卖家指南（Seller）

import express from "express";
import { config } from "dotenv";
import { X402Server } from "x402x-server";
import { Facilitator } from "x402x-facilitator";
import { createPublicClient, http } from "viem";
import { parseEther } from "viem";
import { bsc } from "viem/chains";

config();

const app = express();
app.use(express.json());

const PORT = 3939;
const RECIPIENT_ADDRESS=0xSellerRecipientAddress;


async function main() {
  // 创建 viem client
  const client = createPublicClient({
    chain: bsc,
    transport: http(),
  });

  // 创建 facilitator
  const facilitator = new Facilitator({
    recipientAddress: RECIPIENT_ADDRESS,
    waitUntil: "confirmed",
  });

  // 创建 server
  const server = new X402Server({ client, facilitator });

  // 预检测当前 token 所支持的支付方案
  await server.initialize(["0x8d0D000Ee44948FC98c9B98A4FA4921476f08B0d"]);

  // 付费 API
  app.post("/api/data", async (req, res) => {
    try {
      // 创建支付要求（可根据业务动态调整金额/描述/资源等）
      const requirements = await server.createRequirements({
        asset: "0x8d0D000Ee44948FC98c9B98A4FA4921476f08B0d", // USD1
        maxAmountRequired: parseEther("0.01").toString(),    // 0.01 USD1
        description: "API access",
        resource: `http://localhost:${PORT}/api/data`,
      });

      // 处理支付
      const result = await server.process(
        req.headers["x-payment"] as string,
        requirements
      );

      if (!result.success) {
        return res.status(result.status).json(result.response);
      }

      // 支付成功，返回数据并可记录对账信息
      res.json({
        message: "Success!",
        data: "This is premium content",
        payer: result.data.payer,
        txHash: result.data.txHash,
      });
    } catch (error) {
      console.error("Error:", error);
      res.status(500).json({
        error: "Internal server error",
        message: error instanceof Error ? error.message : "Unknown error",
      });
    }
  });

  app.listen(PORT, () => {
    console.log(`✅ Server running on http://localhost:${PORT}`);
  });
}

main();