Add support for multiple payment methods eip-3009 | erc-7710

Author: jeffsmale90

packages/x402-example/src/client.ts

@@ -1,5 +1,7 @@
 import { config } from 'dotenv';
 import { x402Client, x402HTTPClient } from '@x402/core/client';
+import { toClientEvmSigner } from '@x402/evm';
+import { ExactEvmScheme } from '@x402/evm/exact/client';
 import { wrapFetchWithPayment } from '@x402/fetch';
 import {
   CaveatType,
@@ -12,7 +14,9 @@ import {
 import { encodeDelegations } from '@metamask/smart-accounts-kit/utils';
 import { x402Erc7710Client } from '@metamask/smart-accounts-kit-x402';
 import {
+  createPublicClient,
   getAddress,
+  http,
   type Hex,
 } from 'viem';
 import { privateKeyToAccount } from 'viem/accounts';
@@ -23,12 +27,16 @@ config();
 type CliConfig = {
   privateKey: Hex;
   url: string;
+  paymentMethod: 'erc7710' | 'eip3009';
+  rpcUrl?: string;
 };
 
 function parseCliConfig(): CliConfig {
   const args = process.argv.slice(2);
   const keyArgIndex = args.findIndex((arg) => arg === '--private-key');
   const urlArgIndex = args.findIndex((arg) => arg === '--url');
+  const methodArgIndex = args.findIndex((arg) => arg === '--payment-method');
+  const rpcUrlArgIndex = args.findIndex((arg) => arg === '--rpc-url');
 
   const privateKeyFromArg =
     keyArgIndex >= 0 ? (args[keyArgIndex + 1] as Hex | undefined) : undefined;
@@ -44,7 +52,22 @@ function parseCliConfig(): CliConfig {
   const urlFromArg = urlArgIndex >= 0 ? args[urlArgIndex + 1] : undefined;
   const url = urlFromArg ?? process.env.X402_URL ?? 'http://localhost:4021/random';
 
-  return { privateKey, url };
+  const paymentMethodFromArg =
+    methodArgIndex >= 0 ? args[methodArgIndex + 1] : undefined;
+  const paymentMethod =
+    paymentMethodFromArg ?? process.env.X402_PAYMENT_METHOD ?? 'erc7710';
+
+  if (paymentMethod !== 'erc7710' && paymentMethod !== 'eip3009') {
+    throw new Error(
+      `Unsupported payment method "${paymentMethod}". Expected "erc7710" or "eip3009"`,
+    );
+  }
+
+  const rpcUrlFromArg =
+    rpcUrlArgIndex >= 0 ? args[rpcUrlArgIndex + 1] : undefined;
+  const rpcUrl = rpcUrlFromArg ?? process.env.X402_RPC_URL ?? process.env.RPC_URL;
+
+  return { privateKey, url, paymentMethod, rpcUrl };
 }
 
 function parseChainIdFromNetwork(network: string): number {
@@ -64,8 +87,21 @@ function parseChainIdFromNetwork(network: string): number {
 
 
 async function main() {
-  const { privateKey, url } = parseCliConfig();
+  const { privateKey, url, paymentMethod, rpcUrl } = parseCliConfig();
   const account = privateKeyToAccount(privateKey);
+  const permit2Signer = (() => {
+    if (!rpcUrl) {
+      return account;
+    }
+
+    const publicClient = createPublicClient({
+      transport: http(rpcUrl),
+    });
+
+    return toClientEvmSigner(account, publicClient);
+  })();
+
+  const exactEvmClient = new ExactEvmScheme(permit2Signer);
 
   const erc7710Client = new x402Erc7710Client({
     delegationProvider: async (requirements) => {
@@ -114,10 +150,39 @@ async function main() {
     },
   });
 
-  const httpClient = new x402HTTPClient(new x402Client().register(
-    'eip155:*',
-    erc7710Client
-  ));
+  const selectedClient =
+    paymentMethod === 'erc7710' ? erc7710Client : exactEvmClient;
+
+  const coreClient = new x402Client()
+    .register('eip155:*', selectedClient)
+    .registerPolicy((_x402Version, paymentRequirements) => {
+      const filtered = paymentRequirements.filter(
+        (requirements) =>
+          requirements.extra?.assetTransferMethod === paymentMethod,
+      );
+
+      if (filtered.length > 0) {
+        return filtered;
+      }
+
+      const availableMethods = [
+        ...new Set(
+          paymentRequirements
+            .map((requirements) => requirements.extra?.assetTransferMethod)
+            .filter((method): method is string => typeof method === 'string'),
+        ),
+      ];
+
+      throw new Error(
+        `Requested payment method "${paymentMethod}" was not offered by the server. Available methods: ${
+          availableMethods.length > 0
+            ? availableMethods.join(', ')
+            : 'none'
+        }`,
+      );
+    });
+
+  const httpClient = new x402HTTPClient(coreClient);
 
   const fetchWithPayment = wrapFetchWithPayment(fetch, httpClient);
 

packages/x402-example/src/server.ts

@@ -2,7 +2,6 @@ import { config } from 'dotenv';
 import express from 'express';
 import { HTTPFacilitatorClient } from '@x402/core/server';
 import { paymentMiddleware, x402ResourceServer } from '@x402/express';
-import { ExactEvmScheme } from '@x402/evm/exact/server';
 import {
   type Network,
 } from '@x402/core/types';
@@ -24,6 +23,10 @@ const network = (process.env.NETWORK ?? 'eip155:84532') as Network;
 const port = Number(process.env.PORT ?? 4021);
 const price = '1000' as const;
 const acceptedToken = '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913' as const;
+const acceptedTokenEip712Domain = {
+  name: 'USD Coin',
+  version: '2',
+} as const;
 
 const facilitatorClient = new HTTPFacilitatorClient({ url: facilitatorUrl });
 const app = express();
@@ -55,6 +58,7 @@ app.use(
             },
             extra: {
               assetTransferMethod: 'eip3009',
+              ...acceptedTokenEip712Domain,
             },
           },
         ],
@@ -76,6 +80,6 @@ app.get('/random', (_req: unknown, res: { type: (value: string) => { send: (valu
 
 app.listen(port, () => {
   console.log(
-    `x402 ERC-7710 example server listening on http://localhost:${port}/random`,
+    `x402 ERC-7710 + EIP-3009 example server listening on http://localhost:${port}/random`,
   );
 });