Claude in Chrome: 'Invalid token or user mismatch' persists after full reinstall of Desktop + Extension

Description

Claude Desktop's "Claude in Chrome" integration fails with Invalid token or user mismatch error on the WebSocket bridge (bridge.claudeusercontent.com). The bridge ID persists across full reinstalls of both Claude Desktop and the Chrome extension, suggesting it's server-side per-account.

Steps to Reproduce

1. Use Claude Desktop (Cowork) with Claude in Chrome extension
2. Chrome tool stops working with "Claude in Chrome is not connected"
3. All client-side remediation fails (see below)

Error Log

[Claude in Chrome] Connecting to bridge: wss://bridge.claudeusercontent.com/chrome/<bridge-id>
[Claude in Chrome] WebSocket connected, sending connect message
[Claude in Chrome] Bridge error: Invalid token or user mismatch
[Claude in Chrome] Bridge connection closed (code: 1008, duration: 0ms)

Troubleshooting Attempted (all failed)

• Sign out/in on both Claude Desktop and Chrome extension
• Delete bridge-state.json from Claude Desktop data directory
• Kill native host process + clean stale sockets in /tmp/claude-mcp-browser-bridge-$USER/
• Reload Chrome extension
• Remove and reinstall Chrome extension from Chrome Web Store
• Full uninstall of Claude Desktop (app + all data in ~/Library/Application Support/Claude, ~/Library/Caches/Claude, ~/Library/Logs/Claude) + fresh install
• Clear Chrome browsing data (cookies)
• Restart Chrome

The bridge ID remains identical (14d136f3-...) through all of the above, confirming it's server-side per-account.

Diagnosis

• Native host spawns correctly (/Applications/Claude.app/Contents/Helpers/chrome-native-host)
• Socket created at /tmp/claude-mcp-browser-bridge-$USER/<PID>.sock
• MCP server registered appears in logs
• Bridge WebSocket connects but server immediately rejects with Invalid token or user mismatch (code 1008)
• The bridge ID is sent from Chrome extension → native host → Claude Desktop, and survives extension reinstall

Expected Behavior

After fresh install of both Claude Desktop and Chrome extension with the same account, the bridge connection should authenticate successfully.

Environment

• Claude Desktop: v1.1.9310
• Chrome Extension: Claude in Chrome (Beta) v1.0.64 (ID: fcoeoabgfenejglbffodgkkbkcdhcgfn)
• macOS: Darwin 25.3.0
• Chrome: latest stable