Preflight

{
  "decision": "review",
  "payee": {
    "listed_in": [],
    "manifest": "none"
  },
  "price": {
    "drift": null,
    "listed_usd": null,
    "quoted_usd": 0.02
  },
  "reasons": [
    {
      "code": "payee_new",
      "detail": "No directory lists this payout address and the server's manifest does not name it."
    }
  ],
  "terms": {
    "amount_usd": 0.02,
    "asset_symbol": "USDC",
    "network": "eip155:8453",
    "pay_to": "0x…",
    "resource_url": "https://example.com/api/thing"
  },
  "valid_for_seconds": 120
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://overwing.ai/api/x402/preflight/x402' \
  -H 'content-type: application/json' \
  --data-raw '{"payment_required":"<the PAYMENT-REQUIRED header value, or its decoded JSON>","policy":{"allow_testnets":false,"max_per_call_usd":0.05,"new_payee_max_usd":0.01},"requested_url":"https://example.com/api/thing"}'

# 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://overwing.ai/api/x402/preflight/x402' \
  -H 'content-type: application/json' \
  --data-raw '{"payment_required":"<the PAYMENT-REQUIRED header value, or its decoded JSON>","policy":{"allow_testnets":false,"max_per_call_usd":0.05,"new_payee_max_usd":0.01},"requested_url":"https://example.com/api/thing"}' \
  | 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 $0.002 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.002" });
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 $0.002 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Foverwing.ai%2Fapi%2Fx402%2Fpreflight%2Fx402&method=POST
const res = await pay("https://overwing.ai/api/x402/preflight/x402", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "payment_required": "<the PAYMENT-REQUIRED header value, or its decoded JSON>",
    "policy": {
      "allow_testnets": false,
      "max_per_call_usd": 0.05,
      "new_payee_max_usd": 0.01
    },
    "requested_url": "https://example.com/api/thing"
  }),
});
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 $0.002 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.002"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://overwing.ai/api/x402/preflight/x402",
        json={
            "payment_required": "<the PAYMENT-REQUIRED header value, or its decoded JSON>",
            "policy": {
                "allow_testnets": False,
                "max_per_call_usd": 0.05,
                "new_payee_max_usd": 0.01,
            },
            "requested_url": "https://example.com/api/thing",
        },
    )
    print(res.status_code, res.text)