feat(cache-warming): consume CR-4 lifecycle — tab-close cancel + scope-aware subscriptions

- closeTab now POSTs /conversations/:id/close (abort in-flight turn + stop/disable
  warming server-side); disconnect still leaves both running ([email protected])
- syncSubscriptions honors catalog scope ([email protected]): global surfaces are
  not re-subscribed on conversation switch
- fix(ws): the surface-message parser dropped the conversationId echo (CR-4d was
  ours, not the backend's) — preserved + unit-tested
- secondsUntilNext: 3s stale guard — a past nextWarmAt renders as waiting, not 0s
- re-pinned + re-mirrored [email protected] / [email protected]
- scripts/probe-cache-warming.ts: live CR-4 probe (default-off, future nextWarmAt,
  repeated warms, mid-turn close abort, idempotent re-close) — 17/17 against bin/up

2 files changed, 99 insertions, 2 deletions

diff --git a/src/app/store.svelte.ts b/src/app/store.svelte.ts
index df92b31..2837bb5 100644
--- a/src/app/store.svelte.ts
+++ b/src/app/store.svelte.ts
@@ -256,6 +256,23 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 		socket?.send({ type: "chat.unsubscribe", conversationId });
 	}
 
+	/**
+	 * Tell the backend the user EXPLICITLY closed this conversation's tab
+	 * (`POST /conversations/:id/close`): aborts any in-flight turn (it seals with
+	 * `reason: "aborted"`) and stops + DISABLES its cache-warming (persisted OFF).
+	 * Distinct from a disconnect / `chat.unsubscribe`, which deliberately leave
+	 * both running. Fire-and-forget: a failure is non-fatal (worst case the
+	 * warming keeps running until a later close/toggle), and the endpoint is
+	 * idempotent server-side.
+	 */
+	function closeConversation(conversationId: string): void {
+		void fetchImpl(`${httpBase}/conversations/${encodeURIComponent(conversationId)}/close`, {
+			method: "POST",
+		}).catch(() => {
+			// Non-fatal — see doc comment.
+		});
+	}
+
 	/** The conversation the surfaces should scope to (undefined for a draft). */
 	function focusedConversationId(): string | undefined {
 		return tabsStore.activeConversationId ?? undefined;
@@ -289,7 +306,12 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 	function syncSubscriptions(): void {
 		const cid = focusedConversationId();
 		for (const entry of protocol.catalog) {
-			const result = protocolSubscribe(protocol, entry.id, cid);
+			// A GLOBAL surface ignores conversation scope — subscribe it WITHOUT an id
+			// so a conversation switch doesn't churn a redundant unsubscribe+subscribe
+			// round trip ([email protected] catalog `scope`; ABSENT = assume
+			// conversation-scoped, the conservative pre-0.2.0 policy).
+			const scoped = entry.scope === "global" ? undefined : cid;
+			const result = protocolSubscribe(protocol, entry.id, scoped);
 			protocol = result.state;
 			for (const msg of result.outgoing) {
 				socket?.send(msg);
@@ -489,7 +511,10 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 
 		closeTab(conversationId: string): void {
 			tabsStore.closeTab(conversationId);
-			// Stop watching the closed conversation's turns (does NOT stop the turn).
+			// The user is DONE with this chat for now: abort any in-flight turn and
+			// stop + disable its cache-warming, server-side.
+			closeConversation(conversationId);
+			// Stop watching the closed conversation's turns.
 			unsubscribeChat(conversationId);
 			const store = chatStores.get(conversationId);
 			if (store !== undefined) {
diff --git a/src/app/store.test.ts b/src/app/store.test.ts
index 803d7dc..f4b5a0f 100644
--- a/src/app/store.test.ts
+++ b/src/app/store.test.ts
@@ -674,6 +674,78 @@ describe("createAppStore", () => {
 		store.dispose();
 	});
 
+	it("closing a tab POSTs /conversations/:id/close (abort turn + stop warming)", async () => {
+		const calls: { url: string; method: string }[] = [];
+		const base = fakeFetchImpl();
+		const fetchImpl: typeof fetch = async (input, init) => {
+			const url = typeof input === "string" ? input : input instanceof URL ? input.href : input.url;
+			calls.push({ url, method: init?.method ?? "GET" });
+			if (url.endsWith("/close")) {
+				return new Response(
+					JSON.stringify({ conversationId: url.split("/").at(-2), abortedTurn: false }),
+					{ status: 200 },
+				);
+			}
+			return base(input, init);
+		};
+		const ws = fakeSocket();
+		const store = createAppStore({
+			socketFactory: () => ws,
+			fetchImpl,
+			localStorage: createFakeStorage(),
+		});
+		ws.resolveOpen();
+
+		store.send("first");
+		const convId = activeConversationId(store);
+		store.closeTab(convId);
+		await Promise.resolve(); // flush the fire-and-forget fetch
+
+		const close = calls.find((c) => c.url.endsWith(`/conversations/${convId}/close`));
+		expect(close).toBeDefined();
+		expect(close?.method).toBe("POST");
+
+		store.dispose();
+	});
+
+	it("does NOT re-scope a scope:'global' surface on conversation switch (no churn)", () => {
+		const ws = fakeSocket();
+		const store = createAppStore({
+			socketFactory: () => ws,
+			fetchImpl: fakeFetchImpl(),
+			localStorage: createFakeStorage(),
+		});
+		ws.resolveOpen();
+
+		ws.feedSurfaceMessage({
+			type: "catalog",
+			catalog: [
+				{ id: "s-global", region: "side", title: "Global", scope: "global" },
+				{ id: "s-conv", region: "side", title: "Scoped", scope: "conversation" },
+			],
+		});
+
+		ws.sent.length = 0;
+		store.send("promote the draft"); // draft → real conversation: surfaces re-scope
+		const convId = activeConversationId(store);
+
+		const surfaceMsgs = parseSent(ws).filter(
+			(p): p is { type: string; surfaceId: string; conversationId?: string } =>
+				(p as { type: string }).type === "subscribe" ||
+				(p as { type: string }).type === "unsubscribe",
+		);
+		// The conversation-scoped surface re-scopes: unsubscribe old + subscribe new id.
+		expect(
+			surfaceMsgs.some(
+				(m) => m.type === "subscribe" && m.surfaceId === "s-conv" && m.conversationId === convId,
+			),
+		).toBe(true);
+		// The global surface is untouched — no redundant unsubscribe+subscribe round trip.
+		expect(surfaceMsgs.some((m) => m.surfaceId === "s-global")).toBe(false);
+
+		store.dispose();
+	});
+
 	it("tabs persist to the injected storage and restore on a new store", () => {
 		const ws = fakeSocket();
 		const storage = createFakeStorage();