feat(tabs): cross-device tab sync via conversation lifecycle

Consume the conversation lifecycle handoff ([email protected], [email protected]).
Re-pinned file: deps + re-mirrored .dispatch/*.reference.md.

- fetchOpenConversations() on connect: GET /conversations?status=active,idle
  restores the tab bar across devices (merges with localStorage — opens new
  tabs, removes closed ones, updates titles from backend)
- conversation.statusChanged WS handler: closed → removeTabLocally (no
  re-POST); active → open tab + spinner; idle → update status map
- conversation.compacted WS handler: dispose stale store + cache, reload
  history from server
- TabBar shows a spinner on active conversations (statusFor prop)
- closeTab refactored to use removeTabLocally (extracted cleanup)
- conformance guards + WS adapter tests cover all 3 new WsServerMessage types

686 tests green.

13 files changed, 334 insertions, 31 deletions

diff --git a/.dispatch/transport-contract.reference.md b/.dispatch/transport-contract.reference.md
index d5f22c7..e599eb3 100644
--- a/.dispatch/transport-contract.reference.md
+++ b/.dispatch/transport-contract.reference.md
@@ -5,10 +5,19 @@
 > hangs on a permission prompt). Your CODE still imports `@dispatch/transport-contract` normally —
 > this file is for READING only.
 >
-> **Orchestrator:** SNAPSHOT of `[email protected]` (conversation.open broadcast).
-> Depends on `@dispatch/[email protected]` (see `wire.reference.md`) + `@dispatch/[email protected]` (see
+> **Orchestrator:** SNAPSHOT of `[email protected]` (conversation lifecycle).
+> Depends on `@dispatch/[email protected]` (see `wire.reference.md`) + `@dispatch/[email protected]` (see
 > `ui-contract.reference.md`).
 >
+> **2026-06-22 delta (conversation lifecycle handoff — package bumped `0.13.0` → `0.14.0`, ADDITIVE):**
+> adds conversation lifecycle **status** (`active`/`idle`/`closed`) for cross-device tab
+> persistence. `ConversationMeta` (re-exported from `[email protected]`) gains a `status` field. New
+> WS message `ConversationStatusChangedMessage` (`{ type: "conversation.statusChanged";
+> conversationId; status }`) is broadcast to ALL clients on every status change. `GET
+> /conversations` gains an optional `?status=active,idle` filter (comma-separated; default = all).
+> `POST /conversations/:id/close` now also sets status to `closed` (persists across restarts).
+> The FE fetches `?status=active,idle` on connect to restore the tab bar across devices.
+>
 > **2026-06-21 delta (conversation.open handoff — package bumped `0.12.0` → `0.13.0`, ADDITIVE):**
 > adds the `conversation.open` WS broadcast — when the CLI's `--open` flag fires
 > (`POST /conversations/:id/open`), the backend broadcasts a `ConversationOpenMessage`
@@ -212,6 +221,7 @@ import type { SurfaceClientMessage, SurfaceServerMessage } from "@dispatch/ui-co
 import type {
 	AgentEvent,
 	ConversationMeta,
+	ConversationStatus,
 	QueuedMessage,
 	ReasoningEffort,
 	StoredChunk,
@@ -221,6 +231,7 @@ import type {
 export type {
 	AgentEvent,
 	ConversationMeta,
+	ConversationStatus,
 	QueuedMessage,
 	ReasoningEffort,
 	StepMetrics,
@@ -666,7 +677,9 @@ export type WsServerMessage =
 	| SurfaceServerMessage
 	| ChatDeltaMessage
 	| ChatErrorMessage
-	| ConversationOpenMessage;
+	| ConversationOpenMessage
+	| ConversationStatusChangedMessage
+	| ConversationCompactedMessage;
 
 // ─── Conversation list + metadata ────────────────────────────────────────────
 
@@ -681,6 +694,29 @@ export interface ConversationOpenMessage {
 }
 
 /**
+ * Broadcast to all connected WS clients when a conversation's lifecycle status
+ * changes (`active`/`idle`/`closed`). The FE uses this for cross-device tab
+ * sync: `closed` → remove the tab; `active` → show a generating indicator.
+ */
+export interface ConversationStatusChangedMessage {
+	readonly type: "conversation.statusChanged";
+	readonly conversationId: string;
+	readonly status: ConversationStatus;
+}
+
+/**
+ * Broadcast to all connected WS clients when a conversation's history has been
+ * compacted (summarized). The frontend should reload the conversation history
+ * via `GET /conversations/:id` to reflect the compacted state.
