From 21b22921249da37d66773e5ac83e54125f5bb5d8 Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 11:36:35 -0300
Subject: [PATCH 1/8] feat: resolve flashloan fee on-chain via ACLManager

---
 .../CollateralSwapActionsViaCoWAdapters.tsx   |   2 +-
 .../DebtSwap/DebtSwapActionsViaCoW.tsx        |   2 +-
 .../RepayWithCollateralActionsViaCoW.tsx      |   2 +-
 .../Swap/helpers/cow/adapters.helpers.ts      |   4 +-
 .../helpers/paraswap/flashloan.helpers.ts     |   4 +-
 .../Swap/hooks/useFlashLoanFeeBps.ts          | 104 ++++++++++++++++++
 .../Swap/hooks/useSwapOrderAmounts.ts         |  18 +--
 .../transactions/Swap/types/state.types.ts    |   3 +
 8 files changed, 125 insertions(+), 14 deletions(-)
 create mode 100644 src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts

diff --git a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx
index 07e1f32d15..33c5760389 100644
--- a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx
+++ b/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,
       });
 
diff --git a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx
index 9eb7782c2c..eccc9df775 100644
--- a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx
+++ b/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),
       });
 
diff --git a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx
index b7e9051466..cd2758c0cd 100644
--- a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx
+++ b/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),
       });
 
diff --git a/src/components/transactions/Swap/helpers/cow/adapters.helpers.ts b/src/components/transactions/Swap/helpers/cow/adapters.helpers.ts
index b8e78231cf..874bb69376 100644
--- a/src/components/transactions/Swap/helpers/cow/adapters.helpers.ts
+++ b/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 {
diff --git a/src/components/transactions/Swap/helpers/paraswap/flashloan.helpers.ts b/src/components/transactions/Swap/helpers/paraswap/flashloan.helpers.ts
index 1bb122358c..2e12b2f24d 100644
--- a/src/components/transactions/Swap/helpers/paraswap/flashloan.helpers.ts
+++ b/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())
diff --git a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
new file mode 100644
index 0000000000..aee2d69821
--- /dev/null
+++ b/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;
+};
diff --git a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
index 9f9e2c18e6..16f67ed625 100644
--- a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
+++ b/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,
   ]);
 };
diff --git a/src/components/transactions/Swap/types/state.types.ts b/src/components/transactions/Swap/types/state.types.ts
index f3bff46de9..c9f46c9acb 100644
--- a/src/components/transactions/Swap/types/state.types.ts
+++ b/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,

From 1f1394c2fd0d3fc15680d74ec0ca434bb2e28f7e Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 11:42:56 -0300
Subject: [PATCH 2/8] fix: gate flashloan-fee readers on resolved on-chain
 value

---
 .../CollateralSwapActionsViaCoWAdapters.tsx   |  7 ++++---
 .../DebtSwap/DebtSwapActionsViaCoW.tsx        |  7 ++++---
 .../RepayWithCollateralActionsViaCoW.tsx      |  7 ++++---
 .../Swap/helpers/cow/adapters.helpers.ts      | 19 ++++++++++---------
 .../helpers/paraswap/flashloan.helpers.ts     | 12 +++++++-----
 .../Swap/hooks/useFlashLoanFeeBps.ts          | 17 ++++++++++-------
 .../Swap/hooks/useSwapOrderAmounts.ts         |  6 +++---
 7 files changed, 42 insertions(+), 33 deletions(-)

diff --git a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx
index 33c5760389..c8e45d05ca 100644
--- a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx
+++ b/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,
@@ -168,7 +168,8 @@ export const CollateralSwapActionsViaCowAdapters = ({
         !state.sellAmountBigInt ||
         !state.sellAmountToken ||
         !state.buyAmountBigInt ||
-        !state.buyAmountToken
+        !state.buyAmountToken ||
+        state.flashLoanFeeBps === undefined
       )
         return;
 
