feat: implement idempotency key for critical API endpoints

lib/application/refund/refund_form/refund_form_bloc.dart

@@ -2,6 +2,7 @@ import 'package:bloc/bloc.dart';
 import 'package:dartz/dartz.dart' hide Order;
 import 'package:freezed_annotation/freezed_annotation.dart';
 import 'package:injectable/injectable.dart' hide Order;
+import 'package:uuid/uuid.dart';
 
 import '../../../common/data/refund_data.dart';
 import '../../../domain/order/order.dart';
@@ -34,7 +35,15 @@ class RefundFormBloc extends Bloc<RefundFormEvent, RefundFormState> {
       submitted: (e) async {
         Either<OrderFailure, Unit>? failureOrRefund;
 
-        emit(state.copyWith(isSubmitting: true, failureOrRefund: none()));
+        // Generate new idempotency key saat user intent (tap Refund)
+        // Kalau sedang retry, pakai key yang sama
+        final idempotencyKey = state.idempotencyKey ?? const Uuid().v4();
+
+        emit(state.copyWith(
+          isSubmitting: true,
+          failureOrRefund: none(),
+          idempotencyKey: idempotencyKey,
+        ));
 
         failureOrRefund = await _repository.refundOrder(
           id: state.order.id,
@@ -42,12 +51,15 @@ class RefundFormBloc extends Bloc<RefundFormEvent, RefundFormState> {
               ? state.reason
               : state.refundReason?.value ?? '',
           refundAmount: state.order.totalAmount,
+          idempotencyKey: idempotencyKey,
         );
 
         emit(
           state.copyWith(
             isSubmitting: false,
             failureOrRefund: optionOf(failureOrRefund),
+            // Clear key on success, keep on failure for retry
+            idempotencyKey: failureOrRefund.isRight() ? null : idempotencyKey,
           ),
         );
       },

lib/application/refund/refund_form/refund_form_bloc.freezed.dart

@@ -692,6 +692,11 @@ mixin _$RefundFormState {
       throw _privateConstructorUsedError;
   bool get isSubmitting => throw _privateConstructorUsedError;
 
+  /// Idempotency key untuk refund submission.
+  /// Di-generate saat user tap "Refund", dipakai ulang saat retry,
+  /// di-clear setelah sukses.
+  String? get idempotencyKey => throw _privateConstructorUsedError;
+
   /// Create a copy of RefundFormState
   /// with the given fields replaced by the non-null parameter values.
   @JsonKey(includeFromJson: false, includeToJson: false)
@@ -712,6 +717,7 @@ abstract class $RefundFormStateCopyWith<$Res> {
     RefundReason? refundReason,
     Option<Either<OrderFailure, Unit>> failureOrRefund,
     bool isSubmitting,
+    String? idempotencyKey,
   });
 
   $OrderCopyWith<$Res> get order;
@@ -737,6 +743,7 @@ class _$RefundFormStateCopyWithImpl<$Res, $Val extends RefundFormState>
     Object? refundReason = freezed,
     Object? failureOrRefund = null,
     Object? isSubmitting = null,
+    Object? idempotencyKey = freezed,
   }) {
     return _then(
       _value.copyWith(
@@ -760,6 +767,10 @@ class _$RefundFormStateCopyWithImpl<$Res, $Val extends RefundFormState>
                 ? _value.isSubmitting
                 : isSubmitting // ignore: cast_nullable_to_non_nullable
                       as bool,
+            idempotencyKey: freezed == idempotencyKey
+                ? _value.idempotencyKey
+                : idempotencyKey // ignore: cast_nullable_to_non_nullable
+                      as String?,
           )
           as $Val,
     );
@@ -791,6 +802,7 @@ abstract class _$$RefundFormStateImplCopyWith<$Res>
     RefundReason? refundReason,
     Option<Either<OrderFailure, Unit>> failureOrRefund,
     bool isSubmitting,
+    String? idempotencyKey,
   });
 
