[Windows] All Codex tool calls fail with “code-mode host exited during handshake”

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

26.820.60940

What subscription do you have?

Free

What platform is your computer?

Windows x64; Windows PowerShell 5.1.22621.4391

What issue are you seeing?

Summary

Every Codex tool call fails during the code-mode host handshake, before the requested command is executed. The failure reproduces consistently, including with minimal local commands.

Error

code-mode host exited during handshake

### What steps can reproduce the bug?

1. Open the Codex App on Windows with a local workspace.
2. Use the workspace directory as the working directory.
3. Ask Codex to execute a simple local command such as:
`Get-Location`
4.The tool call fails before the command starts.

### What is the expected behavior?

### Expected behavior
Codex should execute the local PowerShell command and return its output.
### Actual behavior
The tool host exits during the handshake. The command is not executed and no command output is returned.

### Additional information

The interactive PowerShell terminal inside the Codex window works normally. For example, the following commands run successfully when entered manually in the terminal:

Write-Output "TERMINAL_OK"
Get-Location
$PSVersionTable.PSVersion

This indicates that PowerShell and the workspace directory are usable. The failure appears to be specific to the Codex tool bridge or code-mode host.