Bridge with ERC-4337

This guide covers prerequisites, how to create an ERC-4337 account, and how to call the bridge with paymaster configuration.

Prerequisites

• Bundler and paymaster endpoints for your chain (example uses Arbitrum public URLs from the API reference).
• An ERC-4337 source chain with a configured transaction-value helper: Ethereum, Arbitrum, Plasma, or Polygon.

Bridge beta.10 uses concrete classes from its exact ERC-4337 wallet beta.11 dependency. For this helper and approval-batching flow, install that pair in an isolated dependency boundary:

npm install --save-exact @tetherto/wdk-protocol-bridge-usdt0-evm@1.0.0-beta.10 @tetherto/wdk-wallet-evm-erc-4337@1.0.0-beta.11
npm ls @tetherto/wdk-wallet-evm-erc-4337 --all

The dependency tree must contain only @tetherto/wdk-wallet-evm-erc-4337@1.0.0-beta.11, with the bridge's entry marked deduped. If it also shows beta.20 at the application root and beta.11 beneath the bridge, the beta.20 account is a different class instance. Bridge beta.10 then takes its non-batched standard path, skips the transaction-value helper and per-call ERC-4337 configuration, and does not combine approval with the bridge call.

Do not override the bridge's dependency to beta.20 or downgrade an application that needs beta.20. Keep that application on the standard account flow, or isolate this exact beta.10/beta.11 pair in a separate package. The sendTransaction() capability check alone does not enable batching. See account requirements.

Create a WalletAccountEvmErc4337 account

The exact beta.11 package publicly exports WalletAccountEvmErc4337 and accepts seed, path, and a configuration with chain, provider, bundler, Safe modules, and paymaster fields:

import { WalletAccountEvmErc4337 } from '@tetherto/wdk-wallet-evm-erc-4337'

const seedPhrase = 'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about'

const account = new WalletAccountEvmErc4337(seedPhrase, "0'/0/0", {
  chainId: 42161,
  provider: 'https://arb1.arbitrum.io/rpc',
  bundlerUrl: 'https://api.candide.dev/public/v3/42161',
  safeModulesVersion: '0.3.0',
  paymasterUrl: 'https://api.candide.dev/public/v3/42161',
  paymasterAddress: '0x8b1f6cb5d062aa2ce8d581942bbb960420d875ba',
  paymasterToken: { address: '0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9' }
})

You can wrap that account with the new Usdt0ProtocolEvm(account, config?) constructor:

import Usdt0ProtocolEvm from '@tetherto/wdk-protocol-bridge-usdt0-evm'

const bridgeProtocol = new Usdt0ProtocolEvm(account)

Run a gasless bridge with paymaster options

You can execute bridge() with a second argument that includes paymasterToken and an optional bridgeMaxFee override. Do not submit a separate account.approve() call for this flow. The normal ERC-4337 batch is an ERC20 approval to the source-chain transaction-value helper followed by the helper bridge call, submitted in one UserOperation. On Ethereum mainnet, when the resolved token is USD₮ at 0xdAC17F958D2ee523a2206206994597C13D831ec7, the protocol queries the same ERC-4337 account's allowance for that token and helper spender. If the current allowance and computed approveAmount are both greater than zero, it prepends approve(spender, 0), then approve(spender, approveAmount), then the helper bridge call. quoteBridge() uses the same ordering for a WalletAccountReadOnlyEvmErc4337. Standard EVM accounts and every other chain/token path are unchanged.

const USDT_TOKEN_ADDRESS = process.env.USDT_SOURCE_TOKEN_ADDRESS
const USDT0_OFT_ADDRESS = process.env.USDT0_OFT_ADDRESS
const amount = 1000000n
const paymasterToken = { address: '0xFd086bC7CD5C481DCC9C85ebE478A1C0b69FCbb9' }

try {
  const result = await bridgeProtocol.bridge(
    {
      targetChain: 'polygon',
      recipient: '0x742d35Cc6634C0532925a3b8D4C9db96C4b4d8b6',
      token: USDT_TOKEN_ADDRESS,
      amount,
      oftContractAddress: USDT0_OFT_ADDRESS
    },
    {
      paymasterToken
    }
  )

  console.log('Bridge hash:', result.hash)
  console.log('Account fee:', result.fee)
  console.log('Bridge fee:', result.bridgeFee)
} finally {
  account.dispose()
}

Next Steps

Bridge to non-EVM chains in Bridge cross-ecosystem. For failure modes and cleanup, read Handle errors.

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