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If a payment was submitted but could not be settled, the 402 has no PAYMENT-REQUIRED header and the body contains only error and code (payment_required).","headers":{"PAYMENT-REQUIRED":{"description":"Base64-encoded JSON x402 payment requirements","schema":{"type":"string"}}},"content":{"application/json":{"schema":{"$ref":"#/components/schemas/PaymentRequired402"},"example":{"x402Version":2,"accepts":[{"scheme":"exact","network":"eip155:8453","amount":"<amount in USDC micro-units>","asset":"<USDC contract on Base>","payTo":"<pay-to address>","maxTimeoutSeconds":180,"extra":{"name":"USD Coin","version":"2"}},{"scheme":"exact","network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","amount":"<amount in USDC micro-units>","asset":"<USDC mint on Solana>","payTo":"<pay-to address>","maxTimeoutSeconds":180}],"error":"payment_required","code":"payment_required"}}}},"404":{"description":"No such image model; nothing was charged","content":{"application/json":{"schema":{"$ref":"#/components/schemas/ErrorResponse"}}}},"409":{"description":"This payment signature was already used; nothing was charged again","content":{"application/json":{"schema":{"$ref":"#/components/schemas/ErrorResponse"}}}},"413":{"description":"The JSON body is over 128 kB; nothing was charged","content":{"application/json":{"schema":{"$ref":"#/components/schemas/ErrorResponse"},"example":{"error":{"type":"invalid_request_error","message":"The request body is too large.","code":"payload_too_large"}}}}},"503":{"description":"The model list or a seller could not be reached; try again shortly. 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Settled spend by category (chat_answer, data_tool, gift_card, other), by day, credit top-ups apart, and the owner's daily and per-purchase limits with what is left today. Categories only: no purchase details. 30 requests a minute per IP.","parameters":[{"name":"address","in":"path","required":true,"schema":{"type":"string"},"description":"A Base address (0x + 40 hex) or a Solana address (base58)"},{"name":"days","in":"query","required":false,"description":"How many days back, 1 to 90.","schema":{"type":"integer","minimum":1,"maximum":90,"default":30}}],"responses":{"200":{"description":"The report; known:false with zeros for an address SingIt has never seen","content":{"application/json":{"schema":{"type":"object","required":["address","chain","known","window","spent","creditTopUps","allowance","generatedAt"],"properties":{"address":{"type":"string"},"chain":{"type":"string","enum":["base","solana"]},"known":{"type":"boolean"},"window":{"type":"object","properties":{"days":{"type":"integer"},"since":{"type":"integer"},"until":{"type":"integer"}}},"spent":{"type":"object","properties":{"totalAtomic":{"type":"string"},"totalUsd":{"type":"string"},"count":{"type":"integer"},"byCategory":{"type":"object","additionalProperties":{"type":"object","properties":{"count":{"type":"integer"},"atomic":{"type":"string"},"usd":{"type":"string"}}}},"byDay":{"type":"array","items":{"type":"object","properties":{"date":{"type":"string"},"atomic":{"type":"string"},"usd":{"type":"string"},"count":{"type":"integer"}}}}}},"creditTopUps":{"type":"object","properties":{"count":{"type":"integer"},"atomic":{"type":"string"},"usd":{"type":"string"}}},"allowance":{"type":["object","null"],"properties":{"configured":{"type":"boolean"},"state":{"type":"string","enum":["active","paused","expired","none","granted","waiting_for_grant"]},"dailyCapAtomic":{"type":"string"},"perPurchaseCapAtomic":{"type":"string"},"spentTodayAtomic":{"type":"string"},"remainingTodayAtomic":{"type":"string"},"expiry":{"type":"integer"},"limiter":{"type":["string","null"]}}},"generatedAt":{"type":"integer"}}}}}},"400":{"description":"Not an address, or days out of range"},"429":{"description":"Too many requests; see Retry-After"}}}},"/v1/models":{"get":{"operationId":"listModels","summary":"List models that can be asked for now, with prices","responses":{"200":{"description":"Model list"}},"security":[]}},"/health":{"get":{"operationId":"getHealth","security":[],"summary":"Get service, model and payment-rail status","responses":{"200":{"description":"Legacy service fields plus observed health","content":{"application/json":{"example":{"ok":true,"status":"ok","generatedAt":"2026-10-31T12:00:00.000Z","windowHours":24,"statsSince":"2026-10-31T12:00:00.000Z","models":{"deepseek-v4.1-flash":{"status":"up","windowHours":24,"attempts":20,"successes":20,"failures":0,"errorRatePct":0,"lastSuccessAt":"2026-10-31T12:00:00.000Z","lastFailureAt":null,"lastOutcome":"success","sellerFailures":0,"failureReasons":{},"reason":null},"claude-opus-5.5":{"status":"insufficient_data","windowHours":24,"attempts":1,"successes":1,"failures":0,"errorRatePct":0,"lastSuccessAt":"2026-10-31T12:00:00.000Z","lastFailureAt":null,"lastOutcome":"success","sellerFailures":0,"failureReasons":{},"reason":null}},"models_summary":{"up":1,"degraded":0,"down":0,"insufficient_data":1,"unavailable":0},"payments":{"facilitator":null,"networks":{"base":{"status":"unknown","basis":"none","settled":0,"failed":0,"lastSettledAt":null,"lastFailedAt":null},"solana":{"status":"unknown","basis":"none","settled":0,"failed":0,"lastSettledAt":null,"lastFailedAt":null}}}},"schema":{"type":"object","properties":{"ok":{"type":"boolean","const":true},"status":{"enum":["ok","degraded","down"]},"generatedAt":{"type":"string","format":"date-time"},"windowHours":{"type":"integer","const":24},"statsSince":{"type":"string","format":"date-time"},"models_summary":{"type":"object","required":["up","degraded","down","insufficient_data","unavailable"],"properties":{"up":{"type":"integer","minimum":0},"degraded":{"type":"integer","minimum":0},"down":{"type":"integer","minimum":0},"insufficient_data":{"type":"integer","minimum":0},"unavailable":{"type":"integer","minimum":0}}},"models":{"type":"object","additionalProperties":{"type":"object","required":["status","windowHours","attempts","successes","failures","errorRatePct","lastSuccessAt","lastFailureAt","lastOutcome","sellerFailures","failureReasons","reason"],"properties":{"status":{"enum":["up","degraded","down","insufficient_data","unavailable"]},"windowHours":{"type":"integer","const":24},"attempts":{"type":"integer","minimum":0},"successes":{"type":"integer","minimum":0},"failures":{"type":"integer","minimum":0},"sellerFailures":{"type":"integer","minimum":0},"errorRatePct":{"type":"number","minimum":0,"maximum":100},"lastSuccessAt":{"type":["string","null"],"format":"date-time"},"lastFailureAt":{"type":["string","null"],"format":"date-time"},"lastOutcome":{"enum":["success","failure",null]},"reason":{"enum":["no_healthy_sellers","minimum_discount_not_met","other",null]},"failureReasons":{"type":"object","additionalProperties":false,"properties":{"no_healthy_sellers":{"type":"integer","minimum":0},"minimum_discount_not_met":{"type":"integer","minimum":0},"other":{"type":"integer","minimum":0}}},"unavailableUntil":{"type":"string","format":"date-time"},"retryAfterSeconds":{"type":"integer","minimum":30}}}},"payments":{"type":"object","properties":{"facilitator":{"type":["object","null"]},"networks":{"type":"object"}}}}}}}}}}},"/numbers.json":{"get":{"operationId":"getNumbers","security":[],"summary":"Get measured usage numbers with definitions","responses":{"200":{"description":"Calls, USDC volume and unique payer counts since counters began","content":{"application/json":{"schema":{"type":"object","required":["own_payers_configured"],"properties":{"own_payers_configured":{"type":"boolean"}}}}}}}}},"/pricing.json":{"get":{"operationId":"listPricing","summary":"Get per-model upto/exact prices for one reference question","description":"What GET/HEAD discovery and a real paid request would be offered for each model that can be asked for now, computed by the same chooseModel/ceilingAtomic functions, for a documented reference question. 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A model entry with recommendedScheme upto (Claude Opus) is best paid with the upto offer; its exact price carries room for thinking tokens.","responses":{"200":{"description":"Price by model"},"503":{"description":"The model catalogue has never loaded yet; see Retry-After","content":{"application/json":{"schema":{"$ref":"#/components/schemas/ErrorResponse"}}},"headers":{"Retry-After":{"description":"Seconds to wait before trying again","schema":{"type":"integer"}}}}},"security":[]}}},"components":{"schemas":{"ErrorResponse":{"type":"object","required":["error"],"properties":{"error":{"type":"object","required":["type","message","code"],"properties":{"type":{"type":"string"},"message":{"type":"string"},"code":{"type":"string","examples":["invalid_json","invalid_request","payload_too_large","model_not_found","not_found","rate_limited","free_tier_exhausted","free_budget_exhausted","free_tier_busy","payment_required","payment_duplicate","stale_payment_permit","no_billable_answer","no_healthy_sellers","max_tokens_too_small","upstream_unavailable","unauthorized","forbidden","internal_error","invalid_identity","request_changed","already_prepared","previous_quote_pending","unknown_model","already_paid","already_submitted","quote_unavailable","invalid_payment","terms_changed","verification_unavailable","verification_refused","payment_unresolved"]}}}}},"AnthropicErrorResponse":{"type":"object","required":["type","error"],"properties":{"type":{"const":"error"},"error":{"type":"object","required":["type","message","code"],"properties":{"type":{"type":"string"},"message":{"type":"string"},"code":{"type":"string","examples":["invalid_json","invalid_request","payload_too_large","model_not_found","not_found","rate_limited","free_tier_exhausted","free_budget_exhausted","free_tier_busy","payment_required","payment_duplicate","stale_payment_permit","no_billable_answer","no_healthy_sellers","max_tokens_too_small","upstream_unavailable","unauthorized","forbidden","internal_error","invalid_identity","request_changed","already_prepared","previous_quote_pending","unknown_model","already_paid","already_submitted","quote_unavailable","invalid_payment","terms_changed","verification_unavailable","verification_refused","payment_unresolved"]}}}}},"PaymentRequired402":{"type":"object","required":["error","code"],"properties":{"x402Version":{"type":"integer","description":"Present when the 402 is a payment challenge; equals x402Version in the decoded PAYMENT-REQUIRED header. 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