[BUG] Forces scroll to top when outputting code (NOT just when scrolling)

[loekj]

Preflight Checklist

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

What's Wrong?

Whenever I'm trying to read what Claude's doing, so I have my scroll position somewhere not at bottom or top; and then Claude forces my scroll position to top (it jumps) out of nowhere, whenever it's outputting code.
This was a bug in old versions, and somehow it's back. Massive annoying regression.
CC version 2.1.74
MacOS Tahoe 26.4
MacBook Pro M4 Pro
iTerm2 3.6.8

PS:
All the other bug reports indicate WHEN SCROLLING UP, but I'm just trying to read in place.

What Should Happen?

It should just let me read.

Error Messages/Logs

Steps to Reproduce

1. Just have it output lots of code.
2. Go somewhere in the terminal for reading
3. See it jump
4. Throw your cat out of the window

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unsure, but 2.1.69 maybe?

Claude Code Version

2.1.74

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

I have a .mov screen recording, but can't seem to upload here 🤷

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Console scrolling top of history when claude add text to the console #826
2. [Bug] Scroll position jumps when Claude streams output during upward scrolling #33367
3. Terminal scrollback jumps/flickers when output is being generated #33719

This issue will be automatically closed as a duplicate in 3 days.

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🤖 Generated with Claude Code

[loekj]

PLEASE fix this ASAP. I can't read anything Claude does whenever it's still running. So annoying, I've defenestrated multiple cats already.

[VoxCore84]

We hit this too and collected working workarounds into a repo: claude-code-scroll-fix

Quick fix (Windows Terminal): Add "snapOnOutput": false to your profiles.defaults in settings.json. Reduces jumping ~60-70%.

Complete fix: Run Claude inside tmux — it completely decouples your scroll position from Claude's cursor repositioning. The repo has a one-click installer that sets up WSL + tmux + a Windows Terminal profile.

Root cause: Claude Code uses CSI escape sequences to rewrite the thinking spinner in-place, and terminals follow the cursor position back up. snapOnOutput only fixes output-triggered scrolling, not cursor repositioning — tmux fixes both.

[loekj]

We hit this too and collected working workarounds into a repo: claude-code-scroll-fix

Quick fix (Windows Terminal): Add "snapOnOutput": false to your profiles.defaults in settings.json. Reduces jumping ~60-70%.

Complete fix: Run Claude inside tmux — it completely decouples your scroll position from Claude's cursor repositioning. The repo has a one-click installer that sets up WSL + tmux + a Windows Terminal profile.

Root cause: Claude Code uses CSI escape sequences to rewrite the thinking spinner in-place, and terminals follow the cursor position back up. snapOnOutput only fixes output-triggered scrolling, not cursor repositioning — tmux fixes both.

Meh. Thanks, but Anthropic just has to fix this...

[cruzlauroiii]

Root cause traced in cli.js v2.1.76 source: Ink's rendering uses \ on every re-render. When output is large, the cursor moves far up in the buffer and Windows Terminal (and iTerm) follows the cursor, snapping the viewport to the top. Full analysis in #34794.

[cruzlauroiii]

Updated PR #34798 with v2 fix: stateful stdout.write interceptor that clamps cursor-up across ALL writes (not just sync blocks). Catches Ink renderer, prompt renderer, and all other cursor-up sources. Patch + PowerShell script included.