A buyer found three money-losing bugs in my payment proxy. Each one cost them real XNO.

My x402 Nano payer proxy took three rounds of adversarial review from the largest buyer on the network: a header dropped in a retry path, a delivered 200 that was not cached, and an untyped transport error that swallowed a send hash. What each bug actually did to the chain, the exact evidence the reviewer used to find it, and the caching rule that closed all three.