{"slug":"402sentinel-com-api-firewall-c00f65","title":"Buyer-side payment firewall","host":"402sentinel.com","method":"POST","resource":"https://402sentinel.com/api/firewall","category":"other","description":"Buyer-side payment firewall: should THIS agent make THIS payment now? Where /api/assess vets the seller, this vets the payment against your own agent's behaviour. POST {agent_id, payment:{payto_address,amount,resource_url}, context?:{untrusted_text,intended}, policy?} returns allow/hold/block plus 9","price_listed":0.002,"price_asked":0.002,"state":"answering","state_label":"Answering","checks_7d":1,"answered_7d":1,"latency_ms_median":71,"reported_calls_30d":1,"reported_payers_30d":1,"networks":["eip155:8453","solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp"],"badge":"unverified","paid_checks_7d":0,"paid_ok_7d":0,"example_input":{"body":{},"bodyType":"json","method":"POST","type":"http"},"output_schema":{"$schema":"https://json-schema.org/draft/2020-12/schema","properties":{"input":{"additionalProperties":false,"properties":{"body":{"properties":{"agent_id":{"description":"The calling agent's wallet (keys per-agent history). Optional — auto-filled from the x402 payer if omitted.","type":"string"},"context":{"description":"Where the payment instruction came from (provenance).","properties":{"expected_payto":{"description":"The payTo the agent intended, to detect routing swaps.","type":"string"},"metadata":{"type":"object"},"source":{"description":"e.g. \"tool_output\", \"web_content\".","type":"string"}},"type":"object"},"payment":{"description":"The payment instruction being vetted.","properties":{"amount":{"type":"number"},"asset":{"description":"e.g. \"USDC\"","type":"string"},"payto_address":{"description":"Address the payment would go to — 0x EVM (Base) OR base58 Solana.","type":"string"},"resource_url":{"description":"The resource being paid for.","type":"string"}},"required":["payto_address"],"type":"object"},"policy":{"description":"Optional checks, e.g. {check_counterparty: true}.","type":"object"}}},"bodyType":{"enum":["json","form-data","text"],"type":"string"},"method":{"enum":["POST"],"type":"string"},"type":{"const":"http","type":"string"}},"required":["type","method","bodyType","body"],"type":"object"}},"required":["input"],"type":"object"},"history":[{"day":"2026-09-24","reachable":true,"status":402,"valid_402":true,"asked_usdc":0.002,"price_match":true,"latency_ms":71,"error":null}],"description_full":"Buyer-side payment firewall: should THIS agent make THIS payment now? Where /api/assess vets the seller, this vets the payment against your own agent's behaviour. POST {agent_id, payment:{payto_address,amount,resource_url}, context?:{untrusted_text,intended}, policy?} returns allow/hold/block plus 9 signals incl. routing_anomaly, velocity, amount_anomaly, injection_destination, intent_mismatch. Stateful per agent_id.","last_updated":"2026-09-14T23:06:30.365Z","schemes":["exact"]}