feat: resolve flashloan fee on-chain via ACLManager

.gitignore

@@ -51,3 +51,4 @@ package-lock.json
 
 # Sentry Config File
 .env.sentry-build-plugin
+.env*.local

src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx

@@ -13,7 +13,7 @@ import { saveCowOrderToUserHistory } from 'src/utils/swapAdapterHistory';
 import { useShallow } from 'zustand/react/shallow';
 
 import { TrackAnalyticsHandlers } from '../../analytics/useTrackAnalytics';
-import { COW_PARTNER_FEE, FLASH_LOAN_FEE_BPS } from '../../constants/cow.constants';
+import { COW_PARTNER_FEE } from '../../constants/cow.constants';
 import { APP_CODE_PER_SWAP_TYPE } from '../../constants/shared.constants';
 import {
   addOrderTypeToAppData,
@@ -172,6 +172,10 @@ export const CollateralSwapActionsViaCowAdapters = ({
       )
         return;
 
+      if (state.flashLoanFeeBps === undefined) {
+        throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
+      }
+
       const tradingSdk = await getCowTradingSdkByChainIdAndAppCode(
         state.chainId,
         APP_CODE_PER_SWAP_TYPE[state.swapType]
@@ -189,7 +193,7 @@ export const CollateralSwapActionsViaCowAdapters = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps,
         sellAmount: state.sellAmountBigInt,
       });
 

src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx

@@ -14,7 +14,7 @@ import { zeroAddress } from 'viem';
 import { useShallow } from 'zustand/react/shallow';
 
 import { TrackAnalyticsHandlers } from '../../analytics/useTrackAnalytics';
-import { COW_PARTNER_FEE, FLASH_LOAN_FEE_BPS } from '../../constants/cow.constants';
+import { COW_PARTNER_FEE } from '../../constants/cow.constants';
 import { APP_CODE_PER_SWAP_TYPE } from '../../constants/shared.constants';
 import {
   addOrderTypeToAppData,
@@ -187,6 +187,10 @@ export const DebtSwapActionsViaCoW = ({
       )
         return;
 
+      if (state.flashLoanFeeBps === undefined) {
+        throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
+      }
+
       const tradingSdk = await getCowTradingSdkByChainIdAndAppCode(
         state.chainId,
         APP_CODE_PER_SWAP_TYPE[state.swapType]
@@ -215,7 +219,7 @@ export const DebtSwapActionsViaCoW = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps,
         sellAmount: BigInt(sellAmountWithMarginForDustProtection),
       });
 

src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx

@@ -13,7 +13,7 @@ import { saveCowOrderToUserHistory } from 'src/utils/swapAdapterHistory';
 import { useShallow } from 'zustand/react/shallow';
 
 import { TrackAnalyticsHandlers } from '../../analytics/useTrackAnalytics';
-import { COW_PARTNER_FEE, FLASH_LOAN_FEE_BPS } from '../../constants/cow.constants';
+import { COW_PARTNER_FEE } from '../../constants/cow.constants';
 import { APP_CODE_PER_SWAP_TYPE } from '../../constants/shared.constants';
 import {
   addOrderTypeToAppData,
@@ -185,6 +185,10 @@ export const RepayWithCollateralActionsViaCoW = ({
       )
         return;
 
+      if (state.flashLoanFeeBps === undefined) {
+        throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
+      }
+
       const tradingSdk = await getCowTradingSdkByChainIdAndAppCode(
         state.chainId,
         APP_CODE_PER_SWAP_TYPE[state.swapType]
@@ -213,7 +217,7 @@ export const RepayWithCollateralActionsViaCoW = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps,
         sellAmount: BigInt(sellAmountWithMarginForDustProtection),
       });
 

src/components/transactions/Swap/helpers/cow/adapters.helpers.ts

@@ -16,11 +16,7 @@ import {
 } from '@cowprotocol/sdk-flash-loans';
 import { CustomMarket } from 'src/ui-config/marketsConfig';
 
-import {
-  COW_PARTNER_FEE,
-  DUST_PROTECTION_MULTIPLIER,
-  FLASH_LOAN_FEE_BPS,
-} from '../../constants/cow.constants';
+import { COW_PARTNER_FEE, DUST_PROTECTION_MULTIPLIER } from '../../constants/cow.constants';
 import { isCowProtocolRates, OrderType, SwapProvider, SwapState, SwapType } from '../../types';
 import { getCowFlashLoanSdk } from './env.helpers';
 
