feat(app): смена сервера API и очистка данных устройства при выходе

Адрес бэкенда хранится в shared_preferences и читается до runApp; switchApiBaseUrl сбрасывает токены и кэш старого сервера. Выход стирает refresh-токен и sqlite-кэш ответов. Экран настроек переделан под разделы.

app/lib/core/api/api_client.dart

@@ -4,27 +4,21 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../auth/auth_controller.dart';
 import '../cache/cache_interceptor.dart';
-import '../cache/response_cache.dart';
+import '../cache/response_cache_provider.dart';
 import '../config.dart';
 
-/// One sqlite-backed cache of the last successful GET per endpoint+params,
-/// shared by every screen. See `docs/ai/offline-cache.md`.
-final responseCacheDbProvider = Provider<ResponseCacheDatabase>((ref) {
-  final db = ResponseCacheDatabase();
-  ref.onDispose(db.close);
-  return db;
-});
-
 /// Authenticated client: bearer header on every call, one transparent refresh
 /// on 401, and — since [CacheInterceptor] is added last, so it sees a request
 /// only after auth has already handled it — the last cached answer when the
 /// network itself is unreachable.
 final apiProvider = Provider<FintrackerApi>((ref) {
-  final dio = Dio(BaseOptions(
-    baseUrl: apiBaseUrl(),
-    connectTimeout: const Duration(seconds: 10),
-    receiveTimeout: const Duration(seconds: 30),
-  ));
+  final dio = Dio(
+    BaseOptions(
+      baseUrl: ref.watch(apiBaseUrlProvider),
+      connectTimeout: const Duration(seconds: 10),
+      receiveTimeout: const Duration(seconds: 30),
+    ),
+  );
   dio.interceptors.add(DateQueryInterceptor());
   dio.interceptors.add(_AuthInterceptor(ref));
   dio.interceptors.add(CacheInterceptor(ref.watch(responseCacheDbProvider)));
@@ -67,7 +61,10 @@ class _AuthInterceptor extends QueuedInterceptor {
   }
 
   @override
-  Future<void> onError(DioException err, ErrorInterceptorHandler handler) async {
+  Future<void> onError(
+    DioException err,
+    ErrorInterceptorHandler handler,
+  ) async {
     final retried = err.requestOptions.extra['retried'] == true;
     if (err.response?.statusCode != 401 || retried) return handler.next(err);
 
@@ -81,7 +78,9 @@ class _AuthInterceptor extends QueuedInterceptor {
       ..headers['Authorization'] = 'Bearer $token'
       ..extra['retried'] = true;
     try {
-      handler.resolve(await Dio(BaseOptions(baseUrl: opts.baseUrl)).fetch(opts));
+      handler.resolve(
+        await Dio(BaseOptions(baseUrl: opts.baseUrl)).fetch(opts),
+      );
     } on DioException catch (e) {
       handler.next(e);
     }

app/lib/core/auth/auth_controller.dart

@@ -2,6 +2,7 @@ import 'package:dio/dio.dart';
 import 'package:fintracker_api/fintracker_api.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../cache/response_cache_provider.dart';
 import '../config.dart';
 import 'token_store.dart';
 
@@ -20,14 +21,18 @@ final tokenStoreProvider = Provider<TokenStore>((_) => TokenStore());
 
 /// A bare Dio for auth calls: no auth interceptor, so a refresh can never recurse.
 final authDioProvider = Provider<Dio>(
-  (_) => Dio(BaseOptions(
-    baseUrl: apiBaseUrl(),
-    connectTimeout: const Duration(seconds: 10),
-    receiveTimeout: const Duration(seconds: 20),
-  )),
+  (ref) => Dio(
+    BaseOptions(
+      baseUrl: ref.watch(apiBaseUrlProvider),
+      connectTimeout: const Duration(seconds: 10),
+      receiveTimeout: const Duration(seconds: 20),
+    ),
+  ),
 );
 
-final authControllerProvider = NotifierProvider<AuthController, AuthState>(AuthController.new);
+final authControllerProvider = NotifierProvider<AuthController, AuthState>(
+  AuthController.new,
+);
 
 class AuthController extends Notifier<AuthState> {
   @override
@@ -51,7 +56,9 @@ class AuthController extends Notifier<AuthState> {
 
