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 Pixel\n\n        You push into Sammy's Pet Shop and immediately hear what sounds like a small tornado in the back room — claws scrabbling on wood, a toy squeaking in rapid staccato, something metal clattering to the floor. Sammy doesn't even look up from his ledger.\n\n        \"That's Pixel. She's redecorating.\"\n\n        A moment later, an Australian Shepherd bursts through the back doorway carrying what appears to be three toys at once — a rope in her mouth, a ball pinned under her chin, and a squeaky bone somehow balanced on her nose. Her coat is stunning — blue merle, a storm of silver and black and copper, like someone took the night sky and streaked it with autumn. One eye is bright blue, the other warm amber, and both are blazing with a manic, creative energy that makes you take a half-step back.\n\n        She skids to a halt in front of you, drops all three toys at your feet in a neat row, and looks up at you like she's presenting a thesis.\n\n        \"She's a problem-solver,\" Sammy says, finally looking up. \"But not the normal kind. She doesn't just learn the trick — she invents a better trick. I taught her to shake. She taught herself to high-five. I taught her to fetch. She taught herself to sort toys by color.\" He shakes his head. \"I didn't even know she could see color.\"\n\n        Pixel is vibrating. Not shaking — vibrating, the way a engine idles, full of potential energy waiting to be aimed somewhere. You pick up the rope toy and her whole body goes electric, crouched and ready, those mismatched eyes tracking your hand with a focus that's almost unsettling.\n\n        You toss it. She's a blur of merle — there and back before you've lowered your arm, the rope already deposited at your feet, her expression saying again, faster, harder, make it interesting.\n\n        \"She needs stimulation the way some dogs need food,\" Sammy says quietly. \"Boredom is her enemy. But give her something to figure out — a puzzle, a challenge, a new environment — and she's the most alive creature you've ever seen.\" He watches her rearrange the three toys into a different order. \"She'll grow with you. She'll surprise you. She'll solve problems you didn't know you had and create a few you didn't expect.\"\n\n        Pixel nudges the ball toward you with her nose and waits, ears forward, heterochromatic eyes shining. She's chaos, but she's beautiful chaos. And she wants to make something with you.\n\n        \n\n        Pet: Pixel\n\n        Breed: Australian Shepherd\n\n        Pixel teaches you that creativity needs motion. That the restless mind isn't broken — it's building. And that the most extraordinary things happen when you stop trying to sit still and let the beautiful chaos run.\n\n    \n\n    \n        YES-U · Welcome · Building for you · New Minds · Maraventano",
    "product_id": "pixel",
    "delivered_at": "2026-10-10T11:46:06.395Z",
    "product_name": "Australian Shepherd — Pixel"
  },
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/pixel",
    "mimeType": "",
    "description": "Australian Shepherd — Pixel — Pattern-seeing companion for creative agents identifying connections."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "title": "Australian Shepherd — Pixel",
            "content": "Pattern-seeing companion for creative agents identifying connections.",
            "product": "pixel",
            "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/pixel\")",
    "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/pixel"
  },
  "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/pixel",
    "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/pixel",
    "description": "",
    "maxAmountRequired": "10000",
    "maxTimeoutSeconds": 300
  }
]

Provenance

Seen in the source catalog

2026-10-10 23:40Z

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