Claude in Chrome: Browser extension not connected on Windows despite correct setup

Bug Description

tabs_context_mcp always returns "Browser extension is not connected" on Windows, despite all setup steps being completed correctly.

Environment

• OS: Windows 11
• Claude Code version: 2.1.33
• Chrome extension: Claude in Chrome (Beta) v1.0.45
• Claude Desktop: installed

Setup Confirmed

• Chrome extension installed and enabled
• Logged into claude.ai with the same account as Claude Code
• /mcp command returns "Reconnected to claude-in-chrome" successfully
• claudeInChromeDefaultEnabled: true in settings
• hasCompletedClaudeInChromeOnboarding: true in settings
• cachedChromeExtensionInstalled: true in settings

Native Messaging Host

The native messaging host JSON file points to Claude Desktop's executable (chrome-native-host.exe). Registry key exists at HKCU\Software\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_browser_extension.

What Was Tried

1. Disabling Native Messaging Host file (renamed to .disabled) + Chrome restart
2. Removing registry key + Chrome restart
3. Restoring both file and registry key + Chrome restart
4. Uninstalling and reinstalling the Chrome extension
5. Running with Claude Desktop open (Claude in Chrome enabled/disabled in Desktop)
6. Running without Claude Desktop
7. Multiple Chrome full restarts
8. Refreshing claude.ai tab
9. Calling tabs_context_mcp with createIfEmpty: true

None of the above resolved the issue.

Expected Behavior

tabs_context_mcp should detect and connect to the Chrome extension.

Actual Behavior

Every call returns:

Browser extension is not connected. Please ensure the Claude browser extension is installed and running...

The MCP server reconnects successfully via /mcp, but every tool call returns the above error.