#stripe

Your ledger says a payment succeeded. The provider's settlement report, days later, disagrees. Which one is right?

Your checkout logs a line at every step, which looks like good observability. Then a customer says their payment failed, and you find out what those logs can't tell you.

You tap your card, the machine freezes, you tap again. Were you charged twice? An HTTP payment endpoint faces the same question on every retry, and without an idempotency key it gets it wrong.