   @override
@@ -816,6 +828,7 @@ class __$$RefundFormStateImplCopyWithImpl<$Res>
     Object? refundReason = freezed,
     Object? failureOrRefund = null,
     Object? isSubmitting = null,
+    Object? idempotencyKey = freezed,
   }) {
     return _then(
       _$RefundFormStateImpl(
@@ -839,6 +852,10 @@ class __$$RefundFormStateImplCopyWithImpl<$Res>
             ? _value.isSubmitting
             : isSubmitting // ignore: cast_nullable_to_non_nullable
                   as bool,
+        idempotencyKey: freezed == idempotencyKey
+            ? _value.idempotencyKey
+            : idempotencyKey // ignore: cast_nullable_to_non_nullable
+                  as String?,
       ),
     );
   }
@@ -853,6 +870,7 @@ class _$RefundFormStateImpl implements _RefundFormState {
     this.refundReason,
     required this.failureOrRefund,
     this.isSubmitting = false,
+    this.idempotencyKey,
   });
 
   @override
@@ -867,9 +885,15 @@ class _$RefundFormStateImpl implements _RefundFormState {
   @JsonKey()
   final bool isSubmitting;
 
+  /// Idempotency key untuk refund submission.
+  /// Di-generate saat user tap "Refund", dipakai ulang saat retry,
+  /// di-clear setelah sukses.
+  @override
+  final String? idempotencyKey;
+
   @override
   String toString() {
-    return 'RefundFormState(order: $order, reason: $reason, refundReason: $refundReason, failureOrRefund: $failureOrRefund, isSubmitting: $isSubmitting)';
+    return 'RefundFormState(order: $order, reason: $reason, refundReason: $refundReason, failureOrRefund: $failureOrRefund, isSubmitting: $isSubmitting, idempotencyKey: $idempotencyKey)';
   }
 
   @override
@@ -884,7 +908,9 @@ class _$RefundFormStateImpl implements _RefundFormState {
             (identical(other.failureOrRefund, failureOrRefund) ||
                 other.failureOrRefund == failureOrRefund) &&
             (identical(other.isSubmitting, isSubmitting) ||
-                other.isSubmitting == isSubmitting));
+                other.isSubmitting == isSubmitting) &&
+            (identical(other.idempotencyKey, idempotencyKey) ||
+                other.idempotencyKey == idempotencyKey));
   }
 
   @override
@@ -895,6 +921,7 @@ class _$RefundFormStateImpl implements _RefundFormState {
     refundReason,
     failureOrRefund,
     isSubmitting,
+    idempotencyKey,
   );
 
   /// Create a copy of RefundFormState
@@ -916,6 +943,7 @@ abstract class _RefundFormState implements RefundFormState {
     final RefundReason? refundReason,
     required final Option<Either<OrderFailure, Unit>> failureOrRefund,
     final bool isSubmitting,
+    final String? idempotencyKey,
   }) = _$RefundFormStateImpl;
 
   @override
@@ -929,6 +957,12 @@ abstract class _RefundFormState implements RefundFormState {
   @override
   bool get isSubmitting;
 
+  /// Idempotency key untuk refund submission.
+  /// Di-generate saat user tap "Refund", dipakai ulang saat retry,
+  /// di-clear setelah sukses.
+  @override
+  String? get idempotencyKey;
+
   /// Create a copy of RefundFormState
   /// with the given fields replaced by the non-null parameter values.
   @override

lib/application/refund/refund_form/refund_form_state.dart

@@ -8,6 +8,10 @@ class RefundFormState with _$RefundFormState {
     RefundReason? refundReason,
     required Option<Either<OrderFailure, Unit>> failureOrRefund,
     @Default(false) bool isSubmitting,
+    /// Idempotency key untuk refund submission.
+    /// Di-generate saat user tap "Refund", dipakai ulang saat retry,
+    /// di-clear setelah sukses.
+    String? idempotencyKey,
   }) = _RefundFormState;
 
   factory RefundFormState.initial() => RefundFormState(