[BUG] Long sent messages are anchored to top of panel, consuming most of the viewport

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?

After sending a long prompt in the VSCode extension, the sent message is pinned/fixed to the top of the visible panel area. When the message is long, it occupies most of the panel height, making the conversation difficult to follow. This appears to be a regression introduced by a recent scroll-anchoring change (related to #36125).

<img width="330" height="500" alt="Image" src="https://github.com/user-attachments/assets/ffa88933-2bda-4b93-9ec1-4c586395ee0c" />

What Should Happen?

After sending, the view should scroll normally — the sent message should not be so big they block the rest of the panel.

Error Messages/Logs

Steps to Reproduce

1. Open the Claude Code panel in VSCode
2. Type or paste a long multi-line prompt
3. Hit send
4. Observe the sent message is anchored to the top of the panel, covering most of the visible area

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

The VSCode extension is 2.1.89

Platform

Other

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

VS Code on Window 11, using WSL Ubuntu-24.04
VS Code Info:
Version: 1.113.0 (user setup)
Commit: cfbea10c5ffb233ea9177d34726e6056e89913dc
Date: 2026-03-24T15:07:18+01:00
Electron: 39.8.3
ElectronBuildId: 13620978
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.26100