   Future<String?> login(String email, String password) async {
     try {
-      final r = await _api.authLogin(loginRequest: LoginRequest(email: email, password: password));
+      final r = await _api.authLogin(
+        loginRequest: LoginRequest(email: email, password: password),
+      );
       await _accept(r.data!);
       return null;
     } on DioException catch (e) {
@@ -64,32 +71,51 @@ class AuthController extends Notifier<AuthState> {
     final token = refresh ?? await _store.readRefresh();
     if (token == null) return false;
     try {
-      final r = await _api.authRefresh(refreshRequest: RefreshRequest(refreshToken: token));
+      final r = await _api.authRefresh(
+        refreshRequest: RefreshRequest(refreshToken: token),
+      );
       await _accept(r.data!);
       return true;
     } on DioException catch (e) {
-      if (e.response?.statusCode == 401) await _store.clear();
+      if (e.response?.statusCode == 401) await _wipeLocal();
       return false;
     }
   }
 
   Future<void> _accept(TokenPair pair) async {
     await _store.writeRefresh(pair.refreshToken);
-    state = AuthState(AuthStatus.signedIn, accessToken: pair.accessToken, email: state.email);
+    state = AuthState(
+      AuthStatus.signedIn,
+      accessToken: pair.accessToken,
+      email: state.email,
+    );
   }
 
   Future<void> logout() async {
     final refresh = await _store.readRefresh();
     if (refresh != null) {
       try {
-        await _api.authLogout(refreshRequest: RefreshRequest(refreshToken: refresh));
+        await _api.authLogout(
+          refreshRequest: RefreshRequest(refreshToken: refresh),
+        );
       } on DioException {
         // the server may already consider it revoked; local state wins
       }
     }
-    await _store.clear();
+    await _wipeLocal();
     state = const AuthState(AuthStatus.signedOut);
   }
+
+  /// Everything this device keeps for the account: the refresh token and the cached
+  /// responses (the whole financial picture, in plain sqlite / IndexedDB).
+  Future<void> _wipeLocal() async {
+    await _store.clear();
+    try {
+      await ref.read(responseCacheDbProvider).clear();
+    } on Object {
+      // the token is already gone; a cache that cannot be opened must not block signing out
+    }
+  }
 }
 
 /// Human-readable text from an RFC 7807 body, falling back to the transport error.
@@ -102,8 +128,7 @@ String problemMessage(DioException e) {
   return switch (e.type) {
     DioExceptionType.connectionError ||
     DioExceptionType.connectionTimeout ||
-    DioExceptionType.receiveTimeout =>
-      'Сервер недоступен',
+    DioExceptionType.receiveTimeout => 'Сервер недоступен',
     _ => e.message ?? 'Ошибка запроса',
   };
 }

app/lib/core/auth/switch_server.dart

@@ -0,0 +1,17 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../config.dart';
+import 'auth_controller.dart';
+
+/// Points the app at [url] (null = the default). A different server means a different
+/// account, so the session ends first — while the clients still talk to the OLD server, so
+/// the refresh token is revoked there and never sent to the new one — and only then is the
+/// address changed. Takes a container rather than a `WidgetRef`: signing out replaces the
+/// calling screen, and a disposed widget's `ref` throws.
+Future<void> switchApiBaseUrl(ProviderContainer container, String? url) async {
+  final next = url ?? defaultApiBaseUrl();
+  if (next != container.read(apiBaseUrlProvider)) {
+    await container.read(authControllerProvider.notifier).logout();
+  }
+  await container.read(apiBaseUrlProvider.notifier).save(url);
+}

app/lib/core/auth/token_store.dart

@@ -4,12 +4,13 @@ import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 /// (single-user, TLS-only deployment; see plan §7 open question 1).
 class TokenStore {
   TokenStore([FlutterSecureStorage? storage])
-      : _storage = storage ?? const FlutterSecureStorage();
+    : _storage = storage ?? const FlutterSecureStorage();
 
   final FlutterSecureStorage _storage;
   static const _refreshKey = 'refresh_token';
 
