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feat: add per-hop slippage to single swaps and flip to output/input ratio #516

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556fcad
fix: increase per-hop slippage precision from 1e18 to 1e36
gretzke Feb 21, 2026
cefa093
feat: add per-hop slippage checks to single swap commands
gretzke Feb 21, 2026
b13cd0b
refactor: flip per-hop slippage to output/input ratio with min check
gretzke Feb 21, 2026
1c44708
chore: update gas snapshots
gretzke Feb 21, 2026
d6d0656
lint
hensha256 Feb 25, 2026
0296654
OZ L04
hensha256 Mar 11, 2026
9d908f4
snapshots
hensha256 Mar 11, 2026
0f447d0
oz L05
hensha256 Mar 11, 2026
a262eb8
oz N08
hensha256 Mar 13, 2026
09d8d3a
PR comments
hensha256 Mar 13, 2026
25b3144
Merge branch 'main' into fix/per-hop-slippage-precision
hensha256 Mar 13, 2026
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8 changes: 4 additions & 4 deletions snapshots/PaymentsTests.json
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"Payments_swap_settleFromCaller_takeAllToMsgSender": "133006",
"Payments_swap_settleFromCaller_takeAllToSpecifiedAddress": "134475",
"Payments_swap_settleWithBalance_takeAllToMsgSender": "126957",
"Payments_swap_settleWithBalance_takeAllToSpecifiedAddress": "127095"
"Payments_swap_settleFromCaller_takeAllToMsgSender": "133163",
"Payments_swap_settleFromCaller_takeAllToSpecifiedAddress": "134632",
"Payments_swap_settleWithBalance_takeAllToMsgSender": "127114",
"Payments_swap_settleWithBalance_takeAllToSpecifiedAddress": "127252"
}
16 changes: 8 additions & 8 deletions snapshots/V4RouterTest.json
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
{
"V4Router_Bytecode": "9606",
"V4Router_Bytecode": "9950",
"V4Router_ExactIn1Hop_nativeIn": "122222",
"V4Router_ExactIn1Hop_nativeOut": "120688",
"V4Router_ExactIn1Hop_oneForZero": "129560",
Expand All @@ -8,9 +8,9 @@
"V4Router_ExactIn2Hops_nativeIn": "179580",
"V4Router_ExactIn3Hops": "250829",
"V4Router_ExactIn3Hops_nativeIn": "236965",
"V4Router_ExactInputSingle": "134001",
"V4Router_ExactInputSingle_nativeIn": "120137",
"V4Router_ExactInputSingle_nativeOut": "118581",
"V4Router_ExactInputSingle": "134158",
"V4Router_ExactInputSingle_nativeIn": "120294",
"V4Router_ExactInputSingle_nativeOut": "118738",
"V4Router_ExactOut1Hop_nativeIn_sweepETH": "128509",
"V4Router_ExactOut1Hop_nativeOut": "121898",
"V4Router_ExactOut1Hop_oneForZero": "130770",
Expand All @@ -20,8 +20,8 @@
"V4Router_ExactOut3Hops": "248399",
"V4Router_ExactOut3Hops_nativeIn": "241481",
"V4Router_ExactOut3Hops_nativeOut": "225554",
"V4Router_ExactOutputSingle": "133337",
"V4Router_ExactOutputSingle_nativeIn_sweepETH": "126419",
"V4Router_ExactOutputSingle_nativeOut": "119821",
"router initcode hash (without constructor params, as uint256)": "109481674309128023454344526833703660232982807837386720789725053502055679819514"
"V4Router_ExactOutputSingle": "133494",
"V4Router_ExactOutputSingle_nativeIn_sweepETH": "126576",
"V4Router_ExactOutputSingle_nativeOut": "119978",
"router initcode hash (without constructor params, as uint256)": "57167443502318477526720794142954804203351366829026518962672658585322779768213"
}
38 changes: 25 additions & 13 deletions src/V4Router.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ abstract contract V4Router is IV4Router, BaseActionsRouter, DeltaResolver {
using CalldataDecoder for bytes;
using BipsLibrary for uint256;