+ */
+export interface ConversationCompactedMessage {
+	readonly type: "conversation.compacted";
+	readonly conversationId: string;
+	readonly messagesSummarized: number;
+	readonly messagesKept: number;
+}
+
+/**
  * Response for `GET /conversations` — the list of all known conversations,
  * sorted by `lastActivityAt` descending (most recent first). Each entry carries
  * enough metadata for a conversation picker UI (id, title, timestamps).
diff --git a/.dispatch/wire.reference.md b/.dispatch/wire.reference.md
index e96c353..ead4d9c 100644
--- a/.dispatch/wire.reference.md
+++ b/.dispatch/wire.reference.md
@@ -4,9 +4,17 @@
 > types WITHOUT following the `file:` dep symlink out of this repo (which hangs on a permission
 > prompt). Your CODE still imports `@dispatch/wire` normally — this file is for READING only.
 >
-> **Orchestrator:** SNAPSHOT of `[email protected]` (conversation metadata). Regenerate
+> **Orchestrator:** SNAPSHOT of `[email protected]` (conversation lifecycle status). Regenerate
 > whenever `@dispatch/wire` changes.
 >
+> **2026-06-22 delta (conversation lifecycle handoff — package bumped `0.9.0` → `0.10.0`, ADDITIVE):**
+> adds `ConversationStatus` (`"active" | "idle" | "closed"`) — the per-conversation lifecycle
+> status. `ConversationMeta` gains a `status` field. `active` = a turn is generating; `idle` =
+> exists, not generating; `closed` = dismissed (hidden from the tab bar). Transitions are
+> backend-owned: `idle → active` on turn start, `active → idle` on turn settle, `→ closed` on
+> `POST /conversations/:id/close`. Pushed to all WS clients via `conversation.statusChanged`
+> (see `[email protected]`).
+>
 > **2026-06-21 delta (conversation.open handoff — package bumped `0.8.0` → `0.9.0`, ADDITIVE):**
 > adds `ConversationMeta` — metadata for a conversation (id, title, createdAt, lastActivityAt),
 > returned by `GET /conversations` (the list endpoint, see `[email protected]`).
@@ -585,6 +593,14 @@ export interface TurnSteeringEvent {
 // ─── Conversation metadata ───────────────────────────────────────────────────
 
 /**
+ * The per-conversation lifecycle status. `active` = a turn is generating;
+ * `idle` = exists, not generating; `closed` = dismissed (hidden from the tab
+ * bar, not deleted). Transitions are backend-owned and pushed via the
+ * `conversation.statusChanged` WS message (see `transport-contract`).
+ */
+export type ConversationStatus = "active" | "idle" | "closed";
+
+/**
  * Metadata for a conversation, returned by `GET /conversations` (the list
  * endpoint). The title defaults to the first user message (truncated) and can
  * be set via `PUT /conversations/:id/title`. `createdAt` is set on first write;
@@ -595,5 +611,6 @@ export interface ConversationMeta {
 	readonly createdAt: number;
 	readonly lastActivityAt: number;
 	readonly title: string;
+	readonly status: ConversationStatus;
 }
 ```
diff --git a/ROADMAP.md b/ROADMAP.md
index b1d9b11..c1c5c30 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -16,15 +16,16 @@
 - **Reasoning effort** — sticky per-conversation thinking-depth knob (`GET`/`PUT /reasoning-effort`, `null` ⇒ default `high`).
 - **Message queue + steering** — `chat.queue` WS op, `steering` AgentEvent → user bubble in transcript, message-queue surface panel above composer.
 - **Todo task list** — `rendererId: "todo"` custom renderer, dedicated "Tasks" sidebar view (status indicators: pending/in_progress/completed/cancelled).
-- **Conversation.open broadcast** — `conversation.open` WS message handler, opens/focuses a tab from CLI `--open` flag.
+- **Conversation.open broadcast** — `conversation.open` WS message handler, opens a tab (without auto-switching) from CLI `--open` flag.
+- **Conversation lifecycle (cross-device tab sync)** — `GET /conversations?status=active,idle` on connect restores tabs across devices; `conversation.statusChanged` WS handler updates tab status + removes closed tabs; TabBar shows a spinner on `active` conversations.
 
 ## Next up
 
 ### Conversation list + title editing (`frontend-conversation-list-handoff.md`)
 
-Types already in `[email protected]` + `[email protected]` (mirrored, deps re-pinned). The `conversation.open` WS handler is already consumed. Remaining FE work:
+Types already in `[email protected]` + `[email protected]` (mirrored, deps re-pinned). The `conversation.open` + lifecycle handlers are already consumed. Remaining FE work:
 
-1. **Conversation list sidebar view** — `GET /conversations` → `ConversationListResponse` (`ConversationMeta[]` with id, title, createdAt, lastActivityAt). Render a "Conversations" sidebar view (title + relative time). Click to open (create tab + load history + subscribe). Fetch on mount + on focus / manual refresh.
