Index / SurgeFee

pattern · MIT · last updated 2026-08-27

SurgeFee

LP fee scales with swap size vs pool liquidity — no simulate-and-revert.

First-party teaching hook inspired by Spark Surge Fees. Contrast with slippage-fee.yml: that hook simulates the swap and reverts with the post-trade tick to price the fee; SurgeFee reads pool liquidity from StateLibrary and adds surgeFactor * (tradeSize / liquidity) to baseFee in beforeSwap, capped at maxFee. No try/catch simulation — cheaper gas, coarser signal (size vs liquidity, not tick walk). Inherits OpenZeppelin BaseOverrideFee. Requires dynamic fee pool. Experimental. Forge tests in test/SurgeFee.t.sol. Listing is not an audit.

Permission bits

These bits must match the deployed address. Confirm on-chain before you route.

afterInitializebeforeSwap

Solidity

Excerpt from contracts/SurgeFee.sol. Copy the full file to implement this. Not an audit.

// SPDX-License-Identifier: MIT
// v4hooks first-party — excerpt. Full file: source.url
function feeFor(PoolKey calldata key, SwapParams calldata params) public view returns (uint24) {
    uint128 liquidity = poolManager.getLiquidity(key.toId());
    if (liquidity == 0) return baseFee;
    uint256 tradeSize = params.amountSpecified < 0
        ? uint256(-params.amountSpecified)
        : uint256(params.amountSpecified);
    uint256 surge = (tradeSize * uint256(surgeFactor)) / uint256(liquidity);
    uint256 total = uint256(baseFee) + surge;
    if (total > maxFee) return maxFee;
    return uint24(total);
}

function _getFee(address, PoolKey calldata key, SwapParams calldata params, bytes calldata)
    internal
    view
    override
    returns (uint24)
{
    return feeFor(key, params);
}

Spec

FAQ

Can I paste this into production? The snippet is an excerpt. Use the full file at the source URL, match flags to the address, and treat this page as a map, not a guarantee.

How do I build this safely? Start with secure v4 hooks and the OpenZeppelin hooks guide.