fix(terminal): make pane recovery strictly best-effort in timer contexts

Recovery fires from stall-watch timers, replay-guard releases, and onData —
contexts where a throw becomes an unhandled error (CI verify caught this:
pty-connection.test.ts mocks a partial store, other tests advance fake
timers past the stall window, and the certification path hit a missing
remountTerminalTabForRecovery). Guard the store action call and the
ptyIdsByTabId reads so a partial surface yields a false return, never a
throw, and pin it with a regression test.

src/renderer/src/components/terminal-pane/pty-connection.ts

@@ -3337,7 +3337,7 @@ export function connectPanePty(
     if (transport.isConnected() && transport.getPtyId() !== null) {
       return
     }
-    const storePtyId = useAppStore.getState().ptyIdsByTabId[deps.tabId]?.[0] ?? null
+    const storePtyId = useAppStore.getState().ptyIdsByTabId?.[deps.tabId]?.[0] ?? null
     void requestTerminalPaneRecovery({
       tabId: deps.tabId,
       ptyId: transport.getPtyId() ?? storePtyId,
@@ -3351,7 +3351,7 @@ export function connectPanePty(
   const unregisterUndeliverableWriteHandler = registerUndeliverableWriteHandler(
     pane.terminal,
     (reason) => {
-      const storePtyId = useAppStore.getState().ptyIdsByTabId[deps.tabId]?.[0] ?? null
+      const storePtyId = useAppStore.getState().ptyIdsByTabId?.[deps.tabId]?.[0] ?? null
       void requestTerminalPaneRecovery({
         tabId: deps.tabId,
         ptyId: transport.getPtyId() ?? storePtyId,

src/renderer/src/components/terminal-pane/terminal-pane-recovery.test.ts

@@ -149,6 +149,19 @@ describe('requestTerminalPaneRecovery', () => {
     expect(mocks.remountTerminalTabForRecovery).not.toHaveBeenCalled()
   })
 
+  it('never throws when the store surface is partial (timer/callback contexts)', async () => {
+    // Regression: recovery fires from stall-watch timers and write callbacks;
+    // an environment with a partial store (mocked suites, teardown races) must
+    // get a false return, not an unhandled TypeError.
+    mocks.remountTerminalTabForRecovery.mockImplementation(() => {
+      throw new TypeError('remountTerminalTabForRecovery is not a function')
+    })
+
+    await expect(
+      requestTerminalPaneRecovery({ tabId: 'tab-1', ptyId: 'pty-1', reason: 'write-stalled' })
+    ).resolves.toBe(false)
+  })
+
   it('does not consume budget when the tab no longer exists', async () => {
     mocks.remountTerminalTabForRecovery.mockReturnValue(false)
 

src/renderer/src/components/terminal-pane/terminal-pane-recovery.ts

@@ -78,7 +78,15 @@ export async function requestTerminalPaneRecovery(request: RecoveryRequest): Pro
       return false
     }
   }
-  const remounted = useAppStore.getState().remountTerminalTabForRecovery(request.tabId)
+  let remounted = false
+  try {
+    remounted = useAppStore.getState().remountTerminalTabForRecovery(request.tabId)
+  } catch {
+    // Why: recovery fires from timer and write-callback contexts (stall watch,
+    // replay guard, onData) — it is best-effort by contract and must never
+    // surface a throw there (partial store surfaces in tests, teardown races).
+    return false
+  }
   if (!remounted) {
     return false
   }