Bridge USD₮0 EVM Configuration
Configuration options and settings for @tetherto/wdk-protocol-bridge-usdt0-evm
Bridge Protocol Configuration
The Usdt0ProtocolEvm accepts a configuration object that defines how the bridge protocol works:
import Usdt0ProtocolEvm from '@tetherto/wdk-protocol-bridge-usdt0-evm'
import { WalletAccountEvm } from '@tetherto/wdk-wallet-evm'
// Create wallet account first
const account = new WalletAccountEvm(seedPhrase, "0'/0/0", {
provider: 'https://eth.drpc.org'
})
// Create bridge protocol with configuration
const bridgeProtocol = new Usdt0ProtocolEvm(account, {
bridgeMaxFee: 1000000000000000n // Optional standard-account cap in source native base units
})Account Configuration
The bridge protocol uses the wallet account's configuration for blockchain access:
import { WalletAccountEvm, WalletAccountReadOnlyEvm } from '@tetherto/wdk-wallet-evm'
// Full access account
const account = new WalletAccountEvm(
seedPhrase,
"0'/0/0", // BIP-44 derivation path
{
provider: 'https://eth.drpc.org',
transferMaxFee: 100000000000000
}
)
// Read-only account
const readOnlyAccount = new WalletAccountReadOnlyEvm(
'0x...', // Ethereum address
{
provider: 'https://eth.drpc.org'
}
)
// Create bridge protocol
const bridgeProtocol = new Usdt0ProtocolEvm(account, {
bridgeMaxFee: 1000000000000000n
})Configuration Options
Bridge Max Fee
The bridgeMaxFee option rejects bridge() when the implementation's fee + bridgeFee value is equal to or greater than the cap.
Type: number | bigint (optional)
For a standard EVM account, both fields use the source chain's native base unit. For example, Ethereum and Arbitrum report the values in wei.
For an ERC-4337 helper flow, bridgeFee is in bridged-token base units. The account's fee uses native base units for native gas, paymaster-token base units for token-paid gas, or zero for sponsored gas. In 1.0.0-beta.7, the protocol numerically adds these values when enforcing bridgeMaxFee. Do not treat that sum as one currency or set a cap until your payment mode uses compatible units.
Examples:
const config = {
// Standard Ethereum account: reject fee + bridgeFee at or above 0.001 ETH
bridgeMaxFee: 1000000000000000n,
}
// Usage example
try {
await account.approve({
token: '0x...', // USDT contract address
spender: '0x...', // OFT or bridge spender address
amount: 1000000n
})
const result = await bridgeProtocol.bridge({
targetChain: 'arbitrum',
recipient: '0x...', // Recipient address
token: '0x...', // USDT contract address
amount: 1000000n,
oftContractAddress: '0x...' // Same address used as approval spender
})
} catch (error) {
if (error.message.includes('Exceeded maximum fee')) {
console.error('Bridge cancelled: Fee too high')
}
}Provider
The provider option comes from the wallet account configuration and specifies how to connect to the blockchain.
Type: string | Eip1193Provider
Examples:
// Option 1: Using RPC URL
const account = new WalletAccountEvm(seedPhrase, "0'/0/0", {
provider: 'https://eth.drpc.org'
})
// Option 2: Using browser provider (e.g., MetaMask)
const account = new WalletAccountEvm(seedPhrase, "0'/0/0", {
provider: window.ethereum
})
Pass either an RPC URL string or a genuine EIP-1193 provider. An ethers JsonRpcProvider is not an EIP-1193 provider and is not accepted by this wallet release.
ERC-4337 Configuration
When using ERC-4337 accounts, you can override configuration options during bridge operations:
// Bridge with ERC-4337 account
const result = await bridgeProtocol.bridge({
targetChain: 'arbitrum',
recipient: '0x...', // Recipient address
token: '0x...', // USDT contract address
amount: 1000000n,
oftContractAddress: '0x...' // Optional custom OFT contract
}, {
paymasterToken: { address: '0x...' } // Paymaster token for gasless transactions
})The protocol builds the token approval and transaction-value-helper call and submits them as one UserOperation. Do not call account.approve() separately for this flow.