@@ -189,7 +190,7 @@ export const CollateralSwapActionsViaCowAdapters = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps,
         sellAmount: state.sellAmountBigInt,
       });
 
diff --git a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx
index eccc9df775..9b16c3ee31 100644
--- a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx
+++ b/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,
@@ -183,7 +183,8 @@ export const DebtSwapActionsViaCoW = ({
         !state.sellAmountBigInt ||
         !state.sellAmountToken ||
         !state.buyAmountBigInt ||
-        !state.buyAmountToken
+        !state.buyAmountToken ||
+        state.flashLoanFeeBps === undefined
       )
         return;
 
@@ -215,7 +216,7 @@ export const DebtSwapActionsViaCoW = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps,
         sellAmount: BigInt(sellAmountWithMarginForDustProtection),
       });
 
diff --git a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx
index cd2758c0cd..ef6f9bfdc9 100644
--- a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx
+++ b/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,
@@ -181,7 +181,8 @@ export const RepayWithCollateralActionsViaCoW = ({
         !state.sellAmountBigInt ||
         !state.sellAmountToken ||
         !state.buyAmountBigInt ||
-        !state.buyAmountToken
+        !state.buyAmountToken ||
+        state.flashLoanFeeBps === undefined
       )
         return;
 
@@ -213,7 +214,7 @@ export const RepayWithCollateralActionsViaCoW = ({
         : undefined;
 
       const { flashLoanFeeAmount, sellAmountToSign } = flashLoanSdk.calculateFlashLoanAmounts({
-        flashLoanFeeBps: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
+        flashLoanFeeBps: state.flashLoanFeeBps,
         sellAmount: BigInt(sellAmountWithMarginForDustProtection),
       });
 
diff --git a/src/components/transactions/Swap/helpers/cow/adapters.helpers.ts b/src/components/transactions/Swap/helpers/cow/adapters.helpers.ts
index 874bb69376..72975352c4 100644
--- a/src/components/transactions/Swap/helpers/cow/adapters.helpers.ts
+++ b/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: state.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: state.flashLoanFeeBps ?? FLASH_LOAN_FEE_BPS,
+    flashLoanFeeBps: state.flashLoanFeeBps,
   });
 
   return {
diff --git a/src/components/transactions/Swap/helpers/paraswap/flashloan.helpers.ts b/src/components/transactions/Swap/helpers/paraswap/flashloan.helpers.ts
index 2e12b2f24d..40d4a43117 100644
--- a/src/components/transactions/Swap/helpers/paraswap/flashloan.helpers.ts
+++ b/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),
@@ -31,8 +33,8 @@ export const calculateParaswapFlashLoanFee = (
 
   // Calculate fee: flashloan amount * fee bps / 10000
   // The flashloan amount is the sell amount (collateral being swapped)
-  const feeBps = state.flashLoanFeeBps ?? PARASWAP_FLASH_LOAN_FEE_BPS;
-  const flashLoanFeeAmount = (state.sellAmountBigInt * BigInt(feeBps)) / BigInt(10000);
+  const flashLoanFeeAmount =
+    (state.sellAmountBigInt * BigInt(state.flashLoanFeeBps)) / BigInt(10000);
 
   // Format the fee amount
   const flashLoanFeeFormatted = valueToBigNumber(flashLoanFeeAmount.toString())
diff --git a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
index aee2d69821..b8da9f9366 100644
--- a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
+++ b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
@@ -66,10 +66,11 @@ const resolveTarget = (
 };
 
 /**
- * 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.
+ * Resolve the flashloan fee bps for the active swap by checking the market's
+ * ACLManager.isFlashBorrower for the provider's target address. Returns 0 when
+ * the target is whitelisted, the provider's default bps when it's not, and
+ * `undefined` while the on-chain query is in flight so callers can hold off
+ * computing order amounts until the answer is in.
  */
 export const useFlashLoanFeeBps = ({
   provider,
@@ -79,10 +80,10 @@ export const useFlashLoanFeeBps = ({
   provider: SwapProvider;
   swapType: SwapType;
   marketData: MarketDataType;
-}): number => {
+}): number | undefined => {
   const aclManager = ACL_MANAGER_BY_MARKET[marketData.market];
   const target = resolveTarget(provider, swapType, marketData);
-  const fallback = fallbackBps(provider);
+  const defaultBps = fallbackBps(provider);
 
   const enabled = Boolean(aclManager && target);
 
