Claude in Chrome MCP server fails to connect to native host bridge socket

## Bug Description

The Claude in Chrome MCP server (--claude-in-chrome-mcp) fails to connect to
the native host's Unix socket, resulting in "Browser extension is not
connected" error on every tool call.

## Environment

• Claude Code: 2.1.38
• OS: macOS 15 (Darwin 24.6.0)
• Chrome: 144.0.7559.133
• Claude Chrome Extension: 1.0.47 (ID: fcoeoabgfenejglbffodgkkbkcdhcgfn)
• Node: v22.22.0

## Steps to Reproduce

1. Install Claude Chrome extension from Chrome Web Store
2. Log into claude.ai in Chrome
3. Run claude in terminal (starts with --claude-in-chrome-mcp)
4. Attempt any browser automation tool (e.g., tabs_context_mcp)

## Expected Behavior

MCP server should connect to the Chrome extension via the native host bridge
socket.

## Actual Behavior

Every browser tool call returns: "Browser extension is not connected."

## Diagnosis

Both processes start correctly:

• MCP server: 2.1.38 --claude-in-chrome-mcp (PID A)
• Native host: 2.1.38 --chrome-native-host (PID B)

The native host creates a Unix socket at
/tmp/claude-mcp-browser-bridge-<user>/<PID>.sock and listens on it. However,
the MCP server process never connects to this socket.

lsof output confirms:

• Native host has the socket open:

/tmp/claude-mcp-browser-bridge-<user>/<PID>.sock

• MCP server has zero connections to any local Unix socket in that

directory

### Additional complication

The Claude Desktop app (/Applications/Claude.app) registers a competing
native messaging host (com.anthropic.claude_browser_extension) for the same
extension ID. When both are present, Chrome preferentially launches the
Desktop app's native host instead of Claude Code's
(com.anthropic.claude_code_browser_extension). Even after removing the
Desktop app's native messaging host config, the MCP server still does not
connect to the bridge socket.

## Workarounds Attempted (all failed)

• Restarting Chrome
• Restarting Claude Code
• Toggling extension off/on
• Killing stale native host processes
• Removing Claude Desktop app's native messaging host config
• Verifying same account on claude.ai and Claude Code