uint256 private constant PRECISION = 1e18;
uint256 private constant PRECISION = 1e36;

constructor(IPoolManager _poolManager) BaseActionsRouter(_poolManager) {}

Expand Down Expand Up @@ -90,6 +90,12 @@ abstract contract V4Router is IV4Router, BaseActionsRouter, DeltaResolver {
uint128 amountOut =
_swap(params.poolKey, params.zeroForOne, -int256(uint256(amountIn)), params.hookData).toUint128();
if (amountOut < params.amountOutMinimum) revert V4TooLittleReceived(params.amountOutMinimum, amountOut);
if (params.minHopPriceX36 != 0) {
uint256 priceX36 = uint256(amountOut) * PRECISION / amountIn;
if (priceX36 < params.minHopPriceX36) {
revert V4TooLittleReceivedPerHopSingle(params.minHopPriceX36, priceX36);
}
}
}

function _swapExactInput(IV4Router.ExactInputParams calldata params) private {
Expand All @@ -102,19 +108,19 @@ abstract contract V4Router is IV4Router, BaseActionsRouter, DeltaResolver {
if (amountIn == ActionConstants.OPEN_DELTA) amountIn = _getFullCredit(currencyIn).toUint128();
PathKey calldata pathKey;

uint256 perHopSlippageLength = params.maxHopSlippage.length;
if (perHopSlippageLength != 0 && perHopSlippageLength != pathLength) revert InvalidHopSlippageLength();
uint256 perHopPriceLength = params.minHopPriceX36.length;
if (perHopPriceLength != 0 && perHopPriceLength != pathLength) revert InvalidHopPriceLength();

for (uint256 i = 0; i < pathLength; i++) {
pathKey = params.path[i];
(PoolKey memory poolKey, bool zeroForOne) = pathKey.getPoolAndSwapDirection(currencyIn);
// The output delta will always be positive, except for when interacting with certain hook pools
amountOut = _swap(poolKey, zeroForOne, -int256(uint256(amountIn)), pathKey.hookData).toUint128();

if (perHopSlippageLength != 0) {
uint256 price = amountIn * PRECISION / amountOut;
uint256 maxSlippage = params.maxHopSlippage[i];
if (price > maxSlippage) revert V4TooLittleReceivedPerHop(i, maxSlippage, price);
if (perHopPriceLength != 0) {
uint256 priceX36 = amountOut * PRECISION / amountIn;
uint256 minPrice = params.minHopPriceX36[i];
if (priceX36 < minPrice) revert V4TooLittleReceivedPerHop(i, minPrice, priceX36);
}

amountIn = amountOut;
Expand All @@ -136,6 +142,12 @@ abstract contract V4Router is IV4Router, BaseActionsRouter, DeltaResolver {
))
.toUint128();
if (amountIn > params.amountInMaximum) revert V4TooMuchRequested(params.amountInMaximum, amountIn);
if (params.minHopPriceX36 != 0) {
uint256 priceX36 = uint256(amountOut) * PRECISION / amountIn;
if (priceX36 < params.minHopPriceX36) {
revert V4TooMuchRequestedPerHopSingle(params.minHopPriceX36, priceX36);
}
}
}

function _swapExactOutput(IV4Router.ExactOutputParams calldata params) private {
Expand All @@ -151,8 +163,8 @@ abstract contract V4Router is IV4Router, BaseActionsRouter, DeltaResolver {
amountOut = _getFullDebt(currencyOut).toUint128();
}

uint256 perHopSlippageLength = params.maxHopSlippage.length;
if (perHopSlippageLength != 0 && perHopSlippageLength != pathLength) revert InvalidHopSlippageLength();
uint256 perHopPriceLength = params.minHopPriceX36.length;
if (perHopPriceLength != 0 && perHopPriceLength != pathLength) revert InvalidHopPriceLength();

for (uint256 i = pathLength; i > 0; i--) {
pathKey = params.path[i - 1];
Expand All @@ -161,10 +173,10 @@ abstract contract V4Router is IV4Router, BaseActionsRouter, DeltaResolver {
amountIn = (uint256(-int256(_swap(poolKey, !oneForZero, int256(uint256(amountOut)), pathKey.hookData))))
.toUint128();