ERC-4337 helper bridging is configured for these source chains:
| Source chain | Chain ID |
|---|---|
| Ethereum | 1 |
| Arbitrum | 42161 |
| Plasma | 9745 |
| Polygon | 137 |
Other supported EVM source chains require a standard EVM account.
Paymaster Token
The paymasterToken option specifies which token to use for paying gas fees in ERC-4337 accounts.
Type: { address: string } (optional)
Format: Object with token contract address
Example:
const result = await bridgeProtocol.bridge({
targetChain: 'arbitrum',
recipient: '0x...', // Recipient address
token: '0x...', // USDT contract address
amount: 1000000n,
oftContractAddress: '0x...' // Optional custom OFT contract
}, {
paymasterToken: {
address: '0x...' // Paymaster token address
}
})Network Support
The bridge protocol uses EVM wallet providers as source chains and supports both EVM and non-EVM destinations. Change the provider URL in the wallet account configuration:
// Ethereum Mainnet
const ethereumAccount = new WalletAccountEvm(seedPhrase, "0'/0/0", {
provider: 'https://eth.drpc.org'
})
// Arbitrum
const arbitrumAccount = new WalletAccountEvm(seedPhrase, "0'/0/0", {
provider: 'https://arb1.arbitrum.io/rpc'
})
// Polygon
const polygonAccount = new WalletAccountEvm(seedPhrase, "0'/0/0", {
provider: 'https://polygon-rpc.com'
})Bridge Options
When calling the bridge method, you need to provide bridge options. The following allowance step applies to a standard EVM account:
const bridgeOptions = {
targetChain: 'arbitrum', // Destination chain name
recipient: '0x...', // Recipient address
token: '0x...', // USDT contract address
amount: 1000000n, // Amount to bridge in base units
oftContractAddress: '0x...', // Optional custom OFT contract address
dstEid: 30110 // Optional LayerZero destination endpoint ID override
}
await account.approve({
token: bridgeOptions.token,
spender: bridgeOptions.oftContractAddress,
amount: bridgeOptions.amount
})
const result = await bridgeProtocol.bridge(bridgeOptions)Target Chain
The targetChain option specifies which blockchain to bridge tokens to.
Type: string
Supported values: 'ethereum', 'arbitrum', 'optimism', 'polygon', 'berachain', 'ink', 'plasma', 'conflux', 'corn', 'avalanche', 'celo', 'flare', 'hyperevm', 'mantle', 'megaeth', 'monad', 'morph', 'rootstock', 'sei', 'stable', 'unichain', 'xlayer', 'solana', 'ton', 'tron'
Recipient
The recipient option specifies the address that will receive the bridged tokens.
Type: string
Format: Valid address for the target chain
Token
The token option specifies which token contract to bridge.
Type: string
Format: Token contract address on the source chain
Amount
The amount option specifies how many tokens to bridge.
Type: number | bigint
Unit: Base units of the token (e.g., for USD₮: 1 USD₮ = 1000000n)
OFT Contract Address
The optional oftContractAddress option lets you override auto-discovery and force a specific OFT contract.
Type: string (optional)
Format: Valid EVM contract address on the source chain
Destination EID Override
The optional dstEid option lets you override the default LayerZero destination endpoint ID for the selected target chain.
Type: number (optional)
Error Handling
The bridge protocol will throw errors for invalid configurations. This example uses a standard EVM account, so it approves the bridge spender first:
try {
await account.approve({
token: '0x...', // USDT contract address
spender: '0x...', // OFT or bridge spender address
amount: 1000000n
})
const result = await bridgeProtocol.bridge({
targetChain: 'invalid-chain',
recipient: '0x...', // Recipient address
token: '0x...', // USDT contract address
amount: 1000000n,
oftContractAddress: '0x...' // Same address used as approval spender
})
} catch (error) {
if (error.message.includes('not supported')) {
console.error('Chain or token not supported')
}
if (error.message.includes('Exceeded maximum fee')) {
console.error('Bridge fee too high')
}
if (error.message.includes('must be connected to a provider')) {
console.error('Wallet not connected to blockchain')
}
}Node.js Quickstart
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