fix: route sidebar failures through workspace alerts

web/workspace/src/lib/workspace/alerts/store.ts

@@ -40,6 +40,14 @@ export function pushWorkspaceAlert(
 ): string {
   const id = options.id ??
     `${Date.now().toString(36)}-${(sequence++).toString(36)}`;
+  const existing = alerts.find((alert) => alert.id === id);
+  if (
+    existing?.level === level &&
+    existing.title === options.title &&
+    existing.message === message
+  ) {
+    return id;
+  }
   alerts = [
     ...alerts.filter((alert) => alert.id !== id),
     {

web/workspace/src/lib/workspace/console/worker-console.ui.test.ts

@@ -1438,7 +1438,7 @@ Deno.test("Workspace Worker list and Console share the multiplexed connection",
     consolePage.includes("workspaceMultiplexer(target.workspaceId)") &&
       sidebarStore.includes("workspaceMultiplexer(workspaceId)") &&
       multiplexer.includes("const multiplexers = new Map") &&
-      multiplexer.includes("frame: 'worker_protocol'"),
+      multiplexer.includes('frame: "worker_protocol"'),
     "Sidebar and Console should share one Workspace multiplexer and route Worker methods through a subscription lane",
   );
   assert(

web/workspace/src/lib/workspace/multiplexer.browser.spec.ts

@@ -99,7 +99,10 @@ test('invalid inbound frame closes before dispatch and reconnects for a fresh sn
 
   expect(onFrame).not.toHaveBeenCalled();
   expect(first.closes).toEqual([[4002, 'Invalid workspace protocol frame']]);
-  expect(onStatus).toHaveBeenLastCalledWith('closed', 'Workspace protocol frame rejected');
+  expect(onStatus).toHaveBeenLastCalledWith('closed', {
+    kind: 'protocol',
+    message: 'Workspace protocol frame rejected',
+  });
   expect(JSON.stringify(onStatus.mock.calls)).not.toContain('untrusted detail');
 
   vi.advanceTimersByTime(500);
@@ -108,9 +111,84 @@ test('invalid inbound frame closes before dispatch and reconnects for a fresh sn
   second.open();
   expect(second.sent).toHaveLength(1);
   expect(JSON.parse(second.sent[0]).message.method).toBe('subscribe_events');
+
+  first.open();
+  first.message('{"protocol_version":2,"frame":"invalid"}');
+  expect(second.sent).toHaveLength(1);
+  expect(second.closes).toEqual([]);
   multiplexer.dispose();
 });
 
+test('normal disposal closes silently and never schedules a reconnect', () => {
+  vi.useFakeTimers();
+  const multiplexer = new WorkspaceMultiplexer('workspace-dispose-test');
+  const onStatus = vi.fn();
+  multiplexer.subscribe(
+    { topic: 'workspace_workers' },
+    { onFrame: vi.fn(), onStatus },
+  );
+
+  const socket = FakeWebSocket.instances[0];
+  socket.open();
+  onStatus.mockClear();
+  multiplexer.dispose();
+
+  expect(socket.closes).toEqual([[undefined, undefined]]);
+  expect(onStatus).not.toHaveBeenCalled();
+  vi.advanceTimersByTime(1_000);
+  expect(FakeWebSocket.instances).toHaveLength(1);
+});
+
+test('terminal subscription closure does not retry or report normal socket cleanup as transport failure', () => {
+  vi.useFakeTimers();
+  const multiplexer = new WorkspaceMultiplexer('workspace-terminal-test');
+  const onFrame = vi.fn();
+  const onStatus = vi.fn();
+  multiplexer.subscribe(
+    { topic: 'workspace_workers' },
+    { onFrame, onStatus },
+  );
+
+  const socket = FakeWebSocket.instances[0];
+  socket.open();
+  const request = JSON.parse(socket.sent[0]);
+  socket.message(JSON.stringify({
+    protocol_version: 2,
+    frame: 'response',
+    message: {
+      result: 'subscribed',
+      payload: {
+        request_id: request.message.params.request_id,
+        subscription_id: 'subscription-terminal',
+        selector: { topic: 'workspace_workers' },
+        snapshot: { topic: 'workers', data: { workers: [] } },
+      },
+    },
+  }));
+  onStatus.mockClear();
+  const sentBeforeClosure = socket.sent.length;
+
+  socket.message(JSON.stringify({
+    protocol_version: 2,
+    frame: 'event',
+    message: {
+      event: 'subscription_closed',
+      data: {
+        subscription_id: 'subscription-terminal',
+        code: 'unauthorized',
+        message: 'Workspace Worker subscription is no longer authorized',
+      },
+    },
+  }));
+
+  expect(onFrame).toHaveBeenCalledTimes(2);
+  expect(onStatus).not.toHaveBeenCalled();
+  expect(socket.sent).toHaveLength(sentBeforeClosure);
+  expect(socket.closes).toEqual([[undefined, undefined]]);
+  vi.advanceTimersByTime(1_000);
+  expect(FakeWebSocket.instances).toHaveLength(1);
+});
+
 test('valid subscription closure remains isolated and resubscribes only its selector', () => {
   const multiplexer = new WorkspaceMultiplexer('workspace-isolation-test');
   const workersFrame = vi.fn();
@@ -173,15 +251,9 @@ test('valid subscription closure remains isolated and resubscribes only its sele
   );
 
   expect(workersFrame).toHaveBeenCalledTimes(2);
-  expect(workersStatus).toHaveBeenLastCalledWith(
-    'connecting',
-    'resubscribe for a fresh snapshot',
-  );
+  expect(workersStatus).toHaveBeenLastCalledWith('connecting');
   expect(workdirsFrame).toHaveBeenCalledTimes(1);
-  expect(workdirsStatus).not.toHaveBeenCalledWith(
-    'connecting',
-    'resubscribe for a fresh snapshot',
-  );
+  expect(workdirsStatus).not.toHaveBeenCalledWith('connecting');
   expect(socket.sent).toHaveLength(sentBeforeClosure + 1);
   expect(JSON.parse(socket.sent.at(-1)!).message.params.selector).toEqual({
     topic: 'workspace_workers',

web/workspace/src/lib/workspace/multiplexer.ts

@@ -1,19 +1,27 @@
-import { browser } from '$app/env';
+import { browser } from "$app/env";
 import type {
   EventSubscriptionSelector,
   Method,
   SubscriptionFrame,
   SubscriptionId,
-} from '#lib/generated/protocol.ts';
+} from "#lib/generated/protocol.ts";
 import {
   decodeSubscriptionFrame,
   subscriptionFrameMatchesSelector,
-} from '#lib/generated/protocol-validator.ts';
-import { workspaceApiPath } from '#lib/workspace/api/http.ts';
+} from "#lib/generated/protocol-validator.ts";
+import { workspaceApiPath } from "#lib/workspace/api/http.ts";
+
+export type WorkspaceMultiplexerFailure = {
+  kind: "protocol" | "transport";
+  message: string;
+};
 
 type Listener = {
   onFrame(frame: SubscriptionFrame): void;
-  onStatus?(status: 'connecting' | 'open' | 'closed', message?: string): void;
+  onStatus?(
+    status: "connecting" | "open" | "closed",
+    failure?: WorkspaceMultiplexerFailure,
+  ): void;
 };
 
 type ActiveSubscription = {
@@ -33,12 +41,14 @@ const multiplexers = new Map<string, WorkspaceMultiplexer>();
 const INVALID_PROTOCOL_CLOSE_CODE = 4002;
 let nextMultiplexerSequence = 0;
 