   Future<String?> readRefresh() => _storage.read(key: _refreshKey);
-  Future<void> writeRefresh(String token) => _storage.write(key: _refreshKey, value: token);
+  Future<void> writeRefresh(String token) =>
+      _storage.write(key: _refreshKey, value: token);
   Future<void> clear() => _storage.delete(key: _refreshKey);
 }

app/lib/core/cache/cache_interceptor.dart

@@ -28,7 +28,10 @@ class CacheInterceptor extends Interceptor {
   };
 
   @override
-  void onResponse(Response<dynamic> response, ResponseInterceptorHandler handler) {
+  void onResponse(
+    Response<dynamic> response,
+    ResponseInterceptorHandler handler,
+  ) {
     if (response.requestOptions.method == 'GET' && response.statusCode == 200) {
       // Never block the UI on the write: the caller already has its data.
       unawaited(_db.put(requestKey(response.requestOptions), response.data));
@@ -37,8 +40,12 @@ class CacheInterceptor extends Interceptor {
   }
 
   @override
-  Future<void> onError(DioException err, ErrorInterceptorHandler handler) async {
-    if (err.requestOptions.method != 'GET' || !_offlineTypes.contains(err.type)) {
+  Future<void> onError(
+    DioException err,
+    ErrorInterceptorHandler handler,
+  ) async {
+    if (err.requestOptions.method != 'GET' ||
+        !_offlineTypes.contains(err.type)) {
       return handler.next(err);
     }
     final cached = await _db.get(requestKey(err.requestOptions));
@@ -56,7 +63,8 @@ class CacheInterceptor extends Interceptor {
   /// `path?sorted=query` — deliberately excludes the host, so switching the API
   /// origin (dev vs. prod) does not orphan a device's cache.
   static String requestKey(RequestOptions options) {
-    final params = options.queryParameters.entries.toList()..sort((a, b) => a.key.compareTo(b.key));
+    final params = options.queryParameters.entries.toList()
+      ..sort((a, b) => a.key.compareTo(b.key));
     final query = params.map((e) => '${e.key}=${e.value}').join('&');
     return '${options.path}?$query';
   }

app/lib/core/cache/cached.dart

@@ -15,7 +15,8 @@ extension CachedResponseX<T> on Response<T> {
   /// Wraps this response's data with the staleness [CacheInterceptor] recorded
   /// in `extra['fetchedAt']`. A provider that wants offline support returns
   /// `r.cached` instead of `r.data!`.
-  Cached<T> get cached => Cached(data as T, fetchedAt: extra['fetchedAt'] as DateTime?);
+  Cached<T> get cached =>
+      Cached(data as T, fetchedAt: extra['fetchedAt'] as DateTime?);
 }
 
 /// The oldest of several fetch times, or null if none of them is stale.

app/lib/core/cache/response_cache.dart

@@ -38,7 +38,8 @@ class ResponseCacheDatabase extends _$ResponseCacheDatabase {
 
   /// Replaces whatever was cached for [requestKey] — one row per endpoint+params,
   /// never a history.
-  Future<void> put(String requestKey, Object? body) => into(cachedResponses).insertOnConflictUpdate(
+  Future<void> put(String requestKey, Object? body) =>
+      into(cachedResponses).insertOnConflictUpdate(
         CachedResponsesCompanion.insert(
           requestKey: requestKey,
           body: jsonEncode(body),
@@ -46,6 +47,9 @@ class ResponseCacheDatabase extends _$ResponseCacheDatabase {
         ),
       );
 
+  /// Drops every cached body — on sign-out, so the next account (or nobody) never sees them.
+  Future<void> clear() => delete(cachedResponses).go();
+
   /// The body last stored for [requestKey], or null if this endpoint+params was
   /// never fetched successfully on this device.
   Future<CacheEntry?> get(String requestKey) async {
@@ -63,9 +67,9 @@ class ResponseCacheDatabase extends _$ResponseCacheDatabase {
 /// the compiled assets it loads there (regenerate with `just app-web-assets`
 /// whenever the `drift`/`sqlite3` package versions change).
 QueryExecutor _openConnection() => driftDatabase(
-      name: 'response_cache',
-      web: DriftWebOptions(
-        sqlite3Wasm: Uri.parse('sqlite3.wasm'),
-        driftWorker: Uri.parse('drift_worker.js'),
-      ),
-    );
+  name: 'response_cache',
+  web: DriftWebOptions(
+    sqlite3Wasm: Uri.parse('sqlite3.wasm'),
+    driftWorker: Uri.parse('drift_worker.js'),
+  ),
+);

