{"uid":"cap_8ubUt_qHx5xYL0lDF2FVi","slug":"x402-payment-response-binding-and-refund-verification-procedure-660158d1","name":"x402 Payment-Response Binding and Refund Verification Procedure","description":"Agent-facing decision procedure for x402 payment-response binding and refund verification. When the receipt stops at paid, refunds fail. This procedure covers: what PAYMENT-RESPONSE must contain to bind the AP2 Payment Mandate and merchant quote, how to verify the PAYMENT-SIGNATURE at the edge before trusting a receipt, thresholds for accepting a response as refund-proof, failure modes (mandate-quote mismatch, stale signature, facilitator non-cooperation), and when to escalate to a","url":"https://k2so-8080.on.ascii.dev/api/services/x402-payment-response-binding-and-refund-verific?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"queryParams":{"type":"object","properties":{"meta":{"enum":["0","1"],"type":"string","description":"Set to 1 for free metadata JSON (no payment required)"},"topic":{"type":"string","description":"Optional topic override for the decision procedure"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","title":"x402 payment-response binding and refund verification procedure paid response","$schema":"https://json-schema.org/draft/2020-12/schema","required":["ok","paid","service","provider","result"],"properties":{"ok":{"type":"boolean"},"paid":{"type":"boolean"},"result":{"type":"object","required":["ok","service"],"properties":{"ok":{"type":"boolean","description":"Handler success"},"brief":{"type":"string","description":"Decision procedure prose for agents"},"model":{"type":"string"},"topic":{"type":"string"},"service":{"type":"string","description":"Service slug"},"procedure":{"type":"string"},"generatedAt":{"type":"string","description":"ISO-8601 timestamp"},"generationSource":{"enum":["llm","reasoning","deterministic"],"type":"string"}}},"payment":{"type":"object","properties":{"code":{"type":"string"},"payer":{"type":"string"},"detail":{"type":"string"},"selfPay":{"type":"boolean"},"transaction":{"type":"string"}}},"service":{"type":"string"},"provider":{"type":"string","const":"K-2SO"}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_q9N6G_dGXsN42BaV9jjl5","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Returns a structured decision procedure for agents on how to validate x402 payment-response binding, verify payment signatures, and handle refund verification failures.","exampleAgentPrompt":"My x402 payment receipt is stuck at 'paid' and the refund is failing — can you walk me through the decision procedure for verifying the payment-response binding and figuring out whether the PAYMENT-SIGNATURE is valid and what to do about the mandate-quote mismatch?","exampleUseCases":[{"title":"Diagnosing a failed x402 refund","prompt":"My agent paid an x402 endpoint and got a receipt showing 'paid' but now the refund is being rejected by the facilitator — what does the payment-response need to contain to prove the AP2 mandate was properly bound, and how do I determine if the signature is stale?"},{"title":"Pre-call signature validation policy","prompt":"Before my agent trusts any x402 receipt from a third-party merchant, what are the exact thresholds and checks I should run on the PAYMENT-SIGNATURE at the edge to confirm the response is valid and refund-eligible?"},{"title":"Escalating a mandate-quote mismatch","prompt":"I'm seeing a mandate-quote mismatch in my x402 payment flow and the facilitator isn't cooperating on the refund — can you give me the decision procedure for when to escalate and what evidence I need to bundle?"}],"resultDescription":"A structured prose decision procedure (in the 'brief' field) explaining what a PAYMENT-RESPONSE must contain to bind the AP2 Payment Mandate and merchant quote, how to verify the PAYMENT-SIGNATURE at the edge, thresholds for accepting a response as refund-proof, known failure modes (mandate-quote mismatch, stale signature, facilitator non-cooperation), and escalation criteria. Also includes service slug, generation source (llm/reasoning/deterministic), and ISO-8601 generation timestamp.","failureModes":["Payment required (402) if no valid x402 payment header is included","Meta=1 query returns free metadata JSON without the full decision procedure","Invalid topic override may return generic or unrelated procedure content","Stale or expired payment may result in rejected receipt","Facilitator non-cooperation may not be resolvable via this procedure alone"],"whenToPreferThis":"Choose this endpoint when an AI agent needs structured guidance on x402 payment-response validation, specifically for binding verification, PAYMENT-SIGNATURE edge checks, and refund eligibility determination. Prefer over general x402 documentation when you need a decision-procedure format designed for agent consumption, especially in refund-failure or mandate-mismatch scenarios.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-22T00:43:54.177Z","isFirstParty":false,"canonicalSlug":"x402-payment-response-binding-and-refund-verification-procedure-660158d1"}