CLI: Scroll position jumps to top during long conversations

Description

During long CLI conversations, the scroll position unexpectedly jumps to the top of the conversation. This happens frequently and disrupts the workflow.

Reproduction

1. Start a Claude Code CLI session
2. Have a moderately long conversation (multiple exchanges with tool usage)
3. Scroll up to review earlier content — scroll jumps to the top unexpectedly

Triggers

• Mouse wheel scrolling — jumps to top
• Dragging the scrollbar — jumps to top
• During output generation — viewport jumps to top while Claude is streaming a response

Frequency

Happens frequently once the conversation becomes long enough.

Environment

• Claude Code version: 2.1.92
• OS: Windows 11 Home China (10.0.26200)
• Shell: Git Bash (MSYS2)
• Terminal: Windows Terminal (default)