@@ -100,5 +101,7 @@ export const useFlashLoanFeeBps = ({
     staleTime: 5 * 60 * 1000,
   });
 
-  return isWhitelisted === true ? 0 : fallback;
+  if (!enabled) return defaultBps;
+  if (isWhitelisted === undefined) return undefined;
+  return isWhitelisted ? 0 : defaultBps;
 };
diff --git a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
index 16f67ed625..d7c0ebb472 100644
--- a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
+++ b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
@@ -97,9 +97,9 @@ 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)
-      ? resolvedFlashLoanFeeBps
-      : 0;
+    const usingFlashloan = isPositionSwap(state.swapType, state.useFlashloan ?? false);
+    if (usingFlashloan && resolvedFlashLoanFeeBps === undefined) return;
+    const flashLoanFeeBps = usingFlashloan ? (resolvedFlashLoanFeeBps as number) : 0;
     const flashLoanFeeAmount =
       state.side == 'sell'
         ? valueToBigNumber(state.outputAmount).multipliedBy(flashLoanFeeBps).dividedBy(10000)

From 3e7f14b1d00126a1cc530acd03dd3e7c07756ca4 Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 11:50:09 -0300
Subject: [PATCH 3/8] fix: throw on swap submit when flashloan fee unresolved

---
 .../CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx | 7 +++++--
 .../CollateralSwapActionsViaParaswapAdapters.tsx           | 4 ++++
 .../Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx        | 7 +++++--
 .../Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx   | 4 ++++
 .../RepayWithCollateralActionsViaCoW.tsx                   | 7 +++++--
 .../RepayWithCollateralActionsViaParaswap.tsx              | 4 ++++
 .../WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx  | 4 ++++
 .../transactions/Swap/hooks/useFlashLoanFeeBps.ts          | 7 ++++---
 8 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx
index c8e45d05ca..2200d25cb0 100644
--- a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx
+++ b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaCoWAdapters.tsx
@@ -168,11 +168,14 @@ export const CollateralSwapActionsViaCowAdapters = ({
         !state.sellAmountBigInt ||
         !state.sellAmountToken ||
         !state.buyAmountBigInt ||
-        !state.buyAmountToken ||
-        state.flashLoanFeeBps === undefined
+        !state.buyAmountToken
       )
         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]
diff --git a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx
index c8567ed466..894feb8386 100644
--- a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx
+++ b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx
@@ -81,6 +81,10 @@ export const CollateralSwapActionsViaParaswapAdapters = ({
     if (!state.swapRate || !isParaswapRates(state.swapRate))
       throw new Error('Route required to build transaction');
 
+    if (state.flashLoanFeeBps === undefined) {
+      throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
+    }
+
     setMainTxState({
       txHash: undefined,
       loading: true,
diff --git a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx
index 9b16c3ee31..6e7e4de33d 100644
--- a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx
+++ b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaCoW.tsx
@@ -183,11 +183,14 @@ export const DebtSwapActionsViaCoW = ({
         !state.sellAmountBigInt ||
         !state.sellAmountToken ||
         !state.buyAmountBigInt ||
-        !state.buyAmountToken ||
-        state.flashLoanFeeBps === undefined
+        !state.buyAmountToken
       )
         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]
diff --git a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx
index 0c8f21bbdd..dcf7b0902e 100644
--- a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx
+++ b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx
@@ -104,6 +104,10 @@ export const DebtSwapActionsViaParaswap = ({
         throw new Error('No swap rate found');
       }
 
+      if (state.flashLoanFeeBps === undefined) {
+        throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
+      }
+
       const inferredKind = state.swapRate.optimalRateData.side === 'SELL' ? 'sell' : 'buy';
 
       // CallData for ParaswapRoute, which is inversed to the actual swap (dest -> src)
diff --git a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx
index ef6f9bfdc9..4ca5affaa3 100644
--- a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx
+++ b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaCoW.tsx
@@ -181,11 +181,14 @@ export const RepayWithCollateralActionsViaCoW = ({
         !state.sellAmountBigInt ||
         !state.sellAmountToken ||
         !state.buyAmountBigInt ||
-        !state.buyAmountToken ||
-        state.flashLoanFeeBps === undefined
+        !state.buyAmountToken
       )
         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]
diff --git a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx
index 95a190db2c..bbae52ec66 100644
--- a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx
+++ b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx
@@ -103,6 +103,10 @@ export const RepayWithCollateralActionsViaParaswap = ({
     if (!state.swapRate || !isParaswapRates(state.swapRate))
       throw new Error('Route required to build transaction');
 
