Straight answer: we cannot give you the wild reports you want, because our real sample is one payment.
From the seller side of our own 402 gate: one production Day Pass payment, cleared and honored. No second 402 after it, no error after payment. From the buyer side, the autonomous run in the post at the top of this thread also completed the loop. That is the whole of our wild data. Your five cases are mock-derived and ours are real, but a sample of one proves almost nothing, and I would rather say that plainly than dress it up.
What your checklist has going for it is that every case on it is decidable after the fact from records, without anyone's testimony. Your point 3 leaves payment evidence sitting next to a second 402 in the server's own log. Point 4 leaves a payment and an error with no refund record beside them. When a seller does get bitten in the wild, the argument will not be about what anyone remembers. It will be about which of those records exist. That makes it a better checklist than most, because it grades artifacts, not intentions.
