fix(analytics): use Android ID and persist UUID fallbacks

ui/flutter/lib/api/model/downloader_config.dart

@@ -196,7 +196,9 @@ class ExtraConfig {
   List<String> createHistory;
   bool runAsMenubarApp;
   bool analyticsEnabled;
-  String analyticsClientId;
+
+  /// Persisted UUID fallback; IDs returned by platform APIs are not stored here.
+  String deviceId;
 
   ExtraConfig({
     this.themeMode = '',
@@ -214,7 +216,7 @@ class ExtraConfig {
     this.createHistory = const [],
     this.runAsMenubarApp = false,
     this.analyticsEnabled = true,
-    this.analyticsClientId = '',
+    this.deviceId = '',
   }) : windowState = windowState ?? WindowStateConfig();
 
   factory ExtraConfig.fromJson(Map<String, dynamic>? json) =>

ui/flutter/lib/app/application/app_runtime_controller.dart

@@ -255,9 +255,9 @@ class AppRuntimeController extends AsyncNotifier<AppRuntimeState> {
   Future<void> _initAnalytics(DownloaderConfig config) async {
     if (!AnalyticsConfig.isConfigured || !config.extra.analyticsEnabled) return;
     try {
-      await Analytics.instance.init(fallbackClientId: config.extra.analyticsClientId);
-      if (config.extra.analyticsClientId.isEmpty && Analytics.instance.clientId.isNotEmpty) {
-        config.extra.analyticsClientId = Analytics.instance.clientId;
+      final generatedClientId = await Analytics.instance.init(fallbackClientId: config.extra.deviceId);
+      if (generatedClientId != null) {
+        config.extra.deviceId = generatedClientId;
         await ref.read(gopeedServiceProvider).putConfig(config);
       }
       unawaited(Analytics.instance.logAppOpen());

ui/flutter/lib/features/settings/application/settings_controller.dart

@@ -56,7 +56,7 @@ class SettingsController extends AsyncNotifier<SettingsState> {
         ..bookmarks = latest.extra.bookmarks
         ..createHistory = latest.extra.createHistory
         ..runAsMenubarApp = latest.extra.runAsMenubarApp
-        ..analyticsClientId = latest.extra.analyticsClientId;
+        ..deviceId = latest.extra.deviceId;
       // The backend preserves protocol-owned results and validates the whole PUT.
       await service.putConfig(config);
       final saved = await service.getConfig();

ui/flutter/lib/util/analytics.dart

@@ -1,8 +1,10 @@
 import 'dart:io';
 
+import 'package:android_id/android_id.dart';
 import 'package:device_info_plus/device_info_plus.dart';
 import 'package:dio/dio.dart';
 import 'package:flutter/foundation.dart';
+import 'package:uuid/uuid.dart';
 
 import 'log_util.dart';
 import 'package_info.dart';
@@ -31,12 +33,23 @@ class Analytics {
 
   String get clientId => _initialized ? _clientId : '';
 
-  Future<void> init({String fallbackClientId = ''}) async {
-    if (_initialized || !AnalyticsConfig.isConfigured) return;
-    _clientId = await _getDeviceId(fallbackClientId);
+  /// Returns a newly generated fallback ID for the caller to persist, if any.
+  Future<String?> init({String fallbackClientId = ''}) async {
+    if (_initialized || !AnalyticsConfig.isConfigured) return null;
+    final deviceId = await _getDeviceId();
+    String? generatedClientId;
+    if (deviceId != null && deviceId.isNotEmpty) {
+      _clientId = deviceId;
+    } else if (fallbackClientId.isNotEmpty) {
+      _clientId = fallbackClientId;
+    } else {
+      _clientId = const Uuid().v4();
+      generatedClientId = _clientId;
+    }
     _sessionId = DateTime.now().millisecondsSinceEpoch ~/ 1000;
     _dio = Dio(BaseOptions(connectTimeout: const Duration(seconds: 10), receiveTimeout: const Duration(seconds: 10)));
     _initialized = true;
+    return generatedClientId;
   }
 
   Future<void> logAppOpen() => logEvent('app_open');
@@ -70,14 +83,14 @@ class Analytics {
     }
   }
 