-function nextMultiplexerId(kind: 'client' | 'request'): string {
+function nextMultiplexerId(kind: "client" | "request"): string {
   nextMultiplexerSequence += 1;
   return `${kind}-${nextMultiplexerSequence}`;
 }
 
-export function workspaceMultiplexer(workspaceId: string): WorkspaceMultiplexer {
+export function workspaceMultiplexer(
+  workspaceId: string,
+): WorkspaceMultiplexer {
   let multiplexer = multiplexers.get(workspaceId);
   if (!multiplexer) {
     multiplexer = new WorkspaceMultiplexer(workspaceId);
@@ -61,7 +71,7 @@ export class WorkspaceMultiplexer {
   readonly #runtimeSubscriptions = new Map<string, string>();
   #socket: WebSocket | null = null;
   #reconnectTimer: ReturnType<typeof setTimeout> | null = null;
-  #disconnectMessage: string | null = null;
+  #disconnectFailure: WorkspaceMultiplexerFailure | null = null;
   #closed = false;
 
   constructor(workspaceId: string) {
@@ -72,7 +82,7 @@ export class WorkspaceMultiplexer {
     selector: EventSubscriptionSelector,
     listener: Listener,
   ): WorkspaceMultiplexerSubscription {
-    const clientId = nextMultiplexerId('client');
+    const clientId = nextMultiplexerId("client");
     const subscription: ActiveSubscription = {
       clientId,
       selector,
@@ -83,7 +93,7 @@ export class WorkspaceMultiplexer {
     this.#subscriptions.set(clientId, subscription);
     this.#closed = false;
     if (this.#socket?.readyState === WebSocket.OPEN) {
-      subscription.listener.onStatus?.('open');
+      subscription.listener.onStatus?.("open");
       this.#sendSubscribe(subscription);
     } else {
       this.#ensureConnected();
@@ -95,37 +105,48 @@ export class WorkspaceMultiplexer {
   }
 
   #ensureConnected(): void {
-    if (!browser || this.#socket || this.#closed || this.#subscriptions.size === 0) return;
+    if (
+      !browser || this.#socket || this.#closed || this.#subscriptions.size === 0
+    ) return;
     for (const subscription of this.#subscriptions.values()) {
-      subscription.listener.onStatus?.('connecting');
+      subscription.listener.onStatus?.("connecting");
     }
     const url = new URL(
-      workspaceApiPath(this.#workspaceId, '/protocol/ws'),
+      workspaceApiPath(this.#workspaceId, "/protocol/ws"),
       window.location.origin,
     );
-    url.protocol = url.protocol === 'https:' ? 'wss:' : 'ws:';
+    url.protocol = url.protocol === "https:" ? "wss:" : "ws:";
     const socket = new WebSocket(url);
     this.#socket = socket;
-    socket.addEventListener('open', () => {
+    socket.addEventListener("open", () => {
+      if (this.#socket !== socket) return;
       for (const subscription of this.#subscriptions.values()) {
-        subscription.listener.onStatus?.('open');
+        subscription.listener.onStatus?.("open");
         this.#sendSubscribe(subscription);
       }
     });
-    socket.addEventListener('message', (event) => this.#receive(event.data));
-    socket.addEventListener('error', () => socket.close());
-    socket.addEventListener('close', () => {
+    socket.addEventListener("message", (event) => {
+      if (this.#socket !== socket) return;
+      this.#receive(event.data);
+    });
+    socket.addEventListener("error", () => {
+      if (this.#socket !== socket) return;
+      socket.close();
+    });
+    socket.addEventListener("close", () => {
       if (this.#socket !== socket) return;
       this.#socket = null;
-      const disconnectMessage =
-        this.#disconnectMessage ?? 'Workspace subscription disconnected';
-      this.#disconnectMessage = null;
+      const failure = this.#disconnectFailure ?? {
+        kind: "transport" as const,
+        message: "Workspace subscription disconnected",
+      };
+      this.#disconnectFailure = null;
       this.#requests.clear();
       this.#runtimeSubscriptions.clear();
       for (const subscription of this.#subscriptions.values()) {
         subscription.requestId = null;
         subscription.subscriptionId = null;
-        subscription.listener.onStatus?.('closed', disconnectMessage);
+        subscription.listener.onStatus?.("closed", failure);
       }
       if (!this.#closed && this.#subscriptions.size > 0) {
         this.#reconnectTimer = setTimeout(() => this.#ensureConnected(), 500);
@@ -134,14 +155,14 @@ export class WorkspaceMultiplexer {
   }
 
   #sendSubscribe(subscription: ActiveSubscription): void {
-    const requestId = nextMultiplexerId('request');
+    const requestId = nextMultiplexerId("request");
     subscription.requestId = requestId;
     this.#requests.set(requestId, subscription.clientId);
     this.#send({
       protocol_version: 2,
-      frame: 'request',
+      frame: "request",
       message: {
-        method: 'subscribe_events',
+        method: "subscribe_events",
         params: { request_id: requestId, selector: subscription.selector },
       },
     });
@@ -154,9 +175,11 @@ export class WorkspaceMultiplexer {
       return;
     }
     const frame = decoded.value;
-    if (frame.frame === 'response' && frame.message.result === 'subscribed') {
+    if (frame.frame === "response" && frame.message.result === "subscribed") {
       const clientId = this.#requests.get(frame.message.payload.request_id);
-      const subscription = clientId ? this.#subscriptions.get(clientId) : undefined;
+      const subscription = clientId
+        ? this.#subscriptions.get(clientId)
+        : undefined;
       if (!clientId || !subscription) return;
       if (!subscriptionFrameMatchesSelector(frame, subscription.selector)) {
         this.#rejectInboundFrame();
@@ -169,9 +192,14 @@ export class WorkspaceMultiplexer {
       subscription.listener.onFrame(frame);
       return;
     }
-    if (frame.frame === 'response' && frame.message.result === 'subscription_rejected') {
+    if (
+      frame.frame === "response" &&
+      frame.message.result === "subscription_rejected"
+    ) {
       const clientId = this.#requests.get(frame.message.payload.request_id);
-      const subscription = clientId ? this.#subscriptions.get(clientId) : undefined;
+      const subscription = clientId
+        ? this.#subscriptions.get(clientId)
+        : undefined;
       subscription?.listener.onFrame(frame);
       if (clientId) {
         this.#requests.delete(frame.message.payload.request_id);
@@ -179,9 +207,13 @@ export class WorkspaceMultiplexer {
       }
       return;
     }
-    if (frame.frame === 'event') {
-      const clientId = this.#runtimeSubscriptions.get(frame.message.data.subscription_id);
-      const subscription = clientId ? this.#subscriptions.get(clientId) : undefined;
+    if (frame.frame === "event") {
+      const clientId = this.#runtimeSubscriptions.get(
+        frame.message.data.subscription_id,
+      );
+      const subscription = clientId
+        ? this.#subscriptions.get(clientId)
+        : undefined;
       if (
         subscription &&
         !subscriptionFrameMatchesSelector(frame, subscription.selector)
@@ -191,30 +223,45 @@ export class WorkspaceMultiplexer {
       }
       subscription?.listener.onFrame(frame);
       if (
-        frame.message.event === 'subscription_closed' &&
+        frame.message.event === "subscription_closed" &&
         clientId &&
-        subscription &&
-        this.#socket?.readyState === WebSocket.OPEN
+        subscription
       ) {
         this.#runtimeSubscriptions.delete(frame.message.data.subscription_id);
         subscription.subscriptionId = null;
-        subscription.listener.onStatus?.('connecting', frame.message.data.message);
-        this.#sendSubscribe(subscription);
+        if (
+          (frame.message.data.code === "lagged" ||
+            frame.message.data.code === "server_shutdown") &&
+          this.#socket?.readyState === WebSocket.OPEN
+        ) {
+          subscription.listener.onStatus?.("connecting");
+          this.#sendSubscribe(subscription);
+        } else {
+          this.#remove(clientId);
+        }
       }
     }
   }
 
