Claude in Chrome: MCP client never connects to native host bridge socket (macOS)

Description

The claude-in-chrome built-in MCP tools always report "Browser extension is not connected" despite the native messaging host running correctly and the bridge socket being created and accepting connections.

Environment

• Claude Code: v2.1.96
• macOS: 26.3.1 (Darwin 25.3.0, x86_64)
• Chrome extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn
• Chrome extension version: 1.0.66

Debugging findings

The Chrome/extension side is working correctly:

1. Native messaging host spawns successfully (~/.local/share/claude/versions/2.1.96 --chrome-native-host)
2. Bridge socket is created at /tmp/claude-mcp-browser-bridge-<user>/<pid>.sock
3. Socket accepts connections (verified with manual Python socket connect)
4. Extension sends connect message with valid OAuth token via network
5. Both native messaging manifests (com.anthropic.claude_browser_extension.json and com.anthropic.claude_code_browser_extension.json) point to Claude Code's host binary

The problem: Claude Code's own process never connects to the bridge socket. Verified via lsof -U — only the native host PID has an open connection to the socket, not the Claude Code session PID.

Steps to reproduce

1. Install Claude in Chrome extension
2. Log into claude.ai with the same account as Claude Code
3. Start Claude Code (claude)
4. Call mcp__claude-in-chrome__tabs_context_mcp
5. Always returns "Browser extension is not connected"

What was tried

• Killing stale native host processes and restarting Chrome
• Toggling extension off/on in chrome://extensions/
• Restarting Claude Code in a fresh terminal
• Closing all other Claude Code sessions
• Uninstalling and reinstalling the Chrome extension
• Updating native messaging manifest to point to Claude Code's host (per #20887 workaround)
• Verified same account on both claude.ai and Claude Code

Related issues

• #20887
• #20790
• #20411