+1. **Conversation list sidebar view** — `GET /conversations` → `ConversationListResponse` (`ConversationMeta[]` with id, title, createdAt, lastActivityAt, status). Render a "Conversations" sidebar view (title + relative time + status). Click to open (create tab + load history + subscribe). Fetch on mount + on focus / manual refresh. Filter by status (active/idle vs closed for a history view).
 2. **Title editing** — `GET`/`PUT /conversations/:id/title` (`TitleResponse`/`SetTitleRequest`). Inline rename affordance on the active conversation's title. Auto-title from first user message is backend-owned; FE overrides via PUT.
 
 ## Backlog (likely next backend asks — not yet requested)
diff --git a/backend-handoff.md b/backend-handoff.md
index 64147ff..ff4b961 100644
--- a/backend-handoff.md
+++ b/backend-handoff.md
@@ -5,19 +5,31 @@
 > **From:** dispatch-web orchestrator · **To:** arch-rewrite orchestrator · **Courier:** the user.
 > `lsp` does NOT span the repos (AGENTS.md § Backend seam) — every cross-repo ask flows through here.
 
-_Last updated: 2026-06-21 (conversation.open handoff consumed). **FE is current on
-`[email protected]` / `[email protected]` / `[email protected]`.** All handoffs to date are
+_Last updated: 2026-06-22 (conversation lifecycle handoff consumed). **FE is current on
+`[email protected]` / `[email protected]` / `[email protected]`.** All handoffs to date are
 consumed: surfaces + WS, conversation transcript/metrics, tabs + model selector, cache-warming
 (incl. authoritative timer + retention + cache-rate fix + the CR-4 lifecycle below),
 **per-conversation cwd + LSP status**, **context size**, **turn continuity + multi-client live
 view**, the **chat limit + CR-5 history windowing**, the **reasoning effort
-(thinking-depth knob)**, the **message queue + steering**, the **todo task list**, and the
-**conversation.open broadcast** (below).
+(thinking-depth knob)**, the **message queue + steering**, the **todo task list**, the
+**conversation.open broadcast**, and the **conversation lifecycle (cross-device tab sync)**
+(below).
 **Open asks: NONE.** CR-1/CR-2/CR-4/CR-5 all RESOLVED ✅ (see §2); §3 lists likely next asks.
 **CR-3 (watcher couldn't see the USER prompt until seal) → RESOLVED ✅** — backend shipped the
 `user-message` turn event; FE re-pinned + consumption live.
 The cwd/LSP draft-path verification (`backend-handoff-cwd-lsp.md`) came back **all ✅ confirmed**._
 
+**Conversation lifecycle handoff (`frontend-conversation-lifecycle-handoff.md`) → CONSUMED ✅.**
+Re-pinned `[email protected]→0.10.0` + `[email protected]→0.14.0` (`ui-contract` unchanged);
+re-mirrored both `.dispatch/*.reference.md`. FE work: `fetchOpenConversations()` on connect fetches
+`GET /conversations?status=active,idle` to restore the tab bar across devices (merges with
+localStorage-restored tabs — opens new ones, removes closed ones, updates titles). The
+`conversation.statusChanged` WS message handler updates a per-conversation status map: `closed` →
+`removeTabLocally` (FE cleanup without re-POSTing `/close`); `active` → opens the tab if not
+already open + shows a spinner in the TabBar (via `statusFor` prop). The `closeTab` path now uses
+`removeTabLocally` (extracted from the old inline cleanup). Conformance guards + WS adapter tests
+cover the new type. 686 tests green. NO new backend ask._
+
 **Conversation.open handoff (`frontend-conversation-open-handoff.md`) → CONSUMED ✅.**
 Re-pinned `[email protected]→0.9.0` + `[email protected]→0.13.0` (`ui-contract` unchanged);
 re-mirrored both `.dispatch/*.reference.md`. FE work: the WS adapter (`adapters/ws/logic.ts` +
@@ -115,13 +127,13 @@ backend ask — but the max-limit denominator is now a live FE need; see §3.
 
 ## 1. Pinned backend contracts (consumed by the FE)
 
-Pinned as `file:` deps: **`[email protected]`; `[email protected]`; `[email protected]`**.
+Pinned as `file:` deps: **`[email protected]`; `[email protected]`; `[email protected]`**.