   #rejectInboundFrame(): void {
-    this.#disconnectMessage = 'Workspace protocol frame rejected';
-    this.#socket?.close(INVALID_PROTOCOL_CLOSE_CODE, 'Invalid workspace protocol frame');
+    this.#disconnectFailure = {
+      kind: "protocol",
+      message: "Workspace protocol frame rejected",
+    };
+    this.#socket?.close(
+      INVALID_PROTOCOL_CLOSE_CODE,
+      "Invalid workspace protocol frame",
+    );
   }
 
   #sendWorkerMethod(clientId: string, method: Method): void {
     const subscription = this.#subscriptions.get(clientId);
-    if (!subscription?.subscriptionId) throw new Error('Worker protocol subscription is not open');
+    if (!subscription?.subscriptionId) {
+      throw new Error("Worker protocol subscription is not open");
+    }
     this.#send({
       protocol_version: 2,
-      frame: 'worker_protocol',
+      frame: "worker_protocol",
       message: { subscription_id: subscription.subscriptionId, method },
     });
   }
@@ -223,14 +270,16 @@ export class WorkspaceMultiplexer {
     const subscription = this.#subscriptions.get(clientId);
     if (!subscription) return;
     this.#subscriptions.delete(clientId);
-    if (subscription.subscriptionId && this.#socket?.readyState === WebSocket.OPEN) {
+    if (
+      subscription.subscriptionId && this.#socket?.readyState === WebSocket.OPEN
+    ) {
       this.#send({
         protocol_version: 2,
-        frame: 'request',
+        frame: "request",
         message: {
-          method: 'unsubscribe_events',
+          method: "unsubscribe_events",
           params: {
-            request_id: nextMultiplexerId('request'),
+            request_id: nextMultiplexerId("request"),
             subscription_id: subscription.subscriptionId,
           },
         },
@@ -251,12 +300,10 @@ export class WorkspaceMultiplexer {
       clearTimeout(this.#reconnectTimer);
       this.#reconnectTimer = null;
     }
-    for (const subscription of this.#subscriptions.values()) {
-      subscription.listener.onStatus?.('closed', 'Workspace selection changed');
-    }
     this.#subscriptions.clear();
     this.#requests.clear();
     this.#runtimeSubscriptions.clear();
+    this.#disconnectFailure = null;
     this.#socket?.close();
     this.#socket = null;
   }

web/workspace/src/lib/workspace/sidebar/GlobalNavSections.svelte

@@ -44,10 +44,6 @@
     <section class="sidebar-nav-section sidebar-nav-section--category" aria-labelledby="global-workspaces-heading">
       <h2 id="global-workspaces-heading" class="sidebar-nav-section__header">workspaces</h2>
 
-      {#if workspaceError}
-        <p class="workspace-status error">Workspace list unavailable.</p>
-      {/if}
-
       {#if workspaces.length > 0}
         <div class="sidebar-list">
           {#each workspaces as workspace (workspace.workspace_id)}

web/workspace/src/lib/workspace/sidebar/WorkersNavSection.svelte

@@ -30,7 +30,6 @@
 
   let { currentPath = '/', workspaceId }: Props = $props();
   let loading = $state(true);
-  let error = $state<string | null>(null);
   let workers = $state<SidebarWorker[]>([]);
   let expanded = $state(false);
   let openWorkerKey = $state<string | null>(null);
@@ -141,7 +140,6 @@
     const subscription = workspaceWorkersStore(workspaceId);
     return subscription.subscribe((state) => {
       loading = state.loading;
-      error = state.error;
       workers = state.workers.filter(canShowWorkerInSidebar);
     });
   });
@@ -167,7 +165,7 @@
     >
       New
     </a>
-    {#if !loading && !error && workers.length > 0}
+    {#if !loading && workers.length > 0}
       <span class="section-count">{workers.length}</span>
     {/if}
   </div>
@@ -175,9 +173,8 @@
   {#if loading}
     <p class="section-state">Checking workers…</p>
   {:else if workers.length === 0}
-    <p class="section-state" class:error={Boolean(error)}>{error ?? 'No Workers are active.'}</p>
+    <p class="section-state">No Workers are active.</p>
   {:else}
-    {#if error}<p class="section-state error">{error}</p>{/if}
     <ul class="nav-list" aria-label="Workers">
       {#each visibleWorkers as worker (`${worker.runtime_id}:${worker.worker_id}`)}
         {@const href = workerConsoleHref(workspaceId, worker)}

web/workspace/src/lib/workspace/sidebar/WorkspaceSidebar.svelte

@@ -66,9 +66,7 @@
     {:else}
       <div class="workspace-label">
         <div class="workspace-name">Yoi workspace</div>
-        {#if workspaceError}
-          <p class="workspace-status error">Workspace summary unavailable.</p>
-        {:else}
+        {#if !workspaceError}
           <p class="workspace-status">Loading workspace…</p>
         {/if}
       </div>

web/workspace/src/lib/workspace/sidebar/WorkspaceSwitcher.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
   import { onMount, tick } from "svelte";
+  import { dismissWorkspaceAlert, pushWorkspaceAlert } from "#lib/workspace/alerts/store.ts";
   import {
     listWorkspaces,
     type WorkspaceCatalogRecord,
@@ -17,11 +18,11 @@
 
   let workspaces = $state<WorkspaceCatalogRecord[]>([]);
   let loading = $state(true);
-  let error = $state("");
   let open = $state(false);
   let root = $state.raw<HTMLDivElement>();
   let trigger = $state.raw<HTMLButtonElement>();
   let menu = $state.raw<HTMLDivElement>();
+  let loadGeneration = 0;
   const menuId = $derived(`workspace-menu-popover-${variant}`);
 
   const menuWorkspaces = $derived.by(() => {
@@ -39,14 +40,22 @@
   });
 
   async function loadWorkspaces() {
+    const generation = ++loadGeneration;
     loading = true;
-    error = "";
     try {
-      workspaces = await listWorkspaces(fetch);
+      const nextWorkspaces = await listWorkspaces(fetch);
+      if (generation !== loadGeneration) return;
+      workspaces = nextWorkspaces;
+      dismissWorkspaceAlert("workspace-catalog-load");
     } catch (cause) {
-      error = cause instanceof Error ? cause.message : "Failed to load Workspaces.";
+      if (generation !== loadGeneration) return;
+      pushWorkspaceAlert(
+        "error",
+        cause instanceof Error ? cause.message : "Failed to load Workspaces.",
+        { id: "workspace-catalog-load", title: "Workspace list unavailable" },
+      );
     } finally {
-      loading = false;
+      if (generation === loadGeneration) loading = false;
     }
   }
 
