claude-in-chrome: Browser extension not connected despite native host running (macOS 26.4, Claude Code 2.1.86)

Description

mcp__claude-in-chrome__tabs_context_mcp always returns "Browser extension is not connected" despite the Chrome extension being installed, configured correctly, and the native messaging host running.

Environment

• Claude Code: 2.1.86
• Node: v24.2.0
• OS: macOS 26.4 (Darwin 25.4.0), Apple Silicon
• Chrome Extension: "Claude" by Anthropic, v1.0.64
• Extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn

What works

• Native messaging host binary exists at ~/.claude/chrome/chrome-native-host
• Native host config at ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json — allowed_origins matches the extension ID
• Native host process starts and creates a Unix socket at /tmp/claude-mcp-browser-bridge-<user>/<PID>.sock
• Socket accepts connections (tested with Python socket.connect())
• Extension permissions: all sites, pinned, incognito, file URLs — all enabled

What doesn't work

• tabs_context_mcp returns "Browser extension is not connected"
• Socket accepts connections but returns no response to messages
• Toggling extension OFF/ON in chrome://extensions regenerates the socket (new PID) but doesn't fix the issue
• Full Chrome restart (Cmd+Q + reopen) doesn't fix it

Steps to reproduce

1. Install Claude Chrome extension v1.0.64
2. Verify native host config matches extension ID
3. Start Claude Code CLI session
4. Call mcp__claude-in-chrome__tabs_context_mcp
5. Get "Browser extension is not connected"

Diagnostic

Native Host Config:
{
  "name": "com.anthropic.claude_code_browser_extension",
  "path": "/Users/<user>/.claude/chrome/chrome-native-host",
  "type": "stdio",
  "allowed_origins": ["chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/"]
}

Socket: /tmp/claude-mcp-browser-bridge-<user>/<PID>.sock (exists, connectable)
Native host PID: running

Expected behavior

tabs_context_mcp should return tab information from the connected Chrome browser.