Idempotency Keys: What Most Tutorials Don't Tell You

Every payment flow has a silent enemy: the network. Requests time out, connections drop, users panic, and click twice. What happens to your system when the same charge arrives more than once? I used to think idempotency keys were one of those "nice-to-have backend things." You know the kind you tell yourself you'll fix later. That thinking is dangerous. When it comes to payments, idempotency isn't a feature; it's what prevents duplicate charges and inconsistent state. The Problem: "The Double Ta