@@ -111,7 +120,10 @@
   onMount(() => {
     document.addEventListener("pointerdown", handleDocumentPointerDown);
     void loadWorkspaces();
-    return () => document.removeEventListener("pointerdown", handleDocumentPointerDown);
+    return () => {
+      loadGeneration += 1;
+      document.removeEventListener("pointerdown", handleDocumentPointerDown);
+    };
   });
 </script>
 
@@ -191,8 +203,6 @@
 
       {#if loading}
         <p class="workspace-menu-status">Loading Workspaces…</p>
-      {:else if error}
-        <p class="workspace-menu-status error">{error}</p>
       {/if}
     </div>
   {/if}

web/workspace/src/lib/workspace/sidebar/worker-subscription.browser.spec.ts

@@ -0,0 +1,303 @@
+// @vitest-environment happy-dom
+
+import { cleanup, render, screen, waitFor } from "@testing-library/svelte";
+import { afterEach, beforeEach, expect, test, vi } from "vitest";
+import type {
+  SubscriptionFrame,
+  SubscriptionWorker,
+} from "#lib/generated/protocol.ts";
+import WorkspaceAlerts from "#lib/workspace/alerts/WorkspaceAlerts.svelte";
+import {
+  clearWorkspaceAlerts,
+  workspaceAlerts,
+} from "#lib/workspace/alerts/store.ts";
+import WorkersNavSection from "./WorkersNavSection.svelte";
+import {
+  disposeWorkspaceWorkersStore,
+  workspaceWorkersStore,
+} from "./worker-subscription";
+
+const transport = vi.hoisted(() => {
+  type Listener = {
+    onFrame(frame: SubscriptionFrame): void;
+    onStatus?(
+      status: "connecting" | "open" | "closed",
+      failure?: { kind: "protocol" | "transport"; message: string },
+    ): void;
+  };
+  const listeners = new Map<string, Listener[]>();
+  const closes = new Map<string, ReturnType<typeof vi.fn>>();
+  return {
+    listeners,
+    closes,
+    subscribe: vi.fn((workspaceId: string, listener: Listener) => {
+      const workspaceListeners = listeners.get(workspaceId) ?? [];
+      workspaceListeners.push(listener);
+      listeners.set(workspaceId, workspaceListeners);
+      const close = closes.get(workspaceId) ?? vi.fn();
+      closes.set(workspaceId, close);
+      listener.onStatus?.("connecting");
+      return { close, sendWorkerMethod: vi.fn() };
+    }),
+  };
+});
+
+vi.mock("#lib/workspace/multiplexer.ts", () => ({
+  workspaceMultiplexer: (workspaceId: string) => ({
+    subscribe: (
+      _selector: unknown,
+      listener: Parameters<typeof transport.subscribe>[1],
+    ) => transport.subscribe(workspaceId, listener),
+  }),
+}));
+
+beforeEach(() => {
+  transport.listeners.clear();
+  transport.closes.clear();
+  transport.subscribe.mockClear();
+  clearWorkspaceAlerts();
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async (input: RequestInfo | URL) => {
+      const workspaceId = decodeURIComponent(
+        new URL(String(input), "https://example.test").pathname.split("/")[3] ??
+          "",
+      );
+      return Response.json({
+        workspace_id: workspaceId,
+        items: [],
+        diagnostics: [],
+      });
+    }),
+  );
+});
+
+afterEach(() => {
+  cleanup();
+  for (const workspaceId of transport.listeners.keys()) {
+    disposeWorkspaceWorkersStore(workspaceId);
+  }
+  clearWorkspaceAlerts();
+  vi.unstubAllGlobals();
+});
+
+function worker(workspaceId: string, workerId: string): SubscriptionWorker {
+  return {
+    worker_id: workerId,
+    runtime_id: `runtime-${workspaceId}`,
+    resource_key: `W-${workerId}`,
+    availability: "observed",
+    state: "idle",
+    worker_state: null,
+    has_running_internal_workers: false,
+    display_name: `Worker ${workerId}`,
+    workspace_id: workspaceId,
+    workdir_attachments: [],
+  };
+}
+
+function snapshot(
+  workspaceId: string,
+  subscriptionId: string,
+  workers: SubscriptionWorker[],
+): SubscriptionFrame {
+  return {
+    protocol_version: 2,
+    frame: "response",
+    message: {
+      result: "subscribed",
+      payload: {
+        request_id: `request-${subscriptionId}`,
+        subscription_id: subscriptionId,
+        selector: { topic: "workspace_workers" },
+        snapshot: { topic: "workers", data: { workers } },
+      },
+    },
+  };
+}
+
+function latestListener(workspaceId: string) {
+  const listeners = transport.listeners.get(workspaceId) ?? [];
+  const listener = listeners.at(-1);
+  if (!listener) throw new Error(`missing listener for ${workspaceId}`);
+  return listener;
+}
+
+function mount(workspaceId = "workspace-a") {
+  render(WorkspaceAlerts);
+  return render(WorkersNavSection, {
+    workspaceId,
+    currentPath: `/w/${workspaceId}`,
+  });
+}
+
+function alerts(): Element[] {
+  return [...document.querySelectorAll(".workspace-alert")];
+}
+
+function deferred<T>() {
+  let resolve!: (value: T) => void;
+  const promise = new Promise<T>((done) => {
+    resolve = done;
+  });
+  return { promise, resolve };
+}
+
+test("explicit store disposal closes and fences pending fetch and subscription callbacks", async () => {
+  const pendingFetch = deferred<Response>();
+  vi.stubGlobal("fetch", vi.fn(() => pendingFetch.promise));
+  render(WorkspaceAlerts);
+  const states = vi.fn();
+  const unsubscribe = workspaceWorkersStore("workspace-a").subscribe(states);
+  await waitFor(() => expect(transport.subscribe).toHaveBeenCalledOnce());
+  const listener = latestListener("workspace-a");
+
+  disposeWorkspaceWorkersStore("workspace-a");
+  expect(transport.closes.get("workspace-a")).toHaveBeenCalledOnce();
+  listener.onStatus?.("closed", {
+    kind: "transport",
+    message: "late transport failure",
+  });
+  listener.onFrame(
+    snapshot("workspace-a", "subscription-late", [
+      worker("workspace-a", "late"),
+    ]),
+  );
+  pendingFetch.resolve(new Response("late fetch failure", { status: 503 }));
+  await pendingFetch.promise;
+  await Promise.resolve();
+
+  expect(alerts()).toHaveLength(0);
+  expect(JSON.stringify(states.mock.calls)).not.toContain("late");
+  unsubscribe();
+});
+
+test("disconnect and reconnect keep Worker rows, avoid sidebar diagnostics, and dedupe the alert episode", async () => {
+  mount();
+  await waitFor(() => expect(transport.subscribe).toHaveBeenCalledOnce());
+  const listener = latestListener("workspace-a");
+  listener.onFrame(
+    snapshot("workspace-a", "subscription-a", [worker("workspace-a", "old")]),
+  );
+  expect(await screen.findByText("Worker old")).toBeTruthy();
+
+  const failure = { kind: "transport" as const, message: "connection lost" };
+  const alertSnapshots = vi.fn();
+  const unsubscribeAlerts = workspaceAlerts.subscribe(alertSnapshots);
+  alertSnapshots.mockClear();
+  listener.onStatus?.("closed", failure);
+  listener.onStatus?.("closed", failure);
+
+  expect(alertSnapshots).toHaveBeenCalledOnce();
+  unsubscribeAlerts();
+
+  expect(screen.getByText("Worker old")).toBeTruthy();
+  expect(document.querySelector(".sidebar-nav-section")?.textContent).not
+    .toContain(
+      "connection lost",
+    );
+  await waitFor(() => expect(alerts()).toHaveLength(1));
+  expect(alerts()[0]?.textContent).toContain("connection lost");
+
+  listener.onStatus?.("connecting");
+  listener.onFrame(
+    snapshot("workspace-a", "subscription-b", [worker("workspace-a", "new")]),
+  );
+  await waitFor(() => expect(screen.getByText("Worker new")).toBeTruthy());
+  expect(screen.queryByText("Worker old")).toBeNull();
+  expect(alerts()).toHaveLength(0);
+});
+
+test("route switch silently fences delayed old Workspace callbacks and starts the new subscription", async () => {
+  const view = mount("workspace-a");
+  await waitFor(() => expect(transport.subscribe).toHaveBeenCalledOnce());
+  const oldListener = latestListener("workspace-a");
+  oldListener.onFrame(
+    snapshot("workspace-a", "subscription-a", [worker("workspace-a", "a")]),
+  );
+  expect(await screen.findByText("Worker a")).toBeTruthy();
+
+  await view.rerender({
+    workspaceId: "workspace-a",
+    currentPath: "/w/workspace-a/workers",
+  });
+  await waitFor(() => expect(transport.subscribe).toHaveBeenCalledTimes(2));
+  expect(transport.closes.get("workspace-a")).toHaveBeenCalledTimes(1);
+  latestListener("workspace-a").onFrame(
+    snapshot("workspace-a", "subscription-a2", [worker("workspace-a", "same")]),
+  );
+  expect(await screen.findByText("Worker same")).toBeTruthy();
+  expect(alerts()).toHaveLength(0);
+
+  await view.rerender({
+    workspaceId: "workspace-b",
+    currentPath: "/w/workspace-b",
+  });
+  await waitFor(() => expect(transport.subscribe).toHaveBeenCalledTimes(3));
+  expect(transport.closes.get("workspace-a")).toHaveBeenCalledTimes(2);
+
+  oldListener.onStatus?.("closed", {
+    kind: "protocol",
+    message: "OLD WORKSPACE FAILURE",
+  });
+  oldListener.onFrame(
+    snapshot("workspace-a", "subscription-late", [
+      worker("workspace-a", "late"),
+    ]),
+  );
+  latestListener("workspace-b").onFrame(
+    snapshot("workspace-b", "subscription-b", [worker("workspace-b", "b")]),
+  );
+
+  expect(await screen.findByText("Worker b")).toBeTruthy();
+  expect(screen.queryByText("Worker late")).toBeNull();
+  expect(document.body.textContent).not.toContain("OLD WORKSPACE FAILURE");
+  expect(alerts()).toHaveLength(0);
+});
+
+test("terminal subscription rejection is shown only through WorkspaceAlerts", async () => {
+  mount();
+  await waitFor(() => expect(transport.subscribe).toHaveBeenCalledOnce());
+  latestListener("workspace-a").onFrame({
+    protocol_version: 2,
+    frame: "response",
+    message: {
+      result: "subscription_rejected",
+      payload: {
+        request_id: "request-rejected",
+        code: "unauthorized",
+        message: "Worker subscription denied",
+      },
+    },
+  });
+
+  expect(await screen.findByText("No Workers are active.")).toBeTruthy();
+  expect(document.querySelector(".sidebar-nav-section")?.textContent).not
+    .toContain(
+      "Worker subscription denied",
+    );
+  expect(alerts()).toHaveLength(1);
+  expect(alerts()[0]?.textContent).toContain("Worker subscription denied");
+});
+
+test("Workdir fetch failure preserves Worker updates and uses a separate stable alert", async () => {
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async () => new Response("Workdir lookup failed", { status: 503 })),
+  );
+  mount();
+  await waitFor(() => expect(transport.subscribe).toHaveBeenCalledOnce());
+  latestListener("workspace-a").onFrame(
+    snapshot("workspace-a", "subscription-a", [
+      worker("workspace-a", "visible"),
+    ]),
+  );
+
+  expect(await screen.findByText("Worker visible")).toBeTruthy();
+  await waitFor(() => expect(alerts()).toHaveLength(1));
+  expect(alerts()[0]?.textContent).toContain("Workdir lookup failed");
+  expect(document.querySelector(".sidebar-nav-section")?.textContent).not
+    .toContain(
+      "Workdir lookup failed",
+    );
+});

