vet402 pays the x402 endpoint you name, checks what came back against what the seller declared, and answers ALLOW or REFUSE with the tx id of your payment and the tx id of its payment to the seller.
GET /v1/check?url=<x402 endpoint> · 0.05 USDC · network algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=
Your payment settles first; the seller is paid only after that. Caps: 0.100000 USDC per seller call, 3.000000 USDC per day.