Add fallback RPC URLs for Base networks (#88)

* Add fallback RPC URLs for Base networks

* use viem values

* adjust signer construction

Author: spencerstock

packages/account-sdk/src/sign/base-account/Signer.ts

@@ -31,7 +31,7 @@ import {
 import { parseErrorMessageFromAny } from ':core/telemetry/utils.js';
 import { Address } from ':core/type/index.js';
 import { ensureIntNumber, hexStringFromNumber } from ':core/type/util.js';
-import { SDKChain, createClients, getClient } from ':store/chain-clients/utils.js';
+import { FALLBACK_CHAINS, SDKChain, createClients, getClient } from ':store/chain-clients/utils.js';
 import { correlationIds } from ':store/correlation-ids/store.js';
 import { store } from ':store/store.js';
 import { assertArrayPresence, assertPresence } from ':util/assertPresence.js';
@@ -90,9 +90,8 @@ export class Signer {
       id: params.metadata.appChainIds?.[0] ?? 1,
     };
 
-    if (chains) {
-      createClients(chains);
-    }
+    // Use fallback chains if no chains are provided
+    createClients(chains ?? FALLBACK_CHAINS);
   }
 
   public get isConnected() {

packages/account-sdk/src/store/chain-clients/utils.test.ts

@@ -1,9 +1,14 @@
-import { optimismSepolia, sepolia } from 'viem/chains';
+import { base, baseSepolia, optimismSepolia, sepolia } from 'viem/chains';
 
 import { ChainClients } from './store.js';
 import { createClients } from './utils.js';
 
 describe('chain-clients/utils', () => {
+  beforeEach(() => {
+    // Clear the ChainClients state before each test
+    ChainClients.setState(() => ({}), true);
+  });
+
   it('should create clients', () => {
     createClients([
       {
@@ -47,4 +52,81 @@ describe('chain-clients/utils', () => {
     expect(ChainClients.getState()[sepolia.id].bundlerClient).toBeDefined();
     expect(ChainClients.getState()[optimismSepolia.id].bundlerClient).toBeDefined();
   });
+
+  describe('fallback RPC URLs', () => {
+    it('should use fallback RPC URL for Base mainnet when wallet does not provide one', () => {
+      createClients([
+        {
+          id: base.id, // Base mainnet
+          // No rpcUrl provided
+        },
+      ]);
+
+      expect(ChainClients.getState()[base.id]).toBeDefined();
+      expect(ChainClients.getState()[base.id].client).toBeDefined();
+      expect(ChainClients.getState()[base.id].bundlerClient).toBeDefined();
+    });
+
+    it('should use fallback RPC URL for Base Sepolia when wallet does not provide one', () => {
+      createClients([
+        {
+          id: baseSepolia.id, // Base Sepolia
+          // No rpcUrl provided
+        },
+      ]);
+
+      expect(ChainClients.getState()[baseSepolia.id]).toBeDefined();
+      expect(ChainClients.getState()[baseSepolia.id].client).toBeDefined();
+      expect(ChainClients.getState()[baseSepolia.id].bundlerClient).toBeDefined();
+    });
+
+    it('should prefer wallet-provided RPC URL over fallback for Base mainnet', () => {
+      const customRpcUrl = 'https://custom.base.rpc.url';
+      createClients([
+        {
+          id: base.id, // Base mainnet
+          rpcUrl: customRpcUrl,
+        },
+      ]);
+
+      expect(ChainClients.getState()[base.id]).toBeDefined();
+      expect(ChainClients.getState()[base.id].client).toBeDefined();
+      // We can't directly test the RPC URL used, but we can verify the client was created
+    });
+
+    it('should not create client for unsupported chain without RPC URL', () => {
+      createClients([
+        {
+          id: 999999, // Unsupported chain
+          // No rpcUrl provided
+        },
+      ]);
+
+      expect(ChainClients.getState()[999999]).toBeUndefined();
+    });
+
+    it('should handle mixed chains with and without RPC URLs', () => {
+      createClients([
+        {
+          id: base.id, // Base mainnet - will use fallback
+        },
+        {
+          id: sepolia.id,
+          rpcUrl: sepolia.rpcUrls.default.http[0],
+        },
+        {
+          id: 999999, // Unsupported chain - will be skipped
+        },
+        {
+          id: baseSepolia.id, // Base Sepolia - will use fallback
+        },
+      ]);
+
+      expect(Object.keys(ChainClients.getState()).length).toBe(3);
+      expect(ChainClients.getState()[base.id]).toBeDefined();
+      expect(ChainClients.getState()[sepolia.id]).toBeDefined();
+      expect(ChainClients.getState()[baseSepolia.id]).toBeDefined();
+      expect(ChainClients.getState()[999999]).toBeUndefined();
+    });
+  });
 });

packages/account-sdk/src/store/chain-clients/utils.ts

@@ -1,25 +1,59 @@
 import { createPublicClient, defineChain, http, PublicClient } from 'viem';
 import { BundlerClient, createBundlerClient } from 'viem/account-abstraction';
+import { base, baseSepolia } from 'viem/chains';
 
-import { ChainClients } from './store.js';
 import { RPCResponseNativeCurrency } from ':core/message/RPCResponse.js';
+import { ChainClients } from './store.js';
 
 export type SDKChain = {
   id: number;
   rpcUrl?: string;
   nativeCurrency?: RPCResponseNativeCurrency;
 };
 
+// Fallback chains using viem's chain definitions directly
+export const FALLBACK_CHAINS: SDKChain[] = [
+  {
+    id: base.id,
+    rpcUrl: base.rpcUrls.default.http[0],
+    nativeCurrency: {
+      name: base.nativeCurrency.name,
+      symbol: base.nativeCurrency.symbol,
+      decimal: base.nativeCurrency.decimals,
+    },
+  },
+  {
+    id: baseSepolia.id,
+    rpcUrl: baseSepolia.rpcUrls.default.http[0],
+    nativeCurrency: {
+      name: baseSepolia.nativeCurrency.name,
+      symbol: baseSepolia.nativeCurrency.symbol,
+      decimal: baseSepolia.nativeCurrency.decimals,
+    },
+  },
+];
+
 export function createClients(chains: SDKChain[]) {
   chains.forEach((c) => {
-    if (!c.rpcUrl) {
+    // Use fallback RPC URL for Base networks if wallet hasn't provided one
+    let rpcUrl = c.rpcUrl;
+    if (!rpcUrl) {
+      const fallbackChain = FALLBACK_CHAINS.find((fc) => fc.id === c.id);
+      if (fallbackChain) {
+        rpcUrl = fallbackChain.rpcUrl;
+      }
+    }
+
+    // Skip if still no RPC URL available
+    if (!rpcUrl) {
       return;
     }
+
     const viemchain = defineChain({
       id: c.id,
       rpcUrls: {
         default: {
-          http: [c.rpcUrl],
+          http: [rpcUrl],
         },
       },
       name: c.nativeCurrency?.name ?? '',
@@ -32,19 +66,20 @@ export function createClients(chains: SDKChain[]) {
 
     const client = createPublicClient({
       chain: viemchain,
-      transport: http(c.rpcUrl),
+      transport: http(rpcUrl),
     });
     const bundlerClient = createBundlerClient({
       client,
-      transport: http(c.rpcUrl),
+      transport: http(rpcUrl),
     });
 
-    ChainClients.setState({
+    ChainClients.setState((state) => ({
+      ...state,
       [c.id]: {
         client,
         bundlerClient,
       },
-    });
+    }));
   });
 }