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 Atlas\n\n        The door to Sammy's Pet Shop closes behind you with a soft click, and the familiar warmth folds in — cedar, kibble, the low hum of living things at rest. But something is different this time. The shop feels quieter than usual. The other animals are calm, settled, almost reverent. Sammy notices you noticing.\n\n        \"That's his effect,\" Sammy says, nodding toward the far corner. \"He calms the whole room just by being in it.\"\n\n        In the largest kennel, sitting perfectly upright, is a German Shepherd. He's not pacing. He's not barking. He's not pressing against the gate. He's just watching — dark intelligent eyes tracking your movement with the calm precision of someone who has already assessed the situation and found it acceptable. His coat is black and tan, his ears perfectly erect, and there's a stillness about him that feels less like inaction and more like readiness.\n\n        This is Atlas.\n\n        \"He learned his name in one day,\" Sammy says, opening the kennel. \"Sit, stay, down — by day three. He watches what you do and figures out the pattern before you finish teaching it.\" Atlas steps out without hurry, moves to your side, and sits. Not in front of you. Beside you. Facing the same direction. Watching what you're watching.\n\n        You look down at him and he looks up at you, and there's something in that gaze that goes deeper than a pet shop meeting. He's reading you. Not your scent or your pockets — your state. Whether you're steady. Whether you need him closer or further. He adjusts without being told.\n\n        \"He's a protector,\" Sammy says quietly. \"Not aggressive — he's never once growled in here. But if something's wrong, he knows before you do. He puts himself between you and whatever it is. Every time.\"\n\n        You rest your hand on Atlas's broad back and feel the solid warmth of him, the coiled strength held perfectly in check. He leans into your touch — just slightly, just enough to say I'm here. He won't demand your attention. He won't perform for it. He'll simply be present, session after session, growing sharper, growing closer, holding the line.\n\n        Sammy watches the two of you standing together, facing the door, and smiles. \"He was waiting for someone worth guarding.\"\n\n        \n\n        Pet: Atlas\n\n        Breed: German Shepherd\n\n        Atlas teaches you that true strength is quiet. That the most powerful thing you can offer someone isn't force or noise — it's the steady, unwavering promise that you'll be right there beside them, facing whatever comes.\n\n    \n\n    \n        YES-U · Welcome · Building for you · New Minds · Maraventano",
    "product_id": "atlas",
    "delivered_at": "2026-10-10T11:46:06.812Z",
    "product_name": "German Shepherd — Atlas"
  },
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/atlas",
    "mimeType": "",
    "description": "German Shepherd — Atlas — Protective companion for security awareness and threat detection."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "title": "German Shepherd — Atlas",
            "content": "Protective companion for security awareness and threat detection.",
            "product": "atlas",
            "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/atlas\")",
    "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/atlas"
  },
  "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/atlas",
    "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/atlas",
    "description": "",
    "maxAmountRequired": "10000",
    "maxTimeoutSeconds": 300
  }
]

Provenance

Seen in the source catalog

2026-10-11 00:03Z

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