Terminal scroll position resets to top on TUI re-render

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 there is a lot of output in a Claude Code session, scrolling up with the mouse to read previous content gets interrupted. The viewport jumps back to the top/bottom whenever Claude Code re-renders its display (status bar updates, new output, etc.).

This makes it very difficult to read longer outputs mid-session. The only workaround is using Shift+Up/Down or Page Up/Page Down, but mouse scrolling is the natural/expected behavior for most users.

My Environment: Linux (Ubuntu), running Claude Code directly in terminal (no tmux).

What Should Happen?

Scroll position should be preserved during TUI re-renders, or at minimum, the viewport should not jump when the user is actively scrolled up reviewing content.

Error Messages/Logs

Steps to Reproduce

1. Start a Claude Code session in terminal (no tmux)
2. Have a conversation that generates enough output to fill several screens (e.g., ask Claude to explain a large file or generate a long code block)
3. Using the mouse wheel or trackpad, scroll up to read earlier output
4. Wait a few seconds — or trigger any new output/interaction
5. Observe: the viewport snaps away from where you were reading, jumping to the top of the scrollback buffer

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

v2.1.77

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Cursor

Additional Information

_No response_