Shell stops accepting commands after Ctrl+Z suspend/resume over tsh on Slurm Linux host

Summary

When Codex is running in a shell reached through tsh on a Slurm Linux cluster, suspending Codex with Ctrl+Z and then resuming it leaves the terminal/session in a bad state. After Codex comes back up, the shell no longer works properly and commands cannot be submitted.

Environment

• Client terminal: iTerm2 on macOS
• Remote access: ssh into Linux machines on a Slurm cluster
• Remote shell: bash
• Codex CLI: codex-cli 0.142.0
• Remote host observed while filing: Linux fs-mbz-cpu-002 5.15.0-153-generic #163-Ubuntu SMP Thu Aug 7 16:37:18 UTC 2025 x86_64

Steps to reproduce

1. Open iTerm2 on macOS.
2. Use ssh to connect to a Linux machine on a Slurm cluster.
3. Start Codex CLI in the remote shell.
4. Let Codex run work.
5. Press Ctrl+Z to suspend Codex.
6. Resume Codex, for example with fg.

Expected behavior

After resuming, Codex should restore terminal state and job-control handling so shell input continues to work and commands can be submitted normally.

Actual behavior

After Codex comes back up, the shell/terminal input is broken. Commands cannot be submitted properly, leaving the session effectively unusable.

Notes

This looks like a terminal state or job-control restoration issue around SIGTSTP/SIGCONT, possibly exposed by the ssh remote TTY path.