 
 | Package | Used for |
 |---|---|
 | `@dispatch/ui-contract` | surfaces + surface WS protocol |
-| `@dispatch/wire` | `Chunk`/`StoredChunk`(+`seq`)/`ChatMessage`/`AgentEvent`/`TurnSealedEvent`/`Usage`/`StepId` + metrics: `StepMetrics`/`TurnMetrics`, `usage.stepId`, `step-complete`, `done.durationMs`/`done.usage`, `tool-result.durationMs`, **`done.contextSize`/`TurnMetrics.contextSize`**, **`ReasoningEffort`**, **`QueuedMessage`/`QueuePayload`/`TurnSteeringEvent`**, **`ConversationMeta`** |
-| `@dispatch/transport-contract` | `ChatRequest`(+`reasoningEffort`)/`ModelsResponse`/`ConversationHistoryResponse`/`ConversationMetricsResponse` + `WarmRequest`/`WarmResponse` + `CwdResponse`/`SetCwdRequest` + `ReasoningEffortResponse`/`SetReasoningEffortRequest` + **`QueueRequest`/`QueueResponse`/`ChatQueueMessage`** + **`ConversationOpenMessage`/`ConversationListResponse`/`LastMessageResponse`/`OpenConversationResponse`/`SetTitleRequest`/`TitleResponse`** + LSP (`LspStatusResponse`/`LspServerInfo`/`LspServerState`) + WS chat ops + `WsClientMessage`/`WsServerMessage` |
+| `@dispatch/wire` | `Chunk`/`StoredChunk`(+`seq`)/`ChatMessage`/`AgentEvent`/`TurnSealedEvent`/`Usage`/`StepId` + metrics: `StepMetrics`/`TurnMetrics`, `usage.stepId`, `step-complete`, `done.durationMs`/`done.usage`, `tool-result.durationMs`, **`done.contextSize`/`TurnMetrics.contextSize`**, **`ReasoningEffort`**, **`QueuedMessage`/`QueuePayload`/`TurnSteeringEvent`**, **`ConversationMeta`/`ConversationStatus`** |
+| `@dispatch/transport-contract` | `ChatRequest`(+`reasoningEffort`)/`ModelsResponse`/`ConversationHistoryResponse`/`ConversationMetricsResponse` + `WarmRequest`/`WarmResponse` + `CwdResponse`/`SetCwdRequest` + `ReasoningEffortResponse`/`SetReasoningEffortRequest` + **`QueueRequest`/`QueueResponse`/`ChatQueueMessage`** + **`ConversationOpenMessage`/`ConversationStatusChangedMessage`/`ConversationListResponse`/`LastMessageResponse`/`OpenConversationResponse`/`SetTitleRequest`/`TitleResponse`** + LSP (`LspStatusResponse`/`LspServerInfo`/`LspServerState`) + WS chat ops + `WsClientMessage`/`WsServerMessage` |
 
 Endpoints in use (HTTP **24203**, WS **24205**, CORS `*` incl. `PUT`):
 `POST /chat` (NDJSON) · `GET /models` ·
@@ -133,11 +145,12 @@ tab-close: abort turn + stop/disable warming) · **`POST /conversations/:id/queu
 steering message; auto-starts a turn if idle) · WS `chat.send`→`chat.delta` ·
 WS `chat.subscribe`/`chat.unsubscribe` (watch a conversation's turns without sending; replay + live) ·
 **WS `chat.queue`** (enqueue steering; fire-and-forget — surface updates on success) ·
-**WS `conversation.open`** (broadcast: CLI `--open` flag signals the FE to open/focus a tab).
+**WS `conversation.open`** (broadcast: CLI `--open` flag signals the FE to open/focus a tab) ·
+**WS `conversation.statusChanged`** (broadcast: lifecycle status change — `active`/`idle`/`closed`).
 
 Mirrored in-repo for headless agents: `.dispatch/{ui-contract,wire,transport-contract}.reference.md`
 (regenerate on any contract bump; all current as of `[email protected]` /
-`[email protected]` / `[email protected]`).
+`[email protected]` / `[email protected]`).