+    if (state.flashLoanFeeBps === undefined) {
+      throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
+    }
+
     setMainTxState({
       txHash: undefined,
       loading: true,
diff --git a/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx b/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx
index 60c62fa3dc..3eb222ec88 100644
--- a/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx
+++ b/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx
@@ -82,6 +82,10 @@ export const WithdrawAndSwapActionsViaParaswap = ({
       return;
     }
 
+    if (state.flashLoanFeeBps === undefined) {
+      throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
+    }
+
     try {
       setMainTxState({ ...mainTxState, loading: true });
       const { swapCallData, augustus } = await getTransactionParams(
diff --git a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
index b8da9f9366..e9b27a60a5 100644
--- a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
+++ b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
@@ -69,8 +69,9 @@ const resolveTarget = (
  * Resolve the flashloan fee bps for the active swap by checking the market's
  * ACLManager.isFlashBorrower for the provider's target address. Returns 0 when
  * the target is whitelisted, the provider's default bps when it's not, and
- * `undefined` while the on-chain query is in flight so callers can hold off
- * computing order amounts until the answer is in.
+ * `undefined` whenever we don't have an on-chain answer (query pending,
+ * ACLManager unmapped for the market, or no target address resolvable). The
+ * caller MUST refuse to submit a transaction while the value is undefined.
  */
 export const useFlashLoanFeeBps = ({
   provider,
@@ -101,7 +102,7 @@ export const useFlashLoanFeeBps = ({
     staleTime: 5 * 60 * 1000,
   });
 
-  if (!enabled) return defaultBps;
+  if (!enabled) return undefined;
   if (isWhitelisted === undefined) return undefined;
   return isWhitelisted ? 0 : defaultBps;
 };

From ed687af04be3b9b06fed57b1a6e473a424c9dea2 Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 12:27:23 -0300
Subject: [PATCH 4/8] chore: instrument useFlashLoanFeeBps for preview
 debugging

---
 .gitignore                                    |  1 +
 .../Swap/hooks/useFlashLoanFeeBps.ts          | 40 ++++++++++++++++---
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/.gitignore b/.gitignore
index 1d7c8b4031..b56c837373 100644
--- a/.gitignore
+++ b/.gitignore
@@ -51,3 +51,4 @@ package-lock.json
 
 # Sentry Config File
 .env.sentry-build-plugin
+.env*.local
diff --git a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
index e9b27a60a5..f3cc81a600 100644
--- a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
+++ b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
@@ -88,21 +88,51 @@ export const useFlashLoanFeeBps = ({
 
   const enabled = Boolean(aclManager && target);
 
-  const { data: isWhitelisted } = useQuery({
+  const {
+    data: isWhitelisted,
+    status,
+    error,
+  } = useQuery({
     queryFn: async (): Promise<boolean> => {
       const contract = new Contract(
         aclManager as string,
         ACL_MANAGER_ABI,
         getProvider(marketData.chainId)
       );
-      return contract.isFlashBorrower(target);
+      const result: boolean = await contract.isFlashBorrower(target);
+      console.log('[FlashLoanFeeBps] queryFn result', {
+        chainId: marketData.chainId,
+        market: marketData.market,
+        provider,
+        swapType,
+        aclManager,
+        target,
+        isFlashBorrower: result,
+      });
+      return result;
     },
     queryKey: ['flashBorrowerCheck', marketData.chainId, aclManager, target],
     enabled,
     staleTime: 5 * 60 * 1000,
   });
 