app/lib/core/cache/response_cache_provider.dart

@@ -0,0 +1,11 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'response_cache.dart';
+
+/// One sqlite-backed cache of the last successful GET per endpoint+params,
+/// shared by every screen. See `docs/ai/offline-cache.md`.
+final responseCacheDbProvider = Provider<ResponseCacheDatabase>((ref) {
+  final db = ResponseCacheDatabase();
+  ref.onDispose(db.close);
+  return db;
+});

app/lib/core/config.dart

@@ -1,11 +1,58 @@
 import 'package:flutter/foundation.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 
-/// Backend origin. Override at build time:
+const _prefsKey = 'api_base_url';
+
+/// Backend origin when the user has not chosen one. Override at build time:
 /// `flutter run --dart-define=API_BASE_URL=https://fin.example.com`.
 /// On web the default is the page's own origin (Caddy serves app and API together).
-String apiBaseUrl() {
+String defaultApiBaseUrl() {
   const fromEnv = String.fromEnvironment('API_BASE_URL');
   if (fromEnv.isNotEmpty) return fromEnv;
   if (kIsWeb) return Uri.base.origin;
   return 'http://127.0.0.1:8000';
 }
+
+/// The address saved on this device, read in `main()` before `runApp`. Loading it up front,
+/// rather than lazily like the theme, matters: the session restore fires a request on
+/// startup and it must already go to the right server.
+Future<String?> loadStoredApiBaseUrl() async =>
+    (await SharedPreferences.getInstance()).getString(_prefsKey);
+
+/// Overridden in `main()` with [loadStoredApiBaseUrl]; null (tests, nothing saved) means default.
+final initialApiBaseUrlProvider = Provider<String?>((_) => null);
+
+/// Backend origin every client is built against. Watched by `apiProvider` and
+/// `authDioProvider`, so changing it rebuilds them. To switch servers use
+/// `switchApiBaseUrl`: tokens and cached data belong to the old one.
+final apiBaseUrlProvider = NotifierProvider<ApiBaseUrlController, String>(
+  ApiBaseUrlController.new,
+);
+
+class ApiBaseUrlController extends Notifier<String> {
+  @override
+  String build() => ref.watch(initialApiBaseUrlProvider) ?? defaultApiBaseUrl();
+
+  /// [input] as an origin-like URL without a trailing slash, or null if it is not an
+  /// absolute http(s) URL.
+  static String? normalize(String input) {
+    final uri = Uri.tryParse(input.trim());
+    if (uri == null || !uri.hasAuthority || uri.host.isEmpty) return null;
+    if (uri.scheme != 'http' && uri.scheme != 'https') return null;
+    final s = uri.toString();
+    return s.endsWith('/') ? s.substring(0, s.length - 1) : s;
+  }
+
+  /// Persists [url]; null goes back to [defaultApiBaseUrl].
+  Future<void> save(String? url) async {
+    final prefs = await SharedPreferences.getInstance();
+    if (url == null) {
+      await prefs.remove(_prefsKey);
+      state = defaultApiBaseUrl();
+    } else {
+      await prefs.setString(_prefsKey, url);
+      state = url;
+    }
+  }
+}

app/lib/features/login/login_page.dart

@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../core/auth/auth_controller.dart';
 import '../../core/config.dart';
+import '../settings/api_base_url_dialog.dart';
 
