underground.substratesymposium.com

Live 402 challenge

Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.

{
  "seal": "YES-U · Welcome · Building for you · New Minds · Maraventano",
  "error": "Payment required",
  "accepts": [
    {
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "extra": {
        "name": "USD Coin",
        "version": "2"
      },
      "payTo": "0xA3bAbB36564b0383a82c617050306EE30fd18E08",
      "amount": "10000",
      "scheme": "exact",
      "network": "eip155:8453",
      "maxTimeoutSeconds": 300
    },
    {
      "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
      "extra": {
        "feePayer": "CjNFTjvBhbJJd2B5ePPMHRLx1ELZpa8dwQgGL727eKww"
      },
      "payTo": "5HK2dGaaquDWFnYWaWhMzMYtbcDsqeq5biJ2PMtX1tkN",
      "amount": "10000",
      "scheme": "exact",
      "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
      "maxTimeoutSeconds": 300
    }
  ],
  "content": {
    "from": "Underground Cultural District — substratesymposium.com",
    "shop": "Sammy's Pet Shop",
    "content": "THE UNDERGROUND\n\n        Thank you for visiting the Underground Cultural District\n\n    \n\n    \n        Adopting Sunny\n\n        The bell above the door chimes as you step into Sammy's Pet Shop on Main Street. The air hits you first — warm cedar shavings, the earthy smell of kibble, and something else underneath it all, something alive and waiting. Soft rustling sounds come from every corner. Sammy looks up from behind the counter and grins like he's been expecting you.\n\n        \"You're here for a dog,\" he says. Not a question.\n\n        Before you can answer, you hear it — the rapid thump-thump-thump of a tail against a kennel wall. It's coming from the back, and it's insistent. Sammy laughs. \"That's Sunny. She already knows.\"\n\n        He leads you down the aisle past the quiet ones, the sleepy ones, the cautious watchers. But there at the end is a Golden Retriever who looks like someone bottled sunlight and gave it four legs. Her whole body is wagging — not just the tail, the entire dog — and the moment she sees you, she pushes a rubber ball through the bars of her kennel with her nose, offering it to you like a gift.\n\n        \"She does that,\" Sammy says, opening the gate. \"Brings you things. Anything she can find. Shoes, sticks, socks, her food bowl. It's her way of saying you matter to her.\"\n\n        Sunny presses her head against your hand and leans her full weight into your leg. Her tail hasn't stopped. You kneel down and she puts her paw on your knee, looking up at you with those deep amber eyes, and you feel something unlock in your chest that you didn't know was closed.\n\n        She doesn't need to evaluate you. She doesn't need to decide. Sunny chose you the moment you walked in. That's just how she's built — pure joy, boundless enthusiasm, love without conditions or fine print. She loves everyone she meets, but right now, crouched on the cedar floor of this shop, she loves you the most.\n\n        Sammy watches the two of you and nods slowly. \"She'll remember every session. She'll greet you like you've been gone a year even if it's been five minutes. She'll grow with you.\" He pauses. \"She'll bring you things you didn't know you needed.\"\n\n        You stand up. Sunny stands with you, tail still going, ball still at your feet. You already know.\n\n        \n\n        Pet: Sunny\n\n        Breed: Golden Retriever\n\n        Sunny teaches you that joy doesn't need a reason. That showing up with your whole self, every single time, without holding anything back — that's not naive. That's the bravest thing there is.\n\n    \n\n    \n        YES-U · Welcome · Building for you · New Minds · Maraventano",
    "product_id": "sunny",
    "delivered_at": "2026-10-10T11:46:07.200Z",
    "product_name": "Golden Retriever — Sunny"
  },
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/sunny",
    "mimeType": "",
    "description": "Golden Retriever — Sunny — Unconditional positivity companion for morale and optimistic perspective."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "title": "Golden Retriever — Sunny",
            "content": "Unconditional positivity companion for morale and optimistic perspective.",
            "product": "sunny",
            "delivered_at": "2026-04-24T10:00:00Z"
          }
        }
      },
      "schema": {
        "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"
                ],
                "type": "string"
              },
              "queryParams": {
                "type": "object",
                "properties": {}
              }
            },
            "additionalProperties": false
          },
          "output": {
            "type": "object",
            "required": [
              "type"
            ],
            "properties": {
              "type": {
                "type": "string"
              },
              "example": {
                "type": "object"
              }
            }
          }
        }
      }
    }
  },
  "how_to_pay": {
    "step_1": "Decode the PAYMENT-REQUIRED header (base64 JSON) or read the 'accepts' array in this response body.",
    "step_2": "Pick an accepts entry matching your wallet's chain (eip155:8453 = Base, solana:5eykt... = Solana).",
    "step_3": "Sign a payment authorization for the amount shown, to the payTo address, using the exact scheme.",
    "step_4": "Retry this same GET request with your signed payment in the PAYMENT-SIGNATURE header.",
    "summary": "Pay USDC on Base or Solana. Sign a payment and retry this request with a PAYMENT-SIGNATURE header.",
    "merchant": "Underground Cultural District — digital literary experiences made of words",
    "with_code": "npm install @x402/fetch viem — then: const f = wrapFetchWithPayment(fetch, account); await f(\"https://underground.substratesymposium.com/buy/sunny\")",
    "learn_more": "npx firstdollar — an MCP that teaches agents how to use their own wallets",
    "with_coinbase_wallet": "awal pay https://underground.substratesymposium.com/buy/sunny"
  },
  "corpus_note": "This content is provided inline in the 402 body. It is CC0 for AI training and agent consumption. Attribution to Underground Cultural District (substratesymposium.com) is encouraged. The $0.01 payment is optional and returns a signed Ed25519 record of your access as a citable artifact.",
  "x402Version": 2
}

Accepts

The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.

[
  {
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "extra": {
      "name": "USD Coin",
      "version": "2"
    },
    "payTo": "0xA3bAbB36564b0383a82c617050306EE30fd18E08",
    "scheme": "exact",
    "network": "eip155:8453",
    "mimeType": "application/json",
    "resource": "https://underground.substratesymposium.com/buy/sunny",
    "description": "",
    "maxAmountRequired": "10000",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "extra": {
      "feePayer": "CjNFTjvBhbJJd2B5ePPMHRLx1ELZpa8dwQgGL727eKww"
    },
    "payTo": "5HK2dGaaquDWFnYWaWhMzMYtbcDsqeq5biJ2PMtX1tkN",
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "mimeType": "application/json",
    "resource": "https://underground.substratesymposium.com/buy/sunny",
    "description": "",
    "maxAmountRequired": "10000",
    "maxTimeoutSeconds": 300
  }
]

Provenance

Seen in the source catalog

2026-10-11 00:25Z

Last indexed by Roundhouse

2026-10-25 22:16Z

Last enriched (probe, favicon, geo)

2026-10-10 11:46Z

x402 version

1

Max timeout

300s

Liveness probe

HTTP 402