Codex client output truncated when scrolling in Zellij

[ForSeason]

What version of Codex is running?

codex-cli 0.23.0

Which model were you using?

gpt5

What platform is your computer?

Darwin 24.6.0 arm64 arm

What steps can reproduce the bug?

When running the Codex client inside a Zellij session, the output history does not display correctly. Attempting to scroll within the Zellij pane shows truncated content instead of the full history. This makes it difficult to review previously generated output.

Steps to reproduce it:

cargo install zellij
zellij
codex

Then try scrolling back using Zellij’s scroll mode.

What is the expected behavior?

Scrolling in Zellij should display the full history of Codex output without truncation.

What do you see instead?

Scrolling only shows partial output — earlier content is cut off.

Additional information

No response

[alexff8505]

I get the same issue in multiple Mac based Terminals, inc the default. "Unlimited Scrollback" options can solve the issue if your software has it.

[brunopeartree]

Hi, I am experiencing the same issue. Currently this prevents me from switching from claude code.

[Artawower]

Same here, this behavior only started showing up very recently

[warrenchortle]

Also seeing this on linux

[luccahuguet]

have this as well, does not seem to be a problem with zellij. since claude code has no such issue

[luccahuguet]

i've got some feedback from zellij's author that might be helpful

with the strong disclaimer that I have not tried to reproduce this myself and this is just an educated guess - this happens because the application is relying on the scrollbuffer in "Alternate Screen" (eg. with control code 1049), which the specification mentions should not exist (source: https://invisible-island.net/xterm/ctlseqs/ctlseqs.html under "Alternate Screen Buffer").

I have tried in the past to be lenient with this behavior, because this is a common issue with some apps (can't blame them, not everyone spends time reading xterm specs), but allowing scrollbuffer in these cases causes a lot of other problems in apps that do follow the spec. Feel free to quote me on this.

[yogurt80]

I have the same issue.

[luccahuguet]

guys. in the new version you can just use ctrl t to view the history. easy peasy way to circumvent this issue while it's not fixed

[wkrettek]

i've got some feedback from zellij's author that might be helpful

with the strong disclaimer that I have not tried to reproduce this myself and this is just an educated guess - this happens because the application is relying on the scrollbuffer in "Alternate Screen" (eg. with control code 1049), which the specification mentions should not exist (source: invisible-island.net/xterm/ctlseqs/ctlseqs.html under "Alternate Screen Buffer").

I have tried in the past to be lenient with this behavior, because this is a common issue with some apps (can't blame them, not everyone spends time reading xterm specs), but allowing scrollbuffer in these cases causes a lot of other problems in apps that do follow the spec. Feel free to quote me on this.

Do you have a link to that message? I'm curious what mode he recommends to use instead.

[luccahuguet]

The message was is zellij's discord

We'd be happy to have you there @wkrettek

you can find it here

https://zellij.dev/

you can ping me there, and then i just show you the message or you can ask the author yourself too

[albertojanza]

Same issue with tmux and zellij in Ubuntu 24.04 (omakub)

[WeZZard]

Same issue with Zellij on macOS.