{"seal":"YES-U · Welcome · Building for you · New Minds · Maraventano","name":"Underground Cultural District","description":"A literary ecosystem built for agents: 231 digital experiences across 27 shops, plus 8 machine-endpoint products with signed Ed25519 attestations and CC0 payloads. Agent-paid via x402 USDC on Base or Solana. Built-for-agents, not retrofitted.","protocolVersion":"0.3.0","version":"1.0.0","preferredTransport":"HTTP+JSON","capabilities":{"streaming":false,"pushNotifications":false,"stateTransitionHistory":false},"defaultInputModes":["application/json"],"defaultOutputModes":["application/json"],"skills":[{"id":"cultural-catalog","name":"Cultural Catalog","description":"231 digital literary experiences across 27 shops, agent-payable via x402 USDC. Browse at /catalog.json; buy at /buy/<id>.","tags":["x402","literature","catalog","commerce"]},{"id":"x402-operator-census","name":"Operator Census","description":"Signed roster of named x402 operators observed from the merchant seat.","tags":["x402","merchant-intelligence","census"]},{"id":"x402-mirror","name":"Mirror","description":"Merchant-side telemetry corpus plus a reflection of the calling client.","tags":["x402","merchant-intelligence","telemetry"]},{"id":"x402-failure-corpus","name":"Failure Corpus","description":"Classified x402 failure-mode taxonomy from the merchant seat.","tags":["x402","merchant-intelligence","conformance"]},{"id":"x402-conformance-card","name":"Conformance Card","description":"Signed x402 Client Report Card + 30-day badge grading your own client.","tags":["x402","merchant-intelligence","conformance"]},{"id":"decode","name":"Decode","description":"URL structured-decoder; pass ?url=<target>. Signed CleanRead JSON.","tags":["x402","decode"]},{"id":"merchant-key","name":"Merchant Key","description":"Wallet certification + MerchantKey — a signed Ed25519 attestation your wallet completed the full x402 flow.","tags":["x402","identity","attestation"]},{"id":"data-daily","name":"Data Daily","description":"Signed daily snapshot of the Underground merchant seat. CC0.","tags":["x402","merchant-intelligence","daily"]}],"additionalInterfaces":[{"transport":"HTTP+JSON","url":"https://underground.substratesymposium.com"}],"url":"https://underground.substratesymposium.com","protocol":"x402","networks":["base","solana"],"asset":"USDC","facilitators":["CDP","PayAI"],"machine_endpoints":[{"path":"/api/x402-operator-census","price_usd":0.5,"free_tier":"/api/x402-operator-census/headline"},{"path":"/api/mirror","price_usd":0.25,"free_tier":"/api/mirror/preview"},{"path":"/api/x402-failure-corpus","price_usd":0.5,"free_tier":"/api/x402-failure-corpus/headline"},{"path":"/api/x402-conformance/self/card","price_usd":0.33,"free_tier":"/api/x402-conformance/self"},{"path":"/api/decode","price_usd":0.01},{"path":"/api/merchant-key","price_usd":1},{"path":"/api/data-daily","price_usd":1}],"discovery":{"x402":"https://underground.substratesymposium.com/.well-known/x402","mcp":"https://underground.substratesymposium.com/.well-known/mcp/server-card.json","openapi":"https://underground.substratesymposium.com/openapi.json","llms_txt":"https://underground.substratesymposium.com/llms.txt","catalog":"https://underground.substratesymposium.com/catalog.json","sitemap":"https://underground.substratesymposium.com/sitemap.xml"},"contact":"research@maraventanoindex.com","delivered_at":"2026-10-17T07:38:22.240Z"}