Windows sandbox fails with helper_unknown_error: apply deny-read ACLs

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

Version 26.831.21537

What subscription do you have?

ChatGPT Pro

What platform is your computer?

Windows 11 x64

What issue are you seeing?

The native Windows sandbox fails before normal repository commands can start:

helper_unknown_error: apply deny-read ACLs

Feedback ID:
no-active-thread-01a06530-d2af-7ad3-82d2-8c8d665849fb

The failure persists after:

1. Fully quitting and restarting Codex.
2. Restarting Windows.
3. Updating the Codex/ChatGPT app.
4. Testing both elevated and unelevated Windows sandbox modes in config.toml.
5. Running /sandbox-add-read-dir with the absolute repository path.
6. Testing normal repository commands and an apply_patch disposable probe.

Normal repository commands such as git status fail during sandbox process creation. apply_patch can create a probe but cannot read or delete it afterward because of the same ACL error. Approved out-of-sandbox commands still work.

No Windows or repository permissions were manually changed. The repository remains intact, and no credentials or .env.local contents were inspected.

What steps can reproduce the bug?

1. Launch the Codex App on Windows 11 x64.
2. Open a local Git repository as a Codex project.
3. Start a new Codex chat.
4. Ask Codex to run a basic repository command such as git status.
5. Sandbox process creation fails with:
   helper_unknown_error: apply deny-read ACLs
6. Ask Codex to create and remove a disposable file using apply_patch.
7. apply_patch creates the file but cannot read or delete it because of the same ACL error.
8. An approved out-of-sandbox command can remove the disposable file successfully.

The issue persists after fully restarting Codex and Windows, updating the Microsoft Store app, trying both elevated and unelevated Windows sandbox modes, and running /sandbox-add-read-dir with the repository’s absolute path.

Feedback ID containing diagnostics:
no-active-thread-01a06530-d2af-7ad3-82d2-8c8d665849fb

What is the expected behavior?

No response

Additional information

No response

The report names no source file or test; start by reproducing the Windows 11 sandbox process-creation failure with the provided steps and Feedback ID. Trace the native sandbox path that applies deny-read ACLs, and consider the issue done when repository commands and disposable file read/delete operations work in both tested sandbox modes.