Chrome integration: Claude Code never connects to native bridge socket (macOS)

Environment

• Claude Code: 2.1.71
• macOS: Darwin 25.3.0 (arm64, Sequoia)
• Chrome: 145.0.7632.160
• Chrome extension: Claude v1.0.59 (ID: fcoeoabgfenejglbffodgkkbkcdhcgfn)
• Started with: claude --chrome

Problem

mcp__claude-in-chrome__tabs_context_mcp always returns "Browser extension is not connected" despite the native bridge socket being fully functional.

Diagnosis

What works

1. Native Messaging Host launches correctly (Chrome → --chrome-native-host → creates Unix socket)
2. Socket exists at /tmp/claude-mcp-browser-bridge-{username}/{pid}.sock with correct permissions (dir=0700, sock=0600, uid matches)
3. Chrome extension responds to messages through the socket (verified via manual Python connection using Chrome's 4-byte LE length-prefix protocol — returns {"result":{"content":"Unknown method: ..."}} for test messages)
4. Node.js stat() confirms: isSocket: true, mode 0600, uid matches process.getuid()

What fails

• Claude Code (PID) never opens a connection to the socket — confirmed via lsof monitoring during tabs_context_mcp calls. Only the native host process appears on the socket; the Claude Code process never connects.
• This was tested across 5+ restarts of both Claude Code and Chrome, with the socket verified to exist before each Claude Code launch.
• Feature flag tengu_copper_bridge defaults to false, so the code path should use local socket via getSocketPaths → multi-socket client (kRT/ZRT). But the connection never happens.

Code analysis (minified binary)

• h88() correctly routes to kRT (multi-socket client) when bridgeConfig is undefined and getSocketPaths exists
• B77() (getSocketPaths) correctly scans /tmp/claude-mcp-browser-bridge-{username}/ for .sock files
• Socket security validation (validateSocketSecurity) should pass (permissions and ownership are correct)
• The connection class d5T uses this.context.getSocketPath?.() ?? this.context.socketPath — unclear if getSocketPath (singular) is properly wired from getSocketPaths (plural)

Steps to reproduce

1. Install Chrome extension "Claude" from Chrome Web Store
2. Verify socket exists: ls /tmp/claude-mcp-browser-bridge-$(whoami)/
3. Start claude --chrome
4. Call any mcp__claude-in-chrome__* tool
5. Always returns "Browser extension is not connected"

Expected

Claude Code should connect to the existing socket and communicate with the Chrome extension.