Chrome extension not connecting to Claude Code despite correct setup

Description

The Chrome browser automation tools (mcp__claude-in-chrome__*) return "Browser extension is not connected" despite all components being correctly configured.

Environment

• Claude Code: 2.1.71 (Homebrew cask, /opt/homebrew/Caskroom/claude-code/2.1.71/claude)
• macOS: 26.3 (Build 25D125), arm64
• Chrome extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn

What's confirmed working

• Native host process is running: /opt/homebrew/Caskroom/claude-code/2.1.71/claude --chrome-native-host (PID visible in ps aux)
• Native messaging manifest is in place at ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json, pointing to ~/.claude/chrome/chrome-native-host
• Claude Desktop manifest (com.anthropic.claude_browser_extension.json) is disabled (renamed to .disabled) to avoid the first-wins conflict
• Chrome extension is installed and enabled
• Chrome has been restarted after manifest changes
• CLI session was restarted after toggling

What's failing

Calling tabs_context_mcp returns: "Browser extension is not connected."

Additional context

This has reproduced across multiple sessions. The coexistence issue between Claude Desktop and Claude Code native messaging hosts (extension uses first-wins loop) was previously worked around with toggle scripts, but the connection still fails intermittently even when correctly toggled to Code.