For a while now, I've been working on a paper trading app for NEPSE. Virtual money, real prices, and the freedom to make awful trades without it costing a single rupee.

Like most side projects, it kept getting sidelined whenever life got busy. And every time I came back, I had to relearn my own code: what was finished, what was half-broken, and worse, why I'd made some decision in the first place. Past me left very few notes. So this series is partly a favour to future me, a written record of what I built and why, that I can read and argue with. If you want to argue with it too, or suggest something better, I'd love that.

The MVP is small: live quotes, buy and sell orders that actually execute, and a page showing what you hold. It's slowly coming together. Maybe one day it grows into something closer to a real TMS, but that's far off.

On the tech side, the backend is NestJS with Prisma on top of PostgreSQL, Redis and BullMQ for the background work, and SSE (Server-Sent Events) for the live prices.…