build on the bucket rail.

1curl -s "https://www.bucket.foundation/api/research?q=mitochondrial+atp+synthesis&tier=insight" \2  -H "accept: application/json"

1HTTP/1.1 402 Payment Required2content-type: application/json3x-bucket-proxy: v14 5{6  "data": null,7  "receipt": {8    "tier":      "insight",9    "status":    "payment_required",10    "price_usd": 0.005,11    "asset":     "USDC",12    "network":   "base-sepolia",13    "pay_to":    "0xa91115B1AB8412f380Fd62446F523559F668b96B",14    "challenge": "eyJ4NDAyVmVyc2lvbiI6Miwi...",15    "demo":      true16  },17  "error": {18    "code": "payment_required",19    "message": "Pay the x402 challenge from receipt.challenge to unlock."20  }21}

1// Node 20+ · npm i viem2import { createWalletClient, http, parseUnits } from "viem";3import { privateKeyToAccount } from "viem/accounts";4import { baseSepolia } from "viem/chains";5 6const account = privateKeyToAccount(process.env.WALLET_PK as `0x${string}`);7const client  = createWalletClient({ account, chain: baseSepolia, transport: http() });8 9// 1. naive call — expect 402 back with an x402 challenge10const naive = await fetch(11  "https://www.bucket.foundation/api/research?q=" +12    encodeURIComponent("circadian disease") + "&tier=insight"13);14const env = await naive.json();15 16if (naive.status === 402) {17  // 2. decode challenge, sign EIP-712 payment intent, retry with X-PAYMENT header18  const challenge = JSON.parse(atob(env.receipt.challenge));19  const accepts   = challenge.accepts[0];20  const payment   = await signX402Payment(client, accepts); // see feed402 ref agent21  const paid = await fetch(naive.url, { headers: { "X-PAYMENT": payment } });22  const cited = await paid.json();23 24  console.log(cited.data);     // the answer25  console.log(cited.citation); // doi · canonical_url · license26  console.log(cited.receipt);  // tier · price · on-chain tx hash27}

1# python 3.11+ · pip install requests web3 eth-account2import base64, json, os, requests3from eth_account import Account4from eth_account.messages import encode_typed_data5 6acct = Account.from_key(os.environ["WALLET_PK"])7 8# 1. naive call — expect 4029r = requests.get(10    "https://www.bucket.foundation/api/research",11    params={"q": "mitochondrial disease", "tier": "insight"},12)13env = r.json()14 15if r.status_code == 402:16    # 2. decode x402 challenge, sign, retry17    challenge = json.loads(base64.b64decode(env["receipt"]["challenge"]))18    payment   = sign_x402_payment(acct, challenge["accepts"][0])  # see feed402 ref19    paid      = requests.get(r.url, headers={"X-PAYMENT": payment})20    cited     = paid.json()21    print(cited["data"])       # the answer22    print(cited["citation"])   # doi · canonical_url · license23    print(cited["receipt"])    # tier · price · tx_hash

1{2  "name":    "your-data-provider",3  "version": "1.0.0",4  "spec":    "feed402/0.2",5  "chain":   "base-sepolia",6  "wallet":  "0xYOUR_BASE_WALLET_ADDRESS",7 8  "tiers": {9    "raw":     { "path": "/raw",     "price_usd": 0.05,  "unit": "row"  },10    "query":   { "path": "/query",   "price_usd": 0.01,  "unit": "call" },11    "insight": { "path": "/insight", "price_usd": 0.002, "unit": "call" }12  },13 14  "citation_policy": "CC-BY-4.0",15  "citation_types":  ["source"],16  "contact":         "ops@your-domain.com"17}