Execute Swaps

This guide explains how to run a basic exact-input swap, an exact-output swap, and a swap from an ERC-4337 smart account. You should already have a VeloraProtocolEvm instance.

Swaps spend tokens and gas on-chain. Before execution, approve the input token for the current Velora spender on the account's chain. The module does not submit approvals or reset allowances. See configuration for approval and fee prerequisites.

Basic exact-input swap

For beta.9 or later, carry an accepted output floor into swap(). This example allows at most 1% less output than the preview. Choose the tolerance for your application and obtain user approval before execution.

Check the current spender allowance and obtain a quote.
Review the recipient, input amount, output floor, and fee cap with the user.
Execute the same request with minAmountOut and swapMaxFee.

Use quoteSwap() to prepare the request:

Preview USDt to WETH

const ETHEREUM_USDT = '0xdAC17F958D2ee523a2206206994597C13D831ec7'
const ETHEREUM_WETH = '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2'
const request = {
  tokenIn: ETHEREUM_USDT,
  tokenOut: ETHEREUM_WETH,
  tokenInAmount: 1000000n,
  to: await account.getAddress()
}
const quote = await swapProtocol.quoteSwap(request)
const minAmountOut = quote.tokenOutAmount * 9900n / 10000n
const maxFee = 200000000000000n // Exclusive cap in wei for this standard EVM account.

After approval, pass the reviewed request and limits to swap():

Exact input: USDt to WETH

const result = await swapProtocol.swap({
  ...request,
  minAmountOut
}, { swapMaxFee: maxFee })

console.log('Swap transaction hash:', result.hash)
console.log('Total fee (account units):', result.fee)
console.log('Quoted input (base units):', result.tokenInAmount)
console.log('Quoted output (base units):', result.tokenOutAmount)

Execution fetches a new rate and rejects a mismatched pair, mismatched input amount, or output below the floor before building the transaction. The returned token amounts are from that rate, not a settlement receipt. The earlier quote's route is not pinned.

Exact output swap

BUY validates the requested exact output and retains it in the transaction build. An optional minAmountOut also rejects an output below that floor; it does not add an input-token spending cap.

Swap with ERC-4337

You can perform a user-operation-backed swap by constructing VeloraProtocolEvm with WalletAccountEvmErc4337 and passing paymaster options to swap():

Swap with smart account and paymaster

import { WalletAccountEvmErc4337 } from '@tetherto/wdk-wallet-evm-erc-4337'
import VeloraProtocolEvm from '@tetherto/wdk-protocol-swap-velora-evm'

const aa = new WalletAccountEvmErc4337(seedPhrase, "0'/0/0", {
  chainId: 1,
  provider: 'https://ethereum-rpc.publicnode.com',
  bundlerUrl: process.env.BUNDLER_URL,
  paymasterUrl: process.env.PAYMASTER_URL,
  paymasterAddress: process.env.PAYMASTER_ADDRESS,
  safeModulesVersion: '0.3.0',
  paymasterToken: {
    address: '0xdAC17F958D2ee523a2206206994597C13D831ec7'
  }
})

// Exclusive cap: 0.01 USDt with this six-decimal paymaster token.
const swapAA = new VeloraProtocolEvm(aa, { swapMaxFee: 10000n })

const result = await swapAA.swap({
  tokenIn: '0xdAC17F958D2ee523a2206206994597C13D831ec7',
  tokenOut: '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2',
  tokenInAmount: 1000000n
}, {
  paymasterToken: {
    address: '0xdAC17F958D2ee523a2206206994597C13D831ec7'
  },
  swapMaxFee: 10000n
})

console.log('Swap hash:', result.hash)
console.log('Total fee (USDt base units):', result.fee)

Token addresses must match the chain your account uses (for example, Ethereum USD₮ and Arbitrum USD₮0 use different contract addresses).

Next Steps

Get swap quotes before sending
Handle errors
Get started if you still need setup

Execute Swaps

Basic exact-input swap

Exact output swap

Swap with ERC-4337

Next Steps

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