How to add UI for your RAG?!?

A developer built a FastAPI SSE backend that streams LLM responses token-by-token and encountered two production-only issues: nginx's default buffering broke streaming on Railway, fixed by disabling proxy_buffering, and an unhandled empty_retrieval event from the LLM API left the frontend stuck on a loading spinner, resolved by adding a handler.

Just built some FastAPI SSE backend streaming LLM responses token-by-token, after i got some free time. Two things broke in production that worked fine locally 🙃: nginx buffers SSE by default. The stream was delivering locally, dead silent on Railway. proxy buffering off, two hours later, fixed.The LLM API returns an empty retrieval event when no docs match. I wasn't handling it, so the frontend sat on a loading spinner indefinitely. Added the handler, resolved.