 class LoginPage extends ConsumerStatefulWidget {
   const LoginPage({super.key});
@@ -55,9 +56,28 @@ class _LoginPageState extends ConsumerState<LoginPage> {
                       mainAxisSize: MainAxisSize.min,
                       crossAxisAlignment: CrossAxisAlignment.stretch,
                       children: [
-                        Text('fin-tracker', style: Theme.of(context).textTheme.headlineMedium),
+                        Text(
+                          'fin-tracker',
+                          style: Theme.of(context).textTheme.headlineMedium,
+                        ),
                         const SizedBox(height: 4),
-                        Text(apiBaseUrl(), style: Theme.of(context).textTheme.bodySmall),
+                        Row(
+                          mainAxisAlignment: MainAxisAlignment.center,
+                          children: [
+                            Flexible(
+                              child: Text(
+                                ref.watch(apiBaseUrlProvider),
+                                style: Theme.of(context).textTheme.bodySmall,
+                                overflow: TextOverflow.ellipsis,
+                              ),
+                            ),
+                            IconButton(
+                              icon: const Icon(Icons.edit_outlined, size: 16),
+                              tooltip: 'Изменить адрес',
+                              onPressed: () => showApiBaseUrlDialog(context),
+                            ),
+                          ],
+                        ),
                         const SizedBox(height: 24),
                         TextField(
                           controller: _email,
@@ -71,18 +91,29 @@ class _LoginPageState extends ConsumerState<LoginPage> {
                           autofillHints: const [AutofillHints.password],
                           obscureText: true,
                           onSubmitted: (_) => _busy ? null : _submit(),
-                          decoration: const InputDecoration(labelText: 'Пароль'),
+                          decoration: const InputDecoration(
+                            labelText: 'Пароль',
+                          ),
                         ),
                         if (_error != null) ...[
                           const SizedBox(height: 12),
-                          Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
+                          Text(
+                            _error!,
+                            style: TextStyle(
+                              color: Theme.of(context).colorScheme.error,
+                            ),
+                          ),
                         ],
                         const SizedBox(height: 24),
                         FilledButton(
                           onPressed: _busy ? null : _submit,
                           child: _busy
                               ? const SizedBox.square(
-                                  dimension: 18, child: CircularProgressIndicator(strokeWidth: 2))
+                                  dimension: 18,
+                                  child: CircularProgressIndicator(
+                                    strokeWidth: 2,
+                                  ),
+                                )
                               : const Text('Войти'),
                         ),
                       ],

app/lib/features/settings/api_base_url_dialog.dart

@@ -0,0 +1,89 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../core/auth/switch_server.dart';
+import '../../core/config.dart';
+
+/// Asks for a new backend address and applies it. Shared by Настройки and the login screen
+/// (a wrong address there means you can never reach Настройки).
+Future<void> showApiBaseUrlDialog(BuildContext context) async {
+  final container = ProviderScope.containerOf(context);
+  final result = await showDialog<_Choice>(
+    context: context,
+    builder: (_) =>
+        _ApiBaseUrlDialog(current: container.read(apiBaseUrlProvider)),
+  );
+  if (result == null) return;
+  await switchApiBaseUrl(container, result.url);
+}
+
+class _Choice {
+  const _Choice(this.url);
+
+  /// null = back to the default address.
+  final String? url;
+}
+
+class _ApiBaseUrlDialog extends StatefulWidget {
+  const _ApiBaseUrlDialog({required this.current});
+  final String current;
+
+  @override
+  State<_ApiBaseUrlDialog> createState() => _ApiBaseUrlDialogState();
+}
+
+class _ApiBaseUrlDialogState extends State<_ApiBaseUrlDialog> {
+  late final _controller = TextEditingController(text: widget.current);
+  String? _error;
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  void _save() {
+    final url = ApiBaseUrlController.normalize(_controller.text);
+    if (url == null) {
+      setState(() => _error = 'Нужен адрес вида https://fin.example.com');
+      return;
+    }
+    Navigator.pop(context, _Choice(url));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AlertDialog(
+      title: const Text('Адрес API'),
+      content: Column(
+        mainAxisSize: MainAxisSize.min,
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          TextField(
+            controller: _controller,
+            autofocus: true,
+            keyboardType: TextInputType.url,
+            decoration: InputDecoration(errorText: _error),
+            onSubmitted: (_) => _save(),
+          ),
+          const SizedBox(height: 12),
+          Text(
+            'Смена адреса завершит сеанс и очистит локальный кэш.',
+            style: Theme.of(context).textTheme.bodySmall,
+          ),
+        ],
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.pop(context),
+          child: const Text('Отмена'),
+        ),
+        TextButton(
+          onPressed: () => Navigator.pop(context, const _Choice(null)),
+          child: const Text('По умолчанию'),
+        ),
+        FilledButton(onPressed: _save, child: const Text('Сохранить')),
+      ],
+    );
+  }
+}

app/lib/features/settings/settings_page.dart

@@ -7,83 +7,372 @@ import '../../core/auth/auth_controller.dart';
 import '../../core/config.dart';
 import '../../core/theme/theme_controller.dart';
 import '../../core/widgets/async_value_view.dart';
+import 'api_base_url_dialog.dart';
 
