{
  "scheme": "exact",
  "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
  "amount": "1000",
  "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
  "payTo": "2wKupLR9q6wXYppw8Gr2NvWxKBUqm4PPJKkQfoxHDBg4",
  "maxTimeoutSeconds": 60,
  "extra": {
    "feePayer": "EwWqGE4ZFKLofuestmU4LDdK7XM1N4ALgdZccwYugwGd"
  }
}

{
  "x402Version": 2,
  "resource": {
    "url": "https://example.com/api/data",
    "description": "Access to protected content",
    "mimeType": "application/json"
  },
  "accepted": {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "amount": "1000",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "payTo": "2wKupLR9q6wXYppw8Gr2NvWxKBUqm4PPJKkQfoxHDBg4",
    "maxTimeoutSeconds": 60,
    "extra": {
      "feePayer": "EwWqGE4ZFKLofuestmU4LDdK7XM1N4ALgdZccwYugwGd"
    }
  },
  "payload": {
    "transaction": "base64-encoded-partially-signed-versioned-transaction"
  }
}

@x402/core          ← プロトコル共通型・ユーティリティ
@x402/svm           ← Solana決済メカニズム (mechanisms/svm)
  ├── ExactSvmScheme    ← クライアント/ファシリテーター実装
  ├── signer            ← トランザクション署名
  └── utils             ← RPC・トランザクション操作
@x402/mcp           ← MCPトランスポート
  ├── server/           ← createPaymentWrapper
  └── client/           ← createX402MCPClient
@x402/express       ← Express用ミドルウェア
@x402/hono          ← Hono用ミドルウェア
@x402/next          ← Next.js用ミドルウェア

mkdir x402-mcp-server && cd x402-mcp-server
pnpm init
pnpm add @x402/mcp @x402/core @x402/svm \
  @modelcontextprotocol/sdk express zod \
  @solana/kit @scure/base
pnpm add -D typescript tsx @types/node @types/express

{
  "type": "module",
  "scripts": {
    "server": "tsx src/server.ts",
    "client": "tsx src/client.ts"
  }
}

x402-mcp-server/
├── src/
│   ├── server.ts   # MCPサーバー（x402 + StreamableHTTP）
│   └── client.ts   # MCPクライアント（x402決済対応）
├── .env            # SOLANA_WALLET_ADDRESS, SOLANA_PRIVATE_KEY
└── package.json

SOLANA_WALLET_ADDRESS=your-solana-wallet-address
SOLANA_PRIVATE_KEY=your-base58-encoded-private-key
FACILITATOR_URL=https://x402.org/facilitator

import { SOLANA_DEVNET_CAIP2, USDC_DEVNET_ADDRESS } from "@x402/svm";
// SOLANA_DEVNET_CAIP2  = "solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1"
// USDC_DEVNET_ADDRESS  = "4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU"

// サーバー側: parsePrice, enhancePaymentRequirements 等を持つ
import { ExactSvmScheme } from "@x402/svm/exact/server";

// クライアント側: createPaymentPayload, sign 等を持つ
import { ExactSvmScheme } from "@x402/svm";

// src/server.ts
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import { createMcpExpressApp } from "@modelcontextprotocol/sdk/server/express.js";
import { isInitializeRequest } from "@modelcontextprotocol/sdk/types.js";
import { createPaymentWrapper, x402ResourceServer } from "@x402/mcp";
import { HTTPFacilitatorClient } from "@x402/core/server";
import { ExactSvmScheme } from "@x402/svm/exact/server";
import { SOLANA_DEVNET_CAIP2, USDC_DEVNET_ADDRESS } from "@x402/svm";
import { z } from "zod";
import { randomUUID } from "node:crypto";

const facilitatorUrl = process.env.FACILITATOR_URL
  ?? "https://x402.org/facilitator";
const solanaAddress = process.env.SOLANA_WALLET_ADDRESS!;

async function main() {
  // 1. x402リソースサーバーを初期化
  const facilitatorClient = new HTTPFacilitatorClient({
    url: facilitatorUrl,
  });
  const resourceServer = new x402ResourceServer(facilitatorClient);
  resourceServer.register(SOLANA_DEVNET_CAIP2, new ExactSvmScheme());
  await resourceServer.initialize();

  // 2. 支払い条件を構築（$0.001 → amount: "1000"に自動変換）
  const paymentAccepts = await resourceServer.buildPaymentRequirements({
    scheme: "exact",
    network: SOLANA_DEVNET_CAIP2,
    payTo: solanaAddress,
    price: "$0.001",
  });

  // 3. セッション管理
  const transports: Record<string, StreamableHTTPServerTransport> = {};

  function createMcpServer() {
    const server = new McpServer({
      name: "x402-solana-mcp-server",
      version: "1.0.0",
    });

    const wrapWithPayment = createPaymentWrapper(resourceServer, {
      accepts: paymentAccepts,
    });

    // 無料ツール
    server.tool("ping", "Health check (free)", {}, async () => ({
      content: [{ type: "text", text: "pong" }],
    }));

