feat: enhance API error handling and response structure; introduce ApiException for V2 error codes

apps/mobile/packages/core/lib/src/services/api_service/api_service.dart

@@ -5,7 +5,9 @@ import 'feature_gate.dart';
 
 /// A service that handles HTTP communication using the [Dio] client.
 ///
-/// Integrates [FeatureGate] to validate endpoint scopes before each request.
+/// Integrates [FeatureGate] for scope validation and throws typed domain
+/// exceptions ([ApiException], [NetworkException], [ServerException]) on
+/// error responses so repositories never receive silent failures.
 class ApiService implements BaseApiService {
   /// Creates an [ApiService] with the given [Dio] instance.
   ApiService(this._dio);
@@ -27,7 +29,7 @@ class ApiService implements BaseApiService {
       );
       return _handleResponse(response);
     } on DioException catch (e) {
-      return _handleError(e);
+      throw _mapDioException(e);
     }
   }
 
@@ -47,7 +49,7 @@ class ApiService implements BaseApiService {
       );
       return _handleResponse(response);
     } on DioException catch (e) {
-      return _handleError(e);
+      throw _mapDioException(e);
     }
   }
 
@@ -67,7 +69,7 @@ class ApiService implements BaseApiService {
       );
       return _handleResponse(response);
     } on DioException catch (e) {
-      return _handleError(e);
+      throw _mapDioException(e);
     }
   }
 
@@ -87,7 +89,7 @@ class ApiService implements BaseApiService {
       );
       return _handleResponse(response);
     } on DioException catch (e) {
-      return _handleError(e);
+      throw _mapDioException(e);
     }
   }
 
@@ -107,7 +109,7 @@ class ApiService implements BaseApiService {
       );
       return _handleResponse(response);
     } on DioException catch (e) {
-      return _handleError(e);
+      throw _mapDioException(e);
     }
   }
 
@@ -117,43 +119,63 @@ class ApiService implements BaseApiService {
 
   /// Extracts [ApiResponse] from a successful [Response].
   ApiResponse _handleResponse(Response<dynamic> response) {
+    final dynamic body = response.data;
+    final String message = body is Map<String, dynamic>
+        ? body['message']?.toString() ?? 'Success'
+        : 'Success';
+
     return ApiResponse(
       code: response.statusCode?.toString() ?? '200',
-      message: response.data['message']?.toString() ?? 'Success',
-      data: response.data,
+      message: message,
+      data: body,
     );
   }
 
-  /// Extracts [ApiResponse] from a [DioException].
+  /// Maps a [DioException] to a typed domain exception.
   ///
-  /// Supports both legacy error format and V2 API error envelope
-  /// (`{ code, message, details, requestId }`).
-  ApiResponse _handleError(DioException e) {
+  /// The V2 API error envelope is `{ code, message, details, requestId }`.
+  /// This method parses it and throws the appropriate [AppException] subclass
+  /// so that `BlocErrorHandler` can translate it for the user.
+  AppException _mapDioException(DioException e) {
+    // Network-level failures (no response from server).
+    if (e.type == DioExceptionType.connectionTimeout ||
+        e.type == DioExceptionType.receiveTimeout ||
+        e.type == DioExceptionType.sendTimeout ||
+        e.type == DioExceptionType.connectionError) {
+      return NetworkException(technicalMessage: e.message);
+    }
+
+    final int? statusCode = e.response?.statusCode;
+
+    // Parse V2 error envelope if available.
     if (e.response?.data is Map<String, dynamic>) {
       final Map<String, dynamic> body =
           e.response!.data as Map<String, dynamic>;
-      return ApiResponse(
-        code:
-            body['code']?.toString() ??
-            e.response?.statusCode?.toString() ??
-            'error',
-        message: body['message']?.toString() ?? e.message ?? 'Error occurred',
-        data: body['data'] ?? body['details'],
-        errors: _parseErrors(body['errors']),
+
+      final String apiCode =
+          body['code']?.toString() ?? statusCode?.toString() ?? 'UNKNOWN';
+      final String apiMessage =
+          body['message']?.toString() ?? e.message ?? 'An error occurred';
+
+      // Map well-known codes to specific exceptions.
+      if (apiCode == 'UNAUTHENTICATED' || statusCode == 401) {
+        return NotAuthenticatedException(technicalMessage: apiMessage);
+      }
+
+      return ApiException(
+        apiCode: apiCode,
+        apiMessage: apiMessage,
+        statusCode: statusCode,
+        details: body['details'],
+        technicalMessage: '$apiCode: $apiMessage',
       );
     }
-    return ApiResponse(
-      code: e.response?.statusCode?.toString() ?? 'error',
-      message: e.message ?? 'Unknown error',
-      errors: <String, dynamic>{'exception': e.type.toString()},
-    );
-  }
 
-  /// Helper to parse the errors map from various possible formats.
-  Map<String, dynamic> _parseErrors(dynamic errors) {
-    if (errors is Map) {
-      return Map<String, dynamic>.from(errors);
+    // Server error without a parseable body.
+    if (statusCode != null && statusCode >= 500) {
+      return ServerException(technicalMessage: e.message);
     }
-    return const <String, dynamic>{};
+
+    return UnknownException(technicalMessage: e.message);
   }
 }

apps/mobile/packages/domain/lib/src/core/services/api_services/api_response.dart

@@ -8,7 +8,7 @@ class ApiResponse {
     this.errors = const <String, dynamic>{},
   });
 
