ChakramHook

A trading tax hook. It takes a tax on trades, keeps rewards to claim and only lets approved callers create pools.

• Takes a tax on trades

  On top of the normal pool fee, it keeps part of each trade as a tax. The tax can be changed, but never above 3%. The tax builds up in the hook until it is collected.

  The code that does this (beforeSwap):

  function beforeSwap(address sender, PoolKey calldata key, SwapParams calldata params, bytes calldata)
      external
      onlyPoolManager
      returns (bytes4, BeforeSwapDelta, uint24)
  {
      (address token, bool tokenIsZero_) = _match(key);
      if (token == address(0) || !_quoteIsSpecified(params, tokenIsZero_)) {
          return (this.beforeSwap.selector, toBeforeSwapDelta(0, 0), 0);
      }
  
      uint256 amount = params.amountSpecified < 0
          ? SafeCast.toUint256(-params.amountSpecified)
          : SafeCast.toUint256(params.amountSpecified);
  
      bool isBuy = _isBuy(params, tokenIsZero_);
      uint256 fee = _charge(key, token, tokenIsZero_, amount, isBuy, sender);
      // Exact-in buy: pool receives amount - fee. Exact-out sell: pool pays amount + fee.
      _record(token, isBuy, isBuy ? amount - fee : amount + fee);
      return (this.beforeSwap.selector, toBeforeSwapDelta(SafeCast.toInt128(SafeCast.toInt256(fee)), 0), 0);
  }

• Rewards to claim

  It keeps track of what people have earned, and they claim it themselves.

  The code that does this (claimFees):

  function claimFees(address recipient, address quoteToken_) external nonReentrant {
      uint256 amount = claimable[recipient][quoteToken_];
      if (amount == 0) revert Hook__NothingOwed();
      delete claimable[recipient][quoteToken_];
      _send(recipient, quoteToken_, amount);
      emit FeesClaimed(recipient, quoteToken_, amount);
  }

• Only approved callers create pools

  New pools with this hook can only be created by approved callers, for example its own factory or launcher.

  The code that does this (beforeInitialize):

  function beforeInitialize(address sender, PoolKey calldata key, uint160)
      external
      view
      onlyPoolManager
      returns (bytes4)
  {
      if (sender != factory) revert Hook__PoolNotAllowed();
      (address token,) = _match(key);
      if (token == address(0)) revert Hook__PoolNotAllowed();
      return this.beforeInitialize.selector;
  }

Who controls it: The hook developer can change the fee and the tax. The code never lets the fee go above 3%. Control can be passed on or given up. The code cannot be changed.

Based on the hook’s published code.What do these labels mean?