feat: resolve flashloan fee on-chain via ACLManager

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

@@ -189,7 +189,7 @@ export const CollateralSwapActionsViaCowAdapters = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
         sellAmount: state.sellAmountBigInt,
       });
 

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

@@ -215,7 +215,7 @@ export const DebtSwapActionsViaCoW = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
         sellAmount: BigInt(sellAmountWithMarginForDustProtection),
       });
 

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

@@ -213,7 +213,7 @@ export const RepayWithCollateralActionsViaCoW = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
         sellAmount: BigInt(sellAmountWithMarginForDustProtection),
       });
 

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

@@ -92,7 +92,7 @@ export const calculateInstanceAddress = async ({
   };
 
   const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-    flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+    flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
     sellAmount: BigInt(sellAmountWithMarginForDustProtection),
   });
 
@@ -180,7 +180,7 @@ export const calculateFlashLoanAmounts = (
 
   const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
     sellAmount: sellAmount,
-    flashLoanFeeBps: FLASH_LOAN_FEE_BPS,
+    flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
   });
 
   return {

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

@@ -31,8 +31,8 @@ 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);
+  const feeBps = state.flashLoanFeeBps ?? PARASWAP_FLASH_LOAN_FEE_BPS;
+  const flashLoanFeeAmount = (state.sellAmountBigInt * BigInt(feeBps)) / BigInt(10000);
 
   // Format the fee amount
   const flashLoanFeeFormatted = valueToBigNumber(flashLoanFeeAmount.toString())

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

@@ -0,0 +1,104 @@
+import {
+  AaveV3Arbitrum,
+  AaveV3Avalanche,
+  AaveV3Base,
+  AaveV3BNB,
+  AaveV3Ethereum,
+  AaveV3EthereumEtherFi,
+  AaveV3EthereumLido,
+  AaveV3Gnosis,
+  AaveV3Optimism,
+  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)'];
+
+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,
+};
+
+const fallbackBps = (provider: SwapProvider): number =>
+  provider === SwapProvider.COW_PROTOCOL ? FLASH_LOAN_FEE_BPS : PARASWAP_FLASH_LOAN_FEE_BPS;
+
+const resolveTarget = (
+  provider: SwapProvider,
+  swapType: SwapType,
+  marketData: MarketDataType
+): string | undefined => {
+  if (provider === SwapProvider.COW_PROTOCOL) {
+    return ADAPTER_FACTORY[marketData.chainId as unknown as SupportedChainId] || undefined;
+  }
+  if (provider === SwapProvider.PARASWAP) {
+    switch (swapType) {
+      case SwapType.CollateralSwap:
+        return marketData.addresses.SWAP_COLLATERAL_ADAPTER;
+      case SwapType.RepayWithCollateral:
+        return marketData.addresses.REPAY_WITH_COLLATERAL_ADAPTER;
+      case SwapType.DebtSwap:
+        return marketData.addresses.DEBT_SWITCH_ADAPTER;
+      case SwapType.WithdrawAndSwap:
+        return marketData.addresses.WITHDRAW_SWITCH_ADAPTER;
+      default:
+        return undefined;
+    }
+  }
+  return undefined;
+};
+
+/**
+ * Resolve the flashloan fee bps for the active swap, defaulting to the
+ * provider's hardcoded bps when the on-chain ACLManager check is unavailable
+ * or pending. Returns 0 only when the target adapter (Paraswap per-flow) /
+ * factory (CoW) is registered as a FLASH_BORROWER on the market's ACLManager.
+ */
+export const useFlashLoanFeeBps = ({
+  provider,
+  swapType,
+  marketData,
+}: {
+  provider: SwapProvider;
+  swapType: SwapType;
+  marketData: MarketDataType;
+}): number => {
+  const aclManager = ACL_MANAGER_BY_MARKET[marketData.market];
+  const target = resolveTarget(provider, swapType, marketData);
+  const fallback = fallbackBps(provider);
+
+  const enabled = 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,
+  });
+
+  return isWhitelisted === true ? 0 : fallback;
+};

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 (
@@ -96,7 +98,7 @@ export const useSwapOrderAmounts = ({
     // const partnerFeeToken = state.side === 'sell' ? state.destinationToken : state.sourceToken;
 
     const flashLoanFeeBps = isPositionSwap(state.swapType, state.useFlashloan ?? false)
-      ? getFlashLoanFeeBps(state.provider)
+      ? resolvedFlashLoanFeeBps
       : 0;
     const flashLoanFeeAmount =
       state.side == 'sell'
@@ -354,6 +356,7 @@ export const useSwapOrderAmounts = ({
       networkFeeAmountInBuyFormatted,
       partnerFeeAmountFormatted: partnerFeeAmount.toFixed(),
       flashLoanFeeAmountFormatted: flashLoanFeeAmount.toFixed(),
+      flashLoanFeeBps,
       partnerFeeBps: partnetFeeBps,
     });
   }, [
@@ -366,5 +369,6 @@ 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: 0,
   partnerFeeBps: 0,
   limitsOrderButtonBlocked: false,
   showSlippageWarning: false,