web/workspace/src/lib/workspace/sidebar/worker-subscription.ts

@@ -1,9 +1,17 @@
 import { type Readable, readable } from "svelte/store";
 import type { WorkingDirectorySummary } from "#lib/generated/workdir-api.ts";
 import type { SubscriptionWorker } from "#lib/generated/protocol.ts";
+import {
+  dismissWorkspaceAlert,
+  pushWorkspaceAlert,
+} from "#lib/workspace/alerts/store.ts";
 import { loadJson, workspaceApiPath } from "#lib/workspace/api/http.ts";
 import { parseWorkingDirectoryListResponse } from "#lib/workspace/api/workdirs.ts";
-import { workspaceMultiplexer } from "#lib/workspace/multiplexer.ts";
+import {
+  workspaceMultiplexer,
+  type WorkspaceMultiplexerFailure,
+  type WorkspaceMultiplexerSubscription,
+} from "#lib/workspace/multiplexer.ts";
 import {
   applyWorkspaceWorkersFrame,
   createWorkspaceWorkersProjection,
@@ -22,105 +30,213 @@ export type SidebarWorker = Omit<Worker, "workdir_attachments"> & {
 
 export type WorkspaceWorkersState = {
   loading: boolean;
-  error: string | null;
   workers: SidebarWorker[];
 };
 
