Scrollbar up/down arrow buttons no longer scroll output (regression) - Windows desktop

Summary: The window's scrollbar up/down arrow buttons (up/down) no longer scroll the Claude Code output. This previously worked. Mouse wheel still scrolls fine, so it is specific to the arrow buttons.

Environment:

• Claude Code 2.1.191
• Windows 11 Pro, build 10.0.26200
• Desktop app

Steps to reproduce:

1. Open the Claude Code desktop app
2. Produce enough output that the content needs scrolling
3. Click the up or down arrow button on the right-hand scrollbar

Expected: Clicking an arrow scrolls one line up/down (as it did before).

Actual: Arrows are unresponsive on the current version. On an older version the arrows are greyed out / disabled entirely. The same greyed-out behavior also appears when running the CLI in a classic Windows console (conhost), suggesting the app takes over the screen buffer so the host scrollbar has nothing to scroll.

Workaround: Mouse wheel, PageUp/PageDown, and arrow keys still scroll.