Flip the sign of deltas

.forge-snapshots/addLiquidity with empty hook.snap

@@ -1 +1 @@
-312661
+312838

.forge-snapshots/addLiquidity with native token.snap

@@ -1 +1 @@
-192843
+193017

.forge-snapshots/addLiquidity.snap

@@ -1 +1 @@
-192821
+192998

.forge-snapshots/before swap hook, already cached dynamic fee.snap

@@ -1 +1 @@
-184735
+185335

.forge-snapshots/cached dynamic fee, no hooks.snap

@@ -1 +1 @@
-138762
+139362

.forge-snapshots/donate gas with 1 token.snap

@@ -1 +1 @@
-131854
+132225

.forge-snapshots/donate gas with 2 tokens.snap

@@ -1 +1 @@
-176958
+177402

.forge-snapshots/mintWithEmptyHookEOAInitiated.snap

@@ -0,0 +1 @@
+247213

.forge-snapshots/modify position with noop.snap

@@ -0,0 +1 @@
+54090

.forge-snapshots/poolManager bytecode size.snap

@@ -1 +1 @@
-23381
+23459

.forge-snapshots/removeLiquidity with empty hook.snap

@@ -1 +1 @@
-99632
+99591

.forge-snapshots/removeLiquidity with native token.snap

@@ -1 +1 @@
-201005
+200964

.forge-snapshots/removeLiquidity.snap

@@ -1 +1 @@
-197282
+197241

.forge-snapshots/simple swap with native.snap

@@ -1 +1 @@
-187335
+187932

.forge-snapshots/simple swap.snap

@@ -1 +1 @@
-195872
+196472

.forge-snapshots/simpleSwapEOAInitiated.snap

@@ -0,0 +1 @@
+167083

.forge-snapshots/simpleSwapNativeEOAInitiated.snap

@@ -0,0 +1 @@
+165611

.forge-snapshots/swap against liquidity with native token.snap

@@ -1 +1 @@
-117998
+118595

.forge-snapshots/swap against liquidity.snap

@@ -1 +1 @@
-105462
+106062

.forge-snapshots/swap burn 6909 for input.snap

@@ -1 +1 @@
-125651
+126218

.forge-snapshots/swap burn native 6909 for input.snap

@@ -1 +1 @@
-121604
+122171

.forge-snapshots/swap mint native output as 6909.snap

@@ -1 +1 @@
-189861
+190494

.forge-snapshots/swap mint output as 6909.snap

@@ -1 +1 @@
-206666
+207299

.forge-snapshots/swap with dynamic fee.snap

@@ -1 +1 @@
-183836
+184436

.forge-snapshots/swap with hooks.snap

@@ -1 +1 @@
-105440
+106040

.forge-snapshots/update dynamic fee in before swap.snap

@@ -1 +1 @@
-190540
+191140

README.md

@@ -26,7 +26,7 @@ A more detailed description of Uniswap v4 Core can be found in the draft of the
 - `settle`
 - `mint`
 
-Only the net balances owed to the pool (positive) or to the user (negative) are tracked throughout the duration of a lock. This is the `delta` field held in the lock state. Any number of actions can be run on the pools, as long as the deltas accumulated during the lock reach 0 by the lock’s release. This lock and call style architecture gives callers maximum flexibility in integrating with the core code.
+Only the net balances owed to the user (positive) or to the pool (negative) are tracked throughout the duration of a lock. This is the `delta` field held in the lock state. Any number of actions can be run on the pools, as long as the deltas accumulated during the lock reach 0 by the lock’s release. This lock and call style architecture gives callers maximum flexibility in integrating with the core code.
 
 Additionally, a pool may be initialized with a hook contract, that can implement any of the following callbacks in the lifecycle of pool actions:
 

src/PoolManager.sol

@@ -222,16 +222,16 @@ contract PoolManager is IPoolManager, Fees, NoDelegateCall, ERC6909Claims {
         );
 
         _accountPoolBalanceDelta(key, delta);
-        // the fee is on the input currency
 
