- Add CSP, frame and referrer headers for served static files
- Enforce WebSocket origin check to prevent cross-site hijacking
- Trust X-Forwarded-For only when the peer is from a private proxy network
- Limit concurrent connections (500 total / 20 per IP) and rooms (300)
- Add ALLOWED_ORIGINS env var for additional WebSocket origins
- Document reverse proxy setup (NPM/NPMplus) in README
- Add scripts/security-test.mjs to verify origin and limit behavior
