Scrolling during streaming output jumps to top of session

Description

When Claude is streaming output (adding lines to the chat), scrolling with the mouse wheel causes the terminal to jump to the very top of the session instead of scrolling normally.

Steps to reproduce

1. Start a conversation with some history (enough to scroll)
2. Ask Claude something that produces a long response
3. While the response is streaming, touch the scroll wheel on your mouse

Expected behavior

Terminal should scroll relative to current position (up or down depending on scroll direction).

Actual behavior

Terminal jumps to the very beginning of the session (top).

Environment

• Windows 11 Pro 10.0.26200
• Started happening after the latest Claude Code update