@@ -53,7 +49,8 @@ export const calculateInstanceAddress = async ({
     !state.sellAmountBigInt ||
     !state.buyAmountBigInt ||
     !state.sellAmountToken ||
-    !state.buyAmountToken
+    !state.buyAmountToken ||
+    state.flashLoanFeeBps === undefined
   )
     return;
 
@@ -92,7 +89,7 @@ export const calculateInstanceAddress = async ({
   };
 
   const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-    flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+    flashLoanFeeBps: state.flashLoanFeeBps,
     sellAmount: BigInt(sellAmountWithMarginForDustProtection),
   });
 
@@ -171,7 +168,11 @@ export const calculateFlashLoanAmounts = (
       finalSellAmount: BigInt(0),
     };
 
-  if (state.swapType === SwapType.Swap || state.provider !== SwapProvider.COW_PROTOCOL) {
+  if (
+    state.swapType === SwapType.Swap ||
+    state.provider !== SwapProvider.COW_PROTOCOL ||
+    state.flashLoanFeeBps === undefined
+  ) {
     return {
       flashLoanFeeAmount: BigInt(0),
       finalSellAmount: sellAmount,
@@ -180,7 +181,7 @@ export const calculateFlashLoanAmounts = (
 
   const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
     sellAmount: sellAmount,
-    flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+    flashLoanFeeBps: state.flashLoanFeeBps,
   });
 
   return {

src/components/transactions/Swap/helpers/paraswap/flashloan.helpers.ts

@@ -1,11 +1,12 @@
 import { valueToBigNumber } from '@aave/math-utils';
 
-import { PARASWAP_FLASH_LOAN_FEE_BPS } from '../../constants/paraswap.constants';
 import { SwapProvider, SwapState, SwapType } from '../../types';
 
 /**
  * Calculate flashloan fee amount for Paraswap adapter swaps.
- * The fee is 0.05% (5 bps) of the flashloan amount, which is the sell amount.
+ * The fee bps is resolved on-chain via ACLManager.isFlashBorrower; while the
+ * check is in flight `state.flashLoanFeeBps` is undefined and we return zeros
+ * so the caller doesn't render a stale value.
  *
  * @param state - Swap state
  * @returns Object containing flashloan fee amount in bigint and formatted string
@@ -21,7 +22,8 @@ export const calculateParaswapFlashLoanFee = (
     state.swapType === SwapType.Swap ||
     state.provider !== SwapProvider.PARASWAP ||
     !state.useFlashloan ||
-    !state.sellAmountBigInt
+    !state.sellAmountBigInt ||
+    state.flashLoanFeeBps === undefined
   ) {
     return {
       flashLoanFeeAmount: BigInt(0),
@@ -32,7 +34,7 @@ export const calculateParaswapFlashLoanFee = (
   // Calculate fee: flashloan amount * fee bps / 10000
   // The flashloan amount is the sell amount (collateral being swapped)
   const flashLoanFeeAmount =
-    (state.sellAmountBigInt * BigInt(PARASWAP_FLASH_LOAN_FEE_BPS)) / BigInt(10000);
+    (state.sellAmountBigInt * BigInt(state.flashLoanFeeBps)) / BigInt(10000);
 
   // Format the fee amount
   const flashLoanFeeFormatted = valueToBigNumber(flashLoanFeeAmount.toString())

