Deterministic procedure for an agent procuring video generation over x402: pre-pay probe of the video endpoint's 402 con

Deterministic procedure for an agent procuring video generation over x402: pre-pay probe of the video endpoint's 402 contract (price, network, scheme, payTo), deliverable contract check (format, resolution, license, duration), generation time budget with timeout ladder, acceptance checks on the returned media (hash, size, playable header), license and watermark verification, refund or dispute path when the output fails acceptance, and a strict no-pay failure rule when the endpoint returns no