Shell session dies when child Python process runs `os.kill(pid, 0)`

What version of Codex CLI is running?

0.118.0

What subscription do you have?

Pro

Which model were you using?

gpt-5.4 xhigh

What platform is your computer?

Native Windows x64

What terminal emulator and version are you using (if applicable)?

_No response_

What issue are you seeing?

Windows in PowerShell, not WSL. The following command made the shell session disappear before Codex reported the result

What steps can reproduce the bug?

python -c "import os; os.kill(os.getpid(), 0)"

What is the expected behavior?

Codex should stay up and report the command result.

Additional information

The child reaches os.kill(..., 0). After that, Codex does not return a command result. The shell session disappears before completion is reported. I did not see the same effect from missing-PID probes alone. I also did not see it from handle-based Win32 liveness checks.