fix: Swap external send QR using trade currency instead of selected wallet (#3068)

lib/utils/token_utilities.dart

@@ -231,6 +231,15 @@ class TokenUtilities {
     return null;
   }
 
+  static Erc20Token? findErc20TokenForSwap(CryptoCurrency currency) {
+    if (currency is Erc20Token) return currency;
+
+    for (final token in loadDefaultEvmTokensForSwap()) {
+      if (_matchesCurrency(token, currency)) return token;
+    }
+    return null;
+  }
+
   static bool isNativeToken(CryptoCurrency currency) {
     final title = currency.title.toLowerCase();
     final tag = currency.tag?.toLowerCase();

lib/view_model/exchange/exchange_trade_view_model.dart

@@ -478,7 +478,11 @@ abstract class ExchangeTradeViewModelBase with Store {
       return null;
     }
 
-    switch (wallet.type) {
+    // Using trade currency here so the external-send QR encodes the correct scheme
+    final uriWalletType =
+        cryptoCurrencyOrTokenToWalletType(fromCurrency) ?? wallet.type;
+
+    switch (uriWalletType) {
       case WalletType.bitcoin:
         return BitcoinURI(address: inputAddress, amount: amount);
       case WalletType.bitcoinCash:
@@ -524,17 +528,16 @@ abstract class ExchangeTradeViewModelBase with Store {
         contractAddress: null,
       );
     } else {
-      if (isEVMCompatibleChain(wallet.type)) {
-        final erc20Token = TokenUtilities.findErc20Token(currency, wallet);
+      final erc20Token = TokenUtilities.findErc20Token(currency, wallet) ??
+          TokenUtilities.findErc20TokenForSwap(currency);
 
-        if (erc20Token != null) {
-          return ERC681URI(
-            chainId: chainId,
-            address: address,
-            amount: amount,
-            contractAddress: erc20Token.contractAddress,
-          );
-        }
+      if (erc20Token != null) {
+        return ERC681URI(
+          chainId: chainId,
+          address: address,
+          amount: amount,
+          contractAddress: erc20Token.contractAddress,
+        );
       }
       return null;
     }