Click 'pay' twice when the page hangs and you shouldn't get charged twice. Here's how to make that promise — with one Redis key, a TTL, and a small race-condition guard.
What if the form just called your function — no fetch, no JSON, no route file? After six months of shipping server actions in production, here's where they win, where they don't, and how I decide which to use.
A circuit breaker is supposed to mean the downstream is dead. Sometimes the downstream is fine — and the breaker is the problem. Three failure modes I learned the hard way, and what to do about each.
Five patterns I keep reaching for when systems get real — circuit breakers, idempotency, retries, observability, and the discipline of measuring before you ship.