Codex Desktop crashes in DeviceCheck/XPC when running under two macOS users with Fast User Switching

What version of the Codex App are you using (From “About Codex” dialog)?

Codex Desktop 26.623.101652 build 4674 (from the macOS crash report).

What subscription do you have?

Not relevant to the local native crash.

What platform is your computer?

• macOS 15.0 (24A335)
• Apple Silicon / ARM64
• Two macOS user accounts remain logged in concurrently via Fast User Switching
• Codex Desktop is running in both user sessions

What issue are you seeing?

Codex Desktop in one macOS user session exits when switching to the other logged-in user and running Codex there. Two macOS .ips reports show the same deterministic native crash signature in Apple's DeviceCheck/XPC path while Codex generates a device token.

Crash summary:

Exception Type: EXC_BREAKPOINT (SIGTRAP)
Termination Reason: Namespace SIGNAL, Code 5, Trace/BPT trap: 5
Faulting stack:
_xpc_api_misuse
xpc_connection_set_target_uid
-[DCDeviceMetadataDaemonConnection connection]
-[DCDeviceMetadataDaemonConnection synchronousRemoteObjectProxy:]
-[DCDevice _isSupportedReturningError:]
-[DCDevice isSupported]
(anonymous namespace)::GenerateTokenWorker::Execute()
Napi::AsyncWorker::OnExecute(Napi::Env)

The two incident identifiers are:

• 4ACFD62E-3A2A-4200-AAE7-5F5508AFCDE7
• 82C0B5B6-B325-4741-9703-9CEEA6BC1CAA

This does not look like a renderer crash or corrupt workspace state. Both reports terminate at _xpc_api_misuse after xpc_connection_set_target_uid, through devicecheck.node.

Computer Use may be enabled, but the crash occurs in the DeviceCheck token path rather than the Screen Recording or Accessibility permission path.

What steps can reproduce the bug?

1. Create or use two normal macOS user accounts.
2. Log into user A and launch Codex Desktop.
3. Leave user A logged in and use Fast User Switching to user B.
4. Launch or use Codex Desktop in user B.
5. Switch between the two sessions.
6. Codex in the other session exits; macOS writes an .ips report with the DeviceCheck/XPC stack above.

Reproduced at least twice with the identical faulting stack.

What is the expected behavior?

Codex Desktop should remain running independently in both logged-in macOS user sessions. Fast User Switching should not terminate the app in either session.

The user specifically needs both Codex instances to remain running; fully quitting Codex before switching is not an acceptable workaround.

Additional information

A safe workaround may require Codex to avoid calling the DeviceCheck XPC API from an inactive GUI session, serialize/retry device-token generation across user sessions, or treat DCDevice.isSupported / token-generation failure as non-fatal.

Full raw crash reports are available if an OpenAI maintainer requests them. They are not attached publicly because macOS diagnostic reports may contain local machine and path metadata.