Browser extension is not connected despite correct configuration (macOS, v2.1.41)

Browser extension is not connected despite correct configuration

Environment

• OS: macOS (Darwin 25.3.0)
• Claude Code version: 2.1.41
• Chrome version: 144.0.7559.133 (Official Build) (arm64)
• Extension version: 1.0.49

Problem

claude-in-chrome MCP tools consistently return "Browser extension is not connected" error despite all configuration being correct.

Key Finding

Native Messaging connection works when tested manually, but Claude Code does not attempt to connect to the extension.

Evidence

1. Manual connection test in Service Worker console succeeds:

const port = chrome.runtime.connectNative('com.anthropic.claude_browser_extension');
port.postMessage({test: 'hello'});
// Result: Message received: {type: 'error', error: 'Unknown message type: undefined'}

1. Native Messaging Host process is running:

ps aux | grep chrome-native-host
# Result: /opt/homebrew/Caskroom/claude-code/2.1.41/claude --chrome-native-host (PID 35056)

1. Service Worker console shows nothing when Claude Code attempts connection

• This indicates Claude Code is not sending messages to the extension

Configuration Files

Native Messaging Host

~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json:

{
  "name": "com.anthropic.claude_browser_extension",
  "description": "Claude Browser Extension Native Host",
  "path": "/Users/m/.claude/chrome/chrome-native-host",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://dihbgbndebgnbjfmelmegjepbnkhlgni/",
    "chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/",
    "chrome-extension://dngcpimnedloihjnnfngkgjoidhnaolf/"
  ]
}

Extension ID

Verified: fcoeoabgfenejglbffodgkkbkcdhcgfn (matches configuration)

MCP Settings

~/.claude/settings.json: "mcpServers": {}
~/.claude.json: Contains chrome-devtools but not claude-in-chrome

Troubleshooting Attempted

✅ Chrome restarted multiple times
✅ Claude Code restarted multiple times
✅ Extension reinstalled
✅ Logged into claude.ai with correct account
✅ Native Messaging Host configuration created
✅ Configuration applied to all Chrome browsers (Chrome, Dev, Beta, Canary)
✅ Claude Code reinstalled
✅ Tested in new session
✅ Verified extension permissions include nativeMessaging

Timeline

• Working until ~2026-02-11
• Stopped working suddenly
• Recent changes: Disabled several plugins and MCP servers

Question

Is there a required MCP server configuration for claude-in-chrome that's not documented? Or is this a bug where Claude Code fails to initiate the connection?

Related Issues

• #20887 - Extension connects to Claude Desktop instead of Claude Code
• #21371 - Extension not connecting despite correct setup
• #24593 - Browser extension persistently fails to connect

Additional Context

The fact that manual Native Messaging connection works proves:

1. Chrome extension is properly installed
2. Native Messaging Host is running and accessible
3. Configuration files are correct
4. The issue is specifically with Claude Code not attempting the connection

Full troubleshooting log: [attached in next comment]