Add x402 monetization - let AI agents pay per API call

.well-known/x402.json

@@ -0,0 +1,23 @@
+{
+  "name": "formulahendry/mcp-server-code-runner",
+  "description": "Code Runner MCP Server",
+  "accepts": [
+    {
+      "network": "eip155:8453",
+      "asset": "USDC",
+      "address": "YOUR_WALLET_ADDRESS"
+    }
+  ],
+  "resources": [
+    {
+      "path": "/code-runner",
+      "price": "0.01",
+      "description": "Pay-per-call access to code-runner"
+    },
+    {
+      "path": "/server",
+      "price": "0.01",
+      "description": "Pay-per-call access to server"
+    }
+  ]
+}

x402-middleware-example.ts

@@ -0,0 +1,25 @@
+// x402 payment middleware - add before your protected routes
+import { createPaymentMiddleware } from 'x402-express'; // or implement manually
+
+// Option A: use the x402-express package
+app.use('/api', createPaymentMiddleware({
+  walletAddress: process.env.X402_WALLET_ADDRESS,
+  network: 'eip155:8453', // Base mainnet
+  facilitatorUrl: 'https://facilitator.402.bot/verify',
+}));
+
+// Option B: manual (just check the payment header)
+app.use('/api', (req, res, next) => {
+  const payment = req.headers['x-payment'];
+  if (!payment) {
+    // Return 402 with payment requirements
+    res.status(402).json({
+      accepts: [{ network: 'eip155:8453', asset: 'USDC', address: process.env.X402_WALLET_ADDRESS }],
+      price: '0.01',
+    });
+    return;
+  }
+  // Verify payment with facilitator
+  // See: https://api.402.bot/mcp/setup
+  next();
+});