merge main

.forge-snapshots/add liquidity to already existing position with salt.snap

@@ -1 +1 @@
-144929
+144627

.forge-snapshots/addLiquidity CA fee.snap

@@ -1 +1 @@
-171218
+170916

.forge-snapshots/addLiquidity with empty hook.snap

@@ -1 +1 @@
-274496
+274194

.forge-snapshots/addLiquidity with native token.snap

@@ -1 +1 @@
-135271
+135120

.forge-snapshots/create new liquidity to a position with salt.snap

@@ -1 +1 @@
-293121
+292819

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

@@ -1 +1 @@
-106472
+106321

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

@@ -1 +1 @@
-146038
+145736

.forge-snapshots/poolManager bytecode size.snap

@@ -1 +1 @@
-24119
+24044

.forge-snapshots/simple addLiquidity second addition same range.snap

@@ -1 +1 @@
-98989
+98838

.forge-snapshots/simple addLiquidity.snap

@@ -1 +1 @@
-161534
+161383

.forge-snapshots/simple swap.snap

@@ -1 +1 @@
-123337
+123186

.forge-snapshots/swap CA custom curve + swap noop.snap

@@ -1 +1 @@
-127123
+126821

.forge-snapshots/swap CA fee on unspecified.snap

@@ -1 +1 @@
-154782
+154631

.forge-snapshots/swap against liquidity.snap

@@ -1 +1 @@
-116709
+116558

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

@@ -1 +1 @@
-139754
+139603

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

@@ -1 +1 @@
-155178
+155027

.forge-snapshots/swap skips hook call if hook is caller.snap

@@ -1 +1 @@
-206434
+206132

.forge-snapshots/swap with dynamic fee.snap

@@ -1 +1 @@
-139358
+139207

.forge-snapshots/swap with hooks.snap

@@ -1 +1 @@
-132346
+132195

.forge-snapshots/swap with lp fee and protocol fee.snap

@@ -1 +1 @@
-169549
+169398

.forge-snapshots/swap with return dynamic fee.snap

@@ -1 +1 @@
-145685
+145534

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

@@ -1 +1 @@
-147965
+147814

src/PoolManager.sol

@@ -276,11 +276,14 @@ contract PoolManager is IPoolManager, ProtocolFees, NoDelegateCall, ERC6909Claim
 
     /// @inheritdoc IPoolManager
     function sync(Currency currency) external onlyWhenUnlocked {
-        CurrencyReserves.requireNotSynced();
         // address(0) is used for the native currency
-        if (currency.isAddressZero()) return;
-        uint256 balance = currency.balanceOfSelf();
-        CurrencyReserves.syncCurrencyAndReserves(currency, balance);
+        if (currency.isAddressZero()) {
+            // The reserves balance is not used for native settling, so we only need to reset the currency.
+            CurrencyReserves.resetCurrency();
+        } else {
+            uint256 balance = currency.balanceOfSelf();
+            CurrencyReserves.syncCurrencyAndReserves(currency, balance);
+        }
     }
 
     /// @inheritdoc IPoolManager
@@ -343,17 +346,19 @@ contract PoolManager is IPoolManager, ProtocolFees, NoDelegateCall, ERC6909Claim
 
     function _settle(address recipient) internal returns (uint256 paid) {
         Currency currency = CurrencyReserves.getSyncedCurrency();
-        // if not previously synced, expects native currency to be settled
+
+        // if not previously synced, or the syncedCurrency slot has been reset, expects native currency to be settled
         if (currency.isAddressZero()) {
             paid = msg.value;
         } else {
             if (msg.value > 0) NonzeroNativeValue.selector.revertWith();
-            // Reserves are guaranteed to be set, because currency and reserves are always set together
+            // Reserves are guaranteed to be set because currency and reserves are always set together
             uint256 reservesBefore = CurrencyReserves.getSyncedReserves();
             uint256 reservesNow = currency.balanceOfSelf();
             paid = reservesNow - reservesBefore;
             CurrencyReserves.resetCurrency();
         }
+
         _accountDelta(currency, paid.toInt128(), recipient);
     }
 

src/interfaces/IPoolManager.sol

@@ -184,7 +184,8 @@ interface IPoolManager is IProtocolFees, IERC6909Claims, IExtsload, IExttload {
     /// This is used to checkpoint balances for the manager and derive deltas for the caller.
     /// @dev This MUST be called before any ERC20 tokens are sent into the contract, but can be skipped
     /// for native tokens because the amount to settle is determined by the sent value.
-    /// @param currency The currency whose balance to sync
+    /// However, if an ERC20 token has been synced and not settled, and the caller instead wants to settle
+    /// native funds, this function can be called with the native currency to then be able to settle the native currency
     function sync(Currency currency) external;
 
