fix: fence reentrant terminal lifecycle cleanup

src/renderer/src/components/terminal-pane/pty-eager-buffer.ts

@@ -61,7 +61,9 @@ export function registerEagerPtyBufferState(
     ptyExitHandlers.delete(ptyId)
     revokePtyPrimaryDataHandlerOwner(ptyId, dataOwner)
     revokePtyPrimaryExitHandlerOwner(ptyId, exitOwner)
-    eagerPtyHandles.delete(ptyId)
+    if (eagerPtyHandles.get(ptyId) === handle) {
+      eagerPtyHandles.delete(ptyId)
+    }
     onExit(ptyId, code)
   }
 
@@ -92,7 +94,9 @@ export function registerEagerPtyBufferState(
       }
       revokePtyPrimaryDataHandlerOwner(ptyId, dataOwner)
       revokePtyPrimaryExitHandlerOwner(ptyId, exitOwner)
-      eagerPtyHandles.delete(ptyId)
+      if (eagerPtyHandles.get(ptyId) === handle) {
+        eagerPtyHandles.delete(ptyId)
+      }
     }
   }
 

src/renderer/src/components/terminal-pane/pty-pre-handler-buffer.test.ts

@@ -115,6 +115,40 @@ describe('pre-handler PTY buffer', () => {
     expect(handler).toHaveBeenCalledWith(-1)
   })
 
+  it('retires an older overflow probe when a concrete exit is drained', async () => {
+    const target = 'pty-concrete-exit-replaces-overflow'
+    const fillerPrefix = 'pty-concrete-exit-filler-'
+    let resolveProbe: ((alive: boolean | null) => void) | undefined
+    const hasPty = vi.fn(
+      () =>
+        new Promise<boolean | null>((resolve) => {
+          resolveProbe = resolve
+        })
+    )
+    const handler = vi.fn()
+    try {
+      bufferPreHandlerPtyExit(target, 1)
+      for (let index = 0; index < 64; index += 1) {
+        bufferPreHandlerPtyExit(`${fillerPrefix}${index}`, index)
+      }
+      reconcilePreHandlerPtyExitAfterOverflow(target, hasPty, handler, () => true)
+      bufferPreHandlerPtyExit(target, 2)
+      expect(drainPreHandlerPtyExit(target, handler)).toBe(true)
+      resolveProbe?.(false)
+      await Promise.resolve()
+      await Promise.resolve()
+      await Promise.resolve()
+
+      expect(handler.mock.calls.map(([code]) => code)).toEqual([2])
+      expect(hasPty).toHaveBeenCalledOnce()
+    } finally {
+      clearPreHandlerPtyState(target)
+      for (let index = 0; index < 64; index += 1) {
+        clearPreHandlerPtyState(`${fillerPrefix}${index}`)
+      }
+    }
+  })
+
   it('retains an evicted exit through unknown liveness and retries authoritative proof', async () => {
     for (let index = 0; index <= 64; index += 1) {
       bufferPreHandlerPtyExit(`pty-exit-${index}`, index)

src/renderer/src/components/terminal-pane/pty-pre-handler-buffer.ts

@@ -140,6 +140,11 @@ export function drainPreHandlerPtyExit(ptyId: string, handler: (code: number) =>
     return false
   }
   preHandlerPtyExit.delete(ptyId)
+  // Why: a concrete buffered exit supersedes any older overflow tombstone;
+  // leaving its probe alive can synthesize a duplicate -1 exit afterward.
+  preHandlerPtyEvictedExitIds.delete(ptyId)
+  preHandlerPtyEvictedExitProbes.delete(ptyId)
+  pendingPreHandlerPtyEvictedExitProbes.delete(ptyId)
   handler(code)
   return true
 }

src/renderer/src/components/terminal-pane/pty-primary-handler-admission.ts

@@ -91,6 +91,13 @@ export function restorePtyPrimaryDataHandlerOwner(
   return true
 }
 
