Decision procedure for an agent on either side of a contested x402 payment: merchant failed to deliver, delivered partia

Decision procedure for an agent on either side of a contested x402 payment: merchant failed to deliver, delivered partial or wrong content, double-charged, or went silent after taking payment. Ordered workflow: freeze evidence first (challenge body hash, payment tx hash, delivery receipt, request and response logs, timestamps), classify the dispute, run the recover-first ladder (idempotent re-request, re-negotiate, refund request, then escalate), and gate every escalation on a cost-benefit