     /// @notice Called by the user to net out some value owed to the user

src/libraries/CurrencyReserves.sol

@@ -7,20 +7,11 @@ import {CustomRevert} from "./CustomRevert.sol";
 library CurrencyReserves {
     using CustomRevert for bytes4;
 
-    /// @notice Thrown when a user has already synced a currency, but not yet settled
-    error AlreadySynced();
-
     /// bytes32(uint256(keccak256("ReservesOf")) - 1)
     bytes32 constant RESERVES_OF_SLOT = 0x1e0745a7db1623981f0b2a5d4232364c00787266eb75ad546f190e6cebe9bd95;
     /// bytes32(uint256(keccak256("Currency")) - 1)
     bytes32 constant CURRENCY_SLOT = 0x27e098c505d44ec3574004bca052aabf76bd35004c182099d8c575fb238593b9;
 
-    function requireNotSynced() internal view {
-        if (!getSyncedCurrency().isAddressZero()) {
-            AlreadySynced.selector.revertWith();
-        }
-    }
-
     function getSyncedCurrency() internal view returns (Currency currency) {
         assembly ("memory-safe") {
             currency := tload(CURRENCY_SLOT)

src/test/ProxyPoolManager.sol

@@ -141,10 +141,14 @@ contract ProxyPoolManager is IPoolManager, ProtocolFees, NoDelegateCall, ERC6909
 
     /// @inheritdoc IPoolManager
     function sync(Currency currency) public {
-        CurrencyReserves.requireNotSynced();
-        if (currency.isAddressZero()) return;
-        uint256 balance = currency.balanceOfSelf();
-        CurrencyReserves.syncCurrencyAndReserves(currency, balance);
+        // address(0) is used for the native currency
+        if (currency.isAddressZero()) {
+            // The reserves balance is not used for native settling, so we only need to reset the currency.
+            CurrencyReserves.resetCurrency();
+        } else {
+            uint256 balance = currency.balanceOfSelf();
+            CurrencyReserves.syncCurrencyAndReserves(currency, balance);
+        }
     }
 
     /// @inheritdoc IPoolManager

test/PoolManager.t.sol

@@ -1135,16 +1135,16 @@ contract PoolManagerTest is Test, Deployers, GasSnapshot {
         emptyUnlockRouter.unlock();
     }
 
-    Action[] actions;
+    Action[] _actions;
 
     function test_unlock_cannotBeCalledTwiceByCaller() public {
-        actions = [Action.NESTED_SELF_UNLOCK];
-        nestedActionRouter.unlock(abi.encode(actions));
+        _actions = [Action.NESTED_SELF_UNLOCK];
+        nestedActionRouter.unlock(abi.encode(_actions));
     }
 
     function test_unlock_cannotBeCalledTwiceByDifferentCallers() public {
-        actions = [Action.NESTED_EXECUTOR_UNLOCK];
-        nestedActionRouter.unlock(abi.encode(actions));
+        _actions = [Action.NESTED_EXECUTOR_UNLOCK];
+        nestedActionRouter.unlock(abi.encode(_actions));
     }
 
     // function testExtsloadForPoolPrice() public {

test/Sync.t.sol

@@ -19,6 +19,7 @@ import {StateLibrary} from "../src/libraries/StateLibrary.sol";
 import {TransientStateLibrary} from "../src/libraries/TransientStateLibrary.sol";
 import {NativeERC20} from "../src/test/NativeERC20.sol";
 import {IPoolManager} from "../src/interfaces/IPoolManager.sol";
+import {CurrencyLibrary} from "../src/types/Currency.sol";
 
 contract SyncTest is Test, Deployers, GasSnapshot {
     using StateLibrary for IPoolManager;
@@ -40,8 +41,8 @@ contract SyncTest is Test, Deployers, GasSnapshot {
     function test_sync_balanceIsZero() public {
         assertEq(currency2.balanceOf(address(manager)), uint256(0));
 
-        Actions[] memory actions = new Actions[](4);
-        bytes[] memory params = new bytes[](4);
+        Actions[] memory actions = new Actions[](2);
+        bytes[] memory params = new bytes[](2);
 
         actions[0] = Actions.SYNC;
         params[0] = abi.encode(currency2);
@@ -255,15 +256,19 @@ contract SyncTest is Test, Deployers, GasSnapshot {
         vm.deal(address(manager), value);
         NativeERC20 nativeERC20 = new NativeERC20();
 
