Bundler Client

The Bundler Client is a key component in the AbstractJS SDK that provides an interface to interact with ERC-4337 bundlers for sending and managing User Operations in account abstraction implementations.

Overview

A Bundler Client enables smart contract wallets to execute transactions through the ERC-4337 protocol, allowing for features like gasless transactions, batched operations, and custom authorization logic. This client extends the standard bundler functionality with Biconomy-specific enhancements.

Import

import { createBicoBundlerClient, http } from '@biconomy/abstractjs'

Usage

Initialize a Bundler Client with your desired Chain and Transport options:

import { createBicoBundlerClient, http } from '@biconomy/abstractjs'
import { mainnet } from 'viem/chains'
 
const bundlerClient = createBicoBundlerClient({ 
  chain: mainnet,
  apiKey: 'YOUR_API_KEY_HERE' // Optional
})

Configuration

The createBicoBundlerClient function accepts the following parameters:

type BicoBundlerClientConfig = {
  /**
   * Whether to use the test bundler. Conditionally used by the `getGasFeeValues` decorator.
   */
  mock?: boolean
  
  /**
   * The chain to use for the bundler client
   */
  chain?: Chain
  
  /**
   * Optional paymaster configuration
   */
  paymaster?: BundlerClientConfig["paymaster"]
  
  /**
   * Optional paymaster context
   */
  paymasterContext?: unknown
  
  /**
   * Optional user operation configuration
   */
  userOperation?: BundlerClientConfig["userOperation"]
} & OneOf<
  | { transport: Transport }
  | { bundlerUrl: string }
  | { apiKey?: string }
>

You must provide one of the following:

A custom transport instance
A bundlerUrl endpoint
An apiKey (which will use Biconomy's bundler endpoint)
A chain (which will use Biconomy's default bundler endpoint)

Key Features

The Bundler Client provides several actions for working with User Operations:

Standard Bundler Actions

estimateUserOperationGas: Estimates gas costs for a User Operation
sendUserOperation: Sends a User Operation to the bundler
getUserOperationReceipt: Gets the receipt of a User Operation
supportedEntryPoints: Gets the entry points supported by the bundler
getUserOperationByHash: Gets a User Operation by its hash

Biconomy-Specific Actions

getGasFeeValues: Gets recommended gas fee values (slow, standard, fast)
getUserOperationStatus: Gets the status of a User Operation
waitForUserOperationReceipt: Waits for a User Operation receipt
waitForConfirmedUserOperationReceipt: Waits for a confirmed User Operation receipt

ERC-7579 Actions

The client also includes ERC-7579 support for modular smart accounts.

Smart Account Actions

Additional actions for working with smart accounts are available.

Example

Here's an example of sending a User Operation and waiting for its receipt:

import { createBicoBundlerClient, http } from '@biconomy/abstractjs'
import { mainnet } from 'viem/chains'
import { toNexusAccount } from '@biconomy/abstractjs'
 
// Create a Nexus Account
const nexusAccount = await toNexusAccount({
  signer: account, // Your signer account
  chain: mainnet,
  transport: http()
})
 
// Create a Bundler Client
const bundlerClient = createBicoBundlerClient({
  chain: mainnet,
  account: nexusAccount
})
 
// Get gas fees
const gasFees = await bundlerClient.getGasFeeValues()
 
// Send a user operation
const hash = await bundlerClient.sendUserOperation({
  ...gasFees.fast,
  calls: [
    { 
      to: '0xYourAddress', 
      value: 1n 
    }
  ],
  account: nexusAccount
})
 
// Wait for the receipt
const receipt = await bundlerClient.waitForUserOperationReceipt({ hash })
console.log('Transaction successful:', receipt.success)

Gas Buffer Configuration

You can add a buffer to the gas estimates to ensure your transactions don't fail due to gas estimation inaccuracies:

const userOperation = await bundlerClient.prepareUserOperation({
  gasBuffer: {
    factor: 1.2, // 20% buffer
    fields: ["preVerificationGas", "verificationGasLimit"]
  },
  calls: [
    {
      to: account.address,
      value: 1n
    }
  ]
})

Aliases

For backward compatibility, the following aliases are provided:

import { 
  createBicoBundlerClient, 
  createNexusClient, 
  createNexusSessionClient 
} from '@biconomy/abstractjs'
 
// All of these are equivalent to createBicoBundlerClient