Loop Gate

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://agent402.tools/api/loop-gate' \
  -H 'content-type: application/json' \
  --data-raw '{"budget":{"maxUsd":0.5,"spentUsd":0.52},"goal":"Find three peer-reviewed studies on sleep and memory consolidation published since 2020, with DOIs.","history":[{"iteration":2,"summary":"One study found (Nature Neuroscience 2021)."},{"iteration":3,"summary":"Second study found (Sleep 2023); PubMed search for a third in progress."}],"iteration":4,"lastOutput":"Found two studies with DOIs (Nature Neuroscience 2021, Sleep 2023). A third search of PubMed returned review articles only.","maxIterations":6}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://agent402.tools/api/loop-gate' \
  -H 'content-type: application/json' \
  --data-raw '{"budget":{"maxUsd":0.5,"spentUsd":0.52},"goal":"Find three peer-reviewed studies on sleep and memory consolidation published since 2020, with DOIs.","history":[{"iteration":2,"summary":"One study found (Nature Neuroscience 2021)."},{"iteration":3,"summary":"Second study found (Sleep 2023); PubMed search for a third in progress."}],"iteration":4,"lastOutput":"Found two studies with DOIs (Nature Neuroscience 2021, Sleep 2023). A third search of PubMed returned review articles only.","maxIterations":6}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.001 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.001" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.001 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fagent402.tools%2Fapi%2Floop-gate&method=POST
const res = await pay("https://agent402.tools/api/loop-gate", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "budget": {
      "maxUsd": 0.5,
      "spentUsd": 0.52
    },
    "goal": "Find three peer-reviewed studies on sleep and memory consolidation published since 2020, with DOIs.",
    "history": [
      {
        "iteration": 2,
        "summary": "One study found (Nature Neuroscience 2021)."
      },
      {
        "iteration": 3,
        "summary": "Second study found (Sleep 2023); PubMed search for a third in progress."
      }
    ],
    "iteration": 4,
    "lastOutput": "Found two studies with DOIs (Nature Neuroscience 2021, Sleep 2023). A third search of PubMed returned review articles only.",
    "maxIterations": 6
  }),
});
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.001 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.001"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://agent402.tools/api/loop-gate",
        json={
            "budget": {
                "maxUsd": 0.5,
                "spentUsd": 0.52,
            },
            "goal": "Find three peer-reviewed studies on sleep and memory consolidation published since 2020, with DOIs.",
            "history": [
                {
                    "iteration": 2,
                    "summary": "One study found (Nature Neuroscience 2021).",
                },
                {
                    "iteration": 3,
                    "summary": "Second study found (Sleep 2023); PubMed search for a third in progress.",
                },
            ],
            "iteration": 4,
            "lastOutput": "Found two studies with DOIs (Nature Neuroscience 2021, Sleep 2023). A third search of PubMed returned review articles only.",
            "maxIterations": 6,
        },
    )
    print(res.status_code, res.text)