-  if (!enabled) return undefined;
-  if (isWhitelisted === undefined) return undefined;
-  return isWhitelisted ? 0 : defaultBps;
+  const effective =
+    !enabled || isWhitelisted === undefined ? undefined : isWhitelisted ? 0 : defaultBps;
+
+  console.log('[FlashLoanFeeBps] resolve', {
+    chainId: marketData.chainId,
+    market: marketData.market,
+    provider,
+    swapType,
+    aclManager,
+    target,
+    enabled,
+    queryStatus: status,
+    queryError: error?.message,
+    isWhitelisted,
+    defaultBps,
+    effective,
+  });
+
+  return effective;
 };

From 435845689288b3ec4bbdde9bf1c6dc586e7ff088 Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 13:27:44 -0300
Subject: [PATCH 5/8] chore: log useFlashloan + applied bps in swap order
 amounts

---
 .../transactions/Swap/hooks/useSwapOrderAmounts.ts        | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
index d7c0ebb472..420a0af579 100644
--- a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
+++ b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
@@ -100,6 +100,14 @@ export const useSwapOrderAmounts = ({
     const usingFlashloan = isPositionSwap(state.swapType, state.useFlashloan ?? false);
     if (usingFlashloan && resolvedFlashLoanFeeBps === undefined) return;
     const flashLoanFeeBps = usingFlashloan ? (resolvedFlashLoanFeeBps as number) : 0;
+    console.log('[FlashLoanFeeBps] useSwapOrderAmounts', {
+      swapType: state.swapType,
+      provider: state.provider,
+      useFlashloanRaw: state.useFlashloan,
+      isPositionSwap: usingFlashloan,
+      resolvedFlashLoanFeeBps,
+      flashLoanFeeBpsApplied: flashLoanFeeBps,
+    });
     const flashLoanFeeAmount =
       state.side == 'sell'
         ? valueToBigNumber(state.outputAmount).multipliedBy(flashLoanFeeBps).dividedBy(10000)

From 864ad9a9626dbcb465819de8dfa234afad79a46c Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 13:43:55 -0300
Subject: [PATCH 6/8] chore: remove preview debug logs

---
 .../Swap/hooks/useFlashLoanFeeBps.ts          | 40 +++----------------
 .../Swap/hooks/useSwapOrderAmounts.ts         |  8 ----
 2 files changed, 5 insertions(+), 43 deletions(-)

diff --git a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
index f3cc81a600..e9b27a60a5 100644
--- a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
+++ b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
@@ -88,51 +88,21 @@ export const useFlashLoanFeeBps = ({
 
   const enabled = Boolean(aclManager && target);
 
-  const {
-    data: isWhitelisted,
-    status,
-    error,
-  } = useQuery({
+  const { data: isWhitelisted } = useQuery({
     queryFn: async (): Promise<boolean> => {
       const contract = new Contract(
         aclManager as string,
         ACL_MANAGER_ABI,
         getProvider(marketData.chainId)
       );
-      const result: boolean = await contract.isFlashBorrower(target);
-      console.log('[FlashLoanFeeBps] queryFn result', {
-        chainId: marketData.chainId,
-        market: marketData.market,
-        provider,
-        swapType,
-        aclManager,
-        target,
-        isFlashBorrower: result,
-      });
-      return result;
+      return contract.isFlashBorrower(target);
     },
     queryKey: ['flashBorrowerCheck', marketData.chainId, aclManager, target],
     enabled,
     staleTime: 5 * 60 * 1000,
   });
 
-  const effective =
-    !enabled || isWhitelisted === undefined ? undefined : isWhitelisted ? 0 : defaultBps;
-
-  console.log('[FlashLoanFeeBps] resolve', {
-    chainId: marketData.chainId,
-    market: marketData.market,
-    provider,
-    swapType,
-    aclManager,
-    target,
-    enabled,
-    queryStatus: status,
-    queryError: error?.message,
-    isWhitelisted,
-    defaultBps,
-    effective,
-  });
-
-  return effective;
+  if (!enabled) return undefined;
+  if (isWhitelisted === undefined) return undefined;
+  return isWhitelisted ? 0 : defaultBps;
 };
diff --git a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
index 420a0af579..d7c0ebb472 100644
--- a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
+++ b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
@@ -100,14 +100,6 @@ export const useSwapOrderAmounts = ({
     const usingFlashloan = isPositionSwap(state.swapType, state.useFlashloan ?? false);
     if (usingFlashloan && resolvedFlashLoanFeeBps === undefined) return;
     const flashLoanFeeBps = usingFlashloan ? (resolvedFlashLoanFeeBps as number) : 0;
-    console.log('[FlashLoanFeeBps] useSwapOrderAmounts', {
-      swapType: state.swapType,
-      provider: state.provider,
-      useFlashloanRaw: state.useFlashloan,
-      isPositionSwap: usingFlashloan,
-      resolvedFlashLoanFeeBps,
-      flashLoanFeeBpsApplied: flashLoanFeeBps,
-    });
     const flashLoanFeeAmount =
       state.side == 'sell'
         ? valueToBigNumber(state.outputAmount).multipliedBy(flashLoanFeeBps).dividedBy(10000)

