[BUG] Terminal scrolling wildly while Claude Code is executing

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

While I type a response the terminal is stable and usable, but while Claude is responding it very often jumps around and scrolls wildly. I'm really not sure what is going on so I have attached a screen recording of the terminal. I think it is must be rapidly updating the transcript history and spuriously updating which line in the history is supposed to be in the visible part of the viewport. To get it to settle down I have to catch the draggable handle of the scrollbar (see how it jumps around and changes length in the animated gif/video) and drag it all the way down and then start typing something. Of course I can just press Esc or ctrl-c, but those terminate the running command. Often I just wait for it to complete, but that's bad because I can't follow along with what it is doing at all so it becomes wasted time.

!Image

https://github.com/user-attachments/assets/903517a1-cba6-463c-a975-e86b484b4f61

What Should Happen?

Normal progressive addition of a few lines at a time to the transcript in a legible manner, with the input prompt remaining visible and able to be type into.

Error Messages/Logs

Steps to Reproduce

I really don't know, other than the fact that it happens a lot on my larger project.

Note: I submitted a detailed feedback report via the /feedback command
in Claude Code on [date/time] from this account, @aholland . I log into Claude using GitHub.
That report includes full error logs and diagnostic information if needed.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.x I think

Claude Code Version

2.0.9 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

IntelliJ IDEA terminal

Additional Information

Note that I use the Fish shell. See the "What's Wrong?" section for the video / gif (I've provided it in two formats).