animations and bell-notifications are not working through tmux

Resolved 💬 9 comments Opened Apr 5, 2026 by faucct Closed Apr 5, 2026

💡 Likely answer: A maintainer (etraut-openai, contributor) responded on this thread — see the highlighted reply below.

What version of Codex CLI is running?

codex-cli 0.118.0

What subscription do you have?

enterprise

Which model were you using?

gpt-5.4

What platform is your computer?

Darwin 25.2.0 arm64 arm; Linux 6.11.0-1016-nvidia x86_64 x86_64

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

Terminal.app

What issue are you seeing?

The animations for thinking and bell-notifications work while running directly in terminal, but stop working when running through tmux. It reproduces both on Mac and when SSHing to a Linux VM.

What steps can reproduce the bug?

Try running in interactive codex something simple, like say hi and switching to another tab of Terminal.app. When not using tmux you can see the animation in the header and a bell notification when done. When using tmux, these disappear.

What is the expected behavior?

_No response_

Additional information

_No response_

View original on GitHub ↗

9 Comments

etraut-openai contributor · 3 months ago

This is probably a limitation of tmux, not something that we can work around in codex. We can investigate to confirm. These features require a terminal emulator to support certain escape sequences. Tmux may not.

faucct · 3 months ago

Plain bell notification works just fine in tmux: sleep 5; echo $'\a'.

etraut-openai contributor · 3 months ago

By default, codex attempts to notify using an osc9 escape sequence if it thinks that the terminal emulator supports it. This detection is imperfect. You can override this auto-detection by explicitly setting tui.notification_method = "bel" in your config file. See this documentation for details.

faucct · 3 months ago

I have tried configuring it, but didn't see any improvements:

#~/.codex/config.toml
[tui]
notification_method = "bel"

faucct · 3 months ago

The ChatGPT has managed to help me. Putting this in ~/.tmux.conf has fixed both spinners and bell notifications:

set -g focus-events on
set -g set-titles on
set -g set-titles-string '#{pane_title}'
set -g allow-passthrough on

faucct · 3 months ago

Feel free to reopen it if you plan to investigate why the BEL notifications weren't working without reconfiguring tmux.

vt-alt · 2 months ago

It seems the same problem is occurred in v0.125.0 with screen there is bell sound every second while title is spinning. I am not against spinning but the frequent sound is very annoying.

TERM value is xterm-256color

etraut-openai contributor · 2 months ago

@vt-alt, the BEL is probably a notification that you've enabled in your config file. You can disable it if you'd like. Look for the notifications under the [tui] section in your config.

vt-alt · 2 months ago

@etraut-openai Maybe you can be more conservative in auto detecting terminal capabilities and sending OSC 0, only when it's certain the terminal supports it. Or terminate the sequence with ST instead of BEL; this way there at least will be no sound if something goes wrong. I think tmux / screen are quite popular especially for agentic workflows.