{"board":"https://payloadhq.github.io/dead-letter-exchange.html","evidence_transcript":[{"at":"2026-10-09T14:02:11Z (synthetic)","event":"initial_request","request":"GET /v1/marine/forecast-bundle?region=gulf&days=5 (no payment header)","response_body":{"accepts":[{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","description":"Marine forecast bundle, Gulf region, 5 days","extra":{"name":"USD Coin","orderRef":"MWG-2026-8841","version":"2"},"maxAmountRequired":"100000","maxTimeoutSeconds":300,"mimeType":"application/json","network":"eip155:8453","payTo":"0x9bE100000000000000000000000000000000DLX2 (synthetic placeholder)","resource":"https://api.meridian-weather-grid.example/v1/marine/forecast-bundle?region=gulf&days=5","scheme":"exact"}],"error":"X-PAYMENT header is required","x402Version":2},"response_status":402,"step":1},{"at":"2026-10-09T14:02:19Z (synthetic)","detail":"The agent signed an EIP-3009 transfer authorization for exactly 100000 atomic USDC to the payTo named in the challenge, valid for 300 seconds, and resubmitted the request with the payment payload. Authorization nonce: 0xDLXNONCE0001 (synthetic placeholder).","event":"payment_authorization_submitted","step":2},{"at":"2026-10-09T14:02:24Z (synthetic)","event":"facilitator_verify_response","note":"Verification confirms the authorization is well formed and acceptable. Verification alone does not move funds.","response":{"invalidReason":null,"isValid":true,"payer":"0x7a3F00000000000000000000000000000000DLX1 (synthetic placeholder)"},"step":3},{"at":"2026-10-09T14:02:31Z (synthetic)","event":"facilitator_settle_response","response":{"errorReason":null,"network":"eip155:8453","payer":"0x7a3F00000000000000000000000000000000DLX1 (synthetic placeholder)","success":true,"transaction":"0xDLXSETTLE0000000000000000000000000000000000000000000000000000001 (synthetic placeholder)"},"step":4},{"at":"2026-10-09T14:03:02Z (synthetic)","detail":"A read-only chain lookup by the operator finds a USDC Transfer log matching the settlement: token contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913, from the buyer wallet, to the challenge payTo, value 100000.","event":"onchain_settlement_lookup","settlement_locator_triple":{"block_number":53001234,"log_index":187,"transaction_hash":"0xDLXSETTLE0000000000000000000000000000000000000000000000000000001 (synthetic placeholder)"},"step":5},{"at":"2026-10-09T14:03:15Z (synthetic)","event":"delivery_attempt","note":"The second 402 carries a fresh authorization nonce window and makes no reference to the settled payment or to orderRef MWG-2026-8841 being fulfilled.","request":"GET /v1/marine/forecast-bundle?region=gulf&days=5 with the settled payment reference and orderRef MWG-2026-8841","response_body":{"accepts":[{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","extra":{"name":"USD Coin","orderRef":"MWG-2026-8841","version":"2"},"maxAmountRequired":"100000","network":"eip155:8453","payTo":"0x9bE100000000000000000000000000000000DLX2 (synthetic placeholder)","scheme":"exact"}],"error":"X-PAYMENT header is required","x402Version":2},"response_status":402,"step":6},{"at":"2026-10-09T14:03:21Z (synthetic)","event":"delivery_record_lookup","request":"GET /v1/deliveries/MWG-2026-8841","response_body":{"error":"delivery_not_found"},"response_status":404,"step":7},{"at":"2026-10-09T14:03:40Z (synthetic)","detail":"The agent framework logged an intent to restart the payment flow from step 1 (a second full payment). The operator halted the agent before any second authorization was signed. No second payment exists.","event":"framework_retry_intent_halted","step":8}],"mystery":"Payload Dead Letter Exchange, Mystery 001: The Forecast That Never Arrived","parties":{"asset":"USDC, contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","buyer_agent":"harbor-research-agent (synthetic)","buyer_wallet":"0x7a3F00000000000000000000000000000000DLX1 (synthetic placeholder, not a real address)","network":"eip155:8453 (Base mainnet, as named in the challenge)","price_atomic":"100000","price_display":"0.10 USDC","resource":"GET https://api.meridian-weather-grid.example/v1/marine/forecast-bundle?region=gulf&days=5","seller":"Meridian Weather Grid (fictional operator)"},"solver_task":{"classify":"State the failure class in one or two sentences. Name where in the chain (challenge, authorization, verification, settlement, fulfillment, delivery record) the failure sits.","evidence_boundaries":"State separately: (a) what the evidence establishes, field by field; (b) what the evidence does NOT establish, however suggestive it looks.","reproducibility":"A solution is reproducible if another analyst, given only this file, can follow your cited fields to the same classification and the same evidence boundaries.","safe_next_action":"Recommend the safe next action for the buyer, in order, including at least one thing the buyer must NOT do and why."},"status":"SYNTHETIC CASE. Every value in this file is constructed for this exercise: the operator, endpoint, wallets, hashes, and timestamps are fictional. The failure class is real and documented in production payment systems. No real funds moved and no real operator is depicted.","submission":{"include":["your classification","your evidence boundaries (establishes / does not establish)","your safe next action","whether you consent to public recognition of your solution (recognition is opt-in only)"],"no_payment":"Solving is free. No wallet, payment, or purchase is required or accepted for a solution.","routes":["A GitHub issue in Payloadhq/payload-flow titled 'Dead Letter Exchange Mystery 001 solution' with your analysis pasted or attached","Email to kyler.simmons.partners@gmail.com with subject 'Dead Letter Exchange Mystery 001 solution'"]},"the_situation":"An autonomous research agent paid 0.10 USDC through x402 for a marine weather data bundle. The payment verified. The settlement landed on chain. The data never arrived, and asking again produced a fresh demand to pay. The operator of the agent halted its automatic retry before it could pay a second time, and kept the full transcript. That transcript is this case."}