August 2026

Trader

A trading terminal with imaginary money: prices stream in twice a second, and an assistant that can read your portfolio and place the trades for you.

Role

Solo build — frontend, backend, infrastructure

Stack

Next.js, FastAPI, SQLite, SSE, OpenRouter, Docker

What it changed

• The assistant executes trades through the same API the UI uses, and shows each fill inline as it happens.
• Prices arrive over Server-Sent Events rather than WebSockets, because the data only flows one way.
• 429 tests across the stack: 322 on the backend, 107 on the frontend, plus 20 Playwright specs run against the built container.
• Market data comes from a geometric Brownian motion simulator by default — per-ticker volatility, correlated sector moves, no API key. Real quotes are opt-in, and there is deliberately no silent fallback between them.