Index / AntiSnipe

pattern · MIT · last updated 2026-08-27

AntiSnipe

Launch guard — max buy (% supply), snipe tax on exact-input buys for N blocks after init.

First-party teaching hook inspired by Spark's Anti-Snipe launchpad block (usespark.fun/builder). afterInitialize records graduationBlock and requires native currency0 + dynamic fee. beforeSwap applies snipeTax via OVERRIDE_FEE_FLAG on exact-input buys while inGuardWindow; after guard, baseLpFee. afterSwap caps token output to maxBuyBps of totalSupply using afterSwapReturnDelta (FullMath.mulDiv avoids supply overflow). Per-swap cap only — not per-wallet. Sells skip tax and cap. Experimental. Forge tests in test/AntiSnipe.t.sol. Listing is not an audit.

Permission bits

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

afterInitializebeforeSwapafterSwapafterSwapReturnDelta

Solidity

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

// SPDX-License-Identifier: MIT
// v4hooks first-party — excerpt. Full file: source.url
function getHookPermissions() public pure override returns (Hooks.Permissions memory) {
    return Hooks.Permissions({
        beforeInitialize: false,
        afterInitialize: true,
        beforeAddLiquidity: false,
        afterAddLiquidity: false,
        beforeRemoveLiquidity: false,
        afterRemoveLiquidity: false,
        beforeSwap: true,
        afterSwap: true,
        beforeDonate: false,
        afterDonate: false,
        beforeSwapReturnDelta: false,
        afterSwapReturnDelta: true,
        afterAddLiquidityReturnDelta: false,
        afterRemoveLiquidityReturnDelta: false
    });
}

function _beforeSwap(address, PoolKey calldata key, SwapParams calldata params, bytes calldata)
    internal
    view
    override
    returns (bytes4, BeforeSwapDelta, uint24)
{
    bool isExactInputBuy = params.zeroForOne && params.amountSpecified < 0;
    uint24 fee = feeFor(key.toId(), isExactInputBuy);
    return (this.beforeSwap.selector, BeforeSwapDeltaLibrary.ZERO_DELTA, fee | LPFeeLibrary.OVERRIDE_FEE_FLAG);
}

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.