Windows Desktop elevated sandbox hangs after ACL setup and leaks setup helpers; unelevated works (0.145.0-alpha.18)

Summary

This appears to be a regression or an incomplete fix related to #24098, which was closed as completed after the Windows elevated sandbox fix was reported for 0.140.

On the current Codex Desktop build, the elevated Windows sandbox hangs before even a basic workspace read command starts. codex-windows-sandbox-setup.exe processes remain running and do not exit automatically. Switching only the Windows sandbox implementation to unelevated makes the same workspace read/write operations work normally without requiring danger-full-access.

Environment

• Codex Desktop: 26.715.2305.0
• Bundled CLI: codex-cli 0.145.0-alpha.18
• Platform: Microsoft Windows NT 10.0.26200.0 x64
• Top-level sandbox mode: sandbox_mode = "workspace-write"
• Approval policy: on request
• Native Windows workspace (not WSL)

Reproduction

1. Configure:

```toml
sandbox_mode = "workspace-write"

[windows]
sandbox = "elevated"
```

1. Fully restart Codex Desktop.

1. Start a local task in a normal workspace.

1. Run an ordinary read-only command, such as reading a small text file from the workspace.

Actual behavior

• The command does not reach PowerShell and remains stuck for more than 30 seconds.
• The command must be terminated.
• codex-windows-sandbox-setup.exe remains running instead of exiting.
• During the troubleshooting session, six lingering setup helper processes accumulated.
• Helper paths included both:
• the packaged C:\Program Files\WindowsApps\OpenAI.Codex_<version>\app\resources\codex-windows-sandbox-setup.exe
• a copied %LOCALAPPDATA%\OpenAI\Codex\bin\<hash>\codex-windows-sandbox-setup.exe
• The sandbox log reached the ACL phase:
• setup refresh spawned the helper;
• workspace write ACE application was logged;
• the read ACL run completed;
• but setup binary completed was never logged.
• The intended workspace probe file was never created.
• The lingering setup helpers had to be terminated manually.

Unelevated comparison

After changing only:

[windows]
sandbox = "unelevated"

and fully restarting Codex Desktop:

• an ordinary sandboxed command completed in about 0.8 seconds;
• a workspace probe file was created, read back correctly, and deleted;
• the setup helper process count remained 0;
• the probe file left no residue;
• danger-full-access was not needed.

This isolates the failure to the current elevated Windows sandbox path rather than the workspace or PowerShell itself.

Expected behavior

The elevated sandbox should either:

1. complete setup, run the requested command, and exit its setup helper; or
2. fail promptly with an actionable error.

It should not hang indefinitely or accumulate high-CPU setup helper processes.

Diagnostics and related report

• In-product Feedback ID: 019f6df6-f568-7122-8354-a33e5039658a
• Earlier closed issue: #24098
• Detailed reproduction comment on that issue: https://github.com/openai/codex/issues/24098#issuecomment-4998724127

A sanitized sandbox-log excerpt can be provided if needed.