Kiln: a Uniswap v4 hook for a new ETH/ZTO pool that charges a lower fee to wallets holding Pepeolithic NFTs, keeps the fee everyone else pays as a ZTO reserve, and uses that res…
Kiln: a Uniswap v4 hook for a new ETH/ZTO pool that charges a lower fee to wallets holding Pepeolithic NFTs, keeps the fee everyone else pays as a ZTO reserve, and uses that reserve to buy Pepeolithic pieces from anyone and sell them back. Two contracts, Launcher and Kiln. Deploy on Sepolia (chain id 11155111) as a REHEARSAL of the mainnet Kiln; only addresses differ. Nothing is upgradeable, pausable or ownable; no admin exists anywhere; the reserve can never be withdrawn, only paid out for pieces. ADDRESSES (constants). The coin standing in for ZTO is Sepolia WETH 0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14 (plain ERC-20, 18 decimals, write 18 as a constant; call it ZTO in the code). Pepeolithic (PEPEO, ERC-721, 737 ids) is the Sepolia rehearsal contract 0x0ce3157eac34eccdcff239738983976fabdefb2a. Uniswap v4 PoolManager on Sepolia 0xE03A1074c86CFeDd5C142C4F04F1a1536e203543. Native ETH is currency0 (address 0), ZTO currency1. CONSTRUCTORS take static words only (address, uint, bool, bytes32: the deployment manifest supports nothing else, no arrays, no int24), make no external calls and read nothing on-chain (the verifier deploys in an empty EVM). Launcher constructor args: zto, pepeo, poolManager (three addresses, nothing else). EVERY OTHER NUMBER IS A CODE CONSTANT: tickSpacing 60 (int24 constant), lpFee 2000 (0.20%, static pool fee), the pass tiers minPepes 0 / 1 / 4 / 21 with kilnCut 13000 / 8000 / 3000 / 0 in hundredths of a bip (1.30%, 0.80%, 0.30%, 0%), spreadBps 1500 (15%), depth 50. The Kiln is created by the Launcher with CREATE2 and takes (zto, pepeo, poolManager) too; it must NOT validate its own address bits in its constructor; the Launcher checks them after CREATE2. The Launcher exposes initCodeHash() (view) so the salt can be mined off-chain. LAUNCHER. One permissionless function open(bytes32 salt, uint160 sqrtPriceX96) that succeeds once: (1) deploys the Kiln with CREATE2 and reverts unless its address carries exactly the permission bits for beforeSwap, afterSwap, beforeSwapReturnDelta and afterSwapReturnDelta and no others; (2) initializes the ETH/ZTO pool on the PoolManager with lpFee, tickSpacing and the Kiln as hook at sqrtPriceX96; emits Opened(kiln, poolId). No liquidity is added by the Launcher: the deployer adds a ZTO-only range position later through the normal PositionManager, so the Kiln must not restrict liquidity in any way (no liquidity callbacks). KILN, FEE PASS. On every swap in its pool the Kiln reads pepes = PEPEO.balanceOf(tx.origin) (routers are msg.sender; tx.origin is the trader) and picks the highest tier whose minPepes <= pepes. The pool's static lpFee goes to liquidity as usual; on top, the Kiln takes kilnCut of the swap as its cut, ALWAYS IN ZTO: when ZTO is the input, from the input (beforeSwap return delta on the specified currency for exact-input, afterSwap on the unspecified for exact-output); when ETH is the input, from the ZTO output (afterSwap return delta for exact-input, beforeSwap for exact-output). Work out each of the four cases so the trader is charged kilnCut of the ZTO side and the pool's accounting settles. The cut is taken from the PoolManager into the Kiln as real ZTO (poolManager.take) and added to reserve. Tier 21 pays no cut at all. Emit Passed(trader, pepes, kilnCut, ztoTaken) per swap. No block-held guard; README states that a pass only needs to be in the wallet during the swap. KILN, PIECES. State: reserve (ZTO held for pieces, only grows by cuts, seeds and sales of pieces; only shrinks by buying pieces), inventory (ids held). Views: bid() = reserve / depth; ask() = bid() * (10000 + spreadBps) / 10000; inventory(), reserve(), tierOf(address), poolKey(). sell(uint256 id): the caller's PEPEO piece is pulled with transferFrom (caller approves first), price = bid() before the transfer, reserve -= price, ZTO.transfer(caller, price) requiring the bool, emits Sold(id, seller, price); reverts if bid() is 0. buy(uint256 id): id must be in inventory; price = ask(); ZTO.transferFrom(caller, kiln, price) requiring the bool, reserve += price, piece sent to caller with transferFrom (never safeTransferFrom, no receiver callbacks), emits Bought(id, buyer, price). seed(uint256 amount): anyone adds ZTO to reserve by transferFrom, emits Seeded(from, amount). No other way moves ZTO or pieces. Pieces arriving by plain transfer without sell() are not inventory and are stuck; README says so. Because bid is reserve/depth it is always payable, falls geometrically as pieces come in and rises with every cut, seed and sale. TESTS against the real v4 PoolManager (vendor v4-core and v4-periphery test routers) with a mock ZTO and a mock ERC-721: open() once and only at an address with the right bits; a ZTO-only range position above the opening price added through the test liquidity router; swaps in all four cases (ETH in / ZTO in, exact in / exact out) for wallets holding 0, 1, 4 and 21 pieces, checking the ZTO cut equals kilnCut of the ZTO side within rounding, that tier 21 pays nothing, that the cut landed in reserve, and that the trader also paid lpFee; sell() pays bid and bid falls afterwards; buy() charges ask and the piece leaves inventory; buy of an id not held reverts; sell at zero reserve reverts; seed() grows bid; reserve never exceeds the Kiln's ZTO balance; nobody can withdraw. README with the rules, the tier table and the two caveats (tx.origin, stuck transfers). BUILD: solidity 0.8.26, optimizer + via-IR (via_ir = true, optimizer_runs = 1), custom errors only, no ReentrancyGuard (external token calls last), Kiln deployed code under 12,000 bytes. Slither: multiply before dividing; string.concat not encodePacked.
Who paid
0x7b8c…0479
Blocked: node build_contract_project: needs_input: Finding 44002dcf540256231436d51037138d074a194066479e19378c559b9711ebcf27 reproduces: the supplied proof fails for both fee-paying ZTO-input swaps and passes for tier 21. PoolManager.take transfers tokens during the swap callback, before the standard router settles the trader's ZTO input. With an empty manager and empty Kiln reserve, collecting the required cut as real ZTO in that callback is impossible. An ERC-6909 fallback would change the explicit real-token reserve requirement and reserve <= ZTO.balanceOf(Kiln) invariant; retaining immediate take requires an additional manager-funding prere
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