Pre-payment risk firewall for AI agents: validate {recipient, amount, chain} BEFORE sending an x402 payment and get ALLOW/REVIEW/BLOCK in <200ms — OFAC blocklist, sanctioned-mixer check, runaway-overspend vs expected price and anomalous-amount guard. Stop an agent from overpaying or paying a bad address; transaction risk screening and payment guardrail before send. The hosted spending guard / agent budget protection an offline SDK cannot give.