Claude in Chrome: Extension installed and native host running but MCP bridge never connects

Description

The "Claude in Chrome" browser extension is installed and enabled, native host processes spawn correctly, Unix sockets are created, but the MCP bridge consistently reports "Browser extension is not connected."

Environment

• OS: macOS (Darwin 25.3.0)
• Claude Code version: 2.1.56
• Chrome extension version: 1.0.56
• Extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn
• Chrome: Multiple profiles (Default, Profile 2) — extension present in both

What's working

• Native messaging host is properly registered at ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
• Native host wrapper at ~/.claude/chrome/chrome-native-host executes correctly and creates sockets
• Chrome spawns native host processes (confirmed via ps aux)
• Unix sockets created at /tmp/claude-mcp-browser-bridge-<user>/*.sock
• Running the native host manually shows it initializes and creates socket listeners
• Logged into claude.ai in Chrome with the same account

What's not working

• mcp__claude-in-chrome__tabs_context_mcp always returns "Browser extension is not connected"
• Connecting to the sockets directly shows they accept connections but return empty responses — suggesting the extension isn't relaying messages through the native messaging channel
• Chrome Secure Preferences shows state=None for the extension in both profiles even after enabling via chrome://extensions/

Steps to reproduce

1. Install Claude in Chrome extension
2. Enable it in chrome://extensions/
3. Log into claude.ai in Chrome
4. Run mcp__claude-in-chrome__tabs_context_mcp from Claude Code
5. Get "Browser extension is not connected" error

Debugging steps attempted

• Verified native messaging host config and binary
• Confirmed Chrome is running and extension files exist
• Restarted Chrome completely (quit + reopen)
• Opened claude.ai and logged in
• Checked socket directory — sockets exist and accept connections
• Tested direct socket connectivity — accepts connections but empty responses
• Verified extension present in both Chrome profiles
• Confirmed Claude Code version (2.1.56) matches extension version (1.0.56)

Expected behavior

tabs_context_mcp should return tab information and allow browser automation.