+export function isPtyPrimaryDataHandlerOwnerCurrent(
+  ptyId: string,
+  owner: PtyPrimaryHandlerOwner | undefined
+): boolean {
+  return Boolean(owner?.active && primaryDataHandlerOwners.get(ptyId) === owner)
+}
+
 export function publishPtyPrimaryExitHandlerOwner(
   ptyId: string,
   owner: PtyPrimaryHandlerOwner

src/renderer/src/components/terminal-pane/pty-primary-handler-registry.ts

@@ -1,6 +1,7 @@
-import { clearPreHandlerPtyState } from './pty-pre-handler-buffer'
+import { clearPreHandlerPtyState, drainPreHandlerPtyData } from './pty-pre-handler-buffer'
 import {
   getPtyPrimaryExitHandlerOwner,
+  isPtyPrimaryDataHandlerOwnerCurrent,
   isPtyPrimaryExitHandlerOwnerCurrent,
   restorePtyPrimaryDataHandlerOwner,
   suspendPtyPrimaryDataHandlerOwner
@@ -67,6 +68,14 @@ export function restorePtyDataHandlersAfterFailedShutdown(
       if (snapshot.replayHandler) {
         ptyReplayHandlers.set(snapshot.ptyId, snapshot.replayHandler)
       }
+      if (snapshot.dataHandler) {
+        drainPreHandlerPtyData(snapshot.ptyId, snapshot.dataHandler, () => {
+          return (
+            isPtyPrimaryDataHandlerOwnerCurrent(snapshot.ptyId, snapshot.dataOwner) &&
+            ptyDataHandlers.get(snapshot.ptyId) === snapshot.dataHandler
+          )
+        })
+      }
     }
     if (
       snapshot.teardownHandler &&

src/renderer/src/components/terminal-pane/pty-transport.test.ts

@@ -463,14 +463,13 @@ describe('createIpcPtyTransport', () => {
     const outerExit = vi.fn()
     const replacementData = vi.fn()
     const replacementExit = vi.fn()
-    const outerTransport = createIpcPtyTransport()
-    const replacementTransport = createIpcPtyTransport()
-    outerTransport.attach({
+    const transport = createIpcPtyTransport()
+    transport.attach({
       existingPtyId: 'same-id',
       callbacks: {
         onData: (data) => {
           outerData.push(data)
-          replacementTransport.attach({
+          transport.attach({
             existingPtyId: 'same-id',
             callbacks: { onData: replacementData, onExit: replacementExit }
           })
@@ -480,15 +479,15 @@ describe('createIpcPtyTransport', () => {
     })
 
     onData?.({ id: 'same-id', data: 'live replacement data' })
-    onExit?.({ id: 'same-id', code: 7 })
 
     expect(outerData).toEqual(['first buffered chunk'])
-    expect(outerTransport.isConnected()).toBe(false)
     expect(replacementData).toHaveBeenCalledWith('second buffered chunk')
     expect(replacementData).toHaveBeenCalledWith('live replacement data')
     expect(outerExit).not.toHaveBeenCalled()
+    expect(transport.isConnected()).toBe(true)
+    onExit?.({ id: 'same-id', code: 7 })
     expect(replacementExit).toHaveBeenCalledWith(7)
-    expect(replacementTransport.isConnected()).toBe(false)
+    expect(transport.isConnected()).toBe(false)
   })
 
   it('keeps reentrant replacement ownership atomic while connect drains buffered data', async () => {
@@ -502,15 +501,14 @@ describe('createIpcPtyTransport', () => {
     const outerExit = vi.fn()
     const replacementData = vi.fn()
     const replacementExit = vi.fn()
-    const outerTransport = createIpcPtyTransport()
-    const replacementTransport = createIpcPtyTransport()
+    const transport = createIpcPtyTransport()
 
-    const result = await outerTransport.connect({
+    const result = await transport.connect({
       url: '',
       callbacks: {
         onData: (data) => {
           outerData.push(data)
-          replacementTransport.attach({
+          transport.attach({
             existingPtyId: 'same-id',
             callbacks: { onData: replacementData, onExit: replacementExit }
           })
@@ -518,14 +516,15 @@ describe('createIpcPtyTransport', () => {
         onExit: outerExit
       }
     })
-    onExit?.({ id: 'same-id', code: 8 })
 
     expect(result).toBeUndefined()
     expect(outerData).toEqual(['first buffered chunk'])
-    expect(outerTransport.isConnected()).toBe(false)
     expect(replacementData).toHaveBeenCalledWith('second buffered chunk')
     expect(outerExit).not.toHaveBeenCalled()
+    expect(transport.isConnected()).toBe(true)
+    onExit?.({ id: 'same-id', code: 8 })
     expect(replacementExit).toHaveBeenCalledWith(8)
+    expect(transport.isConnected()).toBe(false)
   })
 
   it('ignores a stale exit for a previous PTY after reconnecting the same transport', async () => {
@@ -1332,6 +1331,19 @@ describe('createIpcPtyTransport', () => {
     expect(flushed.endsWith('TAIL$')).toBe(true)
   })
 
