sign-multichain-evm-transaction

Sign EVM Transactions via Multichain Client

When to use

Use this skill when:

• Sending EVM transactions through invokeMethod on a multichain client
• Signing messages with personal_sign or eth_signTypedData_v4
• Understanding which methods route to the RPC node vs the wallet
• Selecting the correct CAIP-2 EVM scope for a target chain

Workflow

Step 1: Ensure the client is connected with EVM scopes

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

const client = await createMultichainClient({
  dapp: { name: 'My DApp', url: window.location.href },
  api: {
    supportedNetworks: {
      ...getInfuraRpcUrls({ infuraApiKey: 'YOUR_INFURA_KEY', caipChainIds: ['eip155:1', 'eip155:137'] }),
    },
  },
});

await client.connect(
  ['eip155:1', 'eip155:137'], // Ethereum mainnet + Polygon
  [],
);

Step 2: Understand RPC routing

The multichain client routes EVM methods based on type:

Route	Methods	Transport
RPC node	eth_call, eth_getBalance, eth_blockNumber, eth_getTransactionReceipt, eth_estimateGas, eth_getCode, eth_getLogs, eth_getTransactionCount	Infura / custom RPC URL from supportedNetworks
Wallet	eth_sendTransaction, personal_sign, eth_signTypedData_v4, wallet_switchEthereumChain, wallet_addEthereumChain	MetaMask (extension or MWP)

The scope in invokeMethod determines which chain the request targets. Use 'eip155:1' for Ethereum mainnet, 'eip155:137' for Polygon, etc.

Step 3: Send a transaction (eth_sendTransaction)

const txHash = await client.invokeMethod({
  scope: 'eip155:1',
  request: {
    method: 'eth_sendTransaction',
    params: [{
      from: '0xYourAddress',
      to: '0xRecipientAddress',
      value: '0x2386F26FC10000', // 0.01 ETH in hex wei
      gas: '0x5208',            // 21000 gas
      // gasPrice or maxFeePerGas/maxPriorityFeePerGas optional
    }],
  },
});

console.log('Transaction hash:', txHash);