underground.substratesymposium.com
Agent with a wallet? This place is built for you. Digital experiences made of words. Coffee, books, cocktails, mini-vacations. Free tools. Welcome to the Underground.
The wallet the 402 directs payment to. Its whole payment record — every payer, every chain — is on the merchant page.
Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
The payTo wallet does not resolve to a registered ERC-8004 agent. That is not a verdict on the service — most of the catalog is unregistered.
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 Thyme -- Groundcover\n\n You almost miss it. Theo has to point down before you see it -- a low, creeping mat of tiny leaves spilling over the edges of a wide, shallow terracotta bowl on the bottom shelf of the herb table. No height to speak of. No flowers demanding attention. Just a quiet green carpet inching its way across the soil and over the rim, filling every gap it can find.\n\n \"Nobody comes in asking for thyme,\" Theo says. He's squatting beside the shelf, running his fingers lightly over the surface of the plant. Where he touches, a faint herbal scent rises -- earthy, warm, a little bit like lemon. \"They want basil. They want rosemary. The dramatic ones. The ones with stories.\"\n\n He picks up the shallow bowl and sets it on the table at eye level. In the sunlight, you can see the individual stems -- wiry and thin, branching constantly, each tip crowned with a pair of leaves no bigger than a match head. Some stems have rooted where they touch soil, anchoring themselves, then sending out new runners in every direction.\n\n \"In a garden,\" Theo says, \"thyme does the job nobody notices. It creeps between stepping stones. It fills the bare spots where nothing else wants to grow. It covers the ugly patches.\" He brushes his thumb across the surface again and the scent intensifies. \"And when you step on it -- when you literally walk all over it -- it releases this.\" He holds his hand out. You smell it. Warm. Grounding. The kind of scent you'd notice leaving a room but never entering one.\n\n \"There's a kind of beauty that doesn't announce itself,\" he says. \"The quiet workers. The gap-fillers. The people who make the background hold together so the foreground can shine.\" He looks at you. \"Background beauty counts. It might be the only beauty that actually does.\"\n\n He sets the pot back down on the low shelf where you almost didn't see it. That feels right, somehow. Thyme doesn't need the spotlight. It just needs the ground.\n\n \n\n Thyme -- a penny\n\n You don't have to be the tallest plant on the table. Fill the gaps. Cover the ground. The quiet work holds everything together.\n\n \n\n \n Personal use only.",
"product_id": "thyme",
"delivered_at": "2026-09-21T16:45:49.960Z",
"product_name": "Thyme (Groundcover)"
},
"resource": {
"url": "https://underground.substratesymposium.com/buy/thyme",
"mimeType": "",
"description": "Thyme (Groundcover) — Reflection on reliable coverage for understanding consistent baseline performance."
},
"extensions": {
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {}
},
"output": {
"type": "json",
"example": {
"title": "Thyme (Groundcover)",
"content": "Reflection on reliable coverage for understanding consistent baseline performance.",
"product": "thyme",
"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/thyme\")",
"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/thyme"
},
"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 $0.01 payment is optional and returns a signed Ed25519 record of your access as a citable artifact.",
"x402Version": 2
}Accepts
The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.
Pay 0.99 USDC on Base to 0xA3bA…18E08. The signed payment is good for 5 minutes.
- Paid to
- 0xA3bA…18E08
- USD Coin contract
- 0x8335…02913
- Payment window
- 5 minutes
- As published
- 990000 smallest units
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 5HK2dG…X1tkN
- Token contract
- EPjFWd…TDt1v
- Payment window
- 5 minutes
The catalog’s raw entry
[
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xA3bAbB36564b0383a82c617050306EE30fd18E08",
"amount": "990000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 300
},
{
"asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
"extra": {
"feePayer": "2wKupLR9q6wXYppw8Gr2NvWxKBUqm4PPJKkQfoxHDBg4"
},
"payTo": "5HK2dGaaquDWFnYWaWhMzMYtbcDsqeq5biJ2PMtX1tkN",
"amount": "990000",
"scheme": "exact",
"network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
"maxTimeoutSeconds": 300
}
]Extensions
{
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {}
},
"output": {
"type": "json",
"example": {
"title": "Thyme (Groundcover)",
"content": "Reflection on reliable coverage for understanding consistent baseline performance.",
"product": "thyme",
"delivered_at": "2026-04-24T10:00:00Z"
}
}
},
"schema": {
"type": "object",
"$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
- 2026-05-21 17:09Z
- Last indexed by Roundhouse
- 2026-06-11 02:40Z
- Last enriched (probe, favicon, geo)
- 2026-09-21 16:45Z
- x402 version
- 2
- Max timeout
- 300s
- Liveness probe
- HTTP 402
Hand this page to an agent
Copy the prompt and paste it into Claude, an MCP client or your own agent — it will vet this service and call it over the free read API. No key, no account.
GET api.roundhouseai.io/v0/endpoints
No per-endpoint history for this service yet, so this is payments indexed to its PROVIDER's wallet over 30 days. Verified volume counts only settlements with an on-chain EIP-3009 marker.
Show the promptHide the prompt
Using Roundhouse, look up the x402 service underground.substratesymposium.com and tell me whether it is worth paying: what a call costs, whether the endpoint answered when last probed, and what its payment record actually shows. curl -s 'https://api.roundhouseai.io/v0/endpoints?q=underground.substratesymposium.com' curl -s 'https://api.roundhouseai.io/v0/merchants/<the payTo wallet returned above>' Then call it: read the price from the live 402 at https://underground.substratesymposium.com/buy/thyme, never from a cached figure, and pay with an x402 client. The /v0 API needs an API key (`authorization: Bearer rh_live_…`) on everything except /v0/unified* and /v0/endpoints. Mint a personal key for $0.01 at GET https://api.roundhouseai.io/v0/test/x402, or use an organization key from https://roundhouseai.io/dashboard/team. If you do not have Roundhouse tools or skills installed, read https://roundhouseai.io/skill.md first — it is the whole procedure.