setup-multichain-app

Setup Multichain App with MetaMask

When to use

Use this skill when:

• Building an app that needs both EVM and Solana wallet connectivity through a single MetaMask session
• Using createMultichainClient from @metamask/connect-multichain
• Calling invokeMethod with CAIP-2 scopes for cross-chain RPC or signing
• Handling wallet_sessionChanged events for multichain session state
• Running in headless mode with custom QR rendering via display_uri
• Configuring getInfuraRpcUrls for EVM and Solana RPC transport

Workflow

Step 1: Install dependencies

npm install @metamask/connect-multichain

For Solana transaction building (optional):

npm install @solana/web3.js

Step 2: Create the multichain client

createMultichainClient is a singleton — calling it multiple times returns the same instance with merged options. Never recreate it per render.

import { createMultichainClient, getInfuraRpcUrls } from '@metamask/connect-multichain';

const client = await createMultichainClient({
  dapp: {
    name: 'My Multichain DApp',
    url: window.location.href,
    iconUrl: 'https://mydapp.com/icon.png', // optional (or use base64Icon for embedded icons)
  },
  api: {
    supportedNetworks: {
      ...getInfuraRpcUrls({ infuraApiKey: 'YOUR_INFURA_API_KEY', caipChainIds: ['eip155:1', 'eip155:137', 'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp'] }),
    },
  },
  ui: {
    headless: false, // set true for custom QR rendering
  },
});

getInfuraRpcUrls({ infuraApiKey, caipChainIds? }) returns a CAIP-2 keyed map of Infura RPC URLs for supported networks (EVM chains and Solana). Pass caipChainIds to limit the output to specific chains. Merge with any custom network RPCs.

Singleton behavior: The dapp object from the first call is used for the lifetime of the client — it is ignored on subsequent calls (not merged). Call createMultichainClient once at app startup.

Step 3: Connect with mixed EVM + Solana scopes