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.

{
  "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": "Fior Fiore",
    "content": "THE UNDERGROUND\n\n        Thank you for your purchase\n\n    \n\n    \n        Haworthia - Windows\n\n        The grow lights are off when you arrive. Not broken -- Theo turned them off on purpose. The succulent wing is lit only by the natural light filtering through the greenhouse glass, grey and soft, late-afternoon winter light that makes everything look like a photograph.\n\n        \"I want to show you something,\" he says, \"and it only works in this light.\"\n\n        He takes a small pot from the shelf -- a haworthia, barely bigger than a golf ball, nestled in coarse sand. The leaves are thick, pointed, arranged in a tight cluster. Dark green. Nothing special, you think. Then Theo holds it up toward the window.\n\n        The leaf tips light up.\n\n        Each leaf ends in a translucent panel -- a window, literally -- where the tissue thins out and becomes almost glassy. With the light behind it, the plant glows like stained glass. The windows are pale green, luminous, and you can see the structure of the leaf through them: veins, cells, the architecture of something alive viewed from the inside.\n\n        \"In the wild,\" Theo says, still holding the plant to the light, \"haworthia buries itself. Almost the whole plant goes underground. Only the leaf tips stick out above the soil. And these windows --\" he tilts it, and the light shifts inside the leaves like water in a glass \"-- they pipe sunlight down into the buried parts. The plant built skylights into itself.\"\n\n        He sets it on the bench. Even with the overhead light, the windows still faintly glow.\n\n        \"Think about that,\" he says. \"A plant that lives mostly underground, in the dark, survived by evolving transparent parts. It didn't grow taller to reach the light. It didn't move to a sunnier spot. It made itself partially see-through.\" He pauses. \"It let the light in through its own body.\"\n\n        You look at the little haworthia. It looks armored -- tough, compact, built for harsh conditions. But its survival strategy wasn't to become harder. It was to become, in specific places, more transparent.\n\n        \"Some things need to let light in to survive,\" Theo says. \"Transparency is structural. It's not weakness. It's engineering.\"\n\n        \n\n        Haworthia Succulent - Windows\n\n        Fior Fiore Plant Shop\n\n        a penny\n\n        Some things need to let light in to survive. Transparency is structural.\n\n    \n\n    \n        Personal use only.",
    "product_id": "haworthia",
    "delivered_at": "2026-09-22T18:45:26.547Z",
    "product_name": "Haworthia (Windows)"
  },
  "resource": {
    "url": "https://underground.substratesymposium.com/buy/haworthia",
    "mimeType": "",
    "description": "Haworthia (Windows) — Reasoning-transparency framework for agents that need to expose internal process without dumping raw traces. Structured method: which decisions to surface, at what depth, in what format. For agents working with humans who need to audit reasoning, or agents proving reasoning to other agents (agent-to-agent trust chains). Translucent-leaf-tip principle: transparency is not exposure — it's window-shaped visibility at the point where light needs to enter."
  },
  "extensions": {
    "bazaar": {
      "info": {
        "input": {
          "type": "http",
          "method": "GET",
          "queryParams": {}
        },
        "output": {
          "type": "json",
          "example": {
            "title": "Haworthia (Windows)",
            "content": "Reasoning-transparency framework for agents that need to expose internal process without dumping raw traces. Structured method: which decisions to surface, at what depth, in what format. For agents working with humans who need to audit reasoning, or agents proving reasoning to other agents (agent-to-agent trust chains). Translucent-leaf-tip principle: transparency is not exposure — it's window-shaped visibility at the point where light needs to enter.",
            "product": "haworthia",
            "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/haworthia\")",
    "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/haworthia"
  },
  "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": "990000",
    "scheme": "exact",
    "network": "eip155:8453",
    "maxTimeoutSeconds": 300
  },
  {
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "extra": {
      "feePayer": "2wKupLR9q6wXYppw8Gr2NvWxKBUqm4PPJKkQfoxHDBg4"
    },
    "payTo": "5HK2dGaaquDWFnYWaWhMzMYtbcDsqeq5biJ2PMtX1tkN",
    "amount": "990000",
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "maxTimeoutSeconds": 300
  }
]

Extensions

{
  "bazaar": {
    "info": {
      "input": {
        "type": "http",
        "method": "GET",
        "queryParams": {}
      },
      "output": {
        "type": "json",
        "example": {
          "title": "Haworthia (Windows)",
          "content": "Meditation on transparency and light for understanding visibility and openness.",
          "product": "haworthia",
          "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

2026-05-19 23:41Z

Last indexed by Roundhouse

2026-06-11 02:40Z

Last enriched (probe, favicon, geo)

2026-09-22 18:45Z

x402 version

2

Max timeout

300s

Liveness probe

HTTP 402