sign-multichain-solana-transaction

Sign Solana Transactions via Multichain Client

When to use

Use this skill when:

• Signing or sending Solana transactions through invokeMethod on a multichain client
• Building Solana transactions with @solana/web3.js and encoding them for the multichain API
• Signing Solana messages through the multichain client
• Selecting the correct Solana CAIP-2 scope (mainnet, devnet)
• Disconnecting only Solana scopes while keeping EVM sessions active

Workflow

Step 1: Connect with Solana 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', 'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp'] }),
    },
  },
});

await client.connect(
  [
    'eip155:1',
    'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp', // mainnet
  ],
  [],
); // resolves with no value — read session via client.provider.getSession()

Solana CAIP-2 scope identifiers:

Network	CAIP-2 Scope
Mainnet	solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp
Devnet	solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1
Testnet	solana:4uhcVJyU9pJkvQyS88uRDiswHXSCkY3z

All three Solana scopes are modeled by the SDK; non-mainnet availability depends on the connected MetaMask build/version, so handle connection errors rather than assuming a cluster is present.

Step 2: Understand Solana RPC routing

All Solana methods route through the wallet. Unlike EVM where read calls go to an RPC node, every Solana invokeMethod call is handled by MetaMask. There is no RPC node fallback for Solana.

Step 3: Sign a message (signMessage)

Method names have no solana_ prefix. The message must be base64 encoded, and the signing account is passed as account: { address }.

const message = btoa('Hello from Solana via MetaMask!');

const result = await client.invokeMethod({
  scope: 'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp',
  request: {
    method: 'signMessage',
    params: {
      account: { address: 'YourSolanaAddressBase58' },
      message,
    },
  },
});

// result: { signature: <base58 string>, signedMessage: <base64>, signatureType: 'ed25519' }
console.log('Signature:', result.signature);