A 402 Can Be Structurally Perfect and Still Unpayable

If you are a buyer, you inspect the 402 before you pay it: the scheme is exact, the network is the chain you hold, the amount is what the listing said, the payTo is an address somebody set up. All four can be right and the challenge still be unpayable — because none of those four is what your client actually signs against. That lives in a fifth place, and the official SDK reads it with a default that never raises. An x402 payment challenge is an array of accepts entries. Four fields describe who gets paid and how much: field answers scheme how the transfer is authorised (exact) network which c