SessionCheckpoint {
+	chatId: string;
+	/** The chat record's `updatedAt` at the time of the fold. */
+	foldedAt: string;
+}
+
 export type LedgerEventKind =
 	| "probe-correct"
 	| "probe-miss"
@@ -136,6 +153,13 @@ export interface GraphSnapshot {
 	nodeSessions: Record<string, string[]>;
 }
 
+/** Derive a short chat title from the learner's first message (pure).
+ *  Used on chat creation; deterministic so tests can pin it. */
+export function titleFromPrompt(prompt: string): string {
+	const oneLine = prompt.replace(/\s+/g, " ").trim();
+	return oneLine.length > 72 ? `${oneLine.slice(0, 72)}…` : oneLine;
+}
+
 // ─── Chat records (the session store's on-disk format) ───────────────────────
 
 /** One persisted session: data/chats/<id>.json. The stored messages are full

src/core/graph-context.ts

@@ -22,7 +22,7 @@
  */
 
 import type { GraphEdge, GraphNode } from "./contracts.ts";
-import { deriveNodeStates, getGraph, type DerivedGraph } from "./graph.ts";
+import { deriveNodeStates, type DerivedGraph } from "./graph.ts";
 import type { NodeStateClass } from "./contracts.ts";
 
 /** The section header the teacher is taught to recognize (50-graph-context.md). */
@@ -59,7 +59,7 @@ function isHotspot(node: GraphNode, state: NodeStateClass): boolean {
  * Render the context block, or null when there is nothing worth injecting
  * (no nodes; or a truncated graph whose selection came out empty).
  *
- * Pure: callers hand in exactly what getGraph() + deriveNodeStates() produce.
+ * Pure: callers hand in exactly what getGraph(graphStore) + deriveNodeStates() produce.
  */
 export function renderGraphContext(
 	nodes: GraphNode[],
@@ -162,11 +162,11 @@ function edgeChains(edges: GraphEdge[]): string[][] {
 // ─── the per-request entry point ─────────────────────────────────────────────
 
 /**
- * Build the graph context block for one request. Stateless — re-reads the
- * ledgers every call, so it self-updates as the graph grows mid-session.
- * Accepts an injected derived graph (tests); defaults to the live one.
+ * Build the graph context block for one request. Pure: the caller hands in
+ * the derived graph (production: getGraph(graphStore) per request in the
+ * chat-handler, so it self-updates as the graph grows mid-session).
  */
-export function buildGraphContext(graph: DerivedGraph = getGraph()): string | null {
+export function buildGraphContext(graph: DerivedGraph): string | null {
 	const states = deriveNodeStates(graph.nodes, graph.events);
 	return renderGraphContext(graph.nodes, graph.edges, states);
 }

src/core/graph.ts

@@ -16,10 +16,12 @@
  * Idempotent + incremental: mappings dedupe nodes, (from,to,type) dedupes
  * edge assertions, chat-scoped refs dedupe events, and sessions.jsonl
  * checkpoints which chats have been folded. Re-emitting a chat appends
- * nothing. The store (src/store/graph.ts) holds the append-only ledgers;
- * everything here derives from them.
+ * nothing. Every function takes the storage ports (core/ports.ts) as
+ * explicit parameters — pure core, no adapter imports; the composition
+ * root (src/server/stores.ts) wires the fs adapters in.
  */
 
+import { randomBytes } from "node:crypto";
 import { isToolUIPart, type UIMessage } from "ai";
 import type {
 	GraphEdge,
@@ -32,13 +34,18 @@ import type {
 	PlanToolResult,
 } from "./contracts.ts";
 import type { QuestionAnswerData } from "./question-core.ts";
-import { getChat, listChats } from "../store/chats.ts";
-import { graphLedgers, newGraphNodeId } from "../store/graph.ts";
+import type { ChatStore, GraphStore } from "./ports.ts";
 
-/** The ledger surface emitChat needs (the real one is src/store/graph.ts).
- *  Injectable so tests can fold fixtures into an in-memory ledger instead of
- *  the live data/graph files. */
-export type GraphLedgers = typeof graphLedgers;
+/** The storage ports every graph operation needs, passed explicitly. */
+export interface GraphDeps {
+	chatStore: ChatStore;
+	graphStore: GraphStore;
+}
+
+/** "n_" + 12 hex chars (contracts.ts GraphNode.id — store-assigned). */
+function newGraphNodeId(): string {
+	return `n_${randomBytes(6).toString("hex")}`;
+}
 
