X402 Payment Identifier Retry Safety Lens

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://api.blockchainmoneymap.com/api/x402/x402-payment-identifier-retry-safety-lens' \
  -H 'content-type: application/json' \
  --data-raw '{"facts":{"cached_response_present":true,"crash_recovery_policy":"resume with same payment id after crash","dedupe_scope":"buyer route resource","identifier_privacy_notes":"opaque random prefix with no identity detail","payment_id_format":"payment-idempotency-key per route and buyer session","retry_cache_policy":"cache response by payment id for safe retries","unique_prefix_present":true},"mode":"audit"}'

# 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://api.blockchainmoneymap.com/api/x402/x402-payment-identifier-retry-safety-lens' \
  -H 'content-type: application/json' \
  --data-raw '{"facts":{"cached_response_present":true,"crash_recovery_policy":"resume with same payment id after crash","dedupe_scope":"buyer route resource","identifier_privacy_notes":"opaque random prefix with no identity detail","payment_id_format":"payment-idempotency-key per route and buyer session","retry_cache_policy":"cache response by payment id for safe retries","unique_prefix_present":true},"mode":"audit"}' \
  | 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 $0.01 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.01" });
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 $0.01 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fapi.blockchainmoneymap.com%2Fapi%2Fx402%2Fx402-payment-identifier-retry-safety-lens&method=POST
const res = await pay("https://api.blockchainmoneymap.com/api/x402/x402-payment-identifier-retry-safety-lens", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "facts": {
      "cached_response_present": true,
      "crash_recovery_policy": "resume with same payment id after crash",
      "dedupe_scope": "buyer route resource",
      "identifier_privacy_notes": "opaque random prefix with no identity detail",
      "payment_id_format": "payment-idempotency-key per route and buyer session",
      "retry_cache_policy": "cache response by payment id for safe retries",
      "unique_prefix_present": true
    },
    "mode": "audit"
  }),
});
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 $0.01 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.01"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://api.blockchainmoneymap.com/api/x402/x402-payment-identifier-retry-safety-lens",
        json={
            "facts": {
                "cached_response_present": True,
                "crash_recovery_policy": "resume with same payment id after crash",
                "dedupe_scope": "buyer route resource",
                "identifier_privacy_notes": "opaque random prefix with no identity detail",
                "payment_id_format": "payment-idempotency-key per route and buyer session",
                "retry_cache_policy": "cache response by payment id for safe retries",
                "unique_prefix_present": True,
            },
            "mode": "audit",
        },
    )
    print(res.status_code, res.text)