-const stores = new Map<string, Readable<WorkspaceWorkersState>>();
+type WorkerAlertKind = "subscription" | "workdirs";
+type WorkspaceWorkersStoreEntry = {
+  store: Readable<WorkspaceWorkersState>;
+  dispose(): void;
+};
+
+const stores = new Map<string, WorkspaceWorkersStoreEntry>();
+
+function workerAlertId(workspaceId: string, kind: WorkerAlertKind): string {
+  return `workspace:${workspaceId}:workers:${kind}`;
+}
+
+function reportWorkerFailure(
+  workspaceId: string,
+  kind: WorkerAlertKind,
+  message: string,
+  level: "warning" | "error" = "error",
+): void {
+  pushWorkspaceAlert(level, message, {
+    id: workerAlertId(workspaceId, kind),
+    title: kind === "workdirs"
+      ? "Worker Workdirs unavailable"
+      : "Worker updates unavailable",
+  });
+}
+
+function clearWorkerFailure(workspaceId: string, kind: WorkerAlertKind): void {
+  dismissWorkspaceAlert(workerAlertId(workspaceId, kind));
+}
+
+function clearWorkerFailures(workspaceId: string): void {
+  clearWorkerFailure(workspaceId, "subscription");
+  clearWorkerFailure(workspaceId, "workdirs");
+}
 
 export function disposeWorkspaceWorkersStore(workspaceId: string): void {
+  const entry = stores.get(workspaceId);
+  if (!entry) {
+    clearWorkerFailures(workspaceId);
+    return;
+  }
   stores.delete(workspaceId);
+  entry.dispose();
 }
 
 export function workspaceWorkersStore(
   workspaceId: string,
 ): Readable<WorkspaceWorkersState> {
   const cached = stores.get(workspaceId);
-  if (cached) return cached;
+  if (cached) return cached.store;
+
+  let stopActive: (() => void) | null = null;
   const store = readable<WorkspaceWorkersState>(
-    { loading: true, error: null, workers: [] },
+    { loading: true, workers: [] },
     (set) => {
       if (!workspaceId) {
-        set({ loading: false, error: null, workers: [] });
+        set({ loading: false, workers: [] });
         return;
       }
       const projection = createWorkspaceWorkersProjection();
+      const workdirRequest = new AbortController();
+      let subscription: WorkspaceMultiplexerSubscription | null = null;
       let workdirs = new Map<string, WorkingDirectorySummary>();
+      let workers: SidebarWorker[] = [];
       let loading = true;
-      let error: string | null = null;
       let disposed = false;
-      const publish = () => {
-        const workers = [...projection.workers.values()]
-          .map((worker) => projectWorker(worker, workdirs))
-          .sort(compareWorkersForSidebar);
-        set({ loading, error, workers });
+      const publish = (): boolean => {
+        if (disposed) return false;
+        try {
+          workers = [...projection.workers.values()]
+            .map((worker) => projectWorker(worker, workdirs))
+            .sort(compareWorkersForSidebar);
+          set({ loading, workers });
+          return true;
+        } catch (cause) {
+          reportWorkerFailure(
+            workspaceId,
+            "subscription",
+            cause instanceof Error
+              ? cause.message
+              : "Invalid Worker subscription frame",
+          );
+          set({ loading: false, workers });
+          return false;
+        }
       };
       const loadWorkdirs = async () => {
         const result = await loadJson(
           fetch,
           workspaceApiPath(workspaceId, "/working-directories"),
-          undefined,
+          { signal: workdirRequest.signal },
           parseWorkingDirectoryListResponse,
         );
-        if (disposed || !result.data) return;
+        if (disposed) return;
+        if (!result.data) {
+          reportWorkerFailure(
+            workspaceId,
+            "workdirs",
+            result.error ?? "Worker Workdirs could not be loaded",
+            "warning",
+          );
+          return;
+        }
         workdirs = new Map(
           result.data.items.map((
             workdir,
           ) => [workdir.working_directory_id, workdir]),
         );
+        clearWorkerFailure(workspaceId, "workdirs");
         publish();
       };
-      const subscription = workspaceMultiplexer(workspaceId).subscribe(
+      subscription = workspaceMultiplexer(workspaceId).subscribe(
         { topic: "workspace_workers" },
         {
           onFrame: (frame) => {
+            if (disposed) return;
+            if (
+              frame.frame === "event" &&
+              frame.message.event === "subscription_closed"
+            ) {
+              loading = projection.workers.size === 0;
+              if (
+                frame.message.data.code === "resource_gone" ||
+                frame.message.data.code === "unauthorized"
+              ) {
+                reportWorkerFailure(
+                  workspaceId,
+                  "subscription",
+                  frame.message.data.message,
+                );
+              }
+              publish();
+              return;
+            }
+            if (
+              frame.frame === "response" &&
+              frame.message.result === "subscription_rejected"
+            ) {
+              loading = false;
+              reportWorkerFailure(
+                workspaceId,
+                "subscription",
+                frame.message.payload.message,
+              );
+              publish();
+              return;
+            }
             try {
-              if (
-                frame.frame === "event" &&
-                frame.message.event === "subscription_closed"
-              ) {
-                throw new Error(frame.message.data.message);
-              }
-              if (
-                frame.frame === "response" &&
-                frame.message.result === "subscription_rejected"
-              ) {
-                throw new Error(frame.message.payload.message);
-              }
               applyWorkspaceWorkersFrame(projection, frame);
               loading = false;
-              error = null;
-              publish();
+              if (publish()) clearWorkerFailure(workspaceId, "subscription");
             } catch (cause) {
               loading = false;
-              error = cause instanceof Error
-                ? cause.message
-                : "invalid Worker subscription frame";
+              reportWorkerFailure(
+                workspaceId,
+                "subscription",
+                cause instanceof Error
+                  ? cause.message
+                  : "Invalid Worker subscription frame",
+              );
               publish();
             }
           },
-          onStatus: (status, message) => {
+          onStatus: (status, failure?: WorkspaceMultiplexerFailure) => {
+            if (disposed) return;
             if (status === "connecting") {
               loading = projection.workers.size === 0;
-              error = null;
               publish();
             }
-            if (status === "closed") {
+            if (status === "closed" && failure) {
               loading = projection.workers.size === 0;
-              error = message ?? null;
+              reportWorkerFailure(
+                workspaceId,
+                "subscription",
+                failure.message,
+                failure.kind === "transport" ? "warning" : "error",
+              );
               publish();
             }
           },
         },
       );
       void loadWorkdirs();
-      return () => {
+
+      const stop = () => {
+        if (disposed) return;
         disposed = true;
-        subscription.close();
+        workdirRequest.abort();
+        subscription?.close();
+        clearWorkerFailures(workspaceId);
+        if (stopActive === stop) stopActive = null;
       };
+      stopActive = stop;
+      return stop;
     },
   );
-  stores.set(workspaceId, store);
+  const entry: WorkspaceWorkersStoreEntry = {
+    store,
+    dispose: () => {
+      stopActive?.();
+      clearWorkerFailures(workspaceId);
+    },
+  };
+  stores.set(workspaceId, entry);
   return store;
 }
 

