Scroll position resets to top of session while processing

Description

During active processing (while Claude is generating a response), the terminal scroll position resets to the top of the session. This forces the user to scroll back down to see the current output, disrupting the workflow.

Steps to Reproduce

1. Start a Claude Code session
2. Have a conversation with enough content that the session is scrollable
3. Scroll up to review earlier context while Claude is processing a response
4. Observe: scroll position jumps back to the top of the session

Expected Behavior

Scroll position should remain stable while Claude is processing. If auto-scroll is intended, it should scroll to the bottom (current output), not the top.

Actual Behavior

Scroll position resets to the top of the session during processing.

Environment

• Claude Code version: 2.1.76
• Terminal: iTerm2 3.6.6
• OS: macOS 26.0.1 (Tahoe, build 25A362)
• Shell: zsh
• Platform: darwin (Apple Silicon)