+source currency pick fix +fx side propagation

frontend/pshared/lib/data/dto/payment/intent/payment.dart

@@ -37,7 +37,6 @@ class PaymentIntentDTO {
     this.feeTreatment,
   });
 
-  factory PaymentIntentDTO.fromJson(Map<String, dynamic> json) =>
-      _$PaymentIntentDTOFromJson(json);
+  factory PaymentIntentDTO.fromJson(Map<String, dynamic> json) => _$PaymentIntentDTOFromJson(json);
   Map<String, dynamic> toJson() => _$PaymentIntentDTOToJson(this);
 }

frontend/pshared/lib/data/mapper/payment/intent/fx.dart

@@ -6,22 +6,22 @@ import 'package:pshared/models/payment/fx/intent.dart';
 
 extension FxIntentMapper on FxIntent {
   FxIntentDTO toDTO() => FxIntentDTO(
-        pair: pair?.toDTO(),
-        side: fxSideToValue(side),
-        firm: firm,
-        ttlMs: ttlMs,
-        preferredProvider: preferredProvider,
-        maxAgeMs: maxAgeMs,
-      );
+    pair: pair?.toDTO(),
+    side: fxSideToValue(side),
+    firm: firm,
+    ttlMs: ttlMs,
+    preferredProvider: preferredProvider,
+    maxAgeMs: maxAgeMs,
+  );
 }
 
 extension FxIntentDTOMapper on FxIntentDTO {
   FxIntent toDomain() => FxIntent(
-        pair: pair?.toDomain(),
-        side: fxSideFromValue(side),
-        firm: firm,
-        ttlMs: ttlMs,
-        preferredProvider: preferredProvider,
-        maxAgeMs: maxAgeMs,
-      );
+    pair: pair?.toDomain(),
+    side: fxSideFromValue(side),
+    firm: firm,
+    ttlMs: ttlMs,
+    preferredProvider: preferredProvider,
+    maxAgeMs: maxAgeMs,
+  );
 }

frontend/pshared/pubspec.yaml

@@ -8,7 +8,7 @@ environment:
 # Add regular dependencies here.
 dependencies:
   analyzer: ^10.0.0
-  json_annotation: ^4.10.0
+  json_annotation: ^4.11.0
   http: ^1.1.0
   provider: ^6.0.5
   flutter:

frontend/pshared/test/payment/request_dto_format_test.dart

@@ -7,7 +7,9 @@ import 'package:pshared/api/requests/payment/initiate_payments.dart';
 import 'package:pshared/api/requests/payment/quote.dart';
 import 'package:pshared/api/responses/payment/quotation.dart';
 import 'package:pshared/data/dto/money.dart';
+import 'package:pshared/data/dto/payment/currency_pair.dart';
 import 'package:pshared/data/dto/payment/endpoint.dart';
+import 'package:pshared/data/dto/payment/intent/fx.dart';
 import 'package:pshared/data/dto/payment/intent/payment.dart';
 import 'package:pshared/data/mapper/payment/payment.dart';
 import 'package:pshared/models/payment/asset.dart';
@@ -76,6 +78,36 @@ void main() {
       expect(destination['type'], equals('cardToken'));
     });
 
+    test('quote payment request serializes fx side to backend value', () {
+      final request = QuotePaymentRequest(
+        idempotencyKey: '',
+        previewOnly: true,
+        intent: const PaymentIntentDTO(
+          kind: 'payout',
+          source: PaymentEndpointDTO(
+            type: 'managedWallet',
+            data: {'managed_wallet_ref': 'mw-1'},
+          ),
+          destination: PaymentEndpointDTO(
+            type: 'cardToken',
+            data: {'token': 'tok_1', 'masked_pan': '4111'},
+          ),
+          amount: MoneyDTO(amount: '10', currency: 'USDT'),
+          settlementMode: 'fix_source',
+          fx: FxIntentDTO(
+            pair: CurrencyPairDTO(base: 'RUB', quote: 'USDT'),
+            side: 'buy_base_sell_quote',
+          ),
+        ),
+      );
+
+      final json =
+          jsonDecode(jsonEncode(request.toJson())) as Map<String, dynamic>;
+      final intent = json['intent'] as Map<String, dynamic>;
+      final fx = intent['fx'] as Map<String, dynamic>;
+      expect(fx['side'], equals('buy_base_sell_quote'));
+    });
+
     test('quote response parses backend fx quote pricedAtUnixMs', () {
       final response = PaymentQuoteResponse.fromJson({
         'accessToken': {'token': 'token', 'expiration': '2026-02-25T00:00:00Z'},