Clicking the editor↔chat divider resizes the left Explorer when Agent chat is in editor-tab mode

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

With Agent chat opened in editor tab mode (chat as an editor tab/group next to the code editor), clicking the vertical boundary between the editor area and the Agent chat unexpectedly widens the left Explorer / primary sidebar, instead of only adjusting the editor↔chat split.

This only happens when chat is in editor-tab mode, not when chats are in legacy stacked mode.

Steps to Reproduce

  1. Open Agent chat in editor tab mode (chat as an editor tab/group next to the code editor).
  2. Keep the Explorer visible on the left (primary sidebar).
  3. Manually shrink the left Explorer to a narrow width.
  4. Click the vertical boundary between the editor area and the Agent chat, do not intentionally drag the sidebar edge.
  5. Observe the left Explorer jump to a larger width.

Expected Behavior

Clicking the editor↔chat boundary should only resize the editor↔chat split. It should not change the Explorer / primary sidebar width.

Operating System

MacOS

Version Information

Version: 3.15.6
VS Code Extension API: 1.128.0
Commit: a1f686545fd0ce8917bbd2449f733551a9bce420
Date: 2026-08-06T01:41:03.876Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.291
OS: Darwin arm64 25.6.0

For AI issues: which model did you use?

Any

Does this stop you from using Cursor

No - Cursor works, but with this issue

Hey, thanks for the detailed report and steps. We can reproduce this and we’re tracking it.

One quick clarification. From your description, it sounds like the Explorer width resets only when you double-click, or do two quick clicks, on the editor to chat divider. That triggers a sash reset that redistributes width across all panels in the row, including Explorer. A single click without dragging shouldn’t do that.

Can you confirm if it happens from a single click, or only from a double-click or two quick clicks? If you can record a short screencast, that’d be ideal.

For now, the workaround is to avoid the reset on that divider and drag it manually instead, or temporarily switch chat back to legacy stacked mode where this doesn’t happen.

I’ll reply here when there’s an update.


Hi Dean,

I confirm that it happens only when double click on the sash/boundary. Single click won’t trigger the width reset. Please see attached screen recording for a demo of the behavior.

Thank you and the team for looking into this.

Thanks for confirming and recording the video, that’s exactly what we needed to verify. I can see the screencast preview showing a double-click on the divider.

So it’s clear what’s happening: a double-click on the editor chat boundary in editor-tab mode triggers a split reset, which redistributes width across all panels in that row, including Explorer. As you noticed, a single click doesn’t do this. We’re tracking it.

For now, as a workaround: don’t use reset on that divider, drag it manually instead, or temporarily switch chat back to legacy stacked mode, where this doesn’t happen.

I can’t share a timeline yet, but I’ll post an update here when I have one.