web/workspace/src/lib/workspace/sidebar/workspace-switcher.browser.spec.ts

@@ -0,0 +1,70 @@
+// @vitest-environment happy-dom
+
+import {
+  cleanup,
+  fireEvent,
+  render,
+  screen,
+  waitFor,
+} from "@testing-library/svelte";
+import { afterEach, expect, test, vi } from "vitest";
+import WorkspaceAlerts from "#lib/workspace/alerts/WorkspaceAlerts.svelte";
+import { clearWorkspaceAlerts } from "#lib/workspace/alerts/store.ts";
+import WorkspaceSwitcher from "./WorkspaceSwitcher.svelte";
+
+afterEach(() => {
+  cleanup();
+  clearWorkspaceAlerts();
+  vi.unstubAllGlobals();
+});
+
+test("Workspace list fetch failure uses WorkspaceAlerts and keeps the menu free of diagnostics", async () => {
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async () =>
+      new Response("Catalog temporarily unavailable", { status: 503 })
+    ),
+  );
+  render(WorkspaceAlerts);
+  render(WorkspaceSwitcher, {
+    currentWorkspaceId: "workspace-a",
+    currentWorkspaceName: "Workspace A",
+    variant: "header",
+  });
+
+  const alert = await screen.findByRole("alert");
+  expect(alert.textContent).toContain("Workspace list unavailable");
+  expect(alert.textContent).toContain("503");
+  await fireEvent.click(screen.getByRole("button", { name: "Workspace A" }));
+  const menu = screen.getByRole("menu", { name: "Workspace menu" });
+  expect(menu.textContent).not.toContain("503");
+  expect(menu.textContent).not.toContain("Workspace list unavailable");
+  expect(screen.getByRole("menuitem", { name: "Workspace A" })).toBeTruthy();
+});
+
+test("unmounted Workspace menu ignores a delayed catalog failure", async () => {
+  let reject!: (cause: Error) => void;
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(() =>
+      new Promise<Response>((_resolve, rejectPromise) => {
+        reject = rejectPromise;
+      })
+    ),
+  );
+  render(WorkspaceAlerts);
+  const view = render(WorkspaceSwitcher, {
+    currentWorkspaceId: "workspace-a",
+    currentWorkspaceName: "Workspace A",
+  });
+  await waitFor(() => expect(fetch).toHaveBeenCalledOnce());
+  view.unmount();
+  reject(new Error("OLD WORKSPACE CATALOG FAILURE"));
+  await Promise.resolve();
+  await Promise.resolve();
+
+  expect(document.body.textContent).not.toContain(
+    "OLD WORKSPACE CATALOG FAILURE",
+  );
+  expect(document.querySelectorAll(".workspace-alert")).toHaveLength(0);
+});

web/workspace/src/routes/+layout.svelte

@@ -3,6 +3,7 @@
   import { setContext } from 'svelte';
   import { MediaQuery } from 'svelte/reactivity';
   import WorkspaceAlerts from '#lib/workspace/alerts/WorkspaceAlerts.svelte';
+  import { dismissWorkspaceAlert, pushWorkspaceAlert } from '#lib/workspace/alerts/store.ts';
   import Bevel from '#lib/workspace/ui/Bevel.svelte';
   import {
     provideHeaderController,
@@ -45,6 +46,18 @@
   const mobileLayout = new MediaQuery('(max-width: 760px)');
   const sidebarOpen = $derived((!mobileLayout.current && sidebarMode === 'pinned') || sidebarTransientOpen);
 
+  $effect(() => {
+    const error = data.workspaceCatalogError;
+    if (error) {
+      pushWorkspaceAlert('error', error, {
+        id: 'workspace-catalog-load',
+        title: 'Workspace list unavailable',
+      });
+    } else {
+      dismissWorkspaceAlert('workspace-catalog-load');
+    }
+  });
+
   $effect(() => {
     const mode = sidebarMode;
     try {

web/workspace/src/routes/sidebar-fold.browser.spec.ts

@@ -30,6 +30,23 @@ afterEach(() => {
   localStorage.clear();
 });
 
+test("Workspace catalog failure uses the shared alert without rendering diagnostics in the sidebar", async () => {
+  render(Layout, {
+    props: {
+      ...props,
+      data: {
+        accessibleWorkspaces: [],
+        workspaceCatalogError: "Workspace catalog request failed",
+      },
+    },
+  });
+  expect((await screen.findByRole("alert")).textContent).toContain(
+    "Workspace catalog request failed",
+  );
+  expect(frame().textContent).not.toContain("Workspace catalog request failed");
+  expect(frame().textContent).not.toContain("Workspace list unavailable");
+});
+
 test("unpinning changes mode, and pointer departure closes the preview", async () => {
   render(Layout, { props });
   expect(screen.getByRole("button", { name: "Unpin sidebar" }).getAttribute("aria-pressed")).toBe("true");

web/workspace/src/routes/w/[workspaceId]/+layout.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { setContext } from 'svelte';
+  import { onDestroy, setContext } from 'svelte';
   import { page } from '$app/state';
   import HeaderOverride from '#lib/workspace/header/HeaderOverride.svelte';
   import WorkspaceBreadcrumbs from '#lib/workspace/header/WorkspaceBreadcrumbs.svelte';
@@ -37,13 +37,23 @@
     workspaceId !== '' && ownsRoutePath(workspaceRoute(workspaceId), page.url.pathname),
   );
 
+  let activeWorkspaceId: string | null = null;
+
+  function disposeWorkspaceResources(workspaceId: string): void {
+    disposeWorkspaceWorkersStore(workspaceId);
+    disposeWorkspaceMultiplexer(workspaceId);
+  }
+
   $effect(() => {
-    const workspaceId = data.workspace?.workspace_id;
-    if (!workspaceId) return;
-    return () => {
-      disposeWorkspaceMultiplexer(workspaceId);
-      disposeWorkspaceWorkersStore(workspaceId);
-    };
+    const nextWorkspaceId = data.workspace?.workspace_id ?? null;
+    if (nextWorkspaceId === activeWorkspaceId) return;
+    const previousWorkspaceId = activeWorkspaceId;
+    activeWorkspaceId = nextWorkspaceId;
+    if (previousWorkspaceId) disposeWorkspaceResources(previousWorkspaceId);
+  });
+
+  onDestroy(() => {
+    if (activeWorkspaceId) disposeWorkspaceResources(activeWorkspaceId);
   });
 </script>
 

web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/console/+page.svelte

@@ -1387,14 +1387,14 @@
                         ];
                     }
                 },
-                onStatus: (status, message) => {
+                onStatus: (status, failure) => {
                     if (token !== reloadToken) return;
                     protocolState = status === "open" ? "connecting" : status;
                     if (status === "connecting" || status === "open") {
-                        showConsoleReconnecting(message);
+                        showConsoleReconnecting(failure?.message);
                     }
                     if (status === "closed") {
-                        showConsoleFailure(message);
+                        showConsoleFailure(failure?.message);
                         rejectPendingCompletion(new Error("Worker protocol WebSocket closed."));
                     }
                 },

web/workspace/src/routes/w/[workspaceId]/workers/[workerRef]/console/console-display.browser.spec.ts

