test(agent-status): cover the closed-tab lift IPC and its renderer trigger

The lift's only production trigger — the renderer re-mirror call — and the IPC
handler that carries it had no test: reverting either left every suite green.
The server-side method was the sole covered hunk.

Also adds liftClosedAgentStatusTabs to the agentHookServer double; the handler
swallows its own errors, so the omitted field would have passed vacuously.

src/main/ipc/agent-hooks.test.ts

@@ -9,6 +9,7 @@ import { makePaneKey } from '../../shared/stable-pane-id'
 
 const dropStatusEntry = vi.fn()
 const dropStatusEntriesByTabPrefix = vi.fn()
+const liftClosedAgentStatusTabs = vi.fn()
 const retirePaneAuthority = vi.fn()
 const transferPaneAuthority = vi.fn()
 const canTransferPaneAuthority = vi.fn(() => true)
@@ -45,6 +46,7 @@ vi.mock('../agent-hooks/server', async () => {
     agentHookServer: {
       dropStatusEntry,
       dropStatusEntriesByTabPrefix,
+      liftClosedAgentStatusTabs,
       retirePaneAuthority,
       transferPaneAuthority,
       canTransferPaneAuthority,
@@ -106,6 +108,7 @@ vi.mock('../kimi/hook-service', () => ({
 beforeEach(() => {
   dropStatusEntry.mockReset()
   dropStatusEntriesByTabPrefix.mockReset()
+  liftClosedAgentStatusTabs.mockReset()
   retirePaneAuthority.mockReset()
   transferPaneAuthority.mockReset()
   canTransferPaneAuthority.mockReset()
@@ -389,6 +392,65 @@ describe('agentStatus:dropByTabPrefix IPC', () => {
   })
 })
 
+describe('agentStatus:liftClosedTabs IPC', () => {
+  it('forwards validated tab ids so a returning tab stops being suppressed', async () => {
+    const { registerAgentHookHandlers } = await import('./agent-hooks')
+    registerAgentHookHandlers()
+
+    const handler = onHandlers.get('agentStatus:liftClosedTabs')
+    expect(handler).toBeDefined()
+    handler!({}, ['tab-1', 'tab-2'])
+
+    expect(liftClosedAgentStatusTabs).toHaveBeenCalledWith(['tab-1', 'tab-2'])
+  })
+
+  it('ignores a payload that is not an array', async () => {
+    const { registerAgentHookHandlers } = await import('./agent-hooks')
+    registerAgentHookHandlers()
+
+    const handler = onHandlers.get('agentStatus:liftClosedTabs')!
+    for (const value of ['tab-1', 123, undefined, null, {}] as unknown[]) {
+      expect(() => handler({}, value)).not.toThrow()
+    }
+
+    expect(liftClosedAgentStatusTabs).not.toHaveBeenCalled()
+  })
+
+  it('filters malformed ids out of an otherwise valid array', async () => {
+    const { registerAgentHookHandlers } = await import('./agent-hooks')
+    registerAgentHookHandlers()
+
+    onHandlers.get('agentStatus:liftClosedTabs')!({}, [
+      'tab-1',
+      123,
+      null,
+      'tab-1:leaf',
+      ' leading-space',
+      'x'.repeat(161)
+    ])
+
+    // Why assert the exact argument: a filter that let a malformed id through would still
+    // "have been called", so only the forwarded value proves the boundary held.
+    expect(liftClosedAgentStatusTabs).toHaveBeenCalledWith(['tab-1'])
+  })
+
+  it('skips the server entirely when every id is rejected', async () => {
+    const { registerAgentHookHandlers } = await import('./agent-hooks')
+    registerAgentHookHandlers()
+
+    onHandlers.get('agentStatus:liftClosedTabs')!({}, ['', 'tab-1:leaf', 'x'.repeat(161)])
+
+    expect(liftClosedAgentStatusTabs).not.toHaveBeenCalled()
+  })
+
+  it('removes any existing listener before registering the lift channel', async () => {
+    const { registerAgentHookHandlers } = await import('./agent-hooks')
+    registerAgentHookHandlers()
+
+    expect(removeAllListeners).toHaveBeenCalledWith('agentStatus:liftClosedTabs')
+  })
+})
+
 describe('agent pane authority IPC', () => {
   it('retires one validated pane authority', async () => {
     const { registerAgentHookHandlers } = await import('./agent-hooks')

src/renderer/src/runtime/web-session-tabs-sync-host-tab-retraction-ghost-rows.test.ts

@@ -273,16 +273,23 @@ function observeSidebar(store: TestStore, now: number): SidebarObservation {
   }
 }
 
+const liftClosedTabs = vi.fn()
+
 describe('a host-retracted paired tab leaves no ghost agent row behind', () => {
   beforeEach(() => {
     vi.useFakeTimers()
     vi.setSystemTime(T0)
     resetWebSessionTabsSnapshotFreshnessForTests()
     resetRendererOwnedAgentStatusPanesForTests()
+    liftClosedTabs.mockClear()
+    // Why stub the bridge: lifting only the renderer marker leaves the tab suppressed in the
+    // main-process closed-tab set, which gates every hook event upstream of the renderer.
+    vi.stubGlobal('window', { ...globalThis.window, api: { agentStatus: { liftClosedTabs } } })
   })
 
   afterEach(() => {
     vi.useRealTimers()
+    vi.unstubAllGlobals()
     resetRendererOwnedAgentStatusPanesForTests()
   })
 
@@ -591,6 +598,10 @@ describe('a host-retracted paired tab leaves no ghost agent row behind', () => {
       store.getState().recentlyClosedAgentStatusTabIds[mirrorTabId(RETRACTED_TAB)],
       'a re-mirrored tab id kept its closed-tab marker'
     ).toBeUndefined()
+    expect(
+      liftClosedTabs.mock.calls.flatMap(([tabIds]) => tabIds as string[]),
+      'the renderer lifted its own marker but left the tab suppressed in the main process'
+    ).toContain(mirrorTabId(RETRACTED_TAB))
 
     // The returning pane's byte-derived status must land again.
     const release2 = replayClientByteStatus(