Claude in Chrome extension not connecting on Windows 10 despite correct NativeMessagingHosts configuration

Bug Description

The Claude in Chrome browser extension (v1.0.40) is installed and enabled, but Claude Code CLI cannot connect to it. The tabs_context_mcp tool consistently returns "Browser extension is not connected".

Environment

• OS: Windows 10 (MSYS_NT-10.0-19045)
• Claude Code CLI version: 2.1.23
• Chrome Extension version: 1.0.40
• Claude Desktop: NOT installed (no conflict)

What I tried

1. ✅ Extension is installed and enabled in Chrome
2. ✅ Created NativeMessagingHosts/com.anthropic.claude_browser_extension.json in Chrome User Data folder
3. ✅ Added Windows Registry entry at HKCU\Software\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_browser_extension
4. ✅ Verified ~/.claude/chrome/chrome-native-host.bat exists and points to correct claude.exe
5. ✅ Restarted Chrome multiple times
6. ✅ Opened Claude side panel in Chrome
7. ✅ Tested native host directly - it initializes correctly and creates pipe: \.\pipe\claude-mcp-browser-bridge-Usuario

NativeMessagingHosts JSON content

{
  "name": "com.anthropic.claude_browser_extension",
  "description": "Claude Code Browser Extension Native Host",
  "path": "C:\Users\Usuario\.claude\chrome\chrome-native-host.bat",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/"
  ]
}

Native host test output

[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Creating socket listener: \.\pipe\claude-mcp-browser-bridge-Usuario
Bun v1.3.5 (1e86cebd) Windows x64 (baseline)

Expected behavior

Claude Code CLI should be able to connect to the Chrome extension and control browser tabs.

Actual behavior

Every MCP tool call returns: "Browser extension is not connected. Please ensure the Claude browser extension is installed and running"

Additional context

• Chrome has 2 user profiles configured
• The extension works on its own (side panel opens, shows Haiku 4.5)
• The connection between CLI and extension never establishes