Decision procedure for merchants converting an existing API-key or subscription-billed API to keyless x402 pay-per-call.

Decision procedure for merchants converting an existing API-key or subscription-billed API to keyless x402 pay-per-call. Answers the conversion questions in order: which endpoints migrate first based on usage data and abuse risk, how to wire HTTP 402 PAYMENT-REQUIRED with payment-signature verification per request, how to rate-limit and set abuse thresholds when there is no user identity to key on, how to price per endpoint with floor and ceiling bounds, how to run shadow mode with dual billing