From 963d0cfe7392ab34bb66e431dbf61cb4dd8cb5d6 Mon Sep 17 00:00:00 2001
From: Neil <4138956+nwparker@users.noreply.github.com>
Date: Mon, 31 Aug 2026 04:22:22 -0700
Subject: [PATCH] fix(terminal): fence stale pane binds after rebind

---
 .../pty-connection-pty-exit-teardown.test.ts  | 35 +++++++++++++++++++
 .../pane-pty-layout-binding.test.ts           | 20 +++++++++++
 .../pane-pty-visibility-bind.ts               |  3 +-
 3 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/src/renderer/src/components/terminal-pane/pty-connection-pty-exit-teardown.test.ts b/src/renderer/src/components/terminal-pane/pty-connection-pty-exit-teardown.test.ts
index 1448ef7a5ee..23e521bd0eb 100644
--- a/src/renderer/src/components/terminal-pane/pty-connection-pty-exit-teardown.test.ts
+++ b/src/renderer/src/components/terminal-pane/pty-connection-pty-exit-teardown.test.ts
@@ -708,6 +708,41 @@ describe('connectPanePty', () => {
     expect(manager.closePane).not.toHaveBeenCalled()
   })
 
+  it('ignores a late spawn callback after the pane adopted a provider replacement', async () => {
+    const { connectPanePty } = await import('./pty-connection')
+    let transportPtyId = 'terminal-old'
+    const transport = createMockTransport(transportPtyId)
+    transport.getPtyId = vi.fn(() => transportPtyId)
+    transportFactoryQueue.push(transport)
+    const manager = createManager(1)
+    const deps = createDeps()
+    const pane = createPane(1)
+
+    connectPanePty(pane as never, manager as never, deps as never)
+    const onPtySpawn = createdTransportOptions[0]?.onPtySpawn as
+      | ((ptyId: string) => void)
+      | undefined
+    const onPtyRebind = createdTransportOptions[0]?.onPtyRebind as
+      | ((ptyId: string, replacedPtyId: string) => void)
+      | undefined
+    expect(onPtySpawn).toBeTypeOf('function')
+    expect(onPtyRebind).toBeTypeOf('function')
+
+    onPtySpawn?.('terminal-old')
+    transportPtyId = 'terminal-reconnected'
+    onPtyRebind?.('terminal-reconnected', 'terminal-old')
+
+    // The fixture dependency is intentionally lightweight, so mirror the live
+    // tab/layout commit that the real store performs atomically on replacement.
+    mockStoreState.tabsByWorktree['wt-1'][0]!.ptyId = 'terminal-reconnected'
+    mockStoreState.terminalLayoutsByTabId['tab-1']!.ptyIdsByLeafId![LEAF_1] = 'terminal-reconnected'
+
+    onPtySpawn?.('terminal-old')
+
+    expect(pane.container.dataset.ptyId).toBe('terminal-reconnected')
+    expect(deps.syncPanePtyLayoutBinding).not.toHaveBeenLastCalledWith(1, 'terminal-old')
+  })
+
   it('closes a split pane when an established PTY exits after output', async () => {
     const { connectPanePty } = await import('./pty-connection')
     const capturedDataCallback: { current: ((data: string) => void) | null } = { current: null }
diff --git a/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-layout-binding.test.ts b/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-layout-binding.test.ts
index 852818b8643..2eff30c3233 100644
--- a/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-layout-binding.test.ts
+++ b/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-layout-binding.test.ts
@@ -22,4 +22,24 @@ describe('shouldIgnoreStalePanePtyLayoutBinding', () => {
       })
     ).toBe(false)
   })
+
+  it('rejects a stale callback after the pane already adopted the replacement', () => {
+    expect(
+      shouldIgnoreStalePanePtyLayoutBinding({
+        existingPtyId: 'pty-new',
+        nextPtyId: 'pty-old',
+        tabPtyId: 'pty-new'
+      })
+    ).toBe(true)
+  })
+
+  it('allows a callback while the tab still owns the callback PTY', () => {
+    expect(
+      shouldIgnoreStalePanePtyLayoutBinding({
+        existingPtyId: 'pty-new',
+        nextPtyId: 'pty-old',
+        tabPtyId: 'pty-old'
+      })
+    ).toBe(false)
+  })
 })
diff --git a/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-visibility-bind.ts b/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-visibility-bind.ts
index 76fa13bffe0..ef6f3062c94 100644
--- a/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-visibility-bind.ts
+++ b/src/renderer/src/components/terminal-pane/pty-connection/pane-pty-visibility-bind.ts
@@ -54,8 +54,7 @@ export function installPanePtyVisibilityBind(session: ConnectPanePtySession): vo
           existingPtyId,
           nextPtyId: ptyId,
           tabPtyId
-        }) &&
-        session.activePanePtyBinding === ptyId
+        })
       ) {
         return
       }