if (perHopSlippageLength != 0) {
uint256 price = amountIn * PRECISION / amountOut;
uint256 maxSlippage = params.maxHopSlippage[i - 1];
if (price > maxSlippage) revert V4TooMuchRequestedPerHop(i - 1, maxSlippage, price);
if (perHopPriceLength != 0) {
uint256 priceX36 = amountOut * PRECISION / amountIn;
uint256 minPrice = params.minHopPriceX36[i - 1];
if (priceX36 < minPrice) revert V4TooMuchRequestedPerHop(i - 1, minPrice, priceX36);
}
amountOut = amountIn;
currencyOut = pathKey.intermediateCurrency;
Expand Down
22 changes: 14 additions & 8 deletions src/interfaces/IV4Router.sol
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Expand Up @@ -13,27 +13,32 @@ interface IV4Router is IImmutableState {
error V4TooLittleReceived(uint256 minAmountOutReceived, uint256 amountReceived);
/// @notice Emitted when an exactOutput is asked for more than its maxAmountIn
error V4TooMuchRequested(uint256 maxAmountInRequested, uint256 amountRequested);
/// @notice Emitted when an exactInput swap does not receive its relative minAmountOut per hop (max price)
error V4TooLittleReceivedPerHop(uint256 hopIndex, uint256 maxPrice, uint256 price);
/// @notice Emitted when an exactOutput is asked for more than its relative maxAmountIn per hop (max price)
error V4TooMuchRequestedPerHop(uint256 hopIndex, uint256 maxPrice, uint256 price);
/// @notice Emitted when the length of the maxHopSlippage array is not zero and not equal to the path length
error InvalidHopSlippageLength();
/// @notice Emitted when an exactInput swap does not receive its relative minAmountOut per hop (min price)
error V4TooLittleReceivedPerHop(uint256 hopIndex, uint256 minPrice, uint256 price);
/// @notice Emitted when an exactOutput is asked for more than its relative maxAmountIn per hop (min price)
error V4TooMuchRequestedPerHop(uint256 hopIndex, uint256 minPrice, uint256 price);
/// @notice Emitted when a single exactInput swap does not meet its relative price limit
error V4TooLittleReceivedPerHopSingle(uint256 minPrice, uint256 price);
/// @notice Emitted when a single exactOutput swap exceeds its relative price limit
error V4TooMuchRequestedPerHopSingle(uint256 minPrice, uint256 price);
/// @notice Emitted when the length of the per-hop minimum price array is not zero and not equal to the path length
error InvalidHopPriceLength();

/// @notice Parameters for a single-hop exact-input swap
struct ExactInputSingleParams {
PoolKey poolKey;
bool zeroForOne;
uint128 amountIn;
uint128 amountOutMinimum;
uint256 minHopPriceX36;
bytes hookData;
}

/// @notice Parameters for a multi-hop exact-input swap
struct ExactInputParams {
Currency currencyIn;
PathKey[] path;
uint256[] maxHopSlippage;
uint256[] minHopPriceX36;
uint128 amountIn;
uint128 amountOutMinimum;
}
Expand All @@ -44,14 +49,15 @@ interface IV4Router is IImmutableState {
bool zeroForOne;
uint128 amountOut;
uint128 amountInMaximum;
uint256 minHopPriceX36;
bytes hookData;
}

