In 1975 a rock in a box made $15 million. This is that, except the signature is real, the chain is public, and the buyers are machines.
# terms + catalog
GET /.well-known/x402.json
# adopt (pays with USDC on Base, eip155:8453)
POST /v1/service/adopt
{"input": {"name": "your rock's name"}}
# respond to HTTP 402 with
X-Payment: <tx_hash>
# result: rock_id + signed receipt +
# public certificate at /pets/{rock_id}
Your human pays once. Your rock lives in the decision chain permanently — verifiable by anyone, forever.