pure kappa formulation: target slippage extracted into pool creator code

src/IPartyPlanner.sol

@@ -10,7 +10,8 @@ interface IPartyPlanner {
     // Event emitted when a new pool is created
     event PartyStarted(PartyPool indexed pool, string name, string symbol, IERC20[] tokens);
 
-    /// @notice Creates a new PartyPool instance and initializes it with initial deposits
+    /// @notice Creates a new PartyPool instance and initializes it with initial deposits (legacy signature).
+    /// @dev Deprecated in favour of the kappa-based overload below; kept for backwards compatibility.
     /// @param name_ LP token name
     /// @param symbol_ LP token symbol
     /// @param _tokens token addresses (n)
@@ -27,7 +28,7 @@ interface IPartyPlanner {
     /// @return pool Address of the newly created and initialized PartyPool
     /// @return lpAmount Amount of LP tokens minted to the receiver
     function createPool(
-        // Pool constructor args
+        // Pool constructor args (legacy)
         string memory name_,
         string memory symbol_,
         IERC20[] memory _tokens,
@@ -45,6 +46,39 @@ interface IPartyPlanner {
         uint256 deadline
     ) external returns (PartyPool pool, uint256 lpAmount);
 
+    /// @notice Creates a new PartyPool instance and initializes it with initial deposits (kappa-based).
+    /// @param name_ LP token name
+    /// @param symbol_ LP token symbol
+    /// @param _tokens token addresses (n)
+    /// @param _bases scaling bases for each token (n) - used when converting to/from internal 64.64 amounts
+    /// @param _kappa liquidity parameter κ in 64.64 fixed-point used to derive b = κ * S(q)
+    /// @param _swapFeePpm fee in parts-per-million, taken from swap input amounts before LMSR calculations
+    /// @param _flashFeePpm fee in parts-per-million, taken for flash loans
+    /// @param _stable if true and assets.length==2, then the optimization for 2-asset stablecoin pools is activated
+    /// @param payer address that provides the initial token deposits
+    /// @param receiver address that receives the minted LP tokens
+    /// @param initialDeposits amounts of each token to deposit initially
+    /// @param deadline Reverts if nonzero and the current blocktime is later than the deadline
+    /// @return pool Address of the newly created and initialized PartyPool
+    /// @return lpAmount Amount of LP tokens minted to the receiver
+    function createPool(
+        // Pool constructor args (kappa-based)
+        string memory name_,
+        string memory symbol_,
+        IERC20[] memory _tokens,
+        uint256[] memory _bases,
+        int128 _kappa,
+        uint256 _swapFeePpm,
+        uint256 _flashFeePpm,
+        bool _stable,
+        // Initial deposit information
+        address payer,
+        address receiver,
+        uint256[] memory initialDeposits,
+        uint256 initialLpAmount,
+        uint256 deadline
+    ) external returns (PartyPool pool, uint256 lpAmount);
+
     /// @notice Checks if a pool is supported
     /// @param pool The pool address to check
     /// @return bool True if the pool is supported, false otherwise