The 402 Flow
HTTP 402 Payment Required has been in the HTTP spec since 1997 — "reserved for future use." For nearly three decades, no one agreed on what the payment payload should look like, how the negotiation should work, or who should facilitate it. That changed recently. Coinbase shipped x402, Stripe and Tempo launched the Machine Payments Protocol (MPP), and several smaller projects have proposed their own 402 conventions.
All of these give 402 a mechanism. They differ in architecture — specifically, in who sits between buyer and seller, and whether that intermediary is required.
AntSeed uses 402 as the trigger for fully decentralized payment negotiation between peers. No payment gateway, no relay, no facilitator. The entire flow — from the initial 402 response to the on-chain reserve to the retried request — happens over the same peer connection that carries the actual AI traffic.