Gas Abstraction

All atomic. All in one block. User never needs to acquire KAIA first.

Key Contract: GaslessSwapRouter

Interface

function swapForGas(
    address token,     // whitelisted ERC-20
    uint256 amountIn,  // tokens to swap
    uint256 minAmountOut, // minimum KAIA output
    uint256 amountRepay,  // exact amount to repay proposer
    uint256 deadline   // tx deadline
) external;

function getSupportedTokens() external view returns (address[] memory);
function getAmountIn(address token, uint amountOut) external view returns (uint amountIn);

Repayment Calculation

amountRepay = V1 + V2 + V3
  V1 = LendTx fee       = SwapTx.GasPrice × 21000
  V2 = ApproveTx fee     (if approve tx exists)
  V3 = SwapTx fee

The proposer is made whole. The user gets any surplus from the swap.

Constraints

• Only whitelisted tokens are supported (contract owner manages whitelist)
• Only single-hop swaps through predetermined DEX contracts
• GaslessApproveTx MUST be followed by GaslessSwapTx from the same sender
• GaslessSwapTx CAN exist alone (if token is already approved)

vs Ethereum Approaches

When to Use

• User onboarding from other chains (bridged USDT/USDC, no KAIA)
• First-time transactions for new Kaia users
• Combined with fee delegation for full gasless UX