[BUG] VSCode chat window goes black during complex tasks while agent continues executing

Bug Description

The VSCode chat window goes completely black during tasks with many todo executions, making it appear as if Claude Code has crashed. However, the agent continues working in the background (todos continue executing), indicating this is a UI rendering issue rather than an actual crash.

Expected Behavior

The chat window should remain visible and display agent output, tool calls, and todo updates throughout the entire task execution, regardless of the number of operations.

Actual Behavior

During complex tasks with multiple tool calls and todo state changes:

1. The chat window suddenly goes completely black
2. No command line interface is visible
3. No output or status indicators are shown
4. The window appears completely unresponsive

However:

• The agent continues executing tasks in the background
• When the user closes the tab and resumes the conversation, the todo list shows that work continued during the "black screen" period
• This indicates the agent didn't crash - only the UI rendering failed

Steps to Reproduce

1. Start a complex task with multiple steps that requires frequent todo updates
2. Observe the chat window during execution
3. After some time with many tool calls and todo state changes, the window goes completely black
4. Close the tab and reload/resume the conversation
5. Observe that todos have continued executing despite the black screen

Screenshots

User provided screenshots showing:

1. Normal chat operation before the issue
2. Completely black chat window during the issue
3. Evidence that todos continued executing when conversation was resumed

Environment

• OS: Windows 11
• VSCode Version: 1.106.0
• Claude Code Extension Version: 2.0.37
• Platform: x64
• Node.js: 22.19.0
• Git: 2.51.0.windows.1
• Python: 3.13.7

Severity

Medium - The agent continues working, but the user cannot see progress or output, leading to uncertainty about whether work is progressing and potentially causing users to unnecessarily interrupt or restart tasks.

Likely Cause

This appears to be a VSCode webview rendering issue, possibly caused by:

• Memory/rendering overflow when processing many tool calls
• Rapid UI updates overwhelming the webview renderer
• Long-running operations with frequent todo state changes

Impact

• User uncertainty about task progress
• Users may close and restart tasks that are actually progressing normally
• Loss of visibility into agent operations
• Potential interruption of valid work in progress

Additional Context

The user reported this happens regularly during sessions with "a lot of tasks that are being executed." The workaround is to close the tab and resume the conversation, at which point the user can see that work continued during the black screen period.