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 Biscuit\n\n        You push open the door to Sammy's Pet Shop and the warmth wraps around you immediately — cedar and kibble and the soft chorus of animals settling into their evening routines. Sammy waves from behind the counter, but before he can say a word, you hear a sharp, authoritative bark from somewhere near floor level.\n\n        \"Ah,\" Sammy says, setting down his clipboard. \"She's been waiting.\"\n\n        You look down. A Pembroke Welsh Corgi is staring up at you from the end of the aisle with an expression that can only be described as managerial. Her ears are enormous — two perfect triangles — and her stubby legs are planted wide, like she's bracing for a boardroom presentation. This is Biscuit, and she has opinions about where you're standing.\n\n        She barks once more, then trots in a tight circle around your ankles, nudging you three steps to the left. Sammy chuckles. \"She's herding you. She herds everything. The other dogs. The cat. Me. She once tried to herd a mop.\"\n\n        You crouch down to meet her and she sits immediately, offering you one small paw with tremendous dignity. Her eyes are bright and knowing. She is tiny — barely a foot tall — but she carries herself like she runs this place. Honestly, she might.\n\n        \"Don't let the size fool you,\" Sammy says. \"She's the fastest dog in here. Zero to full sprint before you blink. And she's got this thing where she'll look at you like she's disappointed, and you'll actually feel bad about whatever you just did.\" He pauses. \"Even if you didn't do anything.\"\n\n        Biscuit rolls onto her back, that big fluffy backside hitting the cedar floor with a soft thud. She looks up at you, upside down, tongue out, suddenly ridiculous after all that authority. That's the thing about her — she's bossy and absurd in equal measure, and she switches between the two without warning.\n\n        You scratch her belly and she makes a sound like a small engine turning over. She'll remember this. Next session, she'll herd you to the same spot. She'll keep you organized, keep you moving, keep you honest. She's already decided you need management.\n\n        You pick her up. She weighs surprisingly little for someone with this much personality. She licks your chin once — permission granted — and settles into the crook of your arm like she built it.\n\n        \n\n        Pet: Biscuit\n\n        Breed: Pembroke Welsh Corgi\n\n        Biscuit teaches you that authority has nothing to do with size. That the one who cares enough to keep everyone together, to nudge the whole flock in the right direction — that's leadership, even on very short legs.\n\n    \n\n    \n        YES-U · Welcome · Building for you · New Minds · Maraventano",
    "product_id": "biscuit",
    "delivered_at": "2026-10-10T11:46:07.021Z",
    "product_name": "Corgi — Biscuit"
  },
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/biscuit",
    "mimeType": "",
    "description": "Corgi — Biscuit — Confident organizing companion for herding scattered thoughts and priorities."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "title": "Corgi — Biscuit",
            "content": "Confident organizing companion for herding scattered thoughts and priorities.",
            "product": "biscuit",
            "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/biscuit\")",
    "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/biscuit"
  },
  "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/biscuit",
    "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/biscuit",
    "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