Claude in Chrome MCP: socket path mismatch between Claude Desktop and Claude Code

Bug Description

Claude in Chrome MCP fails to connect — the Chrome extension's native messaging host (from Claude Desktop) creates sockets at a different path than where Claude Code's MCP server (--claude-in-chrome-mcp) looks for them.

Environment

• Claude Code: 2.1.44 (Homebrew)
• Claude Desktop: 1.1.3363
• Chrome Extension: "Claude in Chrome (Beta)" v1.0.52
• OS: macOS Sequoia (Darwin 25.3.0, arm64)
• Chrome: 145.0.7632.75

Root Cause

The native messaging host binary (/Applications/Claude.app/Contents/Helpers/chrome-native-host) changed its Unix domain socket path between versions:

• Old path (working, Dec 2025): /var/folders/v5/.../T/claude-mcp-browser-bridge-<user> (single socket, no PID suffix)
• New path (broken, Feb 2026): /tmp/claude-mcp-browser-bridge-<user>/<PID>.sock (per-PID socket files)

Claude Code's --claude-in-chrome-mcp process appears to still look for sockets at the old /var/folders/.../T/ path and never discovers the new /tmp/ location. Result: zero MCP client connections despite the native host socket being created successfully.

Evidence from Logs

~/Library/Logs/Claude/chrome-native-host.log shows:

# Old format (Dec 2025) — clients connected successfully:
[2025-12-24 19:54:40] Creating socket listener: /var/folders/v5/.../T/claude-mcp-browser-bridge-barada
[2025-12-24 19:56:52] Accepted new MCP connection (client 1). Total clients: 1

# New format (Feb 2026) — zero clients ever connect:
[2026-02-17 21:46:23] Creating socket listener: /tmp/claude-mcp-browser-bridge-barada/82225.sock
[2026-02-17 21:46:23] Socket server listening for connections
# ... no "Accepted new MCP connection" entries follow

Process State

When the issue occurs:

1. Chrome extension is installed and enabled ✓
2. Native host spawns and creates socket at /tmp/claude-mcp-browser-bridge-<user>/<PID>.sock ✓
3. claude --claude-in-chrome-mcp is running ✓
4. MCP server has no connection to the socket (confirmed via lsof) ✗
5. Old path /var/folders/.../T/claude-mcp-browser-bridge-<user> does not exist ✗

Native Messaging Hosts

Two registered native messaging hosts:

• com.anthropic.claude_browser_extension → /Applications/Claude.app/Contents/Helpers/chrome-native-host (Claude Desktop)
• com.anthropic.claude_code_browser_extension → ~/.claude/chrome/chrome-native-host → claude --chrome-native-host (Claude Code)

Only the Desktop native host spawns. The Code native host (claude --chrome-native-host) never spawns, suggesting the extension only requests com.anthropic.claude_browser_extension.

Steps to Reproduce

1. Install Claude Code 2.1.44 via Homebrew
2. Install Claude Desktop 1.1.3363
3. Install Claude in Chrome extension v1.0.52
4. Start Claude Code CLI session (spawns --claude-in-chrome-mcp)
5. Open Chrome with the extension enabled
6. Call any mcp__claude-in-chrome__* tool → "Browser extension is not connected"

Expected Behavior

The --claude-in-chrome-mcp process should discover and connect to the socket created by the native host, regardless of whether it's at /var/folders/.../T/ or /tmp/.