In conversations with dozens of turns, codex starts to reply to a message but 'forgets' it after the first split

What version of Codex CLI is running?

codex-cli 0.120.0

What subscription do you have?

Pro

Which model were you using?

gpt-5.4

What platform is your computer?

Linux 6.17.0-14-generic x86_64 x86_64

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

Gnome Terminal

What issue are you seeing?

In long conversations (this bug always appears when a conversation is sufficiently long in terms of the number of turns, definitely more than 10), sometimes codex starts replying (analyzing, implementing, etc.) in reply to the latest prompt, but after the first "split" (horizontal line, I don't know the proper term for it in codex parlance) it 'forgets' about my latest message and its first-split work and clearly continues to reply to my previous (penultimate) message.

What steps can reproduce the bug?

Seems to be reproducible quite consistently. At least half of long (dozens of turns) conversations. (Maybe even all of them, but I didn't keep the exact tally.)

What is the expected behavior?

_No response_

Additional information

This issue has been present for a while, over many versions of codex. I think at least since gpt-5.3-codex (early Feb). I didn't report it because I thought this is an 'obvious' bug that should be reported by someone else, but found it surprising it's still not fixed.