Setup AbstractJS

npm install @biconomy/abstractjs viem

import { 
  createMeeClient, 
  toMultichainNexusAccount,
  getMEEVersion,
  MEEVersion 
} from "@biconomy/abstractjs";
import { http } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { base, optimism } from "viem/chains";

// 1. Create a signer (user's wallet)
const signer = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`);

// 2. Create multichain account
const account = await toMultichainNexusAccount({
  signer,
  chainConfigurations: [
    { chain: optimism, transport: http(), version: getMEEVersion(MEEVersion.V2_1_0) },
    { chain: base, transport: http(), version: getMEEVersion(MEEVersion.V2_1_0) }
  ]
});

// 3. Create MEE client
const meeClient = await createMeeClient({ account });

const account = await toMultichainNexusAccount({
  signer,
  chainConfigurations: [
    { 
      chain: base, 
      transport: http(), 
      version: getMEEVersion(MEEVersion.V2_1_0),
      accountAddress: signer.address  // Use EOA directly
    }
  ]
});

// Get address on a specific chain
const baseAddress = account.addressOn(base.id);

// Get address with strict mode (throws if chain is not defined in chainConfigurations)
const strictAddress = account.addressOn(base.id, true);