Start Querying in Minutes

npm install @x402/core @x402/svm @solana/kit

import { x402Client, x402HTTPClient } from "@x402/core/client";
import { registerExactSvmScheme } from "@x402/svm/exact/client";
import { toClientSvmSigner } from "@x402/svm";
import { getBase58Encoder, createKeyPairSignerFromBytes } from "@solana/kit";
import type { PaymentRequired, SettleResponse } from "@x402/core/types";

// Load your Solana keypair
const bytes = getBase58Encoder().encode(process.env.SOLANA_PRIVATE_KEY!);
const signer = await createKeyPairSignerFromBytes(bytes);

// Initialize x402 client
const client = new x402Client();
registerExactSvmScheme(client, { signer: toClientSvmSigner(signer) });
const httpClient = new x402HTTPClient(client);

const BASE_URL = "https://agent.metengine.xyz";

async function paidFetch(
  path: string,
  options?: { method?: string; body?: Record<string, unknown> },
): Promise<{ data: unknown; settlement: SettleResponse; price: number }> {
  const method = options?.method ?? "GET";
  const url = `${BASE_URL}${path}`;
  const fetchOpts: RequestInit = { method };

  if (options?.body) {
    fetchOpts.headers = { "Content-Type": "application/json" };
    fetchOpts.body = JSON.stringify(options.body);
  }

  // Step 1: Get 402 with price
  const initial = await fetch(url, fetchOpts);
  if (initial.status !== 402)
    throw new Error(`Expected 402, got ${initial.status}`);
  const body = await initial.json();

  // Step 2: Parse payment requirements
  const paymentRequired: PaymentRequired =
    httpClient.getPaymentRequiredResponse(
      (name) => initial.headers.get(name),
      body,
    );
  const price = Number(paymentRequired.accepts[0]!.amount);

  // Step 3: Sign payment locally
  const paymentPayload =
    await httpClient.createPaymentPayload(paymentRequired);
  const paymentHeaders =
    httpClient.encodePaymentSignatureHeader(paymentPayload);

  // Step 4: Re-send with payment
  const paid = await fetch(url, {
    ...fetchOpts,
    headers: {
      ...(fetchOpts.headers as Record<string, string>),
      ...paymentHeaders,
    },
  });

  if (paid.status !== 200) {
    const err = await paid.json();
    throw new Error(
      `Payment failed (${paid.status}): ${JSON.stringify(err)}`,
    );
  }

  const paidBody = (await paid.json()) as { data: unknown };

  // Step 5: Extract settlement proof
  const settlement = httpClient.getPaymentSettleResponse(
    (name) => paid.headers.get(name),
  );

  return { data: paidBody.data, settlement, price };
}