    // 有料ツール（Payment Wrapperで包む）
    server.tool(
      "premium_weather",
      "Premium weather data ($0.001 USDC)",
      { city: z.string().describe("City name") },
      wrapWithPayment(async (args: { city: string }) => ({
        content: [{
          type: "text" as const,
          text: JSON.stringify({
            city: args.city,
            temperature: Math.round(Math.random() * 30 + 10),
            condition: ["sunny", "cloudy", "rainy"][
              Math.floor(Math.random() * 3)
            ],
          }, null, 2),
        }],
      })),
    );

    return server;
  }

  // 4. Express app（SDK helperを使用）
  const app = createMcpExpressApp();

  app.post("/mcp", async (req, res) => {
    const sessionId = req.headers["mcp-session-id"] as string | undefined;
    try {
      let transport: StreamableHTTPServerTransport;
      if (sessionId && transports[sessionId]) {
        transport = transports[sessionId];
      } else if (!sessionId && isInitializeRequest(req.body)) {
        transport = new StreamableHTTPServerTransport({
          sessionIdGenerator: () => randomUUID(),
          onsessioninitialized: (sid) => {
            transports[sid] = transport;
          },
        });
        transport.onclose = () => {
          const sid = transport.sessionId;
          if (sid && transports[sid]) delete transports[sid];
        };
        const server = createMcpServer();
        await server.connect(transport);
        await transport.handleRequest(req, res, req.body);
        return;
      } else {
        res.status(400).json({
          jsonrpc: "2.0",
          error: { code: -32000, message: "Bad Request" },
          id: null,
        });
        return;
      }
      await transport.handleRequest(req, res, req.body);
    } catch (error) {
      if (!res.headersSent) {
        res.status(500).json({
          jsonrpc: "2.0",
          error: { code: -32603, message: "Internal server error" },
          id: null,
        });
      }
    }
  });

  app.get("/mcp", async (req, res) => {
    const sessionId = req.headers["mcp-session-id"] as string;
    if (!sessionId || !transports[sessionId]) {
      res.status(400).send("Invalid or missing session ID");
      return;
    }
    await transports[sessionId].handleRequest(req, res);
  });

  app.delete("/mcp", async (req, res) => {
    const sessionId = req.headers["mcp-session-id"] as string;
    if (!sessionId || !transports[sessionId]) {
      res.status(400).send("Invalid or missing session ID");
      return;
    }
    await transports[sessionId].handleRequest(req, res);
  });

  const port = process.env.PORT ?? 4022;
  app.listen(port, () => {
    console.log(`x402 MCP Server running on http://localhost:${port}/mcp`);
  });
}

main().catch(console.error);

// src/client.ts
import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
import { createx402MCPClient } from "@x402/mcp";
import { ExactSvmScheme, SOLANA_DEVNET_CAIP2 } from "@x402/svm";
import { createKeyPairSignerFromBytes } from "@solana/kit";

async function main() {
  // 1. Solanaウォレットのセットアップ
  const { base58 } = await import("@scure/base");
  const signer = await createKeyPairSignerFromBytes(
    base58.decode(process.env.SOLANA_PRIVATE_KEY!),
  );
  console.log(`Address: ${signer.address}`);

  // 2. x402対応MCPクライアントを作成
  const client = createx402MCPClient({
    name: "my-ai-agent",
    version: "1.0.0",
    schemes: [
      {
        network: SOLANA_DEVNET_CAIP2,
        client: new ExactSvmScheme(signer),
      },
    ],
    autoPayment: true,
    onPaymentRequested: async (context) => {
      const price = context.paymentRequired.accepts?.[0];
      console.log(`Payment: ${price?.amount} on ${price?.network}`);
      return true;  // trueを返すと自動支払い
    },
  });

  // 3. MCPサーバーに接続（StreamableHTTPトランスポート）
  const transport = new StreamableHTTPClientTransport(
    new URL("http://localhost:4022/mcp"),
  );
  await client.connect(transport);

  // 4. ツール一覧の取得
  const tools = await client.listTools();
  console.log("Available tools:", tools.tools.map(t => t.name));

  // 5. 無料ツールの呼び出し
  const pingResult = await client.callTool("ping", {});
  console.log("Ping:", pingResult);
  // → { content: [{ text: "pong" }], paymentMade: false }

  // 6. 有料ツールの呼び出し（自動決済フロー）
  const weatherResult = await client.callTool(
    "premium_weather",
    { city: "Tokyo" },
  );
  console.log("Weather:", weatherResult);
  // → paymentMade: true（決済が試行された）

  await client.close();
}

main().catch(console.error);

export SOLANA_WALLET_ADDRESS="your-solana-wallet-address"
npx tsx src/server.ts

export SOLANA_PRIVATE_KEY="your-base58-encoded-private-key"
npx tsx src/client.ts

// config.ts - メインネット設定
export const paymentRequirements: PaymentRequirements[] = [
  {
    scheme: "exact",
    network: "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",  // メインネット
    amount: "10000",  // 0.01 USDC
    asset: "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",  // USDC メインネット
    payTo: process.env.SOLANA_WALLET_ADDRESS!,
    maxTimeoutSeconds: 60,
    extra: {},
  },
];

const paymentRequirements: PaymentRequirements[] = [
  // Solana USDC
  {
    scheme: "exact",
    network: "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    amount: "10000",
    asset: "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    payTo: "your-solana-wallet",
    maxTimeoutSeconds: 60,
    extra: {},
  },
  // Base USDC
  {
    scheme: "exact",
    network: "eip155:8453",
    amount: "10000",
    asset: "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    payTo: "your-evm-wallet",
    maxTimeoutSeconds: 60,
    extra: { name: "USDC", version: "2" },
  },
];

const wrapWithPayment = createPaymentWrapper(resourceServer, {
  accepts: paymentRequirements,
  hooks: {
    // 決済検証後、ツール実行前
    onBeforeExecution: async ({ payment, args }) => {
      console.log("Payment verified, executing tool...");
      // falseを返すとツール実行をキャンセル
      return true;
    },
    // ツール実行後、決済前
    onAfterExecution: async ({ payment, result }) => {
      console.log("Tool executed, settling payment...");
    },
    // 決済完了後
    onAfterSettlement: async ({ settlement }) => {
      console.log("Settlement:", settlement.transaction);
      // 売上レコードの保存、メトリクスの記録等
    },
  },
});