Drag & Drop: Drop indicator desynchronizes from cursor position when scrolling during drag

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?

When dragging a session item in the sidebar list to reorder it, scrolling
with the mouse wheel during the drag causes the drop zone indicator to
become desynchronized from the actual cursor position.

The drop indicator stays at its last calculated position before the scroll
event, while the cursor and visible list content move independently.
See screenshot: green arrow shows cursor position, red arrow shows where
the drop zone appears — displaced from the cursor.

What Should Happen?

The drop zone indicator should follow the cursor position continuously,
even after the list is scrolled during the drag. The indicator should
update dynamically relative to the current viewport position.

Error Messages/Logs

No error messages. Visual-only desync between cursor and drop indicator.

Steps to Reproduce

1. Open Claude Desktop App with a project that has enough sessions to require scrolling
2. Start dragging a session item (hold left mouse button)
3. While holding, scroll the list using the mouse wheel (up or down)
4. Observe: drop zone indicator (red arrow) stays at pre-scroll position

while cursor (green arrow) has moved to a different list position

App: Claude Desktop 1.7196.0 (2dbd78) – Build 2026-05-12
OS: Windows 11 Pro, Version 25H2 (Build 26200.8457)

Claude Model

Other

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.7196.0 (2dbd78) 2026-05-12T05:34:40.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

This bug affects the Claude Desktop App (not the CLI/terminal).
The session list sidebar is a GUI element within the desktop application.
Screenshot attached showing cursor position vs. drop indicator position mismatch.

Additionally, the drop indicator itself appears visually imprecise even
without scrolling: no clear insertion line is shown between items to
indicate the exact drop position. The indicator does not cleanly snap
between two list entries, making it ambiguous whether the item will land
above or below the target.

<img width="556" height="990" alt="Image" src="https://github.com/user-attachments/assets/7fe4231f-7ef8-4058-8d04-fcc261e66b96" />