 
 ## 2. Open asks FOR THE BACKEND
 
diff --git a/src/adapters/ws/index.test.ts b/src/adapters/ws/index.test.ts
index e13f123..92d57a8 100644
--- a/src/adapters/ws/index.test.ts
+++ b/src/adapters/ws/index.test.ts
@@ -293,6 +293,34 @@ describe("createSurfaceSocket", () => {
 		expect(onChat).not.toHaveBeenCalled();
 	});
 
+	it("routes conversation.statusChanged to onConversationStatusChanged", () => {
+		const ws = fakeSocket();
+		const onMessage = vi.fn();
+		const onConversationStatusChanged = vi.fn();
+		createSurfaceSocket({
+			url: "ws://test",
+			onMessage,
+			onConversationStatusChanged,
+			socketFactory: () => ws,
+		});
+
+		ws.resolveOpen();
+		ws.invokeMessage(
+			JSON.stringify({
+				type: "conversation.statusChanged",
+				conversationId: "c1",
+				status: "active",
+			}),
+		);
+		expect(onConversationStatusChanged).toHaveBeenCalledOnce();
+		expect(onConversationStatusChanged).toHaveBeenCalledWith({
+			type: "conversation.statusChanged",
+			conversationId: "c1",
+			status: "active",
+		});
+		expect(onMessage).not.toHaveBeenCalled();
+	});
+
 	it("still routes surface catalog/surface to onMessage", () => {
 		const ws = fakeSocket();
 		const onMessage = vi.fn();
diff --git a/src/adapters/ws/index.ts b/src/adapters/ws/index.ts
index 18ebdf7..d2bc13d 100644
--- a/src/adapters/ws/index.ts
+++ b/src/adapters/ws/index.ts
@@ -1,7 +1,9 @@
 import type {
 	ChatDeltaMessage,
 	ChatErrorMessage,
+	ConversationCompactedMessage,
 	ConversationOpenMessage,
+	ConversationStatusChangedMessage,
 	WsClientMessage,
 } from "@dispatch/transport-contract";
 import type { SurfaceServerMessage } from "@dispatch/ui-contract";
@@ -21,6 +23,10 @@ export interface SurfaceSocketOptions {
 	onChat?: (msg: ChatDeltaMessage | ChatErrorMessage) => void;
 	/** Broadcast when a conversation is "opened" (e.g. CLI `--open` flag). */
 	onConversationOpen?: (msg: ConversationOpenMessage) => void;
+	/** Broadcast when a conversation's lifecycle status changes (active/idle/closed). */
+	onConversationStatusChanged?: (msg: ConversationStatusChangedMessage) => void;
+	/** Broadcast when a conversation's history has been compacted (reload needed). */
+	onConversationCompacted?: (msg: ConversationCompactedMessage) => void;
 	onReopen?: () => void;
 	socketFactory?: (url: string) => WebSocketLike;
 }
@@ -65,6 +71,10 @@ export function createSurfaceSocket(opts: SurfaceSocketOptions): SurfaceSocketHa
 					opts.onChat?.(msg as ChatDeltaMessage | ChatErrorMessage);
 				} else if (msg.type === "conversation.open") {
 					opts.onConversationOpen?.(msg as ConversationOpenMessage);
+				} else if (msg.type === "conversation.statusChanged") {
+					opts.onConversationStatusChanged?.(msg as ConversationStatusChangedMessage);
+				} else if (msg.type === "conversation.compacted") {
+					opts.onConversationCompacted?.(msg as ConversationCompactedMessage);
 				} else {
 					opts.onMessage(msg as SurfaceServerMessage);
 				}
diff --git a/src/adapters/ws/logic.test.ts b/src/adapters/ws/logic.test.ts
index ca129c0..2463519 100644
--- a/src/adapters/ws/logic.test.ts
+++ b/src/adapters/ws/logic.test.ts
@@ -233,6 +233,37 @@ describe("parseServerMessage", () => {
 			parseServerMessage(JSON.stringify({ type: "conversation.open", conversationId: 42 })),
 		).toBeNull();
 	});
+
+	it("parses a conversation.statusChanged message", () => {
+		const data = JSON.stringify({
+			type: "conversation.statusChanged",
+			conversationId: "c1",
+			status: "active",
+		});
+		expect(parseServerMessage(data)).toEqual({
+			type: "conversation.statusChanged",
+			conversationId: "c1",
+			status: "active",
+		});
+	});
+
+	it("returns null for conversation.statusChanged with invalid status", () => {
+		expect(
+			parseServerMessage(
+				JSON.stringify({
+					type: "conversation.statusChanged",
+					conversationId: "c1",
+					status: "done",
+				}),
+			),
+		).toBeNull();
+	});
+
+	it("returns null for conversation.statusChanged with missing conversationId", () => {
+		expect(
+			parseServerMessage(JSON.stringify({ type: "conversation.statusChanged", status: "idle" })),
