Windows app WSL agent mode fails to find bundled CLI and may launch Windows codex.exe via CODEX_CLI_PATH #28086

Component

Codex Desktop for Windows / WSL agent startup / app-server CLI resolution

Version / environment

• Codex Desktop: 26.609.4994.0
• CLI observed in WSL: codex-cli 0.139.0
• Windows OS build: 10.0.26200
• WSL: Ubuntu, WSL2, running
• WSL has a native Linux Codex CLI available at /home/<wsl-user>/.local/bin/codex

Summary

Switching the Windows Codex app agent environment from Windows native to WSL should start the agent/app-server inside WSL without requiring a user-defined CODEX_CLI_PATH. Instead, I am seeing two failure modes:

1. With CODEX_CLI_PATH unset, Codex Desktop fails to start in WSL agent mode.
2. With CODEX_CLI_PATH set to a Windows codex.exe, Codex Desktop starts but appears to launch that Windows executable through WSL interop, producing a hybrid Windows session rather than a real WSL agent session.

This seems inconsistent with the Windows app docs, which say the agent can be switched from Windows native to WSL in Settings and then restarted: https://developers.openai.com/codex/windows

Expected behavior

After setting the agent environment to WSL and restarting the Windows app, Codex should start the WSL/Linux agent using either:

• a Linux Codex CLI already available inside WSL, or
• a correctly bundled/relocated Linux binary for WSL mode.

A normal user should not need to set CODEX_CLI_PATH for this mode switch.

Actual behavior

With the WSL agent setting enabled and CODEX_CLI_PATH removed, the app shows:

Codex failed to start.
Unable to locate the Codex CLI binary. Set CODEX_CLI_PATH or ensure the Electron resources include bin/codex.

The desktop log contains this key line:

bundled_executable_relocation_failed destinationPath=C:\Users\<user>\.codex\bin\wsl\codex ... operation=stat_source ... sourcePath="C:\Program Files\WindowsApps\OpenAI.Codex_26.609.4994.0_x64__2p2nqsd0c76g0\app\resources\codex" ... ENOENT

On disk, the installed Windows app resources contain codex.exe, but not codex:

Test-Path ...\app\resources\codex      -> False
Test-Path ...\app\resources\codex.exe  -> True

When CODEX_CLI_PATH is restored and points to a Windows executable, WSL mode starts but the WSL process list shows the Windows CLI being launched through interop:

/init /mnt/c/Users/<user>/AppData/Local/Programs/OpenAI/Codex/bin/codex.exe ... app-server --analytics-default-enabled

The resulting session behaves like Windows native rather than WSL:

shell: powershell.exe
$PSVersionTable.PSEdition: Desktop
WSL_DISTRO_NAME: empty
Get-Location: C:\
workspace paths resemble C:\mnt\c\... rather than /mnt/c/...

Reproduction steps

1. On Windows, ensure WSL2 Ubuntu is installed/running and has a native Linux codex available.
2. Remove any user/global CODEX_CLI_PATH environment variable.
3. In Codex Desktop settings, set the agent environment to WSL. This writes/uses the WSL agent mode setting (runCodexInWindowsSubsystemForLinux = true).
4. Restart Codex Desktop.
5. Observe the startup error above.
6. Optionally set CODEX_CLI_PATH to a Windows codex.exe and restart.
7. Observe that the app starts, but the app-server appears to be the Windows executable launched from WSL interop, producing a Windows-native/hybrid session.

Suspected cause

The WSL startup path on Windows appears to assume that the Electron/MSIX resources contain a Linux-style app/resources/codex binary and tries to relocate it to %USERPROFILE%\.codex\bin\wsl\codex. In this install, the resource present is app/resources/codex.exe only. Separately, when CODEX_CLI_PATH points at a Windows executable, WSL mode appears to use it without validating that it is a Linux executable, so WSL interop launches the Windows CLI instead of using the native WSL CLI.

Notes

• CODEX_CLI_PATH does not appear to be listed as a normal stable public environment setting in https://developers.openai.com/codex/environment-variables
• The issue is reproducible after creating a fresh Codex Desktop session.
• I can provide a redacted full log if useful.