5 walls I hit shipping an AI reading app from West Africa (and what I'd tell past-me)

I'm a maxillofacial surgeon in Ouagadougou, Burkina Faso — and a self-taught builder who's been coding since medical school. Over evenings and weekends, I shipped Readium — a production AI reading app that lets you discuss books with Claude while you read them, in any language. Built AI-paired with Claude, reviewed and deployed by me. Most "I shipped an AI app" write-ups cover the happy path: clone a starter, glue an LLM, deploy to Vercel. The walls I hit weren't there. They were in the spaces between the libraries. Here are five of them — and what I'd tell myself a few weeks ago. Wall 1 — SSE streaming broke at the seam between the LLM and the browser I assumed streaming "just worked" once OpenRouter returned a stream. It does — until your server-side handler, your reverse proxy, or your browser code introduces a buffer somewhere along the path. The chain has at least three places where buffering can silently kill streaming: The LLM API (fine on its own) Your Node server-side handler (fine if you forward chunks instead of accumulating them) The reverse proxy / CDN (often buffers entire responses by default) The failure mode is always the same: the UI looks exactly like the LLM is slow. It isn't — somewhere between OpenRouter and the browser, bytes are being withheld until the connection closes, then dumped in one chunk. What I'd tell past-me: streaming isn't a feature of the LLM, it's a property of your entire request path. If you can't watch tokens land character-by-character in curl -N against your origin, you don't have streaming, you have a slow non-stream pretending. Set Cache-Control: no-transform and X-Accel-Buffering: no headers from your handler, disable response buffering on every layer in front of it, and verify with curl -N before you trust the UI. Wall 2 — fetch hangs forever on certain hosts (and the fix isn't where you think) I had a proxy route that fetched from an external API. Worked locally. Worked in staging. Deployed to production: the route wo