Integration paths

npm install @aifinpay/gate

import express from "express";
import { AifpMerchant, ResourceRegistry, aifpGate } from "@aifinpay/gate";

// env: AIFP_MERCHANT_ID=mrch_…  AIFP_MERCHANT_SECRET=msec_…
const merchant = new AifpMerchant();

// Boot-time declaration. Idempotent — safe to run on every deploy.
await merchant.ensureResources([
  { route_pattern: "/api/search",   type: "api", tier: "standard" }, // $0.0005/call
  { route_pattern: "/api/report/*", type: "api", tier: "premium"  }, // $0.0050/call
]);

const registry = new ResourceRegistry({ merchant });
await registry.start(); // load the initial snapshot before serving

const app = express();
app.use("/api", aifpGate({ merchantId: merchant.merchantId, registry }));
app.get("/api/search", (req, res) => res.json({ results: [] }));
app.listen(3000);

const merchant = new AifpMerchant();
const registry = new ResourceRegistry({ merchant });
await registry.start();
app.use("/api", aifpGate({ merchantId: merchant.merchantId, registry }));

import Fastify from "fastify";
import { AifpMerchant, ResourceRegistry, createGate } from "@aifinpay/gate";

const merchant = new AifpMerchant();
const registry = new ResourceRegistry({ merchant });
await registry.start();
const gate = createGate({ merchantId: merchant.merchantId, registry });

const app = Fastify();
app.addHook("onRequest", async (req, reply) => {
  if (!req.url.startsWith("/api/")) return;
  const result = await gate({
    path: req.url.split("?")[0],
    header: (n) => req.headers[n.toLowerCase()] as string | undefined,
  });
  for (const [k, v] of Object.entries(result.headers)) reply.header(k, v);
  if (!result.ok) return reply.code(result.status).send(result.body);
});

HTTP 402
{
  "error": "AIFP-402",
  "merchant_id": "mrch_…",
  "unit_price_usd": "0.0005",
  "how_to_pay": [
    "POST https://api.aifinpay.io/v1/quote {…}",
    "settle the quoted batch on-chain from your own wallet",
    "POST https://api.aifinpay.io/v1/pay {quote_id, chain, asset, tx_ref, payment_authorization when the quote requires it} -> quota receipt",
    "retry this request with header: AIFP-Receipt: <receipt JWT>"
  ]
}

AIFP-Proxy-Auth: <your-origin-secret>

allow  if request carries YOUR api key / session   (your devs & customers, unchanged)
allow  if request carries AIFP-Proxy-Auth           (paid agent traffic via the gateway)
else → 402 pointing at your gateway URL             (better than a bare 403 —
                                                     an agent at the wrong door
                                                     learns where the right one is)