Desktop "Create branch" fails with Wsl/Service/E_UNEXPECTED on Windows/WSL even though git succeeds #17961

Summary

When I use the Codex Desktop "Work here" flow to create a branch on Windows with a WSL-backed workspace, the app shows:

Failed to set branch
$ git branch codex/test
Catastrophic failure
Error code:
Wsl/Service/E_UNEXPECTED

The underlying git repo is fine. Running the equivalent git commands directly in the WSL shell succeeds.

Steps to reproduce

1. Open Codex Desktop on Windows against a repo in WSL mounted from a Windows path.
2. In the desktop UI, choose Work here.
3. Enter a branch name such as codex/investigate-email-retry-errors.
4. Click Create.
5. Observe the error dialog.

Expected behavior

Codex Desktop should create and switch to the branch, the same as git switch -c codex/investigate-email-retry-errors.

Actual behavior

The desktop app fails with Wsl/Service/E_UNEXPECTED and says it could not set the branch.

In the same workspace, these commands succeed from the WSL shell:

git branch codex/test
git switch codex/test

That makes this look like a desktop app / WSL integration failure rather than a repo-level git problem.

Environment

• OS: Windows 10.0.26200.8246
• WSL version: 2.6.3.0
• WSL kernel: 6.6.87.2-1
• Default distro: Ubuntu
• Git in WSL: 2.43.0

Additional notes

• The repo is under a OneDrive-backed Windows path mounted into WSL. I have not confirmed whether that is required for the bug, but it may be relevant.
• Possibly related to Windows app appears unstable around branch/worktree state #16290, but this repro is narrower: the branch creation dialog fails even though plain git branch/switch works immediately in the same workspace.