[BUG] SCROLL INTO-TOP ALWAYS ON CLAUDE-CODE CLI

[brasil-pi]

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?

I do want to read live-preview of claude code answer-typing at linux-ubuntu, it keeps the terminal on top, i scroll bottom, it pushies to top. lol.

What Should Happen?

Terminal should always be on bottom (so i can read preview content as it is doing).

Error Messages/Logs

Steps to Reproduce

1- Open claude code.
2- Type wherever thing.
3- Scroll goes then to top instead of keeping at bottom.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

No response

Claude Code Version

Version: 2.1.74

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

No response

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Forces scroll to top when outputting code (NOT just when scrolling) #33814
2. [BUG] Console scrolling top of history when claude add text to the console #826
3. [Bug] Scroll position jumps when Claude streams output during upward scrolling #33367

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🤖 Generated with Claude Code

[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.

[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.

[cruzlauroiii]

Updated PR #34798 with 3 combined patches: (1) stateful stdout.write interceptor clamping cursor-up, (2) render throttle 16ms→200ms, (3) disable synchronized update mode. All three are needed — cursor-up clamping alone does not fix it because Windows Terminal exits scroll mode on ANY stdout write, and sync blocks batch writes into one viewport-resetting update. PowerShell apply/revert script included.

[cruzlauroiii]

v3 update: Previous fixes (cursor-up clamping, disabling sync update) did not work and caused flickering.

Root cause identified: Windows Terminal bug microsoft/terminal#14774 — SetConsoleCursorPosition always scrolls viewport to cursor, even when visible. Every Ink re-render triggers this. Cannot be fixed from within the process.

v3 patch: render throttle SK6=16 → SK6=1000 (1fps). Gives 1 second of uninterrupted reading between viewport resets. Trade-off: streaming text in ~1s chunks. No flickering.

PR #34798 updated. Real fix needs Microsoft (terminal#14774) or Anthropic (PTY proxy/append-only rendering).

[cruzlauroiii]

v5 update: Fundamentally different approach — buffer ALL Ink renders during active work, screen stays frozen (no viewport jumping). Flush only when (a) user types (at prompt/bottom, safe to update) or (b) 5s of no renders (Claude finished). Previous v1-v4 failed because WT bug microsoft/terminal#14774 triggers viewport scroll on ANY cursor positioning. v5 avoids this by not writing to stdout at all during active work. Trade-off: no spinner/progress visible during work. PR #34798 updated.

[cruzlauroiii]

v6: Buffer ALL renders, flush ONLY on user input (stdin). No timer. No auto-flush. Zero viewport jumping while not at bottom. Root cause: WT bug microsoft/terminal#14774. PR #34798.

[cruzlauroiii]

v7: Replay ALL buffered frames on flush (fixes v6 outdated screens). Keeps entire diff chain so screen content is always correct. Still zero viewport jumping — flush only on user input (stdin). PR #34798.

[cruzlauroiii]

Final fix: Ctrl+6 freeze toggle. Press Ctrl+6 to freeze screen (buffer renders, scroll freely). Press again to unfreeze (replay + live output). Tab title shows [FROZEN]. Root cause is WT bug microsoft/terminal#14774 — cannot be detected/fixed automatically. PR #34798.