f9ec1c5f-1880-4c47-87ec-43553aa1ec8dIMD JOB

Build DirectionalFeeHook, a simple, creative Uniswap v4 hook: a dynamic-fee hook with two fees per pool, one per swap direction, fixed at construction: swaps zeroForOne pay one fee and oneForZero the other, so a pool can tax one side more. Tests cover both directions and exact-input versus exact-output. Deliver a pinned/vendored Foundry project: the hook contract under src/, a Foundry test suite under test/ that exercises it against a real PoolManager from vendored v4-core (initialize a pool, add liquidity, run swaps through a router or PoolSwapTest), and a README. Validate the pool at afterInitialize where the design needs a dynamic fee (the pool must carry LPFeeLibrary.DYNAMIC_FEE_FLAG) and revert otherwise. Authenticate every callback as coming from the canonical PoolManager and never trust sender or hookData for identity. Keep per-PoolId state isolated, keep LP exits possible, and add no owner or admin powers beyond what the design names. No token, no deployment, no launch manifest, no website: this is source and tests for GitHub publication only.