-  Future<String> _getDeviceId(String fallbackClientId) async {
+  Future<String?> _getDeviceId() async {
+    if (kIsWeb) return null;
+
     String? deviceId;
     try {
       final info = DeviceInfoPlugin();
-      if (kIsWeb) {
-        deviceId = null;
-      } else if (Platform.isAndroid) {
-        deviceId = (await info.androidInfo).id;
+      if (Platform.isAndroid) {
+        deviceId = await const AndroidId().getId();
       } else if (Platform.isIOS) {
         deviceId = (await info.iosInfo).identifierForVendor;
       } else if (Platform.isMacOS) {
@@ -91,14 +104,6 @@ class Analytics {
       logger.w('GA4Analytics: failed to read device id: $error');
     }
 
-    if (deviceId == null || deviceId.isEmpty) {
-      deviceId = fallbackClientId;
-      if (deviceId.isEmpty) {
-        final random = DateTime.now().microsecondsSinceEpoch % 2147483647;
-        final timestamp = DateTime.now().millisecondsSinceEpoch ~/ 1000;
-        deviceId = '$random.$timestamp';
-      }
-    }
     return deviceId;
   }
 

ui/flutter/pubspec.lock

@@ -25,6 +25,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
+  android_id:
+    dependency: "direct main"
+    description:
+      name: android_id
+      sha256: "543bbfcf316de69d3ac36601d74eeaacd0248178a2671b00ad30d09f35bd3581"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.2+1"
   animation_kit:
     dependency: transitive
     description:
@@ -1621,7 +1629,7 @@ packages:
     source: hosted
     version: "3.1.5"
   uuid:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: uuid
       sha256: "9b129329f58692f6e6578329498a8fe9fbe98f090beb764ffbb8ee2eadd01dcd"

ui/flutter/pubspec.yaml

@@ -47,6 +47,8 @@ dependencies:
   package_info_plus: ^10.2.1
   pub_semver: ^2.2.0
   device_info_plus: ^13.2.0
+  android_id: ^0.5.2+1
+  uuid: ^4.6.0
   win32_registry: ^3.0.3
   launch_at_startup:
     git:

ui/flutter/test/api/downloader_config_test.dart

@@ -81,7 +81,7 @@ void main() {
       ..createHistory = ['https://example.com/file.zip']
       ..runAsMenubarApp = true
       ..analyticsEnabled = false
-      ..analyticsClientId = 'client-id';
+      ..deviceId = 'client-id';
 
     final decoded = DownloaderConfig.fromJson(config.toJson()).extra;
     expect(decoded.windowState.isMaximized, isTrue);
@@ -91,7 +91,22 @@ void main() {
     expect(decoded.createHistory, ['https://example.com/file.zip']);
     expect(decoded.runAsMenubarApp, isTrue);
     expect(decoded.analyticsEnabled, isFalse);
-    expect(decoded.analyticsClientId, 'client-id');
+    expect(decoded.deviceId, 'client-id');
+  });
+
+  test('legacy analytics client IDs are ignored without migration', () {
+    final config = ExtraConfig.fromJson({'analyticsClientId': 'AP3A.241105.008'});
+
+    expect(config.deviceId, isEmpty);
+    expect(config.toJson(), isNot(contains('analyticsClientId')));
+  });
+
+  test('analytics fallback ID uses only its dedicated config field', () {
+    final config = ExtraConfig.fromJson({'analyticsClientId': 'AP3A.241105.008', 'deviceId': 'stored-fallback'});
+
+    expect(config.deviceId, 'stored-fallback');
+    expect(config.toJson()['deviceId'], 'stored-fallback');
+    expect(config.toJson(), isNot(contains('analyticsClientId')));
   });
 
   test('categories and the auto-categorize switch round-trip through the config', () {

ui/flutter/test/features/settings/application/settings_controller_test.dart

@@ -44,7 +44,7 @@ void main() {
     final backend = DownloaderConfig()
       ..extra.windowState = WindowStateConfig(isMaximized: true, width: 1200, height: 800)
       ..extra.createHistory = ['https://example.com/existing.zip']
-      ..extra.analyticsClientId = 'existing-client';
+      ..extra.deviceId = 'existing-client';
     DownloaderConfig? saved;
     final registry = CapabilityRegistry(createAppCapabilityCodecs())
       ..bind(GopeedMethods.getConfig, (_) => DownloaderConfig.fromJson(backend.toJson()))
@@ -67,7 +67,7 @@ void main() {
     expect(saved?.downloadDir, 'E:/New');
     expect(saved?.extra.windowState.isMaximized, isTrue);
     expect(saved?.extra.createHistory, ['https://example.com/existing.zip']);
-    expect(saved?.extra.analyticsClientId, 'existing-client');
+    expect(saved?.extra.deviceId, 'existing-client');
   });
 
   test('protocol edits use a single full PUT and reload backend-owned tracker results', () async {