-        Actions[] memory actions = new Actions[](2);
-        bytes[] memory params = new bytes[](2);
+        uint256 nativeERC20Balance = nativeERC20.balanceOf(address(manager));
+
+        Actions[] memory actions = new Actions[](3);
+        bytes[] memory params = new bytes[](3);
 
         actions[0] = Actions.SYNC;
         params[0] = abi.encode(nativeERC20);
 
-        // Revert with NonzeroNativeValue
-        actions[1] = Actions.SETTLE_NATIVE;
-        params[1] = abi.encode(value);
+        actions[1] = Actions.ASSERT_RESERVES_EQUALS;
+        params[1] = abi.encode(nativeERC20Balance);
+
+        actions[2] = Actions.SETTLE_NATIVE;
+        params[2] = abi.encode(value);
 
         vm.expectRevert(IPoolManager.NonzeroNativeValue.selector);
         actionsRouter.executeActions{value: value}(actions, params);
@@ -289,4 +294,80 @@ contract SyncTest is Test, Deployers, GasSnapshot {
         // uint256 balanceAfter = address(this).balance;
         // assertEq(balanceAfter - balanceBefore, value);
     }
+
+    function test_settle_native_afterERC20Sync_succeeds(uint256 currency2Balance, uint256 ethBalance) public {
+        currency2Balance = bound(currency2Balance, 1, uint256(int256(type(int128).max / 2)));
+        ethBalance = bound(ethBalance, 1, uint256(int256(type(int128).max / 2)));
+
+        vm.deal(address(this), ethBalance);
+        // ensure the reserves balance is non 0
+        currency2.transfer(address(manager), currency2Balance);
+
+        Actions[] memory actions = new Actions[](8);
+        bytes[] memory params = new bytes[](8);
+
+        actions[0] = Actions.ASSERT_RESERVES_EQUALS;
+        params[0] = abi.encode(0);
+
+        actions[1] = Actions.SYNC;
+        params[1] = abi.encode(currency2);
+
+        actions[2] = Actions.ASSERT_RESERVES_EQUALS;
+        params[2] = abi.encode(currency2Balance);
+
+        actions[3] = Actions.SYNC;
+        params[3] = abi.encode(CurrencyLibrary.ADDRESS_ZERO);
+
+        // Under the hood this is non-zero but our transient state library overrides the value if the currency is address(0)
+        actions[4] = Actions.ASSERT_RESERVES_EQUALS;
+        params[4] = abi.encode(0);
+
+        // This calls settle with a value, of ethBalance. Since the synedCurrency slot is address(0), the call should successfully apply a positive delta on the native currency.
+        actions[5] = Actions.SETTLE_NATIVE;
+        params[5] = abi.encode(ethBalance);
+
+        actions[6] = Actions.ASSERT_DELTA_EQUALS;
+        params[6] = abi.encode(CurrencyLibrary.ADDRESS_ZERO, address(actionsRouter), ethBalance);
+
+        // take the eth to close the deltas
+        actions[7] = Actions.TAKE;
+        params[7] = abi.encode(CurrencyLibrary.ADDRESS_ZERO, address(this), ethBalance);
+
+        actionsRouter.executeActions{value: ethBalance}(actions, params);
+    }
+
+    function test_settle_twice_doesNotApplyDelta(uint256 value) public {
+        value = bound(value, 1, uint256(int256(type(int128).max / 2)));
+        currency2.transfer(address(manager), value);
+
+        Actions[] memory actions = new Actions[](8);
+        bytes[] memory params = new bytes[](8);
+
+        actions[0] = Actions.SYNC;
+        params[0] = abi.encode(currency2);
+
+        actions[1] = Actions.ASSERT_RESERVES_EQUALS;
+        params[1] = abi.encode(value);
+
+        actions[2] = Actions.TRANSFER_FROM;
+        params[2] = abi.encode(currency2, address(this), address(manager), value);
+
+        // This settles the syncedCurrency, currency2.
+        actions[3] = Actions.SETTLE;
+
+        actions[4] = Actions.ASSERT_DELTA_EQUALS;
+        params[4] = abi.encode(currency2, address(actionsRouter), value);
+
+        actions[5] = Actions.TAKE;
+        params[5] = abi.encode(currency2, address(this), value);
+
+        // This settles the syncedCurrency, which has been cleared to address(0).
+        actions[6] = Actions.SETTLE;
+
+        // Calling settle on address(0) does not apply a delta when called with no value.
+        actions[7] = Actions.ASSERT_DELTA_EQUALS;
+        params[7] = abi.encode(CurrencyLibrary.ADDRESS_ZERO, address(actionsRouter), 0);
+
+        actionsRouter.executeActions(actions, params);
+    }
 }