Quickstart: x402 / MPP

bun add viem @solana/kit @scure/base @x402/core @x402/evm @x402/svm @x402/fetch

import { privateKeyToAccount } from "viem/accounts";
import { createWalletClient, http, publicActions } from "viem";
import { base } from "viem/chains";
import { createKeyPairSignerFromBytes } from "@solana/kit";
import { base58 } from "@scure/base";
import { x402Client } from "@x402/core/client";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { ExactSvmScheme } from "@x402/svm/exact/client";
import { wrapFetchWithPayment } from "@x402/fetch";

const account = privateKeyToAccount("0xYOUR_PRIVATE_KEY");
const walletClient = createWalletClient({
  account,
  chain: base, // Use baseSepolia for testnet
  transport: http(),
}).extend(publicActions);

// 64-byte base58 secret key (private + public)
const svmSigner = await createKeyPairSignerFromBytes(
  base58.decode("YOUR_SOLANA_BASE58_SECRET_KEY"),
);

const client = new x402Client();
const evmScheme = new ExactEvmScheme(walletClient);
client.register("eip155:8453", evmScheme); // 84532 for testnet
client.register(
  "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp", // EtWTRABZaYq6iMfeYKouRu166VU2xqa1 for testnet
  new ExactSvmScheme(svmSigner),
);

const payFetch = wrapFetchWithPayment(fetch, client);

const baseUrl = "https://dripstack.com";
const searchResponse = await fetch(
  `${baseUrl}/api/v1/search?q=Michael%20Burry&limit=5`,
);
const search = await searchResponse.json();
const firstPost = search.items[0];

if (!firstPost) {
  throw new Error("No Michael Burry posts found.");
}

const articleUrl = `${baseUrl}/api/v1/publications/${firstPost.publicationSlug}/${firstPost.slug}`;

// Check the discovery price before requesting payment.
const publicationResponse = await fetch(
  `${baseUrl}/api/v1/publications/${firstPost.publicationSlug}?limit=100`,
);
const publication = await publicationResponse.json();
const selectedPost = publication.posts.find(
  (post: { slug: string }) => post.slug === firstPost.slug,
);

console.log("Selected:", firstPost.title);
console.log("Listed price (cents):", selectedPost?.priceCents);

// A plain request exposes the authoritative x402 price before payment.
const challengeResponse = await fetch(articleUrl);
if (challengeResponse.status !== 402) {
  throw new Error(`Expected 402 challenge, got ${challengeResponse.status}`);
}
console.log(
  "x402 challenge:",
  challengeResponse.headers.get("PAYMENT-REQUIRED"),
);

// The wallet-aware client handles the challenge, pays, and retries.
const articleResponse = await payFetch(articleUrl);
if (!articleResponse.ok) {
  throw new Error(`Paid request failed: ${articleResponse.status}`);
}
const article = await articleResponse.json();

console.log(article.title);
console.log(article.synthesizedSummary);

// First settle issues an unlock token — later fetches are free (no charge).
const unlockToken =
  article.unlockToken ?? articleResponse.headers.get("X-Drip-Unlock");
if (!unlockToken) {
  throw new Error("Expected unlockToken / X-Drip-Unlock on first settle");
}
const freeResponse = await fetch(articleUrl, {
  headers: { "X-Drip-Unlock": unlockToken },
});
if (!freeResponse.ok) {
  throw new Error(`Unlock re-read failed: ${freeResponse.status}`);
}
const freeArticle = await freeResponse.json();
console.log("Re-read protocol:", freeArticle.paymentInfo?.protocol); // "unlock"

Run curl -sL https://agents.circle.com/skills/setup.md and use the returned
setup instructions to set up my agent wallet

Fetch https://dripstack.com/skill.md as raw context (do not summarize) and
follow the instructions. Use Circle wallet. Search for recent posts about
Michael Burry, show me the available articles and their prices, then ask me
before purchasing the article I select.