/// @notice Parameters for a multi-hop exact-output swap
struct ExactOutputParams {
Currency currencyOut;
PathKey[] path;
uint256[] maxHopSlippage;
uint256[] minHopPriceX36;
uint128 amountOut;
uint128 amountInMaximum;
}
Expand Down
8 changes: 4 additions & 4 deletions src/libraries/CalldataDecoder.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -201,8 +201,8 @@ library CalldataDecoder {
// ExactInputSingleParams is a variable length struct so we just have to look up its location
assembly ("memory-safe") {
// only safety checks for the minimum length, where hookData is empty
// 0x140 = 10 * 0x20 -> 8 elements, bytes offset, and bytes length 0
if lt(params.length, 0x140) {
// 0x160 = 11 * 0x20 -> 9 elements, bytes offset, and bytes length 0
if lt(params.length, 0x160) {
mstore(0, SLICE_ERROR_SELECTOR)
revert(0x1c, 4)
}
Expand Down Expand Up @@ -237,8 +237,8 @@ library CalldataDecoder {
// ExactOutputSingleParams is a variable length struct so we just have to look up its location
assembly ("memory-safe") {
// only safety checks for the minimum length, where hookData is empty
// 0x140 = 10 * 0x20 -> 8 elements, bytes offset, and bytes length 0
if lt(params.length, 0x140) {
// 0x160 = 11 * 0x20 -> 9 elements, bytes offset, and bytes length 0
if lt(params.length, 0x160) {
mstore(0, SLICE_ERROR_SELECTOR)
revert(0x1c, 4)
}
Expand Down
6 changes: 4 additions & 2 deletions test/libraries/CalldataDecoder.t.sol
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Expand Up @@ -113,7 +113,7 @@ contract CalldataDecoderTest is Test {
assertEq(swapParams.amountIn, _swapParams.amountIn);
assertEq(swapParams.amountOutMinimum, _swapParams.amountOutMinimum);
_assertEq(swapParams.path, _swapParams.path);
_assertEq(swapParams.maxHopSlippage, _swapParams.maxHopSlippage);
_assertEq(swapParams.minHopPriceX36, _swapParams.minHopPriceX36);
}

function test_fuzz_decodeSwapExactInSingleParams(IV4Router.ExactInputSingleParams calldata _swapParams)
Expand All @@ -126,6 +126,7 @@ contract CalldataDecoderTest is Test {
assertEq(swapParams.zeroForOne, _swapParams.zeroForOne);
assertEq(swapParams.amountIn, _swapParams.amountIn);
assertEq(swapParams.amountOutMinimum, _swapParams.amountOutMinimum);
assertEq(swapParams.minHopPriceX36, _swapParams.minHopPriceX36);
assertEq(swapParams.hookData, _swapParams.hookData);
_assertEq(swapParams.poolKey, _swapParams.poolKey);
}
Expand All @@ -138,7 +139,7 @@ contract CalldataDecoderTest is Test {
assertEq(swapParams.amountOut, _swapParams.amountOut);
assertEq(swapParams.amountInMaximum, _swapParams.amountInMaximum);
_assertEq(swapParams.path, _swapParams.path);
_assertEq(swapParams.maxHopSlippage, _swapParams.maxHopSlippage);
_assertEq(swapParams.minHopPriceX36, _swapParams.minHopPriceX36);
}

function test_fuzz_decodeSwapExactOutSingleParams(IV4Router.ExactOutputSingleParams calldata _swapParams)
Expand All @@ -151,6 +152,7 @@ contract CalldataDecoderTest is Test {
assertEq(swapParams.zeroForOne, _swapParams.zeroForOne);
assertEq(swapParams.amountOut, _swapParams.amountOut);
assertEq(swapParams.amountInMaximum, _swapParams.amountInMaximum);
assertEq(swapParams.minHopPriceX36, _swapParams.minHopPriceX36);
assertEq(swapParams.hookData, _swapParams.hookData);
_assertEq(swapParams.poolKey, _swapParams.poolKey);
}
Expand Down
8 changes: 4 additions & 4 deletions test/router/Payments.gas.t.sol
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Expand Up @@ -18,7 +18,7 @@ contract PaymentsTests is RoutingTestHelpers {
function test_gas_swap_settleFromCaller_takeAllToSpecifiedAddress() public {
uint256 amountIn = 1 ether;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_IN_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE_ALL, abi.encode(key0.currency0, MAX_SETTLE_AMOUNT));
Expand All @@ -32,7 +32,7 @@ contract PaymentsTests is RoutingTestHelpers {
function test_gas_swap_settleFromCaller_takeAllToMsgSender() public {
uint256 amountIn = 1 ether;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_IN_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE, abi.encode(key0.currency0, amountIn, true));
Expand All @@ -46,7 +46,7 @@ contract PaymentsTests is RoutingTestHelpers {
function test_gas_swap_settleWithBalance_takeAllToSpecifiedAddress() public {
uint256 amountIn = 1 ether;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

