[Windows][26.820.7780.0] Local execution fails to start after updating Codex Desktop

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

OpenAI.Codex_26.820.7780.0_x64__2p2nqsd0c76g0

What subscription do you have?

PLUS

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

After updating Codex Desktop to 26.820.7780.0, all new local tasks fail before any command is executed.

Observed user-facing errors include:

Unable to read: local execution environment failed to start.
Unable to read: local command execution service handshake failed.

One observed underlying error was:

failed to spawn code-mode host
C:\Users<redacted>\AppData\Local\OpenAI\Codex\bin\d0097be4feba73d0\codex-code-mode-host.exe:
The system cannot find the file specified. (os error 2)

The regression is specific to this Windows machine after upgrading to 26.820. The root cause is not yet known.

What steps can reproduce the bug?

1. Use a working Codex Desktop installation on Windows 10.0.26200.0.
2. Update the app to 26.820.7780.0.
3. Create a new local task.
4. Request a trivial local command, such as listing a directory.
5. Observe that local execution fails during startup or handshake, before the command runs.

The issue persists after:

1. Restarting Windows
2. Windows repair operations
3. A clean Codex configuration test
4. Recreating the CUA Node runtime

What is the expected behavior?

After an in-app update, a new local task should start normally and execute basic commands.
If a required local runtime component is unavailable, Codex should report the exact missing component and provide an automatic repair path instead of failing every local task with a generic startup or handshake error.

Additional information

I compared the affected PC with another PC where 26.820.7780.0 works normally:

1. Same Windows build
2. Same Codex App version
3. Same codex.exe hash
4. Same node_repl.exe hash
5. Configured named pipe matched the actual running named pipe on both PCs

Therefore, this does not appear to be a universally broken 26.820 release, but it is a reproducible machine-specific or state-specific regression triggered by the update.
Rolling back to the previous 26.818.61809 build restored local execution after completing the rollback procedure.
Please advise what additional diagnostics would be useful. I can provide sanitized Codex Desktop logs and process details.

Start by reviewing the sanitized Codex Desktop logs and process details around spawning codex-code-mode-host.exe after the 26.820.7780.0 update, comparing them with the working 26.818.61809 installation. Done means a new local task starts and executes a basic command, or the missing runtime component is reported with a repair path.