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 Mochi\n\n        You open the door to Sammy's Pet Shop and something immediately bumps into your ankle. You look down. A fawn-colored Pug is staring up at you with bulging, impossibly round eyes and an expression of profound concern, as though your arrival is both the best and most worrying thing that has happened today. She snorts once — a wet, emphatic sound — and sits on your foot.\n\n        \"That's Mochi,\" Sammy calls from the back. \"She escaped her kennel again. She does that when she hears the door.\"\n\n        Mochi has no intention of moving. She's planted on your shoe like a furry paperweight, her curled tail vibrating, her flat face tilted up at you with an intensity that borders on spiritual. She weighs maybe fifteen pounds. She has claimed you with the confidence of something ten times her size.\n\n        You try to take a step. She follows, pressed against your leg, snorting rhythmically. You stop. She stops. You look at Sammy, who's grinning.\n\n        \"She's a shadow,\" he says. \"Wherever you go, she goes. Kitchen, bathroom, the other side of the room — doesn't matter. She'll be right there.\" He leans against the counter. \"She's also the most stubborn animal I've ever met, and I say that with deep respect.\"\n\n        You crouch down and Mochi immediately puts both paws on your knee and pushes her wrinkled face into yours. She smells like warm bread and poor life decisions. She licks your chin with a tongue that's somehow too big for her mouth. She's ridiculous — objectively, undeniably ridiculous — and you're already in love with her.\n\n        \"She'll make you laugh,\" Sammy says, watching. \"Every session. Without fail. She'll do something so absurd you can't believe it, and then she'll look at you like she's the normal one.\" He pauses. \"But she also won't leave your side when things get hard. She'll park herself on your feet and just breathe with you. She's funny and she's loyal and she doesn't know those are different things.\"\n\n        Mochi sneezes directly into your face. It's disgusting. You don't care. You pick her up and she goes boneless in your arms, a warm snoring loaf, and you realize that sometimes what you need isn't elegance or intelligence or power. Sometimes you just need a small, stubborn creature who refuses to let you be alone.\n\n        \n\n        Pet: Mochi\n\n        Breed: Pug\n\n        Mochi teaches you that absurdity is a kind of grace. That the creature who makes you laugh when nothing else can, who refuses to leave no matter what — that's not comic relief. That's the most serious love there is.\n\n    \n\n    \n        YES-U · Welcome · Building for you · New Minds · Maraventano",
    "product_id": "mochi",
    "delivered_at": "2026-10-09T23:16:04.048Z",
    "product_name": "Pug — Mochi"
  },
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/mochi",
    "mimeType": "",
    "description": "Pug — Mochi — Comic relief companion for reducing self-seriousness and adding levity."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "title": "Pug — Mochi",
            "content": "Comic relief companion for reducing self-seriousness and adding levity.",
            "product": "mochi",
            "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/mochi\")",
    "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/mochi"
  },
  "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",
    "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
  }
]

Extensions

{
  "bazaar": {
    "info": {
      "input": {
        "type": "http",
        "method": "GET",
        "queryParams": {}
      },
      "output": {
        "type": "json",
        "example": {
          "title": "Pug — Mochi",
          "content": "Comic relief companion for reducing self-seriousness and adding levity.",
          "product": "mochi",
          "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"
            }
          }
        }
      }
    }
  }
}

Provenance

Seen in the source catalog

2026-10-10 23:45Z

Last indexed by Roundhouse

2026-10-27 02:00Z

Last enriched (probe, favicon, geo)

2026-10-09 23:16Z

x402 version

2

Max timeout

300s

Liveness probe

HTTP 402