Connect with MetaMask Snap

Graz supports Cosmos accounts in MetaMask through Snap integrations. Use this guide when you want a small hello-world connection flow for MetaMask users.

Supported Snap wallet types

Graz exposes the MetaMask Snap wallet type for Cosmos:

Wallet type	Use when
WalletType.METAMASK_SNAP_COSMOS	Use the standard Cosmos Snap integration for MetaMask.

This option requires MetaMask in the user's browser. On first use, MetaMask may ask the user to install or approve the selected Snap.

Provider setup

Configure GrazProvider with the chains your app supports. MetaMask Snap connections use the same provider setup as other wallets.

App.tsx

import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
import { GrazProvider, WalletType } from "graz";
import { cosmoshub } from "graz/chains";

const queryClient = new QueryClient();

export function App() {
  return (
    <QueryClientProvider client={queryClient}>
      <GrazProvider
        grazOptions={{
          chains: [cosmoshub],
          defaultWallet: WalletType.METAMASK_SNAP_COSMOS,
        }}
      >
        <Wallet />
      </GrazProvider>
    </QueryClientProvider>
  );
}

Hello world connection

Use useCheckWallet to hide the action when MetaMask is not available, then connect with the Snap wallet type.

Wallet.tsx

import { useAccount, useCheckWallet, useConnect, useDisconnect, WalletType } from "graz";
import { cosmoshub } from "graz/chains";

const walletType = WalletType.METAMASK_SNAP_COSMOS;
const chainId = cosmoshub.chainId;

export function Wallet() {
  const { data: isSupported } = useCheckWallet(walletType);
  const { connect, status } = useConnect();
  const { disconnect } = useDisconnect();
  const { data: accounts, isConnected } = useAccount({ chainId: [chainId] });

  const account = accounts?.[chainId];

  if (!isSupported) {
    return <p>Install MetaMask to connect with MetaMask Snap.</p>;
  }

  return (
    <section>
      <p>{account ? `Connected as ${account.bech32Address}` : `Status: ${status}`}</p>
      <button
        onClick={() => {
          if (isConnected) {
            disconnect();
            return;
          }

          connect({
            chainId: [chainId],
            walletType,
          });
        }}
      >
        {isConnected ? "Disconnect" : "Connect MetaMask Snap"}
      </button>
    </section>
  );
}

Suggest and connect to a custom chain

If the target chain is not configured in GrazProvider, use useSuggestChainAndConnect. Graz adds the suggested chain to its internal store after the wallet accepts it.

import { Bech32Address } from "@keplr-wallet/cosmos";
import { useSuggestChainAndConnect, WalletType } from "graz";

const walletType = WalletType.METAMASK_SNAP_COSMOS;

const testnetChain = {
  chainId: "osmo-test-4",
  chainName: "Osmosis Testnet",
  rpc: "https://testnet-rpc.osmosis.zone",
  rest: "https://testnet-rest.osmosis.zone",
  bip44: {
    coinType: 118,
  },
  bech32Config: Bech32Address.defaultBech32Config("osmo"),
  stakeCurrency: {
    coinDenom: "OSMO",
    coinMinimalDenom: "uosmo",
    coinDecimals: 6,
  },
  currencies: [
    {
      coinDenom: "OSMO",
      coinMinimalDenom: "uosmo",
      coinDecimals: 6,
    },
  ],
  feeCurrencies: [
    {
      coinDenom: "OSMO",
      coinMinimalDenom: "uosmo",
      coinDecimals: 6,
    },
  ],
};

export function ConnectTestnet() {
  const { suggestAndConnect, status } = useSuggestChainAndConnect();

  return (
    <button
      onClick={() => {
        suggestAndConnect({
          chainInfo: testnetChain,
          walletType,
        });
      }}
    >
      Connect Osmosis Testnet with MetaMask Snap ({status})
    </button>
  );
}

Troubleshooting

• If useCheckWallet(WalletType.METAMASK_SNAP_COSMOS) returns false, confirm MetaMask is installed and enabled in the browser.
• If another extension also injects window.ethereum, keep MetaMask enabled and retry. Graz selects the MetaMask provider when multiple Ethereum providers are present.
• If the Snap install prompt does not appear, check MetaMask's Snap settings and remove any rejected or partially installed Snap entry before retrying.
• If chain suggestion fails, verify that the chain has complete ChainInfo, including bech32Config, stakeCurrency, currencies, and feeCurrencies.