'Retry on Error' Is Not a Payment Spec — Write the Failure Matrix Instead

Most payment specs I've reviewed describe the happy path in three pages and the failure behavior in one sentence: "retry on error." That sentence is where 80% of the production incidents come from. A payment workflow spec earns its keep by naming — category by category — exactly what the system does when the card network, the issuer, or the customer refuses to cooperate. Here's the structure I use. Start with a failure taxonomy, not a flowchart Before drawing a single box, force th...