Implement the hook so it charges a fixed swap fee in basis points, taken from the input currency on every swap in both directions, and accrued to the hook rather than to the pool.

Implement the hook so it charges a fixed swap fee in basis points, taken from the input currency on every swap in both directions, and accrued to the hook rather than to the pool. The fee rate is set once at construction and cannot be changed afterwards. Nothing else about the pool changes: liquidity, donations and the zero-liquidity case must all behave exactly as they do with no fee.

Reuse the vendored BaseHook and the existing launch-pool harness rather than adding dependencies.