Claude Desktop and Claude Code native messaging hosts conflict, breaking Chrome extension

Bug Description

Claude Desktop and Claude Code both register Chrome native messaging hosts that claim the same extension ID, causing a conflict where only one can work at a time. After a Claude Desktop update, the Chrome extension stops working with Claude Code entirely.

Environment

• OS: macOS (Darwin 25.3.0)
• Claude Code Version: 2.1.19
• Chrome Version: 144.0.7559.98
• Claude Desktop: Installed (updated Jan 27, 2025)

Steps to Reproduce

1. Have both Claude Code and Claude Desktop installed
2. Claude Desktop updates and writes to ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
3. Try to use Chrome extension with Claude Code
4. Connection fails with: "Browser extension is not connected"

Root Cause

Two native messaging host files exist:

Claude Desktop (com.anthropic.claude_browser_extension.json - updated Jan 27):

{
  "name": "com.anthropic.claude_browser_extension",
  "description": "Claude Browser Extension Native Host",
  "path": "/Applications/Claude.app/Contents/Helpers/chrome-native-host",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://dihbgbndebgnbjfmelmegjepbnkhlgni/",
    "chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/",
    "chrome-extension://dngcpimnedloihjnnfngkgjoidhnaolf/"
  ]
}

Claude Code (com.anthropic.claude_code_browser_extension.json - Dec 19):

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

Both claim extension ID fcoeoabgfenejglbffodgkkbkcdhcgfn. Chrome routes to Claude Desktop's native host, which doesn't communicate with Claude Code.

Workaround

Rename or delete the Claude Desktop native host file:

mv ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json.backup

Then restart Chrome.

Expected Behavior

• Claude Code and Claude Desktop should be able to coexist without conflicts
• Either use different extension IDs, or have a proper conflict resolution mechanism
• Updates to one product should not break the other

Impact

• Users with both products installed cannot use Chrome extension with Claude Code
• No error messaging indicates the actual problem
• Standard troubleshooting (restart, reinstall extension) does not help
• Requires manual investigation of native messaging host files to diagnose