 // ─── transcript scanning ─────────────────────────────────────────────────────
 
@@ -109,11 +116,12 @@ export interface EmissionStats {
  * turn (chat-handler onFinish) and again on catch-up (GET /api/graph). Sync
  * and fast: a handful of small-file reads plus one append per new record.
  *
- * `ledgers` is injectable for tests (in-memory ledger); production always
- * uses the live store.
+ * The storage ports are explicit (tests pass in-memory ledgers; production
+ * passes the fs adapters from src/server/stores.ts).
  */
-export function emitChat(chatId: string, ledgers: GraphLedgers = graphLedgers): EmissionStats {
-	const record = getChat(chatId);
+export function emitChat(chatId: string, deps: GraphDeps): EmissionStats {
+	const { graphStore: ledgers } = deps;
+	const record = deps.chatStore.getChat(chatId);
 	if (!record) return { nodes: 0, edges: 0, events: 0 };
 	const stats: EmissionStats = { nodes: 0, edges: 0, events: 0 };
 
@@ -297,11 +305,11 @@ export interface DerivedGraph {
  * edges are merged by (from,to,type) with unioned provenance, first-seen
  * order. `store events, derive state` — this is the only reader that matters.
  */
-export function getGraph(): DerivedGraph {
-	const nodes = graphLedgers.readNodes();
+export function getGraph(graphStore: GraphStore): DerivedGraph {
+	const nodes = graphStore.readNodes();
 	const merged: GraphEdge[] = [];
 	const byKey = new Map<string, GraphEdge>();
-	for (const line of graphLedgers.readEdges()) {
+	for (const line of graphStore.readEdges()) {
 		const key = `${line.from}\u0000${line.to}\u0000${line.type}`;
 		const existing = byKey.get(key);
 		if (existing) {
@@ -314,7 +322,7 @@ export function getGraph(): DerivedGraph {
 			merged.push(edge);
 		}
 	}
-	return { nodes, edges: merged, events: graphLedgers.readEvents() };
+	return { nodes, edges: merged, events: graphStore.readEvents() };
 }
 
 const QUIZ_EVENT_KINDS: ReadonlySet<string> = new Set([
@@ -366,8 +374,8 @@ export function deriveNodeStates(nodes: GraphNode[], events: LedgerEvent[]): Rec
 // ─── the /api/graph payload ──────────────────────────────────────────────────
 
 /** Everything the home graph view needs, in one fetch (shape: contracts). */
-export function graphSnapshot(): GraphSnapshot {
-	const { nodes, edges, events } = getGraph();
+export function graphSnapshot(deps: GraphDeps): GraphSnapshot {
+	const { nodes, edges, events } = getGraph(deps.graphStore);
 	const nodeStates = deriveNodeStates(nodes, events);
 
 	const nodeChats = new Map<string, Set<string>>();
@@ -379,7 +387,7 @@ export function graphSnapshot(): GraphSnapshot {
 		}
 		chats.add(chatId);
 	};
-	for (const m of graphLedgers.readMappings()) touch(m.graphNodeId, m.chatId);
+	for (const m of deps.graphStore.readMappings()) touch(m.graphNodeId, m.chatId);
 	for (const edge of edges) {
 		for (const chatId of edge.provenance) {
 			touch(edge.from, chatId);
@@ -397,7 +405,7 @@ export function graphSnapshot(): GraphSnapshot {
 	}
 	const sessions: Record<string, string> = {};
 	for (const id of chatIds) {
-		const chat = getChat(id);
+		const chat = deps.chatStore.getChat(id);
 		if (chat) sessions[id] = chat.title;
 	}
 
@@ -417,9 +425,9 @@ export function graphSnapshot(): GraphSnapshot {
  * sessions deposit value — vision §1 "frequent updates"). Called at the top
  * of GET /api/graph; the chat-handler onFinish hook covers the live path.
  */
-export function foldStaleChats(): number {
+export function foldStaleChats(deps: GraphDeps): number {
 	const checkpoints = new Map<string, string>();
-	for (const checkpoint of graphLedgers.readCheckpoints()) {
+	for (const checkpoint of deps.graphStore.readCheckpoints()) {
 		const previous = checkpoints.get(checkpoint.chatId);
 		if (previous === undefined || checkpoint.foldedAt > previous) {
 			checkpoints.set(checkpoint.chatId, checkpoint.foldedAt);
@@ -427,11 +435,11 @@ export function foldStaleChats(): number {
 	}
 
 	let folded = 0;
-	for (const chat of listChats()) {
+	for (const chat of deps.chatStore.listChats()) {
 		const foldedAt = checkpoints.get(chat.id);
 		if (foldedAt !== undefined && chat.updatedAt <= foldedAt) continue;
 		try {
-			emitChat(chat.id);
+			emitChat(chat.id, deps);
 			folded++;
 		} catch (err) {
 			console.error(`[graph] fold failed for chat ${chat.id}:`, err);

