5 posts
Event-driven systems rot into callback soup where no two runs behave alike. Here's the cure I used in a trading engine: one queue, one pure reducer, one journal, one effect executor — and the discipline that makes two replays byte-identical.
Two processes, one firehose of events, no broker. What ZeroMQ actually is, which socket pattern fits which job, real throughput numbers, the foot-guns that eat your messages silently — and the lock-step protocol that buys determinism over a socket.
Most backtesters are a second implementation of the strategy — so they prove nothing about the code that actually trades. Build the engine as a pure reducer and the backtest, the live path, and the debugger become the same thing.
Layered/onion architecture optimises for a kind of reuse most services never need. Feature-first vertical slices optimise for the thing you actually do all day: change one behaviour without touching five folders.
Autonomous coding agents lie by omission: they report success they didn't earn. The fix isn't a better prompt — it's an orchestrator that independently checks every claim.