refactor: centralize Firebase logging in HTTP interceptor

lib/main.dart

@@ -32,7 +32,6 @@ Future<void> main() async {
   }
 
   final container = ProviderContainer();
-  final firebase = container.read(firebaseServiceProvider);
 
   firebase.log('App starting...');
 
@@ -83,7 +82,7 @@ Future<void> main() async {
   final authRepository = container.read(authRepositoryProvider);
   final user = await authRepository.getUser();
   final initialLocation = user != null ? AppRoutes.home : AppRoutes.intro;
-  final router = createAppRouter(firebase, initialLocation: initialLocation);
+  final router = createAppRouter(initialLocation: initialLocation);
 
   runApp(
     UncontrolledProviderScope(

lib/router/app_router.dart

@@ -21,10 +21,8 @@ abstract class AppRoutes {
   static const about = '/about';
 }
 
-/// Creates a configured [GoRouter] with the provided [firebase] service
-/// for analytics observers, starting at [initialLocation].
-GoRouter createAppRouter(
-  FirebaseService firebase, {
+/// Creates a configured [GoRouter] starting at [initialLocation].
+GoRouter createAppRouter({
   required String initialLocation,
 }) => GoRouter(
   navigatorKey: rootNavigatorKey,

lib/services/firebase_service.dart

@@ -1,6 +1,5 @@
 import 'package:firebase_analytics/firebase_analytics.dart';
 import 'package:firebase_crashlytics/firebase_crashlytics.dart';
-import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 /// Global toggle for Firebase features.
 ///
@@ -11,25 +10,27 @@ const bool useFirebase = bool.fromEnvironment(
   defaultValue: false,
 );
 
-/// Provider for the [FirebaseService].
-final firebaseServiceProvider = Provider<FirebaseService>((ref) {
-  return FirebaseService();
-});
-
 /// Unified service for Firebase Analytics and Crashlytics.
 ///
 /// Exposes nullable getters that return real instances when [useFirebase] is
 /// true, or `null` when disabled. Callers use null-aware access:
 ///
 /// ```dart
-/// ref.read(firebaseServiceProvider).analytics?.logAppOpen();
-/// ref.read(firebaseServiceProvider).crashlytics?.recordError(e, stack);
+/// firebase.analytics?.logAppOpen();
+/// firebase.crashlytics?.recordError(e, stack);
 /// ```
 class FirebaseService {
+  const FirebaseService();
+
   /// The [FirebaseAnalytics] instance, or `null` if Firebase is disabled.
   FirebaseAnalytics? get analytics =>
       useFirebase ? FirebaseAnalytics.instance : null;
 
+  /// Returns a [FirebaseAnalyticsObserver] for use with navigation observers, or
+  /// `null` if Firebase is disabled.
+  FirebaseAnalyticsObserver? get analyticsObserver =>
+      useFirebase ? FirebaseAnalyticsObserver(analytics: analytics!) : null;
+
   /// The [FirebaseCrashlytics] instance, or `null` if Firebase is disabled.
   FirebaseCrashlytics? get crashlytics =>
       useFirebase ? FirebaseCrashlytics.instance : null;
@@ -41,9 +42,7 @@ class FirebaseService {
   void log(String message) {
     crashlytics?.log(message);
   }
-
-  /// Returns a [FirebaseAnalyticsObserver] for use with navigation observers, or
-  /// `null` if Firebase is disabled.
-  FirebaseAnalyticsObserver? get analyticsObserver =>
-      useFirebase ? FirebaseAnalyticsObserver(analytics: analytics!) : null;
 }
+
+/// Global [FirebaseService] instance.
+const firebase = FirebaseService();

lib/services/portal_service.dart

@@ -5,7 +5,6 @@ import 'package:dio_redirect_interceptor/dio_redirect_interceptor.dart';
 import 'package:html/parser.dart';
 import 'package:http_parser/http_parser.dart';
 import 'package:riverpod/riverpod.dart';
-import 'package:tattoo/services/firebase_service.dart';
 import 'package:tattoo/utils/http.dart';
 
 /// Represents a logged-in NTUT Portal user.
@@ -44,7 +43,7 @@ enum PortalServiceCode {
 
 /// Provides the singleton [PortalService] instance.
 final portalServiceProvider = Provider<PortalService>((ref) {
-  return PortalService(ref.read(firebaseServiceProvider));
+  return PortalService();
 });
 
 /// Service for authenticating with NTUT Portal and performing SSO.
@@ -60,9 +59,8 @@ final portalServiceProvider = Provider<PortalService>((ref) {
 /// calling [sso] for each required service.
 class PortalService {
   late final Dio _portalDio;
-  final FirebaseService _firebase;
 