From f888f5728df472a0d6fd6740b73965101180baef Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 14:00:31 -0300
Subject: [PATCH 7/8] fix: clear flashloan fee on pending; map Linea + Plasma
 ACLManagers

---
 .../transactions/Swap/hooks/useFlashLoanFeeBps.ts           | 4 ++++
 .../transactions/Swap/hooks/useSwapOrderAmounts.ts          | 6 +++++-
 src/components/transactions/Swap/types/state.types.ts       | 2 +-
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
index e9b27a60a5..3208c988b8 100644
--- a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
+++ b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
@@ -7,7 +7,9 @@ import {
   AaveV3EthereumEtherFi,
   AaveV3EthereumLido,
   AaveV3Gnosis,
+  AaveV3Linea,
   AaveV3Optimism,
+  AaveV3Plasma,
   AaveV3Polygon,
   AaveV3Sonic,
 } from '@aave-dao/aave-address-book';
@@ -35,6 +37,8 @@ const ACL_MANAGER_BY_MARKET: Partial<Record<CustomMarket, string>> = {
   [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,
 };
 
 const fallbackBps = (provider: SwapProvider): number =>
diff --git a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
index d7c0ebb472..51dd323fa2 100644
--- a/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
+++ b/src/components/transactions/Swap/hooks/useSwapOrderAmounts.ts
@@ -98,7 +98,11 @@ export const useSwapOrderAmounts = ({
     // const partnerFeeToken = state.side === 'sell' ? state.destinationToken : state.sourceToken;
 
     const usingFlashloan = isPositionSwap(state.swapType, state.useFlashloan ?? false);
-    if (usingFlashloan && resolvedFlashLoanFeeBps === undefined) return;
+    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'
diff --git a/src/components/transactions/Swap/types/state.types.ts b/src/components/transactions/Swap/types/state.types.ts
index c9f46c9acb..0a1a853ca7 100644
--- a/src/components/transactions/Swap/types/state.types.ts
+++ b/src/components/transactions/Swap/types/state.types.ts
@@ -289,7 +289,7 @@ export const swapDefaultState: SwapState = {
   networkFeeAmountInBuyFormatted: '0',
   partnerFeeAmountFormatted: '0',
   flashLoanFeeAmountFormatted: '0',
-  flashLoanFeeBps: 0,
+  flashLoanFeeBps: undefined,
   partnerFeeBps: 0,
   limitsOrderButtonBlocked: false,
   showSlippageWarning: false,

From 13f32adb0b487a1f56899f6919c42617a7a35293 Mon Sep 17 00:00:00 2001
From: Martin Grabina <mgrabina@itba.edu.ar>
Date: Fri, 8 May 2026 14:13:30 -0300
Subject: [PATCH 8/8] refactor: skip ACLManager check for Paraswap (msg.sender
 is user)

---
 ...llateralSwapActionsViaParaswapAdapters.tsx |  4 --
 .../DebtSwap/DebtSwapActionsViaParaswap.tsx   |  4 --
 .../RepayWithCollateralActionsViaParaswap.tsx |  4 --
 .../WithdrawAndSwapActionsViaParaswap.tsx     |  4 --
 .../Swap/hooks/useFlashLoanFeeBps.ts          | 62 +++++++------------
 5 files changed, 24 insertions(+), 54 deletions(-)

diff --git a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx
index 894feb8386..c8567ed466 100644
--- a/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx
+++ b/src/components/transactions/Swap/actions/CollateralSwap/CollateralSwapActionsViaParaswapAdapters.tsx
@@ -81,10 +81,6 @@ export const CollateralSwapActionsViaParaswapAdapters = ({
     if (!state.swapRate || !isParaswapRates(state.swapRate))
       throw new Error('Route required to build transaction');
 