src/core/index.ts

@@ -9,13 +9,16 @@
  *   components/**  →  "@/src/core"        (this barrel, ONLY)
  *   app/**         →  "@/src/core" + "@/src/server"
  *
- * IO-bound modules (core/graph.ts, core/graph-context.ts read the ledgers
- * via the store) stay internal to the server side until the storage-port
- * stage inverts their dependency; they are deliberately NOT re-exported
- * here.
+ * Server-only core modules (core/graph.ts emission/derivation,
+ * core/graph-context.ts) are pure but need storage ports passed in by a
+ * server caller, so they are deliberately NOT re-exported here — the
+ * server imports them directly. The storage PORT TYPES are types-only and
+ * browser-safe, hence re-exported.
  */
 
 export * from "./contracts.ts";
+export * from "./ports.ts";
+
 export * from "./question-core.ts";
 export * from "./plan-tree.ts";
 export * from "./phases.ts";

src/core/ports.ts

@@ -0,0 +1,95 @@
+/**
+ * Storage ports (the hexagonal seams — vision §1 "storage stays swappable").
+ *
+ * One port per ENTITY, with domain operations — never one generic
+ * key/value interface. Core and the service layer that orbits it code
+ * against these types only; concrete adapters live in src/store/ (fs
+ * JSON/JSONL today, SQLite drop-in later) and are wired exactly once, in
+ * the composition root (src/server/stores.ts). Dependencies point one way:
+ * adapters may import core; core NEVER imports an adapter.
+ */
+
+import type { UIMessage } from "ai";
+import type {
+	ChatRecord,
+	ChatSummary,
+	GraphEdge,
+	GraphNode,
+	JobKind,
+	JobRecord,
+	LedgerEvent,
+	NodeMapping,
+	PlanTree,
+	SessionCheckpoint,
+} from "./contracts.ts";
+
+// ─── ChatStore — the session record's home (data/chats) ─────────────────────
+
+export interface ChatStore {
+	/** Create a session record (persisted immediately). */
+	createChat(title: string): ChatRecord;
+	/** The full record, or null if unknown id / corrupt file. */
+	getChat(id: string): ChatRecord | null;
+	/** All sessions, newest activity first (the sidebar's list view). */
+	listChats(): ChatSummary[];
+	/** Persist the full message list (client state + new response) after a turn. */
+	saveMessages(id: string, messages: UIMessage[]): void;
+	/** Persist the session plan tree (plan tools call this in execute). */
+	saveTree(id: string, tree: PlanTree): void;
+}
+
+// ─── GraphStore — the append-only evidence ledgers (data/graph) ──────────────
+// v1 surface = the five JSONL ledgers (nodes / edges / events / mappings /
+// sessions). Reads return the raw append-order lines; merging edge assertions
+// by (from, to, type) is DERIVED in core/graph.ts — the store never decides.
+// The extraction pipeline (next stage) becomes the sole writer; this read
+// surface stays.
+
+export interface GraphStore {
+	/** Append one GraphNode (ids are unique — no merging needed). */
+	appendNode(node: GraphNode): void;
+	/** Raw node lines in append order. */
+	readNodes(): GraphNode[];
+
+	/** Append one edge ASSERTION (a second session asserting the same
+	 *  (from, to, type) appends another line; readers merge). */
+	appendEdge(assertion: GraphEdge): void;
+	readEdges(): GraphEdge[];
+
+	/** Append one quiz outcome / taught event. */
+	appendEvent(event: LedgerEvent): void;
+	readEvents(): LedgerEvent[];
+
+	/** Append one identity-map line (chat's tree node → graph node). */
+	appendMapping(mapping: NodeMapping): void;
+	readMappings(): NodeMapping[];
+
+	/** Append one emission checkpoint. */
+	appendCheckpoint(checkpoint: SessionCheckpoint): void;
+	readCheckpoints(): SessionCheckpoint[];
+}
+
+// ─── JobStore — background sub-agent jobs (data/jobs) ─────────────────────────
+
+export interface CreateJobInit {
+	kind: JobKind;
+	chatId: string;
+	toolCallId: string;
+	/** First activity line (defaults to "starting"). */
+	activity?: string;
+}
+
+/** Mergeable fields — identity (id, kind, chatId, toolCallId, createdAt) is immutable. */
+export type JobPatch = Partial<Omit<JobRecord, "id" | "kind" | "chatId" | "toolCallId" | "createdAt">>;
+
+export interface JobStore {
+	/** Create a running job (keyed by toolCallId for spawn dedup). */
+	createJob(init: CreateJobInit): JobRecord;
+	getJob(id: string): JobRecord | null;
+	/** Merge a patch into the record; null if unknown id. */
+	updateJob(id: string, patch: JobPatch): JobRecord | null;
+	/** All jobs for a chat, newest activity first. */
+	listJobs(chatId: string): JobRecord[];
+	/** The job fulfilling a given tool part, if any (spawn-hook dedup). */
+	findJobByToolCallId(chatId: string, toolCallId: string): JobRecord | null;
+}