+        // the fee is on the input currency
         unchecked {
             if (feeForProtocol > 0) {
                 protocolFeesAccrued[params.zeroForOne ? key.currency0 : key.currency1] += feeForProtocol;
             }
         }
 
         emit Swap(
-            id, msg.sender, delta.amount0(), delta.amount1(), state.sqrtPriceX96, state.liquidity, state.tick, swapFee
+            id, msg.sender, -delta.amount0(), -delta.amount1(), state.sqrtPriceX96, state.liquidity, state.tick, swapFee
         );
 
         key.hooks.afterSwap(key, params, delta, hookData);
@@ -259,7 +259,8 @@ contract PoolManager is IPoolManager, Fees, NoDelegateCall, ERC6909Claims {
 
     /// @inheritdoc IPoolManager
     function take(Currency currency, address to, uint256 amount) external override noDelegateCall isLocked {
-        _accountDelta(currency, amount.toInt128());
+        // flipping a postive number in an int is always safe
+        _accountDelta(currency, -(amount.toInt128()));
         reservesOf[currency] -= amount;
         currency.transfer(to, amount);
     }
@@ -269,19 +270,19 @@ contract PoolManager is IPoolManager, Fees, NoDelegateCall, ERC6909Claims {
         uint256 reservesBefore = reservesOf[currency];
         reservesOf[currency] = currency.balanceOfSelf();
         paid = reservesOf[currency] - reservesBefore;
-        // subtraction must be safe
-        _accountDelta(currency, -(paid.toInt128()));
+        _accountDelta(currency, paid.toInt128());
     }
 
     /// @inheritdoc IPoolManager
     function mint(address to, uint256 id, uint256 amount) external override noDelegateCall isLocked {
-        _accountDelta(CurrencyLibrary.fromId(id), amount.toInt128());
+        // flipping a postive number in an int is always safe
+        _accountDelta(CurrencyLibrary.fromId(id), -(amount.toInt128()));
         _mint(to, id, amount);
     }
 
     /// @inheritdoc IPoolManager
     function burn(address from, uint256 id, uint256 amount) external override noDelegateCall isLocked {
-        _accountDelta(CurrencyLibrary.fromId(id), -(amount.toInt128()));
+        _accountDelta(CurrencyLibrary.fromId(id), amount.toInt128());
         _burnFrom(from, id, amount);
     }
 

src/libraries/Pool.sol

@@ -210,7 +210,7 @@ library Pool {
                 // current tick is below the passed range; liquidity can only become in range by crossing from left to
                 // right, when we'll need _more_ currency0 (it's becoming more valuable) so user must provide it
                 result = result
-                    + toBalanceDelta(
+                    - toBalanceDelta(
                         SqrtPriceMath.getAmount0Delta(
                             TickMath.getSqrtRatioAtTick(params.tickLower),
                             TickMath.getSqrtRatioAtTick(params.tickUpper),
@@ -220,7 +220,7 @@ library Pool {
                     );
             } else if (self.slot0.tick < params.tickUpper) {
                 result = result
-                    + toBalanceDelta(
+                    - toBalanceDelta(
                         SqrtPriceMath.getAmount0Delta(
                             self.slot0.sqrtPriceX96, TickMath.getSqrtRatioAtTick(params.tickUpper), params.liquidityDelta
                         ).toInt128(),
@@ -236,7 +236,7 @@ library Pool {
                 // current tick is above the passed range; liquidity can only become in range by crossing from right to
                 // left, when we'll need _more_ currency1 (it's becoming more valuable) so user must provide it
                 result = result
-                    + toBalanceDelta(
+                    - toBalanceDelta(
                         0,
                         SqrtPriceMath.getAmount1Delta(
                             TickMath.getSqrtRatioAtTick(params.tickLower),
@@ -248,7 +248,7 @@ library Pool {
         }
 
         // Fees earned from LPing are removed from the pool balance.
-        result = result - toBalanceDelta(feesOwed0.toInt128(), feesOwed1.toInt128());
+        result = result + toBalanceDelta(feesOwed0.toInt128(), feesOwed1.toInt128());
     }
 
     struct SwapCache {
@@ -444,16 +444,17 @@ library Pool {
             self.feeGrowthGlobal1X128 = state.feeGrowthGlobalX128;
         }
 
