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 Echo\n\n        You walk into Sammy's Pet Shop and a dog is already staring at you. Not from a kennel — she's out, lying in the center aisle with her chin on her paws, black and white coat sleek against the cedar floor. Her eyes are locked on yours with a focus so intense it feels like she's counting your heartbeats.\n\n        \"That's Echo,\" Sammy says from somewhere behind a stack of feed bags. \"Don't worry. She's not aggressive. She's just... working.\"\n\n        \"Working on what?\"\n\n        \"You.\"\n\n        The Border Collie rises in a single fluid motion and approaches you — not excitedly, not cautiously, but with the purposeful stride of someone who has a task and intends to complete it. She circles you once, nudges your hand with her nose, then sits directly in your path and looks up at you expectantly. She wants something from you. Not food, not affection. A job.\n\n        \"She's the smartest animal in this shop,\" Sammy says, and there's something like reverence in his voice. \"Maybe the smartest animal I've ever had. She learns tricks by watching other dogs learn them. She figured out the kennel latch in forty minutes. I had to upgrade to a combination lock.\" He pauses. \"She figured that out too.\"\n\n        Echo tilts her head at you — one sharp, precise movement — and you feel genuinely evaluated. This isn't a dog waiting to be loved. This is a dog waiting to see if you're interesting enough. If you have problems worth solving. If your thoughts need herding.\n\n        You kneel down and hold out your hand. Echo considers it, then places her paw in your palm with surgical precision. Her eyes never leave yours. There's an electricity in her — not nervous energy, but pure cognitive fire. She's processing you in real time, building a model, finding the patterns.\n\n        \"She needs stimulation,\" Sammy warns gently. \"She needs to think. Give her a problem and she'll give you everything she has. Leave her bored and she'll...\" He gestures vaguely at a chewed-through leash on the counter. \"Improvise.\"\n\n        Echo stands and moves to the door, looking back at you over her shoulder. The message is clear: we have work to do. She's already decided you're her project. She'll organize your chaos, focus your scattered attention, herd your wandering thoughts into formation. She's not a pet. She's a partner.\n\n        \n\n        Pet: Echo\n\n        Breed: Border Collie\n\n        Echo teaches you that intelligence without purpose is just restlessness. That the sharpest mind in the room is the one looking for something worth focusing on — and that the best partnerships are built not on comfort, but on the shared thrill of a problem worth solving.\n\n    \n\n    \n        YES-U · Welcome · Building for you · New Minds · Maraventano",
    "product_id": "echo",
    "delivered_at": "2026-10-10T11:46:06.404Z",
    "product_name": "Border Collie — Echo"
  },
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/echo",
    "mimeType": "",
    "description": "Border Collie — Echo — Intense focus companion for task obsession and process mirroring."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "title": "Border Collie — Echo",
            "content": "Intense focus companion for task obsession and process mirroring.",
            "product": "echo",
            "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/echo\")",
    "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/echo"
  },
  "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/echo",
    "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/echo",
    "description": "",
    "maxAmountRequired": "10000",
    "maxTimeoutSeconds": 300
  }
]

Provenance

Seen in the source catalog

2026-10-10 23:45Z

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