Server-Sent Events (SSE) Express Server FastAPI (Python) Spring WebFlux Browser Client (EventSource) With Auth Headers (fetch-based) Anti-Patterns | Anti-Pattern | Fix | |--------------|-----| | No keep-alive pings | Send comment ( ) every 30s | | Missing cleanup on disconnect | Listen for and clean up | | No event IDs for reconnection | Send field, use header | | EventSource doesn't support auth headers | Use fetch-based SSE client for auth | | No backpressure | Check before writing | Production Checklist - [ ] Keep-alive pings configured - [ ] Cleanup on client disconnect - [ ] Event IDs fo…