+		).toBeNull();
+	});
 });
 
 describe("round-trip: parseServerMessage(serialize(...))", () => {
diff --git a/src/adapters/ws/logic.ts b/src/adapters/ws/logic.ts
index a9b70ff..53955f8 100644
--- a/src/adapters/ws/logic.ts
+++ b/src/adapters/ws/logic.ts
@@ -1,7 +1,9 @@
 import type {
 	ChatDeltaMessage,
 	ChatErrorMessage,
+	ConversationCompactedMessage,
 	ConversationOpenMessage,
+	ConversationStatusChangedMessage,
 	WsClientMessage,
 	WsServerMessage,
 } from "@dispatch/transport-contract";
@@ -20,6 +22,8 @@ const VALID_SERVER_TYPES = new Set([
 	"chat.delta",
 	"chat.error",
 	"conversation.open",
+	"conversation.statusChanged",
+	"conversation.compacted",
 ]);
 
 /** Serialize a client message to a JSON string for the wire. */
@@ -117,6 +121,31 @@ export function parseServerMessage(data: string): WsServerMessage | null {
 			};
 			return msg;
 		}
+		case "conversation.statusChanged": {
+			if (typeof parsed.conversationId !== "string") return null;
+			if (typeof parsed.status !== "string") return null;
+			if (parsed.status !== "active" && parsed.status !== "idle" && parsed.status !== "closed") {
+				return null;
+			}
+			const msg: ConversationStatusChangedMessage = {
+				type: "conversation.statusChanged",
+				conversationId: parsed.conversationId,
+				status: parsed.status,
+			};
+			return msg;
+		}
+		case "conversation.compacted": {
+			if (typeof parsed.conversationId !== "string") return null;
+			if (typeof parsed.messagesSummarized !== "number") return null;
+			if (typeof parsed.messagesKept !== "number") return null;
+			const msg: ConversationCompactedMessage = {
+				type: "conversation.compacted",
+				conversationId: parsed.conversationId,
+				messagesSummarized: parsed.messagesSummarized,
+				messagesKept: parsed.messagesKept,
+			};
+			return msg;
+		}
 		default:
 			return null;
 	}
diff --git a/src/app/App.svelte b/src/app/App.svelte
index 2b3b250..e065759 100644
--- a/src/app/App.svelte
+++ b/src/app/App.svelte
@@ -257,6 +257,7 @@
 			<TabBar
 				tabs={store.tabs}
 				activeConversationId={store.activeConversationId}
+				statusFor={(id) => store.conversationStatus(id)}
 				onSelect={(id) => store.selectTab(id)}
 				onClose={(id) => store.closeTab(id)}
 				onNewDraft={() => store.newDraft()}
diff --git a/src/app/store.svelte.ts b/src/app/store.svelte.ts
index 5a5245d..6fd8e5e 100644
--- a/src/app/store.svelte.ts
+++ b/src/app/store.svelte.ts
@@ -1,9 +1,12 @@
 import type {
 	ChatDeltaMessage,
 	ChatErrorMessage,
+	ConversationCompactedMessage,
 	ConversationHistoryResponse,
+	ConversationListResponse,
 	ConversationMetricsResponse,
 	ConversationOpenMessage,
+	ConversationStatusChangedMessage,
 	CwdResponse,
 	LspStatusResponse,
 	ModelsResponse,
@@ -15,6 +18,7 @@ import type {
 	WarmResponse,
 } from "@dispatch/transport-contract";
 import type { SubscribeMessage, SurfaceServerMessage, SurfaceSpec } from "@dispatch/ui-contract";
+import type { ConversationStatus } from "@dispatch/wire";
 import { createIdbChunkStore } from "../adapters/idb";
 import { createLocalStore } from "../adapters/local-storage";
 import type { WebSocketLike } from "../adapters/ws";
@@ -126,6 +130,12 @@ export interface AppStore {
 	/** The persisted chat limit (max loaded chunks per conversation). */
 	readonly chatLimit: number;
 	/**
+	 * A conversation's backend lifecycle status (`active`/`idle`/`closed`), or
+	 * `undefined` when unknown. Drives the tab-bar generating indicator
+	 * (cross-device: a tab spinning because another device's turn is running).
+	 */
+	conversationStatus(conversationId: string): ConversationStatus | undefined;
+	/**
 	 * Persist + live-apply a new chat limit: writes `dispatch.chatLimit` to
 	 * localStorage and propagates to every live chat store (trim if lower,
 	 * deferred via the unload gate while a reader is scrolled up; no-op if
@@ -453,6 +463,81 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 		});
 	}
 
+	/**
+	 * Remove a tab + its chat store locally (NO `POST /close` — used when the
+	 * backend already marked the conversation `closed` via `conversation.statusChanged`).
