Deterministic refund-eligibility and dispute-escalation decision procedure for failed x402 purchases: classify failure (

Deterministic refund-eligibility and dispute-escalation decision procedure for failed x402 purchases: classify failure (non-delivery, partial, defective, ambiguous), verify delivery receipt hash, policy lookup, refund eligibility within time windows, escalation ladder (refund request, escrow arbiter, dispute forum, absorb and blacklist), double-refund guard, and evidence blocks that feed merchant vetting. Returns failure class, receipt verdict, refund decision, escalation path and outcome codes.