+        // in an unchecked block so sign flipping is not safe without a helper function
         unchecked {
             if (params.zeroForOne == exactInput) {
                 result = toBalanceDelta(
-                    (params.amountSpecified - state.amountSpecifiedRemaining).toInt128(),
-                    state.amountCalculated.toInt128()
+                    (params.amountSpecified - state.amountSpecifiedRemaining).toInt128().flipSign(),
+                    state.amountCalculated.toInt128().flipSign()
                 );
             } else {
                 result = toBalanceDelta(
-                    state.amountCalculated.toInt128(),
-                    (params.amountSpecified - state.amountSpecifiedRemaining).toInt128()
+                    state.amountCalculated.toInt128().flipSign(),
+                    (params.amountSpecified - state.amountSpecifiedRemaining).toInt128().flipSign()
                 );
             }
         }
@@ -462,7 +463,7 @@ library Pool {
     /// @notice Donates the given amount of currency0 and currency1 to the pool
     function donate(State storage state, uint256 amount0, uint256 amount1) internal returns (BalanceDelta delta) {
         if (state.liquidity == 0) revert NoLiquidityToReceiveFees();
-        delta = toBalanceDelta(amount0.toInt128(), amount1.toInt128());
+        delta = toBalanceDelta(-(amount0.toInt128()), -(amount1.toInt128()));
         unchecked {
             if (amount0 > 0) {
                 state.feeGrowthGlobal0X128 += FullMath.mulDiv(amount0, FixedPoint128.Q128, state.liquidity);

src/libraries/SafeCast.sol

@@ -37,4 +37,12 @@ library SafeCast {
         if (y > uint128(type(int128).max)) revert SafeCastOverflow();
         z = int128(int256(y));
     }
+
+    /// @notice Flip the sign of an int128, revert on overflow
+    /// @param y The int128 to flip the sign of
+    /// @return The flipped integer, still an int128
+    function flipSign(int128 y) internal pure returns (int128) {
+        // this is not unchecked, so it will revert if y==type(int128).min
+        return -y;
+    }
 }

src/test/PoolClaimsTest.sol

@@ -40,7 +40,7 @@ contract PoolClaimsTest is PoolTestBase {
 
         if (data.deposit) {
             manager.mint(data.user, data.currency.toId(), uint128(data.amount));
-            _settle(data.currency, data.user, data.amount.toInt128(), true);
+            _settle(data.currency, data.user, -data.amount.toInt128(), true);
         } else {
             manager.burn(data.user, data.currency.toId(), uint128(data.amount));
             _take(data.currency, data.user, data.amount.toInt128(), true);

src/test/PoolDonateTest.sol

@@ -6,11 +6,10 @@ import {IPoolManager} from "../interfaces/IPoolManager.sol";
 import {PoolKey} from "../types/PoolKey.sol";
 import {BalanceDelta, BalanceDeltaLibrary} from "../types/BalanceDelta.sol";
 import {PoolTestBase} from "./PoolTestBase.sol";
-import {Test} from "forge-std/Test.sol";
 import {IHooks} from "../interfaces/IHooks.sol";
 import {Hooks} from "../libraries/Hooks.sol";
 
-contract PoolDonateTest is PoolTestBase, Test {
+contract PoolDonateTest is PoolTestBase {
     using CurrencyLibrary for Currency;
     using Hooks for IHooks;
 
@@ -59,14 +58,13 @@ contract PoolDonateTest is PoolTestBase, Test {
 
         assertEq(reserveBefore0, reserveAfter0);
         assertEq(reserveBefore1, reserveAfter1);
+        assertEq(deltaAfter0, -int256(data.amount0));
+        assertEq(deltaAfter1, -int256(data.amount1));
 
-        assertEq(deltaAfter0, int256(data.amount0));
-        assertEq(deltaAfter1, int256(data.amount1));
-
-        if (deltaAfter0 > 0) _settle(data.key.currency0, data.sender, int128(deltaAfter0), true);
-        if (deltaAfter1 > 0) _settle(data.key.currency1, data.sender, int128(deltaAfter1), true);
-        if (deltaAfter0 < 0) _take(data.key.currency0, data.sender, int128(deltaAfter0), true);
-        if (deltaAfter1 < 0) _take(data.key.currency1, data.sender, int128(deltaAfter1), true);
+        if (deltaAfter0 < 0) _settle(data.key.currency0, data.sender, int128(deltaAfter0), true);
+        if (deltaAfter1 < 0) _settle(data.key.currency1, data.sender, int128(deltaAfter1), true);
+        if (deltaAfter0 > 0) _take(data.key.currency0, data.sender, int128(deltaAfter0), true);
+        if (deltaAfter1 > 0) _take(data.key.currency1, data.sender, int128(deltaAfter1), true);
 
         return abi.encode(delta);
     }

src/test/PoolModifyLiquidityTest.sol

@@ -65,18 +65,18 @@ contract PoolModifyLiquidityTest is Test, PoolTestBase {
         (,,, int256 delta0) = _fetchBalances(data.key.currency0, data.sender, address(this));
         (,,, int256 delta1) = _fetchBalances(data.key.currency1, data.sender, address(this));
 