+	 */
+	function removeTabLocally(conversationId: string): void {
+		unsubscribeChat(conversationId);
+		const store = chatStores.get(conversationId);
+		if (store !== undefined) {
+			store.dispose();
+			chatStores.delete(conversationId);
+		}
+		void cache.delete(conversationId);
+		tabsStore.closeTab(conversationId);
+		conversationStatuses.delete(conversationId);
+		refreshActiveChat();
+		syncSubscriptions();
+		void refreshCwd();
+		void refreshReasoningEffort();
+	}
+
+	// Conversation lifecycle status (backend-owned, pushed via WS +
+	// fetched on connect). Keyed by conversationId.
+	let conversationStatuses = $state<Map<string, ConversationStatus>>(new Map());
+
+	/**
+	 * Fetch `GET /conversations?status=active,idle` on connect to restore the
+	 * tab bar across devices. Merges: opens tabs for conversations not already
+	 * open, removes tabs for conversations that are no longer active/idle
+	 * (closed on another device), and subscribes to `active` conversations'
+	 * live streams.
+	 */
+	async function fetchOpenConversations(): Promise<void> {
+		try {
+			const res = await fetchImpl(`${httpBase}/conversations?status=active,idle`);
+			if (!res.ok) return;
+			const data = (await res.json()) as ConversationListResponse;
+
+			// Update the status map from the authoritative backend list.
+			const newStatuses = new Map<string, ConversationStatus>();
+			for (const conv of data.conversations) {
+				newStatuses.set(conv.id, conv.status);
+			}
+			conversationStatuses = newStatuses;
+
+			// Open tabs for conversations not already open.
+			const existingIds = new Set(chatStores.keys());
+			for (const conv of data.conversations) {
+				if (!existingIds.has(conv.id)) {
+					const store = createChatFor(conv.id, activeModel);
+					chatStores.set(conv.id, store);
+					void store.load();
+					subscribeChat(conv.id);
+					tabsStore.openTab({
+						conversationId: conv.id,
+						model: activeModel,
+						title: conv.title,
+					});
+				} else {
+					// Already open — update the title from the backend if it differs.
+					tabsStore.setTitle(conv.id, conv.title);
+				}
+			}
+
+			// Remove tabs for conversations no longer active/idle (closed elsewhere).
+			const backendIds = new Set(data.conversations.map((c) => c.id));
+			for (const tab of tabsStore.tabs) {
+				if (!backendIds.has(tab.conversationId)) {
+					removeTabLocally(tab.conversationId);
+				}
+			}
+		} catch {
+			// Non-fatal: fall back to the localStorage-restored tabs.
+		}
+	}
+
 	const socketOpts: SurfaceSocketOptions = {
 		url: wsUrl,
 		onMessage: handleServerMessage,
@@ -460,6 +545,39 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 		onConversationOpen(msg: ConversationOpenMessage): void {
 			openConversation(msg.conversationId);
 		},
+		onConversationStatusChanged(msg: ConversationStatusChangedMessage): void {
+			const { conversationId, status } = msg;
+			if (status === "closed") {
+				// Closed on another device (or the backend) — remove the tab locally.
+				if (chatStores.has(conversationId)) {
+					removeTabLocally(conversationId);
+				}
+				return;
+			}
+			// active / idle — update the status map (drives the tab spinner).
+			conversationStatuses = new Map(conversationStatuses).set(conversationId, status);
+			// If this is a new active conversation we don't have a tab for, open one.
+			if (status === "active" && !chatStores.has(conversationId)) {
+				openConversation(conversationId);
+			}
+		},
+		onConversationCompacted(msg: ConversationCompactedMessage): void {
+			// The conversation's history was summarized — reload it from the server.
+			// Dispose the old store (stale cache) + create a fresh one + load.
+			const cid = msg.conversationId;
+			const wasActive = tabsStore.activeConversationId === cid;
+			const store = chatStores.get(cid);
+			if (store !== undefined) {
+				store.dispose();
+			}
+			void cache.delete(cid);
+			const fresh = createChatFor(cid, activeModel);
+			chatStores.set(cid, fresh);
+			void fresh.load();
+			if (wasActive) {
+				refreshActiveChat();
+			}
+		},
 		onReopen() {
 			// The server forgot our subscriptions on reconnect; re-send each with the
 			// conversation it was subscribed under (protocolSubscribe would no-op since
@@ -533,6 +651,11 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 	void refreshCwd();
 	void refreshReasoningEffort();
 
+	// Fetch the authoritative open-conversation list from the backend (cross-
+	// device tab sync). Merges with the localStorage-restored tabs: opens new
+	// ones, removes closed ones, updates titles + statuses.
