[Bug] Claude in Chrome crashes when clicked in macOS split view mode (EXC_BREAKPOINT)

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?

The Claude Chrome extension causes Chrome to crash completely when clicked while Chrome is in macOS split view mode on Sequoia. This is a critical crash that makes the extension unusable for users working in split view.

Crash Details:

• Exception Type: EXC_BREAKPOINT (SIGTRAP)
• Crashed Thread: CrBrowserMain
• Crash Location: ChromeMain + 50208788
• All Chrome tabs and windows close immediately
• User loses any unsaved work

100% reproducible - happens every single time when Chrome is in macOS split view mode and the Claude extension icon is clicked.

What Should Happen?

Claude extension side panel should open without issues, Chrome should remain stable, and users can interact with Claude in the side panel normally - regardless of whether Chrome is in split view mode or not.

Error Messages/Logs

Exception Type:        EXC_BREAKPOINT (SIGTRAP)
Exception Codes:       0x0000000000000001, 0x0000000000000000
Termination Reason:    Namespace SIGNAL, Code 5 Trace/BPT trap: 5
Crashed Thread:        0  CrBrowserMain

Kernel Triage:
"VM - Waiting on busy page was interrupted" (multiple times)

This indicates the crash occurs during memory management operations related to 
window rendering, likely when the sidePanel attempts to create its view in 
split screen configuration.

Steps to Reproduce

1. Install Claude in Chrome extension from https://claude.ai/chrome
2. Open Chrome on macOS Sequoia
3. Enter macOS split view mode:

• Click the green window button on Chrome
• Select "Tile Window to Left of Screen" or "Tile Window to Right of Screen"
• Chrome is now in split view alongside another application

1. Click the Claude extension icon in the Chrome toolbar
2. Observe: Chrome crashes immediately with EXC_BREAKPOINT (SIGTRAP)

Environment:

• Extension: Claude in Chrome (latest version)
• Chrome: 143.0.7499.170 (Official Build) arm64
• macOS: 26.1 Sequoia (25B78)
• Hardware: Apple Silicon (M1/M2/M3)

Does NOT crash when:

• Chrome is in normal window mode
• Chrome is in standard full screen mode (without split view)

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

N/A - Chrome extension issue, not Claude Code CLI

Claude Code Version

N/A - This is a Claude Chrome extension issue, not a Claude Code CLI issue

Platform

Other

Operating System

macOS

Terminal/Shell

Other

Additional Information

Root Cause Analysis

After investigation, this crash is caused by the convergence of three issues:

1. Chromium Bug #355266358: The chrome.sidePanel API has a known crash bug on macOS ARM systems
2. macOS Sequoia Changes: Window management changes in Sequoia 26.1 trigger the crash condition
3. Claude Extension Architecture: The extension uses the sidePanel API, which triggers the vulnerable code path

Current Workaround

Users must:

1. Exit split view mode before clicking Claude extension
2. Use Claude extension in normal window mode
3. Re-enter split view after closing Claude side panel

Alternative: Use Claude directly on https://claude.ai in a browser tab

Proposed Short-Term Fix

Until the upstream Chromium bug is fixed, the extension could implement a workaround:

Option 1: Detect and warn about split view

chrome.action.onClicked.addListener(async () => {
  const window = await chrome.windows.getCurrent();
  if (isLikelyInSplitView(window)) {
    chrome.notifications.create({
      type: 'basic',
      title: 'Split View Detected',
      message: 'Please exit split view mode to use Claude and avoid Chrome crashes.'
    });
    return; // Don't open sidePanel
  }
  chrome.sidePanel.open({ windowId: window.id });
});

////-----------
Option 2: Fallback to popup UI in split view

const canUseSidePanel = !isInSplitView();
if (canUseSidePanel) {
  chrome.sidePanel.open();
} else {
  chrome.action.setPopup({ popup: 'popup.html' });
}

Ref:https://issues.chromium.org/issues/473120381