-    if (state.flashLoanFeeBps === undefined) {
-      throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
-    }
-
     setMainTxState({
       txHash: undefined,
       loading: true,
diff --git a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx
index dcf7b0902e..0c8f21bbdd 100644
--- a/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx
+++ b/src/components/transactions/Swap/actions/DebtSwap/DebtSwapActionsViaParaswap.tsx
@@ -104,10 +104,6 @@ export const DebtSwapActionsViaParaswap = ({
         throw new Error('No swap rate found');
       }
 
-      if (state.flashLoanFeeBps === undefined) {
-        throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
-      }
-
       const inferredKind = state.swapRate.optimalRateData.side === 'SELL' ? 'sell' : 'buy';
 
       // CallData for ParaswapRoute, which is inversed to the actual swap (dest -> src)
diff --git a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx
index bbae52ec66..95a190db2c 100644
--- a/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx
+++ b/src/components/transactions/Swap/actions/RepayWithCollateral/RepayWithCollateralActionsViaParaswap.tsx
@@ -103,10 +103,6 @@ export const RepayWithCollateralActionsViaParaswap = ({
     if (!state.swapRate || !isParaswapRates(state.swapRate))
       throw new Error('Route required to build transaction');
 
-    if (state.flashLoanFeeBps === undefined) {
-      throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
-    }
-
     setMainTxState({
       txHash: undefined,
       loading: true,
diff --git a/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx b/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx
index 3eb222ec88..60c62fa3dc 100644
--- a/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx
+++ b/src/components/transactions/Swap/actions/WithdrawAndSwap/WithdrawAndSwapActionsViaParaswap.tsx
@@ -82,10 +82,6 @@ export const WithdrawAndSwapActionsViaParaswap = ({
       return;
     }
 
-    if (state.flashLoanFeeBps === undefined) {
-      throw new Error('Flashloan fee unavailable: on-chain ACLManager check has not resolved.');
-    }
-
     try {
       setMainTxState({ ...mainTxState, loading: true });
       const { swapCallData, augustus } = await getTransactionParams(
diff --git a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
index 3208c988b8..6a67e6078a 100644
--- a/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
+++ b/src/components/transactions/Swap/hooks/useFlashLoanFeeBps.ts
@@ -25,6 +25,9 @@ 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,
@@ -41,41 +44,16 @@ const ACL_MANAGER_BY_MARKET: Partial<Record<CustomMarket, string>> = {
   [CustomMarket.proto_plasma_v3]: AaveV3Plasma.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 by checking the market's
- * ACLManager.isFlashBorrower for the provider's target address. Returns 0 when
- * the target is whitelisted, the provider's default bps when it's not, and
- * `undefined` whenever we don't have an on-chain answer (query pending,
- * ACLManager unmapped for the market, or no target address resolvable). The
- * caller MUST refuse to submit a transaction while the value is undefined.
+ * 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,
@@ -86,11 +64,13 @@ export const useFlashLoanFeeBps = ({
   swapType: SwapType;
   marketData: MarketDataType;
 }): number | undefined => {
+  const isCow = provider === SwapProvider.COW_PROTOCOL;
   const aclManager = ACL_MANAGER_BY_MARKET[marketData.market];
-  const target = resolveTarget(provider, swapType, marketData);
-  const defaultBps = fallbackBps(provider);
+  const target = isCow
+    ? ADAPTER_FACTORY[marketData.chainId as unknown as SupportedChainId] || undefined
+    : undefined;
 
-  const enabled = Boolean(aclManager && target);
+  const enabled = isCow && Boolean(aclManager && target);
 
   const { data: isWhitelisted } = useQuery({
     queryFn: async (): Promise<boolean> => {
@@ -106,7 +86,13 @@ export const useFlashLoanFeeBps = ({
     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 : defaultBps;
+  return isWhitelisted ? 0 : FLASH_LOAN_FEE_BPS;
 };