Codex app-server crashes on Windows with Codex process is not available and invalid experimental feature key apps_mcp_path_override

What version of the IDE extension are you using?

26.623.42026

What subscription do you have?

Plus

Which IDE are you using?

Vscode

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

Codex crashes immediately and the app-server becomes unavailable.

The error shown in the UI is:

An error has occurred

Codex crashed with the following error:

Codex process errored: Codex process is not available

codex_app_server::request_processors::config_processor:
ignoring invalid experimental feature enablement keys: apps_mcp_path_override

The message suggests checking config.toml, but this does not look like a normal user config parse error. The suspicious part is that apps_mcp_path_override appears to be an experimental / feature-flag-related key, and the installed app-server/runtime seems to reject or ignore it before Codex becomes unavailable.

What steps can reproduce the bug?

Open VS Code on Windows.
Open the Codex panel.
Start or resume a Codex session.
Codex crashes before becoming usable.
Reloading Codex shows the same crash again.

If relevant:

The crash started after enabling / using WSL mode.
The crash also happens after clicking reload.
The crash still happens after restarting VS Code.
The crash still happens even if config.toml does not explicitly contain apps_mcp_path_override.

What is the expected behavior?

Codex should start normally.

If apps_mcp_path_override is an unsupported or rollout-only experimental key, the app-server should ignore it safely without crashing or making the Codex process unavailable.
Actual behavior

Codex app-server becomes unavailable and the UI shows:

Codex process errored: Codex process is not available

with this warning:

ignoring invalid experimental feature enablement keys: apps_mcp_path_override
Local config check

Please fill in after checking:

Get-Content $env:USERPROFILE\.codex\config.toml

Sanitized result:

paste sanitized config.toml here

Additional information

codex --version
where codex
code --version

Please also check the VS Code Output panel for Codex logs and attach the relevant sanitized lines.

Notes

There are existing similar reports around Codex process is not available on Windows / VS Code extension, and other reports where an unknown or invalid feature key causes the app-server to become unavailable. This case may be another feature flag / runtime compatibility mismatch involving apps_mcp_path_override.