@@ -25,7 +25,10 @@ vi.mock("svelte/motion", () => ({ prefersReducedMotion: { current: true } }));
 const multiplexer = vi.hoisted(() => {
   type Listener = {
     onFrame(frame: unknown): void;
-    onStatus?(status: "connecting" | "open" | "closed", message?: string): void;
+    onStatus?(
+      status: "connecting" | "open" | "closed",
+      failure?: { kind: "protocol" | "transport"; message: string },
+    ): void;
   };
   const listeners: Listener[] = [];
   return {
@@ -393,7 +396,7 @@ test("queue-only state hides notifications and disables cancellation when discon
   await screen.findByText("送信内容");
   expect(screen.queryByRole("group", { name: "Notifications" })).toBeNull();
   expect(screen.queryByRole("heading", { name: "Notifications" })).toBeNull();
-  latestListener().onStatus?.("closed", "connection lost");
+  latestListener().onStatus?.("closed", { kind: "transport", message: "connection lost" });
   await waitFor(() => expect((screen.getByRole("button", { name: "Cancel queued input 1" }) as HTMLButtonElement).disabled).toBe(true));
 });
 
@@ -450,7 +453,7 @@ test("file completions consume stale responses before the latest prefix and clos
   expect(screen.queryByRole("option")).toBeNull();
   receive("new-result");
   expect((await screen.findByRole("option")).textContent).toContain("@new-result");
-  latestListener().onStatus?.("closed", "connection lost");
+  latestListener().onStatus?.("closed", { kind: "transport", message: "connection lost" });
   await waitFor(() => expect(screen.queryByRole("listbox")).toBeNull());
   receive("late-result");
   await settleMicrotasks();
@@ -689,7 +692,10 @@ test("distinguishes typed unavailability and an initial live connection closure"
   );
   await fireEvent.click(screen.getByRole("button", { name: "Retry" }));
   await waitFor(() => expect(multiplexer.subscribe).toHaveBeenCalledOnce());
-  latestListener().onStatus?.("closed", "subscription ended before snapshot");
+  latestListener().onStatus?.("closed", {
+    kind: "transport",
+    message: "subscription ended before snapshot",
+  });
 
   expect((await screen.findByRole("alert")).textContent).toContain(
     "subscription ended before snapshot",
@@ -714,7 +720,10 @@ test("preserves rendered content while reconnecting", async () => {
       .findByText("kept message"),
   ).not.toBeNull();
 
-  latestListener().onStatus?.("closed", "Workspace subscription disconnected");
+  latestListener().onStatus?.("closed", {
+    kind: "transport",
+    message: "Workspace subscription disconnected",
+  });
   expect(await screen.findByText("Conversation updates are unavailable")).not
     .toBeNull();
   expect(
@@ -724,7 +733,7 @@ test("preserves rendered content while reconnecting", async () => {
   ).not.toBeNull();
   expect(screen.queryByText("No conversation to display")).toBeNull();
 
-  latestListener().onStatus?.("connecting", "resubscribing");
+  latestListener().onStatus?.("connecting");
   expect(await screen.findByText("Refreshing conversation")).not.toBeNull();
   expect(
     within(screen.getByRole("article", { name: "main transcript" })).getByText(
@@ -761,8 +770,11 @@ test("reconnect snapshot refreshes lineage and removes stale sibling history", a
     expectHistoryTurn("question 1")
   );
 
-  latestListener().onStatus?.("closed", "disconnected during rewind");
-  latestListener().onStatus?.("connecting", "reconnecting");
+  latestListener().onStatus?.("closed", {
+    kind: "transport",
+    message: "disconnected during rewind",
+  });
+  latestListener().onStatus?.("connecting");
   latestListener().onFrame(
     subscribedFrame(sessionWithUserMessage("lineage B current")),
   );
@@ -898,7 +910,10 @@ test("route changes clear prior content and fence stale Session responses", asyn
       .findByText("previous worker content"),
   ).not.toBeNull();
 
-  latestListener().onStatus?.("closed", "reload old worker");
+  latestListener().onStatus?.("closed", {
+    kind: "transport",
+    message: "reload old worker",
+  });
   await fireEvent.click(
     await screen.findByRole("button", { name: "Retry" }),
   );

web/workspace/src/routes/w/[workspaceId]/workspace-layout-lifecycle.browser.spec.ts

@@ -0,0 +1,91 @@
+// @vitest-environment happy-dom
+
+import { cleanup, render } from "@testing-library/svelte";
+import { afterEach, expect, test, vi } from "vitest";
+import { createRawSnippet } from "svelte";
+import Layout from "./+layout.svelte";
+
+const resources = vi.hoisted(() => {
+  const events: string[] = [];
+  return {
+    events,
+    disposeMultiplexer: vi.fn((workspaceId: string) => {
+      events.push(`multiplexer:${workspaceId}`);
+    }),
+    disposeWorkers: vi.fn((workspaceId: string) => {
+      events.push(`workers:${workspaceId}`);
+    }),
+  };
+});
+
+vi.mock("$app/state", () => ({
+  page: {
+    params: { workspaceId: "workspace-a" },
+    url: new URL("https://example.test/w/workspace-a"),
+  },
+}));
+vi.mock("#lib/workspace/multiplexer.ts", () => ({
+  disposeWorkspaceMultiplexer: resources.disposeMultiplexer,
+}));
+vi.mock("#lib/workspace/sidebar/worker-subscription.ts", () => ({
+  disposeWorkspaceWorkersStore: resources.disposeWorkers,
+  workspaceWorkersStore: () => ({
+    subscribe: (
+      subscriber: (state: { loading: boolean; workers: never[] }) => void,
+    ) => {
+      subscriber({ loading: false, workers: [] });
+      return () => {};
+    },
+  }),
+}));
+vi.mock("#lib/workspace/sidebar/context.ts", () => ({
+  SIDEBAR_CONTEXT: Symbol("test-sidebar"),
+  getSidebarController: () => ({ registerSidebar: () => () => {} }),
+}));
+vi.mock("#lib/workspace/header/context.ts", () => ({
+  getHeaderController: () => ({ registerContent: () => () => {} }),
+}));
+
+const children = createRawSnippet(() => ({ render: () => "<p>content</p>" }));
+function data(workspaceId: string, displayName = workspaceId) {
+  return {
+    workspace: { workspace_id: workspaceId, display_name: displayName },
+    workspaceError: null,
+    repositories: [],
+    repositoriesError: null,
+  };
+}
+
+afterEach(() => {
+  cleanup();
+  resources.events.length = 0;
+  resources.disposeMultiplexer.mockClear();
+  resources.disposeWorkers.mockClear();
+});
+
+test("same-Workspace layout data refresh keeps resources, while route switch and exit dispose in order", async () => {
+  const view = render(Layout, {
+    props: { data: data("workspace-a"), children } as never,
+  });
+  expect(resources.events).toEqual([]);
+
+  await view.rerender({
+    data: data("workspace-a", "Updated display name"),
+    children,
+  } as never);
+  expect(resources.events).toEqual([]);
+
+  await view.rerender({ data: data("workspace-b"), children } as never);
+  expect(resources.events).toEqual([
+    "workers:workspace-a",
+    "multiplexer:workspace-a",
+  ]);
+
+  view.unmount();
+  expect(resources.events).toEqual([
+    "workers:workspace-a",
+    "multiplexer:workspace-a",
+    "workers:workspace-b",
+    "multiplexer:workspace-b",
+  ]);
+});