[BUG] Left sidebar clips chat content on hover in macOS Desktop app

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?

In the Claude macOS Desktop app, hovering over the left sidebar causes it to expand and clip the left edge of the chat content area instead of overlaying it or properly reflowing the layout. Approximately one character is cut off from the start of each line in the main chat pane, making the content partially unreadable.The issue first appeared immediately after Claude generated an HTML landing page that was rendered in the right-hand Artifact preview panel. Before that moment in the session, the layout behaved normally. The broken state has persisted ever since, across all subsequent chats.

What Should Happen?

The sidebar should either float above the chat content or push it rightward without clipping when it expands on hover. The full chat text should remain readable at all times, regardless of whether an Artifact has been previously rendered in the session. Closing the Artifact preview panel should fully reset any layout state it introduced.

Error Messages/Logs

Steps to Reproduce

Open the Claude macOS Desktop app.
Ensure the left sidebar is in its default (collapsed / hover-expand) state.
Move the mouse cursor over the left sidebar area — no click required.
Observe the chat content pane.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.3109.0 (35cbf6) 2026-04-16T20:32:01.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

<img width="2270" height="1626" alt="Image" src="https://github.com/user-attachments/assets/2366061f-2d51-46e4-8ff4-dae23f8e337c" />