Windows CLI regression in 0.156.x/0.157.0: startup and command execution open multiple terminal windows #48070

Summary

On Windows, Codex CLI 0.156.x and 0.157.0 open many separate terminal windows during startup and when running commands. These windows appear in front of the working terminal and interrupt normal use. Downgrading the npm-installed CLI to 0.155.0 resolves the behavior on the same machine.

Versions tested

• codex-cli 0.157.0: reproduces.
• codex-cli 0.156.x: reproduces (exact patch version not recorded).
• codex-cli 0.155.0: does not reproduce.

Steps to reproduce

1. On Windows, install the CLI globally with npm (npm install -g @openai/codex@0.157.0).
2. Close/terminate existing Codex processes and start codex in the terminal.
3. Observe multiple separate terminal windows opening at startup. Command execution also opens separate windows.
4. Downgrade with npm install -g @openai/codex@0.155.0 and start Codex again: the extra windows stop appearing.

Expected behavior

Codex starts and runs its commands without spawning visible separate terminal windows or stealing focus.

Additional context

The behavior persisted after terminating Codex processes and starting a new session on 0.156.x/0.157.0. The specific child executable shown in the extra windows and the exact Windows build/terminal host have not yet been captured. This may be related to #44856, but that report describes the symptom in a second concurrent session, whereas here it occurs on startup after restarting Codex. Also possibly related to #37599 if the spawned executable is codex-code-mode-host.exe; this has not been confirmed.