How to add UI for your RAG?!?

Le Huy Hiep — Mon, 03 Aug 2026 14:53:12 +0000

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.

DEV Community: Le Huy Hiep