src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts

@@ -0,0 +1,98 @@
+import {
+  AaveV3Arbitrum,
+  AaveV3Avalanche,
+  AaveV3Base,
+  AaveV3BNB,
+  AaveV3Ethereum,
+  AaveV3EthereumEtherFi,
+  AaveV3EthereumLido,
+  AaveV3Gnosis,
+  AaveV3Linea,
+  AaveV3Optimism,
+  AaveV3Plasma,
+  AaveV3Polygon,
+  AaveV3Sonic,
+} from '@aave-dao/aave-address-book';
+import { SupportedChainId } from '@cowprotocol/cow-sdk';
+import { useQuery } from '@tanstack/react-query';
+import { Contract } from 'ethers';
+import { CustomMarket, MarketDataType } from 'src/ui-config/marketsConfig';
+import { getProvider } from 'src/utils/marketsAndNetworksConfig';
+
+import { ADAPTER_FACTORY, FLASH_LOAN_FEE_BPS } from '../constants/cow.constants';
+import { PARASWAP_FLASH_LOAN_FEE_BPS } from '../constants/paraswap.constants';
+import { SwapProvider, SwapType } from '../types';
+
+const ACL_MANAGER_ABI = ['function isFlashBorrower(address) view returns (bool)'];
+
+// CoW per-market ACLManager addresses. Only CoW flows do the on-chain lookup —
+// Paraswap flows always have the user EOA as msg.sender to Pool.flashLoan, so
+// they pay the default premium and don't need a check.
+const ACL_MANAGER_BY_MARKET: Partial<Record<CustomMarket, string>> = {
+  [CustomMarket.proto_mainnet_v3]: AaveV3Ethereum.ACL_MANAGER,
+  [CustomMarket.proto_lido_v3]: AaveV3EthereumLido.ACL_MANAGER,
+  [CustomMarket.proto_etherfi_v3]: AaveV3EthereumEtherFi.ACL_MANAGER,
+  [CustomMarket.proto_arbitrum_v3]: AaveV3Arbitrum.ACL_MANAGER,
+  [CustomMarket.proto_base_v3]: AaveV3Base.ACL_MANAGER,
+  [CustomMarket.proto_polygon_v3]: AaveV3Polygon.ACL_MANAGER,
+  [CustomMarket.proto_optimism_v3]: AaveV3Optimism.ACL_MANAGER,
+  [CustomMarket.proto_avalanche_v3]: AaveV3Avalanche.ACL_MANAGER,
+  [CustomMarket.proto_sonic_v3]: AaveV3Sonic.ACL_MANAGER,
+  [CustomMarket.proto_gnosis_v3]: AaveV3Gnosis.ACL_MANAGER,
+  [CustomMarket.proto_bnb_v3]: AaveV3BNB.ACL_MANAGER,
+  [CustomMarket.proto_linea_v3]: AaveV3Linea.ACL_MANAGER,
+  [CustomMarket.proto_plasma_v3]: AaveV3Plasma.ACL_MANAGER,
+};
+
+/**
+ * Resolve the flashloan fee bps for the active swap.
+ *
+ * - CoW: msg.sender to Pool.flashLoan is the CoW factory. Check
+ *   ACLManager.isFlashBorrower(factory) on chain. Returns 0 when whitelisted,
+ *   FLASH_LOAN_FEE_BPS when not, and `undefined` while the query is pending or
+ *   when we can't run the check (factory or ACLManager not mapped for the
+ *   chain). Submit handlers MUST refuse to send while the value is undefined.
+ * - Paraswap: msg.sender is always the user EOA, so the role can never apply.
+ *   Returns the constant immediately, no on-chain call.
+ */
+export const useFlashLoanFeeBps = ({
+  provider,
+  swapType,
+  marketData,
+}: {
+  provider: SwapProvider;
+  swapType: SwapType;
+  marketData: MarketDataType;
+}): number | undefined => {
+  const isCow = provider === SwapProvider.COW_PROTOCOL;
+  const aclManager = ACL_MANAGER_BY_MARKET[marketData.market];
+  const target = isCow
+    ? ADAPTER_FACTORY[marketData.chainId as unknown as SupportedChainId] || undefined
+    : undefined;
+
+  const enabled = isCow && Boolean(aclManager && target);
+
+  const { data: isWhitelisted } = useQuery({
+    queryFn: async (): Promise<boolean> => {
+      const contract = new Contract(
+        aclManager as string,
+        ACL_MANAGER_ABI,
+        getProvider(marketData.chainId)
+      );
+      return contract.isFlashBorrower(target);
+    },
+    queryKey: ['flashBorrowerCheck', marketData.chainId, aclManager, target],
+    enabled,
+    staleTime: 5 * 60 * 1000,
+  });
+
+  if (!isCow) {
+    // Acknowledge swapType to keep the dep narrow even though Paraswap
+    // doesn't branch on it for fee resolution.
+    void swapType;
+    return PARASWAP_FLASH_LOAN_FEE_BPS;
+  }
+  if (!enabled) return undefined;
+  if (isWhitelisted === undefined) return undefined;
+  return isWhitelisted ? 0 : FLASH_LOAN_FEE_BPS;
+};

src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts

@@ -3,8 +3,7 @@ import { OrderKind } from '@cowprotocol/cow-sdk';
 import { Dispatch, useEffect } from 'react';
 import { useRootStore } from 'src/store/root';
 
