Codex CLI 0.154.0 hangs when launched inside tmux.

What version of Codex CLI is running?

codex-cli 0.154.0

What subscription do you have?

Organizational

Which model were you using?

No response

What platform is your computer?

Linux 4.18.0-553.158.1.el8_10.x86_64 x86_64 x86_64

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

tmux

Codex doctor report

What issue are you seeing?

Summary

Codex CLI 0.154.0 hangs when launched inside tmux.

Environment

• Codex CLI: 0.154.0
• tmux: 3.4
• OS: Rocky Linux 8
• Shell: bash

Steps to reproduce

1. Open a tmux pane.
2. Run:

   codex
   
   

Actual behavior

Codex never reaches the interactive UI. Its startup blocks on:

tmux display-message -p #{extended-keys-format}

The tmux child remains in a poll/wait state.

Expected behavior

Codex should start normally inside tmux, as it did before the Codex update.

Workaround

This starts Codex successfully:

env -u TMUX -u TMUX_PANE codex

This suggests the tmux capability-detection step is hanging.

What steps can reproduce the bug?

Open a tmux pane.
Run:
codex

What is the expected behavior?

Codex should start normally inside tmux, as it did before the Codex update.

Additional information

Workaround
This starts Codex successfully:

env -u TMUX -u TMUX_PANE codex

Reproduce the hang by running codex in a tmux 3.4 pane on Rocky Linux 8, then compare it with env -u TMUX -u TMUX_PANE codex. Start at the startup tmux capability-detection step that runs tmux display-message -p #{extended-keys-format}; done means Codex reaches its interactive UI inside tmux without the workaround.