fix(agent-status): guard against re-entrant pending-status flush (crash 9fc89529) (#8671)

Co-authored-by: Orca <help@stably.ai>

src/renderer/src/hooks/useIpcEvents.test.ts

@@ -4873,6 +4873,104 @@ describe('useIpcEvents agent status snapshot integration', () => {
     )
   })
 
+  it('does not recurse when flushing a pending status re-enters via the store subscriber', async () => {
+    // Repro for crash 9fc89529 (RangeError: Maximum call stack size exceeded):
+    // the store subscriber calls flushPendingAgentStatuses() on every update.
+    // flush -> applyAgentStatus -> store.setAgentStatus notifies subscribers
+    // synchronously (like Zustand) -> subscriber -> flush again while the same
+    // event is still queued -> infinite recursion. Model setAgentStatus with a
+    // real synchronous notify so the re-entrancy is exercised end to end.
+    const subscribeListenerRef: { current: StoreSubscribeListener | null } = { current: null }
+    const onSetListenerRef: { current: ((data: AgentStatusSetData) => void) | null } = {
+      current: null
+    }
+    let setAgentStatusCalls = 0
+    const notify = (): void => {
+      const listener = subscribeListenerRef.current
+      if (listener) {
+        listener(storeState, storeState)
+      }
+    }
+    const storeState: StoreLike = buildStoreState({
+      // Why: mirror Zustand — a state mutation notifies subscribers synchronously.
+      setAgentStatus: (paneKey: string, entry: unknown) => {
+        setAgentStatusCalls += 1
+        storeState.agentStatusByPaneKey = {
+          ...(storeState.agentStatusByPaneKey as Record<string, unknown>),
+          [paneKey]: entry
+        }
+        notify()
+      },
+      workspaceSessionReady: true,
+      settings: { terminalFontSize: 13, notifications: { enabled: false } },
+      // Pane does not exist yet -> the incoming event is buffered as pending.
+      tabsByWorktree: {},
+      terminalLayoutsByTabId: {}
+    })
+
+    stubReactSyncEffect()
+    vi.doMock('../store', () => ({
+      useAppStore: {
+        subscribe: vi.fn((listener: StoreSubscribeListener) => {
+          subscribeListenerRef.current = listener
+          return () => {
+            subscribeListenerRef.current = null
+          }
+        }),
+        getState: () => storeState
+      }
+    }))
+    stubAuxiliaryModules()
+    vi.stubGlobal(
+      'window',
+      buildWindowApi({
+        onSet: (cb) => {
+          onSetListenerRef.current = cb
+          return () => {}
+        }
+      })
+    )
+
+    const { useIpcEvents } = await import('./useIpcEvents')
+    useIpcEvents()
+    await Promise.resolve()
+
+    if (typeof onSetListenerRef.current !== 'function') {
+      throw new Error('Expected agentStatus.onSet listener to be registered')
+    }
+    if (typeof subscribeListenerRef.current !== 'function') {
+      throw new Error('Expected useAppStore.subscribe listener to be registered')
+    }
+
+    // Event lands before the tab exists -> buffered as a pending retry.
+    onSetListenerRef.current({
+      paneKey: FUTURE_PANE_KEY,
+      state: 'working',
+      prompt: 'p',
+      agentType: 'claude',
+      receivedAt: 1_700_000_000_100,
+      stateStartedAt: 1_699_999_999_100
+    })
+    expect(setAgentStatusCalls).toBe(0)
+
+    // Tab hydrates; the next store update flushes the pending event. Without the
+    // re-entrancy guard this overflows the stack instead of applying once.
+    storeState.tabsByWorktree = {
+      'wt-1': [{ id: 'tab-future', ptyId: 'pty-1', worktreeId: 'wt-1', title: 'Future Tab' }]
+    }
+    storeState.terminalLayoutsByTabId = {
+      'tab-future': {
+        root: { type: 'leaf', leafId: FUTURE_LEAF_ID },
+        activeLeafId: FUTURE_LEAF_ID,
+        expandedLeafId: null
+      }
+    }
+
+    expect(() => notify()).not.toThrow()
+    // Applied exactly once — the re-entrant flush is a no-op, not a loop.
+    expect(setAgentStatusCalls).toBe(1)
+  })
+
   it('applies ready push events for an unmounted inactive terminal tab', async () => {
     const setAgentStatus = vi.fn()
     const onSetListenerRef: { current: ((data: AgentStatusSetData) => void) | null } = {

src/renderer/src/hooks/useIpcEvents.ts

@@ -842,6 +842,11 @@ export function useIpcEvents(): void {
     type AgentStatusApplyResult = 'applied' | 'pending' | 'dropped'
     const pendingAgentStatusEvents: PendingAgentStatusEvent[] = []
     let pendingAgentStatusRetryTimer: ReturnType<typeof setTimeout> | null = null
+    // Why: applyAgentStatus -> store.setAgentStatus notifies the store
+    // subscriber synchronously, which re-enters flushPendingAgentStatuses while
+    // the queue is still mid-drain. Guard against that re-entrancy so the same
+    // event is not reprocessed forever (crash 9fc89529: stack overflow).
+    let isFlushingAgentStatuses = false
 
     unsubs.push(attachMobileMarkdownBridge())
 
@@ -2917,25 +2922,37 @@ export function useIpcEvents(): void {
     }
 
     function flushPendingAgentStatuses(): void {
+      // Why: a re-entrant call (store subscriber firing during a setAgentStatus
+      // inside the loop below) must not reprocess the still-queued events — the
+      // outer flush already owns them. Bailing here breaks the infinite
+      // recursion without dropping work; the outer loop finishes the drain.
+      if (isFlushingAgentStatuses) {
+        return
+      }
       if (pendingAgentStatusEvents.length === 0) {
         return
       }
-      const now = Date.now()
-      const remaining: PendingAgentStatusEvent[] = []
-      for (const event of pendingAgentStatusEvents) {
-        if (now - event.firstSeenAt > PENDING_AGENT_STATUS_TTL_MS) {
-          continue
+      isFlushingAgentStatuses = true
+      try {
+        const now = Date.now()
+        const remaining: PendingAgentStatusEvent[] = []
+        for (const event of pendingAgentStatusEvents) {
+          if (now - event.firstSeenAt > PENDING_AGENT_STATUS_TTL_MS) {
+            continue
+          }
+          const result = applyAgentStatus(event.data, { retry: true })
+          if (result === 'pending') {
+            remaining.push(event)
+          }
         }
-        const result = applyAgentStatus(event.data, { retry: true })
-        if (result === 'pending') {
-          remaining.push(event)
+        pendingAgentStatusEvents.length = 0
+        pendingAgentStatusEvents.push(...remaining)
+        if (pendingAgentStatusEvents.length === 0 && pendingAgentStatusRetryTimer !== null) {
+          globalThis.clearTimeout(pendingAgentStatusRetryTimer)
+          pendingAgentStatusRetryTimer = null
         }
-      }
-      pendingAgentStatusEvents.length = 0
-      pendingAgentStatusEvents.push(...remaining)
-      if (pendingAgentStatusEvents.length === 0 && pendingAgentStatusRetryTimer !== null) {
-        globalThis.clearTimeout(pendingAgentStatusRetryTimer)
-        pendingAgentStatusRetryTimer = null
+      } finally {
+        isFlushingAgentStatuses = false
       }
       schedulePendingAgentStatusFlush()
     }