diff --git a/config/reliability-gates.jsonc b/config/reliability-gates.jsonc
index 9b0939373ff..62c9b3c29ce 100644
--- a/config/reliability-gates.jsonc
+++ b/config/reliability-gates.jsonc
@@ -3963,6 +3963,7 @@
             "provider reconnect retries durable shutdown intent with its generation and pane identity",
             "persisted local shutdown waits for daemon startup instead of accepting unknown-id success from the fallback provider",
             "an in-flight replaced local provider cannot complete or delete the newer shutdown owner",
+            "local and SSH stale-provider not-found rejections preserve replacement ownership and coalesced callers fail closed",
             "host-scoped liveness lists only the selected provider instead of fanning out to unrelated SSH hosts",
             "relay generation reuse removes stale retry ownership without touching the new PTY"
           ]
diff --git a/src/main/ipc/pty.test.ts b/src/main/ipc/pty.test.ts
index ae48f61811d..77ec50a8f02 100644
--- a/src/main/ipc/pty.test.ts
+++ b/src/main/ipc/pty.test.ts
@@ -3496,7 +3496,10 @@ describe('registerPtyHandlers', () => {
 
   it('does not let an in-flight old provider complete persisted shutdown ownership', async () => {
     vi.useFakeTimers()
-    const oldShutdown = makeDeferred()
+    let rejectOldShutdown!: (error: Error) => void
+    const oldShutdown = new Promise<void>((_resolve, reject) => {
+      rejectOldShutdown = reject
+    })
     const makeProvider = (shutdown: (id: string) => Promise<void>) =>
       ({
         shutdown,
@@ -3506,7 +3509,7 @@ describe('registerPtyHandlers', () => {
       }) as never
     const newShutdown = vi.fn().mockResolvedValue(undefined)
     const removePendingLocalPtyShutdown = vi.fn()
-    setLocalPtyProvider(makeProvider(() => oldShutdown.promise))
+    setLocalPtyProvider(makeProvider(() => oldShutdown))
     handlers.clear()
     registerPtyHandlers(mainWindow as never, undefined, undefined, undefined, undefined, {
       getPendingLocalPtyShutdowns: () => [{ ptyId: 'daemon-pty', requestedAt: 1 }],
@@ -3515,8 +3518,10 @@ describe('registerPtyHandlers', () => {
     } as never)
     await vi.advanceTimersByTimeAsync(0)
 
+    const coalescedKill = handlers.get('pty:kill')!(null, { id: 'daemon-pty' }) as Promise<void>
     setLocalPtyProvider(makeProvider(newShutdown))
-    oldShutdown.resolve()
+    rejectOldShutdown(new Error('Session not found: daemon-pty'))
+    await expect(coalescedKill).rejects.toThrow('PTY shutdown still pending')
     await vi.advanceTimersByTimeAsync(0)
 
     expect(newShutdown).toHaveBeenCalledOnce()
@@ -3526,6 +3531,64 @@ describe('registerPtyHandlers', () => {
     vi.useRealTimers()
   })
 
+  it('does not let a stale SSH provider not-found rejection delete replacement ownership', async () => {
+    vi.useFakeTimers()
+    let rejectOldShutdown!: (error: Error) => void
+    const oldShutdown = vi.fn(
+      () =>
+        new Promise<void>((_resolve, reject) => {
+          rejectOldShutdown = reject
+        })
+    )
+    const newShutdown = vi.fn().mockResolvedValue(undefined)
+    const lease = {
+      targetId: 'ssh-1',
+      ptyId: 'relay-pty',
+      relayInstanceId: 'boot-1',
+      state: 'detached' as const,
+      shutdownRequestedAt: 2,
+      createdAt: 1,
+      updatedAt: 2
+    }
+    const store = {
+      getSshRemotePtyLeases: vi.fn(() => [lease]),
+      markSshRemotePtyLease: vi.fn()
+    }
+    handlers.clear()
+    registerPtyHandlers(
+      mainWindow as never,
+      undefined,
+      undefined,
+      undefined,
+      undefined,
+      store as never
+    )
+    registerSshPtyProvider('ssh-1', {
+      shutdown: oldShutdown,
+      onExit: vi.fn(() => () => {})
+    } as never)
+    await vi.advanceTimersByTimeAsync(0)
+
+    registerSshPtyProvider('ssh-1', {
+      shutdown: newShutdown,
+      onExit: vi.fn(() => () => {})
+    } as never)
+    rejectOldShutdown(new Error('PTY "relay-pty" not found'))
+    await vi.advanceTimersByTimeAsync(0)
+
+    expect(oldShutdown).toHaveBeenCalledOnce()
+    expect(newShutdown).toHaveBeenCalledOnce()
+    expect(store.markSshRemotePtyLease).toHaveBeenCalledWith(
+      'ssh-1',
+      'ssh:ssh-1@@boot-1@@relay-pty',
+      'terminated'
+    )
+    unregisterSshPtyProvider('ssh-1')
+    await vi.advanceTimersByTimeAsync(30_000)
+    expect(vi.getTimerCount()).toBe(0)
+    vi.useRealTimers()
+  })
+
   it('synthesizes runtime exit after ordinary daemon-backed pty kill', async () => {
     const shutdown = vi.fn(async () => undefined)
     const runtime = {
diff --git a/src/main/ipc/pty.ts b/src/main/ipc/pty.ts
index e570bc2e52e..9355b07b3fc 100644
--- a/src/main/ipc/pty.ts
+++ b/src/main/ipc/pty.ts
@@ -647,6 +647,9 @@ function attemptRetainedPtyShutdown(retained: RetainedPtyShutdown): Promise<void
       if (ownerMap.get(retained.id) !== retained) {
         return
       }
+      if (retained.provider !== currentProvider) {
+        return
+      }
       if (isPtyAlreadyGoneError(error)) {
         completeRetainedPtyShutdown(retained, false)
         return
@@ -5243,9 +5246,15 @@ export function registerPtyHandlers(
       const ownedConnectionId = ptyOwnership.get(args.id)
       const parsedSshId = ownedConnectionId === undefined ? parseAppSshPtyId(args.id) : null
       const connectionId = ownedConnectionId ?? parsedSshId?.connectionId
-      const retainedRetry = pendingSshShutdownRetries.get(args.id)
+      const retainedRetry = connectionId
+        ? pendingSshShutdownRetries.get(args.id)
+        : pendingLocalShutdownRetries.get(args.id)
       if (retainedRetry?.inFlight) {
         await retainedRetry.inFlight
+        const ownerMap = connectionId ? pendingSshShutdownRetries : pendingLocalShutdownRetries
+        if (ownerMap.get(args.id) === retainedRetry) {
+          throw new Error('PTY shutdown still pending')
+        }
         return
       }
       const provider = connectionId ? sshProviders.get(connectionId) : tryGetProviderForPty(args.id)