Skim hook (ArtCoinsHookSkimFee)

0x636c050296B5Cc528D8785169Bf8923716FCa9cc · view on evm.now

The Uniswap V4 hook attached to the official $111/ETH pool (pool id 0xf860d8f4896aed6cc1c68d234ba728680902f0ae43a459fbee6f6baa8036f795). It takes the protocol's skim on every swap, splits it three ways inside the same transaction, and attests official-pool buys as exempt from the $111 token's venue-scoped transfer tax.

The hook is launch infrastructure from the artcoins stack, so this page is not an exhaustive per-function reference. It documents what an integrator touching the pool needs: the fee taken, where it goes, and the two behaviors (intra-swap flush, canonical-budget attestation) that affect routing and accounting. The full ABI is served at /abis/ArtCoinsHookSkimFee.json. The hook can host other pools via initializePoolOpen; every number below is the official pool's configuration, readable on-chain via skimConfig(poolId).

The 6% baseline skim

Every swap on the official pool pays a 6% skim on the ETH side of the swap volume (baselineSkimBps = 6_000 in the hook's 100,000 denominator), taken by the hook itself. This is separate from the pool's 0.5% LP fee (lpFee = 5_000 ppm), which flows to in-range liquidity positions per standard V4 mechanics.

The skim splits into three legs at swap time:

The referral slice is deducted from the protocol leg, never from the live-bid leg. It pays only when the swap carries valid attribution hookData naming a referrer (see the swap-with-attribution guide); with no or invalid attribution the full protocol slice flows to the fee escrow. The per-swap referral is clamped to min(requested referralBps, maxReferralBpsOfVolume) of volume AND to the available protocol slice. The cap launches at 250 (0.25% of volume, 100k denominator) and is tunable within [0, 1_000] via TokenAdminPoker's setHookMaxReferralBps, which forwards to the hook's setMaxReferralBpsOfVolume; the hook's compiled ceiling is MAX_REFERRAL_CAP_OF_VOLUME = 1_000 (1% of volume), unreachable by any admin.

Intra-swap flush: the hook holds no balance

The split is computed in beforeSwap (exact-input swaps) or afterSwap (exact-output swaps). At the end of afterSwap of the same swap, the hook burns its ERC-6909 claim tokens, takes native ETH from the pool manager, and forwards every leg to its recipient:

• the live-bid leg forwards to LiveBidAdapter; a failed forward reverts the whole swap (BidForwardFailed)
• the protocol leg deposits into the launch stack's fee escrow under ProtocolFeePhaseAdapter's balance, pulled later via its sweep()
• the referral leg pays ReferralPayout.notify(referrer) under a gas cap; a failed payout folds the slice into the protocol leg instead (ReferralFoldedToProtocol), and the swap proceeds

There is no held or retried balance: between swaps the hook's claim balance is zero, so nothing accrues on the hook itself and there is nothing for a keeper to flush.

Anti-sniper window (expired)

For the first 30 minutes after pool initialization, the MEV module (ArtCoinsMevLinearSkim at 0xb038D597365FfD108D63C265Bb0621444a1D8B83) reported an elevated skim that decayed linearly from 90% down to the 6% baseline (roughly 2.8 percentage points per minute). The overage above baseline (antiSniperExtra in the hook's accounting) routed 100% to the live-bid leg; the baseline portion split as in the table above.

That window has expired and the module has self-disabled. The pool runs the static 6% baseline; currentSniperExtraFeePpm(poolId) returns 0.

Canonical-budget attestation (tax exemption)

The $111 token charges a venue-scoped, buy-side transfer tax on $111 leaving a known trading venue. Buys on the official pool are exempt, and this hook is what makes them exempt: in afterSwap (buys) and afterRemoveLiquidity (public LP exits) it attests the realized $111 output into an amount-pinned, transient (EIP-1153) exemption budget on the token (attestCanonicalBudget). The token accepts the attestation only from this hook and only for the official pool id, so no side pool can earn a budget. The budget clears at the end of the transaction. Details on the tax itself: the $111 token.

For routers and aggregators: official-pool buys realize the full quote; only side-pool routes see the token's buy-side tax.

Reading the config

cast call 0x636c050296B5Cc528D8785169Bf8923716FCa9cc \
  "skimConfig(bytes32)(uint24,uint16,uint24,uint24,address,address,address,address)" \
  0xf860d8f4896aed6cc1c68d234ba728680902f0ae43a459fbee6f6baa8036f795 \
  --rpc-url https://ethereum-rpc.publicnode.com

Returns (baselineSkimBps, bountyBps, maxReferralBpsOfVolume, lpFee, bountyRecipient, protocolRecipient, referralPayout, quoteToken). On the official pool: bountyRecipient is LiveBidAdapter, protocolRecipient is ProtocolFeePhaseAdapter, referralPayout is ReferralPayout, and quoteToken is address(0) (the pool is native-ETH paired).

Events an indexer should watch

The protocol's own indexer consumes SkimSplit for its lifetime swap-volume counters; see the indexer page.