CLI --chrome flag does not connect to native host socket

Bug Description

When running claude --chrome, the CLI correctly enables the mcp__claude-in-chrome__* tools, but never connects to the native host Unix socket. All MCP tool calls return "Browser extension is not connected."

Environment

• Claude Code: 2.1.81
• Chrome extension: Claude v1.0.63 (ID: fcoeoabgfenejglbffodgkkbkcdhcgfn)
• macOS 25.3.0 (Apple Silicon)
• Chrome: 146.0.7680.81

Steps to Reproduce

1. Install Claude Chrome extension, log in
2. Open Chrome side panel (Claude icon)
3. Run claude --chrome in terminal
4. Call any mcp__claude-in-chrome__* tool (e.g., tabs_context_mcp)

Expected: Tool returns tab information
Actual: "Browser extension is not connected"

Diagnosis

Through extensive testing, we confirmed:

1. Chrome extension <-> Native host: WORKS

• chrome.runtime.connectNative("com.anthropic.claude_code_browser_extension") succeeds
• Ping/pong handshake works
• get_status returns {"type":"status_response","native_host_version":"1.0.0"}

1. Native host socket: EXISTS and WORKS

• Socket created at /tmp/claude-mcp-browser-bridge-{user}/{pid}.sock
• Uses Chrome native messaging protocol (4-byte LE length prefix + JSON)
• Manually sending {"method":"execute_tool","params":{"tool":"tabs_context_mcp","args":{"createIfEmpty":true}}} returns correct tab data

1. CLI <-> Socket: NEVER CONNECTS

• lsof -p {cli_pid} shows no connection to the bridge socket
• The CLI process has --chrome flag confirmed via ps aux
• Socket is accessible (manual Python connection works)

Workaround

Direct socket communication via Python script works perfectly. We wrote a bridge script that connects to the native host socket and executes tools:

sock.connect('/tmp/claude-mcp-browser-bridge-{user}/{pid}.sock')
send_msg(sock, {"method": "execute_tool", "params": {"tool": "tabs_context_mcp", "args": {}}})
# Returns correct response

Additional Context

• Also encountered native messaging host config file conflict: com.anthropic.claude_browser_extension.json (Desktop) vs com.anthropic.claude_code_browser_extension.json (CLI). Both files existed, and Chrome's extension tries Desktop first by alphabetical order. This was resolved by pointing both files to the CLI native host path.

• The extension's service worker code in service-worker.ts-Cx-yMGFD.js shows it tries both native host names in order: Desktop first, then Claude Code.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>