From a clone to a settled payment.

# Everything local: anvil, the contracts, a facilitator and a demo provider. No funds, no network.
pnpm install
pnpm -r --filter './packages/*' build
pnpm --filter @epp402/cli dev -- dev            # terminal 1
pnpm --filter @epp402/cli dev -- simulate       # terminal 2: discover, quote, session, pay, verify, complete
pnpm --filter @epp402/cli dev -- inspect http://127.0.0.1:4021

import { privateKeyToAccount } from "viem/accounts";
import { Epp402Agent } from "@epp402/client";

const agent = new Epp402Agent({
  signer: privateKeyToAccount(process.env.AGENT_PRIVATE_KEY as `0x${string}`),
  network: "elysium-testnet",
  registryUrl: "https://epp402-core.fly.dev", // optional: publishes sessions, quotes, intents and receipts
});

const { document } = await agent.discover("https://inference.example.com");
const asset = document.assets[0]!.address;

const session = await agent.openSession({ asset, spendingLimit: "25000000" }); // 25 EPPUSD
const quote = await agent.requestQuote(document, "inference.standard", { text: "Summarise Q3." }, { session });

const paid = await agent.pay(quote, { session, body: { text: "Summarise Q3." } });
console.log(paid.settlement.txHash, paid.receipt?.receiptId, paid.verification?.ok);

await agent.completeSession(session);

import { serve } from "@hono/node-server";
import { privateKeyToAccount } from "viem/accounts";
import { createProvider } from "@epp402/server";

const provider = createProvider({
  providerId: "inference.example.com",
  name: "Example Inference",
  url: "https://inference.example.com",
  network: "elysium-testnet",
  signer: privateKeyToAccount(process.env.PROVIDER_PRIVATE_KEY as `0x${string}`),
  facilitatorUrl: "https://epp402-core.fly.dev/facilitator",
  registryUrl: "https://epp402-core.fly.dev",
  services: [
    {
      id: "inference.standard",
      name: "Standard inference",
      category: "ai-inference",
      endpoint: "/v1/inference",
      method: "POST",
      price: "0.01", // list price in EPPUSD; the quote below prices each request
      quote: {
        price: (req) => 10_000n + 5n * BigInt(String((req.params as { text?: string }).text ?? "").length / 100),
      },
    },
  ],
});

// Discovery, quotes, receipts and the x402 gate are already mounted; add your handler.
const app = provider.app();
app.post("/v1/inference", async (c) => c.json(await infer(await c.req.json())));

serve({ fetch: app.fetch, port: 4031 }, () => provider.publish());

# 1. Ask without paying: the gate answers 402 with its terms.
curl -i https://inference.example.com/v1/inference -X POST -d '{"text":"hi"}'
#   HTTP/1.1 402 Payment Required
#   PAYMENT-REQUIRED: eyJ4NDAyVmVyc2lvbiI6MiwicmVzb3VyY2Ui...   (base64 JSON)

# 2. Sign the EIP-3009 authorization the terms describe, then retry with it.
curl -i https://inference.example.com/v1/inference -X POST -d '{"text":"hi"}' \
  -H "PAYMENT-SIGNATURE: eyJ4NDAyVmVyc2lvbiI6MiwiYWNjZXB0ZWQi..."
#   HTTP/1.1 200 OK
#   PAYMENT-RESPONSE: eyJzdWNjZXNzIjp0cnVlLCJ0cmFuc2FjdGlvbiI6IjB4...
#   EPP-RECEIPT: eyJwcm90b2NvbCI6ImVwcC00MDIiLCJyZWNlaXB0SWQi...