-import { COW_PARTNER_FEE, FLASH_LOAN_FEE_BPS } from '../constants/cow.constants';
-import { PARASWAP_FLASH_LOAN_FEE_BPS } from '../constants/paraswap.constants';
+import { COW_PARTNER_FEE } from '../constants/cow.constants';
 import {
   isCowProtocolRates,
   OrderType,
@@ -13,6 +12,7 @@ import {
   SwapState,
   SwapType,
 } from '../types';
+import { useFlashLoanFeeBps } from './useFlashLoanFeeBps';
 import { swapTypesThatRequiresInvertedQuote } from './useSwapQuote';
 
 const marketOrderKindPerSwapType: Record<SwapType, OrderKind> = {
@@ -27,10 +27,6 @@ const isPositionSwap = (swapType: SwapType, usingFlashloan: boolean) => {
   return swapType != SwapType.Swap && usingFlashloan;
 };
 
-const getFlashLoanFeeBps = (provider: SwapProvider) => {
-  return provider === SwapProvider.COW_PROTOCOL ? FLASH_LOAN_FEE_BPS : PARASWAP_FLASH_LOAN_FEE_BPS;
-};
-
 /**
  * Computes normalized sell/buy amounts used to build transactions.
  *
@@ -50,6 +46,12 @@ export const useSwapOrderAmounts = ({
   setState: Dispatch<Partial<SwapState>>;
 }) => {
   const currentMarket = useRootStore((state) => state.currentMarket);
+  const currentMarketData = useRootStore((store) => store.currentMarketData);
+  const resolvedFlashLoanFeeBps = useFlashLoanFeeBps({
+    provider: state.provider,
+    swapType: state.swapType,
+    marketData: currentMarketData,
+  });
 
   useEffect(() => {
     if (
@@ -95,9 +97,13 @@ export const useSwapOrderAmounts = ({
         : valueToBigNumber(state.inputAmount).multipliedBy(partnetFeeBps).dividedBy(10000);
     // const partnerFeeToken = state.side === 'sell' ? state.destinationToken : state.sourceToken;
 
-    const flashLoanFeeBps = isPositionSwap(state.swapType, state.useFlashloan ?? false)
-      ? getFlashLoanFeeBps(state.provider)
-      : 0;
+    const usingFlashloan = isPositionSwap(state.swapType, state.useFlashloan ?? false);
+    if (usingFlashloan && resolvedFlashLoanFeeBps === undefined) {
+      // Clear any stale fee from a previous render so submit handlers see the loading state.
+      if (state.flashLoanFeeBps !== undefined) setState({ flashLoanFeeBps: undefined });
+      return;
+    }
+    const flashLoanFeeBps = usingFlashloan ? (resolvedFlashLoanFeeBps as number) : 0;
     const flashLoanFeeAmount =
       state.side == 'sell'
         ? valueToBigNumber(state.outputAmount).multipliedBy(flashLoanFeeBps).dividedBy(10000)
@@ -354,6 +360,7 @@ export const useSwapOrderAmounts = ({
       networkFeeAmountInBuyFormatted,
       partnerFeeAmountFormatted: partnerFeeAmount.toFixed(),
       flashLoanFeeAmountFormatted: flashLoanFeeAmount.toFixed(),
+      flashLoanFeeBps,
       partnerFeeBps: partnetFeeBps,
     });
   }, [
@@ -366,5 +373,6 @@ export const useSwapOrderAmounts = ({
     state.swapType,
     state.orderType,
     state.useFlashloan,
+    resolvedFlashLoanFeeBps,
   ]);
 };

src/components/transactions/Swap/types/state.types.ts

@@ -97,6 +97,8 @@ export type TokensSwapState = {
   partnerFeeAmountFormatted?: string;
   /** Flash loan fee amount applied to this order, normalized to the fee token units (depends on side). */
   flashLoanFeeAmountFormatted?: string;
+  /** Flash loan fee in basis points used to compute flashLoanFeeAmountFormatted. Resolved on-chain from ACLManager.isFlashBorrower. */
+  flashLoanFeeBps?: number;
   /** Partner fee in basis points used to compute partnerFeeAmountFormatted. */
   partnerFeeBps?: number;
 
@@ -287,6 +289,7 @@ export const swapDefaultState: SwapState = {
   networkFeeAmountInBuyFormatted: '0',
   partnerFeeAmountFormatted: '0',
   flashLoanFeeAmountFormatted: '0',
+  flashLoanFeeBps: undefined,
   partnerFeeBps: 0,
   limitsOrderButtonBlocked: false,
   showSlippageWarning: false,