Nexus Account

The Nexus Account is a smart contract account that enables powerful account abstraction features and cross-chain functionality within the AbstractJS SDK.

Overview

The Nexus Account provides a seamless way to interact with smart contracts across multiple chains while leveraging account abstraction capabilities (ERC-4337). It serves as the foundation for executing transactions through both the Bundler Client and MEE Client.

Modularity & Benefits

Nexus implements the ERC-7579 modular smart account standard with five key module types:

Validator Modules: Handle transaction authorization and signature validation
Executor Modules: Execute custom transaction logic across protocols
Hook Modules: Perform checks before and after transaction execution
Fallback Modules: Handle specialized contract interactions
Prevalidation Hooks: Process transaction details before validation

This modular architecture delivers significant advantages:

User Experience

Gasless transactions with any token for gas fees
Batch multiple operations in single transactions
Transaction automation and session keys

Security

Custom validation rules and multi-signature support
Account recovery mechanisms
Spending limits and transaction guards

Cross-Chain

Interact with multiple blockchains using a single account
Build complex workflows with runtime-resolved values
Seamless asset transfers between networks

The modular design ensures Nexus accounts can adapt to evolving blockchain ecosystems while maintaining security and user-friendliness.

Key Features

Feature	Description
Account Abstraction	Based on ERC-4337 standard for gasless transactions and batch operations
Cross-Chain Support	Works seamlessly across multiple blockchain networks
Modular Architecture	Supports customizable validation modules and executor modules
Composability	Enables complex cross-chain transactions through runtime values
EIP-1271 Signatures	Native support for contract-based signatures verification
Delegation	Ability to delegate transaction authorization via EIP-7702

Creating a Nexus Account

import { toNexusAccount } from '@biconomy/abstractjs';
import { createWalletClient, http } from 'viem';
import { mainnet } from 'viem/chains';
 
// Create a basic Nexus account with default settings
const nexusAccount = await toNexusAccount({
  chain: mainnet,
  transport: http(),
  signer: yourSigner // EOA, private key, or other signer
});
 
// Create a Nexus account with custom settings
const customNexusAccount = await toNexusAccount({
  chain: mainnet,
  transport: http(),
  signer: yourSigner,
  index: 1n, // Optional salt for account address derivation
  validators: [customValidator], // Custom validator modules
  executors: [customExecutor], // Custom executor modules
  hook: customHook, // Custom hook module
  fallbacks: [customFallback] // Custom fallback modules
});

Core Methods

Method	Description
`getAddress()`	Gets the counterfactual address of the account
`getInitCode()`	Gets the initialization code required for account deployment
`encodeExecute(call)`	Encodes a single transaction call
`encodeExecuteBatch(calls)`	Encodes multiple transaction calls for batch execution
`encodeExecuteComposable(calls)`	Encodes calls for composable execution with runtime values
`signMessage(message)`	Signs a message using the account's active module
`signTypedData(data)`	Signs typed data (EIP-712) with the account
`getNonce()`	Gets the current nonce for the account
`getModule()`	Gets the active validation module
`setModule(validationModule)`	Sets a new active validation module
`toDelegation()`	Creates authorization data for EOA to smart account delegation
`unDelegate()`	Revokes previous delegation
`isDelegated()`	Checks if the account is currently delegated

Important Notes

When using composable transactions with runtime values (such as runtimeERC20BalanceOf), you must use encodeExecuteComposable() method.
The account can be used with both the Bundler Client for regular transactions and the MEE Client for cross-chain operations.
For security-sensitive operations, you can configure custom validation modules that implement different signature validation schemes.

Bundler Client Methods

The Nexus Account can be used with the Bundler Client to perform various operations. See the following method references for detailed information:

sendUserOperation - Submit a custom User Operation
sendTokenPaymasterUserOp - Send a transaction with ERC-20 token for gas
waitForUserOperationReceipt - Wait for a User Operation to be confirmed
estimateUserOperationGas - Estimate gas for a User Operation
getUserOperation - Retrieve information about a User Operation
getUserOperationReceipt - Get the receipt for a User Operation
prepareUserOperation - Prepare a User Operation without sending it
prepareTokenPaymasterUserOp - Prepare a User Operation with token paymaster
getSupportedEntryPoints - Get the supported EntryPoints
getChainId - Get the current chain ID
debugUserOperation - Debug a User Operation
upgradeSmartAccount - Upgrade your Nexus Account implementation

For a complete overview of all available methods, see the methods index.