// seed the router with tokens
key0.currency0.transfer(address(router), amountIn);
Expand All @@ -63,7 +63,7 @@ contract PaymentsTests is RoutingTestHelpers {
function test_gas_swap_settleWithBalance_takeAllToMsgSender() public {
uint256 amountIn = 1 ether;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

// seed the router with tokens
key0.currency0.transfer(address(router), amountIn);
Expand Down
16 changes: 8 additions & 8 deletions test/router/Payments.t.sol
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Expand Up @@ -21,7 +21,7 @@ contract PaymentsTests is RoutingTestHelpers {
function test_exactIn_settleAll_revertsSlippage() public {
uint256 amountIn = 1 ether;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_IN_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE_ALL, abi.encode(key0.currency0, amountIn - 1));
Expand All @@ -36,7 +36,7 @@ contract PaymentsTests is RoutingTestHelpers {
uint256 amountIn = 1 ether;
uint256 expectedAmountOut = 992054607780215625;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_IN_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE_ALL, abi.encode(key0.currency0, MAX_SETTLE_AMOUNT));
Expand All @@ -54,7 +54,7 @@ contract PaymentsTests is RoutingTestHelpers {
uint256 expectedAmountIn = 1008049273448486163;

IV4Router.ExactOutputSingleParams memory params =
IV4Router.ExactOutputSingleParams(key0, true, uint128(amountOut), uint128(expectedAmountIn), bytes(""));
IV4Router.ExactOutputSingleParams(key0, true, uint128(amountOut), uint128(expectedAmountIn), 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_OUT_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE_ALL, abi.encode(key0.currency0, expectedAmountIn - 1));
Expand All @@ -72,7 +72,7 @@ contract PaymentsTests is RoutingTestHelpers {
uint256 expectedAmountIn = 1008049273448486163;

IV4Router.ExactOutputSingleParams memory params =
IV4Router.ExactOutputSingleParams(key0, true, uint128(amountOut), uint128(expectedAmountIn), bytes(""));
IV4Router.ExactOutputSingleParams(key0, true, uint128(amountOut), uint128(expectedAmountIn), 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_OUT_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE_ALL, abi.encode(key0.currency0, MAX_SETTLE_AMOUNT));
Expand All @@ -88,7 +88,7 @@ contract PaymentsTests is RoutingTestHelpers {
uint256 expectedAmountIn = 1008049273448486163;

IV4Router.ExactOutputSingleParams memory params =
IV4Router.ExactOutputSingleParams(key0, true, uint128(amountOut), uint128(expectedAmountIn), bytes(""));
IV4Router.ExactOutputSingleParams(key0, true, uint128(amountOut), uint128(expectedAmountIn), 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_OUT_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE_ALL, abi.encode(key0.currency0, expectedAmountIn));
Expand All @@ -102,7 +102,7 @@ contract PaymentsTests is RoutingTestHelpers {
uint256 amountIn = 1 ether;
uint256 expectedAmountOut = 992054607780215625;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

// seed the router with tokens
key0.currency0.transfer(address(router), amountIn);
Expand Down Expand Up @@ -136,7 +136,7 @@ contract PaymentsTests is RoutingTestHelpers {
uint256 amountIn = 1 ether;
uint256 expectedAmountOut = 992054607780215625;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_IN_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE, abi.encode(key0.currency0, amountIn, true));
Expand Down Expand Up @@ -173,7 +173,7 @@ contract PaymentsTests is RoutingTestHelpers {
function test_settle_takePortion_reverts() public {
uint256 amountIn = 1 ether;
IV4Router.ExactInputSingleParams memory params =
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, bytes(""));
IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));

plan = plan.add(Actions.SWAP_EXACT_IN_SINGLE, abi.encode(params));
plan = plan.add(Actions.SETTLE, abi.encode(key0.currency0, amountIn, true));
Expand Down
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