fix(volume-fee): control safe app fees for stablecoins with ff (#5187)

Author: shoom3301

apps/cowswap-frontend/src/modules/volumeFee/state/safeAppFeeAtom.ts

@@ -38,7 +38,7 @@ const FEE_PERCENTAGE_BPS = {
 export const safeAppFeeAtom = atom<VolumeFee | null>((get) => {
   const { chainId } = get(walletInfoAtom)
   const { isSafeApp } = get(walletDetailsAtom)
-  const { isSafeAppFeeEnabled } = get(featureFlagsAtom)
+  const { isSafeAppFeeEnabled, isSafeAppStableCoinsFeeEnabled } = get(featureFlagsAtom)
   const { inputCurrency, outputCurrency, inputCurrencyFiatAmount, outputCurrencyFiatAmount, orderKind } =
     get(derivedTradeStateAtom) || {}
 
@@ -54,6 +54,8 @@ export const safeAppFeeAtom = atom<VolumeFee | null>((get) => {
   const isOutputStableCoin = !!outputCurrency && stablecoins.has(getCurrencyAddress(outputCurrency).toLowerCase())
   const isStableCoinTrade = isInputStableCoin && isOutputStableCoin
 
+  if (isStableCoinTrade && !isSafeAppStableCoinsFeeEnabled) return null
+
   const bps = (() => {
     if (fiatAmount < FEE_TIERS.TIER_1) {
       return isStableCoinTrade ? FEE_PERCENTAGE_BPS.STABLE.TIER_1 : FEE_PERCENTAGE_BPS.REGULAR.TIER_1

libs/common-const/src/tokens.ts

@@ -322,6 +322,14 @@ export const USDC_SEPOLIA = new TokenWithLogo(
   'USDC',
   'USDC (test)',
 )
+export const USDT_SEPOLIA = new TokenWithLogo(
+  USDT.logoURI,
+  SupportedChainId.SEPOLIA,
+  '0x58eb19ef91e8a6327fed391b51ae1887b833cc91',
+  6,
+  'USDT',
+  'Tether USD',
+)
 
 export const USDC: Record<SupportedChainId, TokenWithLogo> = {
   [SupportedChainId.MAINNET]: USDC_MAINNET,
@@ -483,16 +491,22 @@ const BASE_STABLECOINS = [
   CGUSD_BASE.address,
   USD_PLUS_BASE.address,
   EUSD_BASE.address,
+  USDT_BASE.address,
 ].map((t) => t.toLowerCase())
 
+// Not used for fees
+const SEPOLIA_STABLECOINS = [USDC_SEPOLIA.address, USDT_SEPOLIA.address].map((t) => t.toLowerCase())
+
 export const STABLECOINS: Record<ChainId, Set<string>> = {
   [SupportedChainId.MAINNET]: new Set(MAINNET_STABLECOINS),
   [SupportedChainId.GNOSIS_CHAIN]: new Set(GNOSIS_CHAIN_STABLECOINS),
   [SupportedChainId.ARBITRUM_ONE]: new Set(ARBITRUM_ONE_STABLECOINS),
-  [SupportedChainId.SEPOLIA]: new Set([USDC_SEPOLIA.address]),
+  [SupportedChainId.SEPOLIA]: new Set(SEPOLIA_STABLECOINS),
   [SupportedChainId.BASE]: new Set(BASE_STABLECOINS),
 }
 
+console.debug('STABLECOINS', STABLECOINS)
+
 /**
  * Addresses related to COW vesting for Locked GNO
  * These are used in src/custom/pages/Account/LockedGnoVesting hooks and index files