fix(runtime): fail session tab list with a retryable error instead of hanging when no graph publishes

src/main/runtime/orca-runtime-wait-for-session-tabs-inventory-publication.ts

@@ -2,13 +2,26 @@
 // @ts-nocheck -- mechanically split from OrcaRuntimeService; behavior is covered by AST equivalence and characterization tests.
 import { OrcaRuntimeWithCollectMobileVisibleGraphChangedWorktrees } from './orca-runtime-collect-mobile-visible-graph-changed-worktrees'
 
+// Why bounded: an old client is withheld until the renderer publishes (it would prune tabs from
+// an unpublished list), but a host whose graph never publishes must refuse, not hang the call.
+export const SESSION_TABS_INVENTORY_PUBLICATION_WAIT_MS = 30_000
+
 export class OrcaRuntimeWithWaitForSessionTabsInventoryPublication extends OrcaRuntimeWithCollectMobileVisibleGraphChangedWorktrees {
-  protected waitForSessionTabsInventoryPublication(signal?: AbortSignal): Promise<void> {
+  protected waitForSessionTabsInventoryPublication(
+    signal?: AbortSignal,
+    timeoutMs = SESSION_TABS_INVENTORY_PUBLICATION_WAIT_MS
+  ): Promise<void> {
     if (this.getAuthoritativeSessionTabsInventoryEpoch() !== null) {
       return Promise.resolve()
     }
     return new Promise<void>((resolve, reject) => {
+      const timer = setTimeout(() => {
+        cleanup()
+        reject(new Error('runtime_unavailable'))
+      }, timeoutMs)
+      timer.unref?.()
       const cleanup = (): void => {
+        clearTimeout(timer)
         this.sessionTabsInventoryWaiters.delete(onPublished)
         signal?.removeEventListener('abort', onAbort)
       }

src/main/runtime/session-tabs-inventory-publication.test.ts

@@ -1,5 +1,8 @@
 import { describe, expect, it, vi } from 'vitest'
 import { OrcaRuntimeService } from './orca-runtime'
+import { SESSION_TABS_INVENTORY_PUBLICATION_WAIT_MS } from './orca-runtime-wait-for-session-tabs-inventory-publication'
+import { RpcDispatcher } from './rpc/dispatcher'
+import { SESSION_TAB_METHODS } from './rpc/methods/session-tabs'
 
 type InventoryInternals = {
   sessionTabsInventoryWaiters: Set<() => void>
@@ -368,6 +371,50 @@ describe('authoritative session tab inventory publication', () => {
     expect((runtime as unknown as InventoryInternals).sessionTabsInventoryWaiters.size).toBe(0)
   })
 
+  it('refuses with runtime_unavailable instead of hanging when no graph ever publishes', async () => {
+    vi.useFakeTimers()
+    try {
+      const runtime = createInventoryRuntime()
+      runtime.attachWindow(1)
+      const pending = runtime.listAllMobileSessionTabsInventory()
+      const settled = pending.catch((error: unknown) => error)
+      await waitForInventoryWaiter(runtime)
+
+      await vi.advanceTimersByTimeAsync(SESSION_TABS_INVENTORY_PUBLICATION_WAIT_MS)
+
+      expect(await settled).toEqual(new Error('runtime_unavailable'))
+      expect((runtime as unknown as InventoryInternals).sessionTabsInventoryWaiters.size).toBe(0)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  it('answers an old client over RPC with runtime_unavailable when no graph publishes', async () => {
+    vi.useFakeTimers()
+    try {
+      const runtime = createInventoryRuntime()
+      runtime.attachWindow(1)
+      const dispatcher = new RpcDispatcher({ runtime, methods: SESSION_TAB_METHODS })
+      const messages: string[] = []
+      // No clientCapabilities: the pre-capability client shape.
+      const pending = dispatcher.dispatchStreaming(
+        { id: 'req-1', authToken: 'tok', method: 'session.tabs.listAll' },
+        (message) => messages.push(message),
+        { clientKind: 'runtime' }
+      )
+      await waitForInventoryWaiter(runtime)
+      await vi.advanceTimersByTimeAsync(SESSION_TABS_INVENTORY_PUBLICATION_WAIT_MS)
+      await pending
+
+      expect(JSON.parse(messages[0]!)).toMatchObject({
+        ok: false,
+        error: { code: 'runtime_unavailable' }
+      })
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
   it('does not scan when the inventory request is already cancelled', async () => {
     const runtime = createInventoryRuntime()
     const collect = vi.spyOn(