-/// Настройки: API endpoint, signed-in account, theme and logout.
-class SettingsPage extends ConsumerWidget {
+/// One entry of the left menu and the panel it opens.
+class _Section {
+  const _Section(this.title, this.build);
+
+  final String title;
+  final Widget Function(BuildContext context, WidgetRef ref) build;
+}
+
+/// A tab along the top: a group of sections.
+class _Group {
+  const _Group(this.title, this.icon, this.sections);
+
+  final String title;
+  final IconData icon;
+  final List<_Section> sections;
+}
+
+final _groups = [
+  _Group('Аккаунт', Icons.person_outline, [
+    _Section('Приватные данные', _privateData),
+    _Section('Безопасность', _security),
+  ]),
+  _Group('Отображение', Icons.palette_outlined, [_Section('Тема', _theme)]),
+  _Group('Сервер', Icons.dns_outlined, [
+    _Section('Адрес API', _apiAddress),
+    _Section('О приложении', _about),
+  ]),
+];
+
+/// Настройки, laid out like Snowball's account page: tabs along the top and, inside the tab,
+/// a menu of its sections on the left. Below 720 px the menu becomes a row of chips above the
+/// panel — a 240 px menu beside a form would leave the form nothing.
+class SettingsPage extends ConsumerStatefulWidget {
   const SettingsPage({super.key});
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
-    final me = ref.watch(meProvider);
-    final themeMode = ref.watch(themeModeProvider);
+  ConsumerState<SettingsPage> createState() => _SettingsPageState();
+}
 
