fix: map internal worker terminal lifecycles

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

@@ -5,7 +5,7 @@
     workspaceWorkersStore,
     type SidebarWorker,
   } from './worker-subscription';
-  import { canShowWorkerInSidebar } from './workers';
+  import { canShowWorkerInSidebar, sidebarWorkerActivity } from './workers';
 
   const COLLAPSED_WORKER_COUNT = 6;
 
@@ -69,6 +69,7 @@
     <ul class="nav-list" aria-label="Workers">
       {#each visibleWorkers as worker (`${worker.runtime_id}:${worker.worker_id}`)}
         {@const href = workerConsoleHref(worker, workspaceId)}
+        {@const activity = sidebarWorkerActivity(worker)}
         <li>
           <a
             href={href}
@@ -77,11 +78,11 @@
             aria-current={currentPath === href ? 'page' : undefined}
           >
             <span class="worker-status-indicator">
-              {#if worker.state === 'running'}
+              {#if activity === 'worker-running'}
                 <span class="worker-status-spinner"><Spinner label="Running" /></span>
-              {:else if worker.has_running_internal_workers}
+              {:else if activity === 'subworker-running'}
                 <span class="worker-status-spinner is-subworker"><Spinner label="SubWorker running" /></span>
-              {:else if worker.state === 'idle'}
+              {:else if activity === 'idle'}
                 <span class="worker-status-dot" aria-label="Idle"></span>
               {/if}
             </span>

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

@@ -14,13 +14,18 @@ declare const Deno: {
   test(name: string, fn: () => void | Promise<void>): void;
 };
 
-function worker(runtimeId: string, workerId: string, revision: number): SubscriptionWorker {
+function worker(
+  runtimeId: string,
+  workerId: string,
+  revision: number,
+  hasRunningInternalWorkers = false,
+): SubscriptionWorker {
   return {
     worker_id: workerId,
     runtime_id: runtimeId,
     subject_revision: revision,
     state: 'idle',
-    has_running_internal_workers: false,
+    has_running_internal_workers: hasRunningInternalWorkers,
     workspace_id: 'workspace-test',
     display_name: null,
     profile: null,
@@ -88,3 +93,28 @@ Deno.test('workspace Worker reducer ignores stale events and removes composite s
   assertEquals(projection.workers.size, 0);
   assertEquals(projection.revisions.get('runtime-a:1'), 4);
 });
+
+Deno.test('fatal child stop replaces the running-child sidebar projection', () => {
+  const projection = createWorkspaceWorkersProjection();
+  projection.workers.set('runtime-a:1', worker('runtime-a', '1', 1, true));
+  projection.revisions.set('runtime-a:1', 1);
+
+  applyWorkspaceWorkersFrame(projection, {
+    protocol_version: 1,
+    frame: 'event',
+    message: {
+      event: 'event',
+      data: {
+        subscription_id: 'subscription-1',
+        subject_revision: 2,
+        payload: {
+          event: 'worker_upserted',
+          data: { worker: worker('runtime-a', '1', 2, false) },
+        },
+      },
+    },
+  });
+
+  assertEquals(projection.workers.get('runtime-a:1')?.has_running_internal_workers, false);
+  assertEquals(projection.revisions.get('runtime-a:1'), 2);
+});

web/workspace/src/lib/workspace/sidebar/workers.test.ts

@@ -2,6 +2,7 @@ import {
   canOpenWorkerConsole,
   canShowWorkerInSidebar,
   compareWorkersForSidebar,
+  sidebarWorkerActivity,
 } from "./workers.ts";
 import type { Worker } from "./types.ts";
 
@@ -77,3 +78,21 @@ Deno.test("sidebar workers sort running then idle then stopped", () => {
   workers.sort(compareWorkersForSidebar);
   assertEquals(workers.map((candidate) => candidate.worker_id).join(","), "2,1,4,3");
 });
+
+Deno.test("fatal child stop clears the sidebar SubWorker spinner activity", () => {
+  const parent = { state: "idle", has_running_internal_workers: true };
+  assertEquals(sidebarWorkerActivity(parent), "subworker-running");
+
+  parent.has_running_internal_workers = false;
+  assertEquals(sidebarWorkerActivity(parent), "idle");
+});
+
+Deno.test("stopped parents do not fall back to the idle indicator", () => {
+  assertEquals(
+    sidebarWorkerActivity({
+      state: "stopped",
+      has_running_internal_workers: false,
+    }),
+    "none",
+  );
+});

web/workspace/src/lib/workspace/sidebar/workers.ts

@@ -1,5 +1,24 @@
 import type { Worker } from './types';
 
+export type SidebarWorkerActivity =
+  | 'worker-running'
+  | 'subworker-running'
+  | 'idle'
+  | 'none';
+
+type WorkerActivitySource = Pick<Worker, 'state'> & {
+  has_running_internal_workers: boolean;
+};
+
+export function sidebarWorkerActivity(
+  worker: WorkerActivitySource,
+): SidebarWorkerActivity {
+  if (worker.state === 'running') return 'worker-running';
+  if (worker.has_running_internal_workers) return 'subworker-running';
+  if (worker.state === 'idle') return 'idle';
+  return 'none';
+}
+
 export function canShowWorkerInSidebar(worker: Worker): boolean {
   return worker.implementation.kind !== 'backend_worker_registry';
 }