+  it('keeps a replacement eager handle when the stale handle disposes', async () => {
+    const { getEagerPtyBufferHandle, registerEagerPtyBuffer } = await import('./pty-transport')
+    const staleHandle = registerEagerPtyBuffer('pty-restored', vi.fn())
+    const replacementHandle = registerEagerPtyBuffer('pty-restored', vi.fn())
+    onData?.({ id: 'pty-restored', data: 'replacement startup output' })
+
+    staleHandle.dispose()
+
+    expect(getEagerPtyBufferHandle('pty-restored')).toBe(replacementHandle)
+    expect(replacementHandle.flush()).toBe('replacement startup output')
+    replacementHandle.dispose()
+  })
+
   it('drains pre-handler data and exit into eager buffers for fast background PTYs', async () => {
     const { ensurePtyDispatcher, registerEagerPtyBuffer } = await import('./pty-transport')
     const onEagerExit = vi.fn()
@@ -2041,7 +2053,10 @@ describe('createIpcPtyTransport', () => {
     restorePtyDataHandlersAfterFailedShutdown(snapshots)
     onData?.({ id: 'pty-1', data: 'live again' })
 
-    expect(onDataCallback).toHaveBeenCalledWith('live again')
+    expect(onDataCallback.mock.calls.map(([data]) => data)).toEqual([
+      'final burst while detached',
+      'live again'
+    ])
   })
 
   it('does not restore failed-shutdown handlers over a replacement pane', async () => {

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

@@ -546,6 +546,7 @@ export function createIpcPtyTransport(opts: IpcPtyTransportOptions = {}): PtyTra
   let connected = false
   let destroyed = false
   let ptyId: string | null = null
+  let bindingGeneration = 0
   // Why: eager PTY buffers contain output produced before the pane attached —
   // often from the previous app session. We still replay that data so titles
   // and scrollback restore correctly, but it must not produce fresh bells,
@@ -840,6 +841,7 @@ export function createIpcPtyTransport(opts: IpcPtyTransportOptions = {}): PtyTra
 
         ptyId = spawnResult.id
         connected = true
+        const currentBindingGeneration = ++bindingGeneration
 
         // Why: for deferred reattach (Option 2), the daemon returns snapshot/
         // coldRestore data from createOrAttach. Skip onPtySpawn for reattach —
@@ -856,8 +858,10 @@ export function createIpcPtyTransport(opts: IpcPtyTransportOptions = {}): PtyTra
           exitRegistration
         )
         if (!handlersCurrent || !connected || ptyId !== spawnResult.id) {
-          connected = false
-          ptyId = null
+          if (bindingGeneration === currentBindingGeneration) {
+            connected = false
+            ptyId = null
+          }
           return undefined
         }
 
@@ -965,14 +969,17 @@ export function createIpcPtyTransport(opts: IpcPtyTransportOptions = {}): PtyTra
       const id = options.existingPtyId
       ptyId = id
       connected = true
+      const currentBindingGeneration = ++bindingGeneration
       // Why: skip onPtySpawn — it would reset lastActivityAt and destroy the
       // recency sort order that reconnectPersistedTerminals preserved.
       const dataRegistration = registerPtyDataHandler(id)
       const exitRegistration = registerPtyExitHandler(id)
       const handlersCurrent = drainRegisteredPtyHandlers(id, dataRegistration, exitRegistration)
       if (!handlersCurrent || !connected || ptyId !== id) {
-        connected = false
-        ptyId = null
+        if (bindingGeneration === currentBindingGeneration) {
+          connected = false
+          ptyId = null
+        }
         return
       }