-  /// The response code (e.g., '200', '404', or custom error code).
+  /// The response code (e.g., '200', '404', or V2 error code like 'VALIDATION_ERROR').
   final String code;
 
   /// A descriptive message about the response.
@@ -19,4 +19,13 @@ class ApiResponse {
 
   /// A map of field-specific error messages, if any.
   final Map<String, dynamic> errors;
+
+  /// Whether the response indicates success (HTTP 2xx).
+  bool get isSuccess {
+    final int? statusCode = int.tryParse(code);
+    return statusCode != null && statusCode >= 200 && statusCode < 300;
+  }
+
+  /// Whether the response indicates failure.
+  bool get isFailure => !isSuccess;
 }

apps/mobile/packages/domain/lib/src/core/services/api_services/base_core_service.dart

@@ -1,3 +1,4 @@
+import '../../../exceptions/app_exception.dart';
 import 'api_response.dart';
 import 'base_api_service.dart';
 
@@ -14,10 +15,13 @@ abstract class BaseCoreService {
 
   /// Standardized wrapper to execute API actions.
   ///
-  /// This handles generic error normalization for unexpected non-HTTP errors.
+  /// Rethrows [AppException] subclasses (domain errors) directly.
+  /// Wraps unexpected non-HTTP errors into an error [ApiResponse].
   Future<ApiResponse> action(Future<ApiResponse> Function() execution) async {
     try {
       return await execution();
+    } on AppException {
+      rethrow;
     } catch (e) {
       return ApiResponse(
         code: 'CORE_INTERNAL_ERROR',

apps/mobile/packages/domain/lib/src/exceptions/app_exception.dart

@@ -286,6 +286,54 @@ class NoActiveShiftException extends ShiftException {
 // NETWORK/GENERIC EXCEPTIONS
 // ============================================================
 
+// ============================================================
+// API EXCEPTIONS (mapped from V2 error envelope codes)
+// ============================================================
+
+/// Thrown when the V2 API returns a non-success response.
+///
+/// Carries the full error envelope so callers can inspect details.
+class ApiException extends AppException {
+  /// Creates an [ApiException].
+  const ApiException({
+    required String apiCode,
+    required String apiMessage,
+    this.statusCode,
+    this.details,
+    super.technicalMessage,
+  }) : super(code: apiCode);
+
+  /// The HTTP status code (e.g. 400, 404, 500).
+  final int? statusCode;
+
+  /// The V2 API error code string (e.g. 'VALIDATION_ERROR').
+  String get apiCode => code;
+
+  /// Optional details from the error envelope.
+  final dynamic details;
+
+  @override
+  String get messageKey {
+    switch (code) {
+      case 'VALIDATION_ERROR':
+        return 'errors.generic.validation_error';
+      case 'NOT_FOUND':
+        return 'errors.generic.not_found';
+      case 'FORBIDDEN':
+        return 'errors.generic.forbidden';
+      case 'UNAUTHENTICATED':
+        return 'errors.auth.not_authenticated';
+      case 'CONFLICT':
+        return 'errors.generic.conflict';
+      default:
+        if (statusCode != null && statusCode! >= 500) {
+          return 'errors.generic.server_error';
+        }
+        return 'errors.generic.unknown';
+    }
+  }
+}
+
 /// Thrown when there is no network connection.
 class NetworkException extends AppException {
   const NetworkException({super.technicalMessage})

apps/mobile/packages/features/client/authentication/lib/src/data/repositories_impl/auth_repository_impl.dart

@@ -55,20 +55,6 @@ class AuthRepositoryImpl implements AuthRepositoryInterface {
       final Map<String, dynamic> body =
           response.data as Map<String, dynamic>;
 
-      // Check for V2 error responses.
-      if (response.code != '200' && response.code != '201') {
-        final String errorCode = body['code']?.toString() ?? response.code;
-        if (errorCode == 'INVALID_CREDENTIALS' ||
-            response.message.contains('INVALID_LOGIN_CREDENTIALS')) {
-          throw InvalidCredentialsException(
-            technicalMessage: response.message,
-          );
-        }
-        throw SignInFailedException(
-          technicalMessage: '$errorCode: ${response.message}',
-        );
-      }
-
       // Step 2: Sign in locally so AuthInterceptor can attach Bearer tokens
       // to subsequent requests. The V2 API already validated credentials, so
       // email/password sign-in establishes the local Firebase Auth state.
@@ -115,12 +101,7 @@ class AuthRepositoryImpl implements AuthRepositoryInterface {
         },
       );
 
-      // Check for V2 error responses.
       final Map<String, dynamic> body = response.data as Map<String, dynamic>;
-      if (response.code != '201' && response.code != '200') {
-        final String errorCode = body['code']?.toString() ?? response.code;
-        _throwSignUpError(errorCode, response.message);
-      }
 
       // Step 2: Sign in locally to Firebase Auth so AuthInterceptor works
       // for subsequent requests. The V2 API already created the Firebase