[BUG] iTerm2: Scroll position resets while model is generating output

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?

When using Claude Code in iTerm2, if I scroll up to review previously
generated code while the model is still producing output, the scroll
position suddenly jumps back to the top of the buffer. This forces me
to manually scroll down again repeatedly to find where I was reading.

This happens consistently whenever new text is being streamed and I
attempt to scroll through earlier output. It makes it very difficult
to review code that was generated moments ago while waiting for the
model to finish its current response.

Environment:

• Terminal: iTerm2
• OS: macOS 15.x (Sequoia)
• Claude Code: latest version

What Should Happen?

Expected behavior: Scroll position should remain stable while
reviewing previous output, even if new content is being appended
at the bottom.

Actual behavior: Scroll jumps to the top of the terminal buffer
as soon as new output is rendered, losing the current reading position.

Error Messages/Logs

Steps to Reproduce

Trying to scroll

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.81

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_