-        if (data.params.liquidityDelta > 0) {
+        if (data.params.liquidityDelta < 0) {
             assert(delta0 > 0 || delta1 > 0);
             assert(!(delta0 < 0 || delta1 < 0));
-        } else if (data.params.liquidityDelta < 0) {
+        } else if (data.params.liquidityDelta > 0) {
             assert(delta0 < 0 || delta1 < 0);
             assert(!(delta0 > 0 || delta1 > 0));
         }
 
-        if (delta0 > 0) _settle(data.key.currency0, data.sender, int128(delta0), data.settleUsingTransfer);
-        if (delta1 > 0) _settle(data.key.currency1, data.sender, int128(delta1), data.settleUsingTransfer);
-        if (delta0 < 0) _take(data.key.currency0, data.sender, int128(delta0), data.withdrawTokens);
-        if (delta1 < 0) _take(data.key.currency1, data.sender, int128(delta1), data.withdrawTokens);
+        if (delta0 < 0) _settle(data.key.currency0, data.sender, int128(delta0), data.settleUsingTransfer);
+        if (delta1 < 0) _settle(data.key.currency1, data.sender, int128(delta1), data.settleUsingTransfer);
+        if (delta0 > 0) _take(data.key.currency0, data.sender, int128(delta0), data.withdrawTokens);
+        if (delta1 > 0) _take(data.key.currency1, data.sender, int128(delta1), data.withdrawTokens);
 
         return abi.encode(delta);
     }

src/test/PoolNestedActionsTest.sol

@@ -124,8 +124,8 @@ contract NestedActionExecutor is Test, PoolTestBase {
 
         assertEq(deltaLockerBefore0, deltaLockerAfter0, "Locker delta 0");
         assertEq(deltaLockerBefore1, deltaLockerAfter1, "Locker delta 1");
-        assertEq(deltaThisBefore0 + SWAP_PARAMS.amountSpecified, deltaThisAfter0, "Executor delta 0");
-        assertEq(deltaThisBefore1 - 98, deltaThisAfter1, "Executor delta 1");
+        assertEq(deltaThisBefore0 - SWAP_PARAMS.amountSpecified, deltaThisAfter0, "Executor delta 0");
+        assertEq(deltaThisBefore1 + 98, deltaThisAfter1, "Executor delta 1");
         assertEq(delta.amount0(), deltaThisAfter0, "Swap delta 0");
         assertEq(delta.amount1(), deltaThisAfter1, "Swap delta 1");
 
@@ -202,10 +202,10 @@ contract NestedActionExecutor is Test, PoolTestBase {
 
         assertEq(deltaLockerBefore0, deltaLockerAfter0, "Locker delta 0");
         assertEq(deltaLockerBefore1, deltaLockerAfter1, "Locker delta 1");
-        assertEq(deltaThisBefore0 + int256(DONATE_AMOUNT0), deltaThisAfter0, "Executor delta 0");
-        assertEq(deltaThisBefore1 + int256(DONATE_AMOUNT1), deltaThisAfter1, "Executor delta 1");
-        assertEq(delta.amount0(), int256(DONATE_AMOUNT0), "Donate delta 0");
-        assertEq(delta.amount1(), int256(DONATE_AMOUNT1), "Donate delta 1");
+        assertEq(deltaThisBefore0 - int256(DONATE_AMOUNT0), deltaThisAfter0, "Executor delta 0");
+        assertEq(deltaThisBefore1 - int256(DONATE_AMOUNT1), deltaThisAfter1, "Executor delta 1");
+        assertEq(-delta.amount0(), int256(DONATE_AMOUNT0), "Donate delta 0");
+        assertEq(-delta.amount1(), int256(DONATE_AMOUNT1), "Donate delta 1");
 
         _settle(key.currency0, user, int128(deltaThisAfter0), true);
         _settle(key.currency1, user, int128(deltaThisAfter1), true);