-  PortalService(this._firebase) {
+  PortalService() {
     // Emulate the NTUT iOS app's HTTP client
     _portalDio = createDio()
       ..options.baseUrl = 'https://app.ntut.edu.tw/'
@@ -83,20 +81,16 @@ class PortalService {
   ///
   /// Throws an [Exception] if login fails due to invalid credentials.
   Future<UserDto> login(String username, String password) async {
-    _firebase.log('Attempting login');
     final response = await _portalDio.post(
       'login.do',
       queryParameters: {'muid': username, 'mpassword': password},
     );
 
     final body = jsonDecode(response.data);
     if (!body['success']) {
-      _firebase.log('Login failed');
       throw Exception('Login failed. Please check your credentials.');
     }
 
-    _firebase.log('Login successful');
-
     final String? passwordExpiredRemind = body['passwordExpiredRemind'];
 
     // Normalize empty strings to null for consistency

lib/utils/http.dart

@@ -10,6 +10,7 @@ import 'package:dio_cookie_manager/dio_cookie_manager.dart';
 import 'package:intl/intl.dart';
 // ignore: implementation_imports
 import 'package:dio/src/transformers/util/consolidate_bytes.dart';
+import 'package:tattoo/services/firebase_service.dart';
 
 export 'package:dio/dio.dart';
 
@@ -83,6 +84,9 @@ class PlainTextTransformer extends BackgroundTransformer {
 }
 
 /// One-line log [Interceptor] for requests and responses.
+///
+/// Logs to both `dart:developer` and Firebase Crashlytics for breadcrumb
+/// context in crash reports.
 class LogInterceptor extends Interceptor {
   @override
   void onResponse(Response response, ResponseInterceptorHandler handler) {
@@ -119,7 +123,9 @@ class LogInterceptor extends Interceptor {
       if (cookies > 0) "$cookies cookie${cookies != 1 ? 's' : ''}",
     ].join(' ');
 
-    log("$requestLog => $responseLog", name: 'HTTP');
+    final message = "$requestLog => $responseLog";
+    log(message, name: 'HTTP');
+    firebase.log(message);
     handler.next(response);
   }
 }

test/services/course_service_test.dart

@@ -1,7 +1,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:tattoo/models/course.dart';
 import 'package:tattoo/services/course_service.dart';
-import 'package:tattoo/services/firebase_service.dart';
 import 'package:tattoo/services/portal_service.dart';
 
 import '../test_helpers.dart';
@@ -16,7 +15,7 @@ void main() {
     });
 
     setUp(() async {
-      portalService = PortalService(FirebaseService());
+      portalService = PortalService();
       courseService = CourseService();
 
       await portalService.login(

test/services/i_school_plus_service_test.dart

@@ -1,5 +1,4 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:tattoo/services/firebase_service.dart';
 import 'package:tattoo/services/i_school_plus_service.dart';
 import 'package:tattoo/services/portal_service.dart';
 
@@ -14,7 +13,7 @@ void main() {
     setUpAll(() async {
       TestCredentials.validate();
 
-      portalService = PortalService(FirebaseService());
+      portalService = PortalService();
       iSchoolPlusService = ISchoolPlusService();
 
       await portalService.login(
@@ -33,7 +32,7 @@ void main() {
     });
 
     setUp(() async {
-      portalService = PortalService(FirebaseService());
+      portalService = PortalService();
       iSchoolPlusService = ISchoolPlusService();
 
       await portalService.login(

test/services/portal_service_test.dart

@@ -1,5 +1,4 @@
 import 'package:flutter_test/flutter_test.dart';
-import 'package:tattoo/services/firebase_service.dart';
 import 'package:tattoo/services/portal_service.dart';
 import 'package:tattoo/utils/http.dart';
 
@@ -14,7 +13,7 @@ void main() {
     });
 
     setUp(() async {
-      portalService = PortalService(FirebaseService());
+      portalService = PortalService();
       await respectfulDelay();
     });
 

test/services/student_query_service_test.dart

@@ -2,7 +2,6 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:tattoo/models/ranking.dart';
 import 'package:tattoo/models/score.dart';
 import 'package:tattoo/models/user.dart';
-import 'package:tattoo/services/firebase_service.dart';
 import 'package:tattoo/services/portal_service.dart';
 import 'package:tattoo/services/student_query_service.dart';
 
@@ -18,7 +17,7 @@ void main() {
     });
 
     setUp(() async {
-      portalService = PortalService(FirebaseService());
+      portalService = PortalService();
       studentQueryService = StudentQueryService();
 
       await portalService.login(