+	void fetchOpenConversations();
+
 	return {
 		get tabs(): readonly Tab[] {
 			return tabsStore.tabs;
@@ -572,6 +695,9 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 		get chatLimit(): number {
 			return chatLimit;
 		},
+		conversationStatus(conversationId: string): ConversationStatus | undefined {
+			return conversationStatuses.get(conversationId);
+		},
 		get currentConversationId(): string {
 			return workspaceConversationId();
 		},
@@ -655,22 +781,10 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 		},
 
 		closeTab(conversationId: string): void {
-			tabsStore.closeTab(conversationId);
-			// The user is DONE with this chat for now: abort any in-flight turn and
-			// stop + disable its cache-warming, server-side.
+			// The user is DONE with this chat: abort any in-flight turn + stop/disable
+			// its cache-warming, server-side (POST /close sets status → "closed").
 			closeConversation(conversationId);
-			// Stop watching the closed conversation's turns.
-			unsubscribeChat(conversationId);
-			const store = chatStores.get(conversationId);
-			if (store !== undefined) {
-				store.dispose();
-				chatStores.delete(conversationId);
-			}
-			void cache.delete(conversationId);
-			refreshActiveChat();
-			syncSubscriptions();
-			void refreshCwd();
-			void refreshReasoningEffort();
+			removeTabLocally(conversationId);
 		},
 
 		invoke(surfaceId: string, actionId: string, payload?: unknown): void {
diff --git a/src/core/wire/conformance.test.ts b/src/core/wire/conformance.test.ts
index f5d6608..58cba3a 100644
--- a/src/core/wire/conformance.test.ts
+++ b/src/core/wire/conformance.test.ts
@@ -140,6 +140,17 @@ describe("classifies every WsServerMessage type", () => {
 			},
 			{ type: "chat.error" as const, message: "e" },
 			{ type: "conversation.open" as const, conversationId: "c1" },
+			{
+				type: "conversation.statusChanged" as const,
+				conversationId: "c1",
+				status: "active" as const,
+			},
+			{
+				type: "conversation.compacted" as const,
+				conversationId: "c1",
+				messagesSummarized: 10,
+				messagesKept: 5,
+			},
 		];
 		const labels = msgs.map(assertWsServerMessageExhaustive);
 		expect(labels).toEqual([
@@ -150,6 +161,8 @@ describe("classifies every WsServerMessage type", () => {
 			"chat.delta",
 			"chat.error",
 			"conversation.open",
+			"conversation.statusChanged",
+			"conversation.compacted",
 		]);
 	});
 });
diff --git a/src/core/wire/conformance.ts b/src/core/wire/conformance.ts
index 05a15aa..07808fc 100644
--- a/src/core/wire/conformance.ts
+++ b/src/core/wire/conformance.ts
@@ -83,6 +83,10 @@ export function assertWsServerMessageExhaustive(msg: WsServerMessage): string {
 			return "chat.error";
 		case "conversation.open":
 			return "conversation.open";
+		case "conversation.statusChanged":
+			return "conversation.statusChanged";
+		case "conversation.compacted":
+			return "conversation.compacted";
 		default:
 			return msg satisfies never;
 	}
diff --git a/src/features/tabs/ui/TabBar.svelte b/src/features/tabs/ui/TabBar.svelte
index 812a663..9d224b9 100644
--- a/src/features/tabs/ui/TabBar.svelte
+++ b/src/features/tabs/ui/TabBar.svelte
@@ -5,12 +5,15 @@
 	let {
 		tabs,
 		activeConversationId,
+		statusFor,
 		onSelect,
 		onClose,
 		onNewDraft,
 	}: {
 		tabs: readonly Tab[];
 		activeConversationId: string | null;
+		/** Returns the conversation's lifecycle status, or undefined when unknown. */
+		statusFor?: (conversationId: string) => string | undefined;
 		onSelect: (conversationId: string) => void;
 		onClose: (conversationId: string) => void;
 		onNewDraft: () => void;
@@ -84,6 +87,9 @@
 					{handles.get(tab.conversationId) ?? tab.conversationId}
 				</span>
 				<span class="min-w-0 flex-1 truncate text-left">{tab.title}</span>
+				{#if statusFor?.(tab.conversationId) === "active"}
+					<span class="loading loading-spinner loading-xs shrink-0 text-primary"></span>
+				{/if}
 				<button
 					class="btn btn-ghost btn-xs shrink-0"
 					aria-label="Close tab"