Release Holder Discount (token symbol NFTD) on Sepolia as a univ4_hook launch.

Token: Holder Discount (NFTD), total supply 1,000,000,000 NFTD with 18 decimals, minted once to the deployer.

Hook: NFTHolderDiscountHook, a Uniswap v4 hook on the token's native-ETH pool (currency0 native ETH, currency1 NFTD, LP fee 3000, tickSpacing 60; the factory seeds one-sided NFTD liquidity, so the first buy lands in a pool holding no ETH). In v4, amountSpecified < 0 is exact input and zeroForOne is a buy (ETH in, NFTD out).

The hook extends v4-periphery BaseHook; its only constructor argument is the Sepolia PoolManager 0xE03A1074c86CFeDd5C142C4F04F1a1536e203543 (constructor (IPoolManager poolManager)); no $owner or $token. getHookPermissions enables exactly afterSwap and afterSwapReturnDelta; the manifest lists the same set. State is keyed by PoolId, so any pool may attach the hook.

COLLECTION is the source constant 0x429ba70129df741B2Ca2a85BC3A2a3328e5c09b4, the Uniswap v4 PositionManager on Sepolia ("Uniswap v4 Positions NFT", an ERC-721 anyone gets by opening a v4 position); tests put a mock ERC-721 at that address with vm.etch.

Fee: 100 bps (1%), or 50 bps when COLLECTION.balanceOf(tx.origin) >= 1, read with a low-level staticcall capped at 50,000 gas and decoded only when it returns exactly 32 bytes (a Solidity try/catch would not catch a bad return); a revert, out-of-gas or malformed return means the full 1%, never a failed swap.

The fee is taken on the unspecified currency in afterSwap through the afterSwapReturnDelta (exact input: it comes off the output; exact output: it is added to the input): fee = ceil(|unspecified amount| x bps / 10,000), capped at that amount. Fees are credited to the hook as ERC-6909 claims with poolManager.mint inside the callback; no ETH or tokens are pushed during a swap.

Anyone may call donateFees(PoolKey): it unlocks the PoolManager, burns that pool's accrued claims in both currencies and donates them to in-range LPs with poolManager.donate; it reverts NoLiquidity while in-range liquidity is zero and the claims wait for a later call. unlockCallback accepts only the PoolManager, and only during a call the hook itself started. No owner, no admin.

Why tx.origin: this hook credits nobody, so the context's hookData identity rule does not apply, and a hookData address would let anyone claim a holder's discount; the v4 sender is the router and hookData is not authenticated, so the transaction signer is the only identity the hook can check without a trusted router.

Document the limits in NatSpec and README: contract and ERC-4337 wallets are judged by the relayer or bundler EOA, a relayer holding one NFT passes the discount to everyone it relays, an EIP-7702 account can hold a borrowed NFT during its own transaction, and it only ever lowers a fee (never authorisation).

Events: FeeCharged(PoolId indexed poolId, address origin, bool discounted, Currency currency, uint256 fee), FeesDonated(poolId, amount0, amount1).

Views: feeBpsFor(address account), accrued(poolId) for both currencies. Tests run against a real v4-core PoolManager and include a launch rehearsal: one-sided NFTD liquidity below the opening price, a first buy into the ETH-less pool, then a sell.

Acceptance: holder vs non-holder via vm.prank(sender, origin) in all four swap types; the discount ends when the NFT moves away; a collection that reverts, returns garbage or burns all gas gives the full fee, not a revert; invariant: claims held == accrued; donateFees reaches in-range LPs.

Then a small website that shows the configured collection, the connected wallet's NFT balance and the fee it would pay, lifetime fees and the discounted share, a donate button and a swap form. Swaps go through PoolSwapTest 0x9B6b46e2c869aa39918Db7f52f5557FE577B6eEe (it forwards hookData and sqrtPriceLimitX96), prices come from StateView 0xE1Dd9c3fA50EDB962E442f60DfBc432e24537E4C and quotes from V4Quoter 0x61B3f2011A92d183C7dbaDBdA940a7555Ccf9227 (all live on Sepolia).

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