-    return Scaffold(
-      appBar: AppBar(title: const Text('Настройки')),
-      body: ListView(
-        padding: const EdgeInsets.symmetric(vertical: 8),
-        children: [
-          const ListTile(
-            leading: Icon(Icons.dns_outlined),
-            title: Text('Адрес API'),
-          ),
-          ListTile(
-            contentPadding: const EdgeInsets.only(left: 56, right: 16),
-            title: SelectableText(apiBaseUrl()),
-          ),
-          const Divider(),
-          ListTile(
-            leading: const Icon(Icons.account_circle_outlined),
-            title: const Text('Аккаунт'),
-            subtitle: AsyncValueView(
-              value: me,
-              data: (u) => Text(u.email),
-              onRetry: () => ref.invalidate(meProvider),
-            ),
-          ),
-          const Divider(),
-          const ListTile(
-            leading: Icon(Icons.palette_outlined),
-            title: Text('Тема'),
-          ),
-          Padding(
-            padding: const EdgeInsets.symmetric(horizontal: 16),
-            child: SegmentedButton<ThemeMode>(
-              segments: const [
-                ButtonSegment(
-                  value: ThemeMode.system,
-                  label: Text('Системная'),
-                  icon: Icon(Icons.brightness_auto_outlined),
-                ),
-                ButtonSegment(
-                  value: ThemeMode.light,
-                  label: Text('Светлая'),
-                  icon: Icon(Icons.light_mode_outlined),
-                ),
-                ButtonSegment(
-                  value: ThemeMode.dark,
-                  label: Text('Тёмная'),
-                  icon: Icon(Icons.dark_mode_outlined),
-                ),
+class _SettingsPageState extends ConsumerState<SettingsPage> {
+  int _group = 0;
+  int _section = 0;
+
+  @override
+  Widget build(BuildContext context) {
+    final scheme = Theme.of(context).colorScheme;
+    final group = _groups[_group];
+    final section =
+        group.sections[_section.clamp(0, group.sections.length - 1)];
+    final wide = MediaQuery.sizeOf(context).width >= 720;
+
+    final menu = wide
+        ? SizedBox(
+            width: 240,
+            child: Column(
+              children: [
+                for (var i = 0; i < group.sections.length; i++)
+                  _MenuItem(
+                    title: group.sections[i].title,
+                    selected: group.sections[i] == section,
+                    onTap: () => setState(() => _section = i),
+                  ),
               ],
-              selected: {themeMode},
-              onSelectionChanged: (selection) =>
-                  ref.read(themeModeProvider.notifier).setMode(selection.first),
+            ),
+          )
+        : Wrap(
+            spacing: 8,
+            children: [
+              for (var i = 0; i < group.sections.length; i++)
+                ChoiceChip(
+                  label: Text(group.sections[i].title),
+                  selected: group.sections[i] == section,
+                  onSelected: (_) => setState(() => _section = i),
+                ),
+            ],
+          );
+
+    return ListView(
+      padding: const EdgeInsets.all(16),
+      children: [
+        Card(
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.stretch,
+            children: [
+              Container(
+                decoration: BoxDecoration(
+                  border: Border(
+                    bottom: BorderSide(color: scheme.outlineVariant),
+                  ),
+                ),
+                padding: const EdgeInsets.symmetric(horizontal: 12),
+                child: SingleChildScrollView(
+                  scrollDirection: Axis.horizontal,
+                  child: Row(
+                    children: [
+                      for (var i = 0; i < _groups.length; i++)
+                        _TopTab(
+                          icon: _groups[i].icon,
+                          title: _groups[i].title,
+                          selected: i == _group,
+                          onTap: () => setState(() {
+                            _group = i;
+                            _section = 0;
+                          }),
+                        ),
+                    ],
+                  ),
+                ),
+              ),
+              Padding(
+                padding: const EdgeInsets.all(24),
+                child: wide
+                    ? Row(
+                        crossAxisAlignment: CrossAxisAlignment.start,
+                        children: [
+                          menu,
+                          const SizedBox(width: 24),
+                          Expanded(child: section.build(context, ref)),
+                        ],
+                      )
+                    : Column(
+                        crossAxisAlignment: CrossAxisAlignment.start,
+                        children: [
+                          menu,
+                          const SizedBox(height: 20),
+                          section.build(context, ref),
+                        ],
+                      ),
+              ),
+            ],
+          ),
+        ),
+      ],
+    );
+  }
+}
+
+class _TopTab extends StatelessWidget {
+  const _TopTab({
+    required this.icon,
+    required this.title,
+    required this.selected,
+    required this.onTap,
+  });
+
+  final IconData icon;
+  final String title;
+  final bool selected;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    final scheme = Theme.of(context).colorScheme;
+    return InkWell(
+      onTap: onTap,
+      child: Container(
+        padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 16),
+        decoration: BoxDecoration(
+          border: Border(
+            bottom: BorderSide(
+              color: selected ? scheme.primary : Colors.transparent,
+              width: 2,
             ),
           ),
-          const Divider(),
-          const ListTile(
-            leading: Icon(Icons.info_outline),
-            title: Text('Версия приложения'),
-            subtitle: Text(appVersion),
-          ),
-          const Divider(),
-          ListTile(
-            leading: Icon(Icons.logout, color: Theme.of(context).colorScheme.error),
-            title: Text('Выйти', style: TextStyle(color: Theme.of(context).colorScheme.error)),
-            onTap: () => ref.read(authControllerProvider.notifier).logout(),
-          ),
-        ],
+        ),
+        child: Row(
+          children: [
+            Icon(
+              icon,
+              size: 20,
+              color: selected ? scheme.primary : scheme.onSurfaceVariant,
+            ),
+            const SizedBox(width: 8),
+            Text(
+              title,
+              style: TextStyle(
+                color: selected ? scheme.onSurface : scheme.onSurfaceVariant,
+                fontWeight: selected ? FontWeight.w600 : FontWeight.w500,
+              ),
+            ),
+          ],
+        ),
       ),
     );
   }
 }
+
+class _MenuItem extends StatelessWidget {
+  const _MenuItem({
+    required this.title,
+    required this.selected,
+    required this.onTap,
+  });
+
+  final String title;
+  final bool selected;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    final scheme = Theme.of(context).colorScheme;
+    return Padding(
+      padding: const EdgeInsets.only(bottom: 4),
+      child: Material(
+        color: selected ? scheme.surfaceContainerHigh : Colors.transparent,
+        borderRadius: BorderRadius.circular(8),
+        child: InkWell(
+          borderRadius: BorderRadius.circular(8),
+          onTap: onTap,
+          child: Container(
+            width: double.infinity,
+            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 14),
+            child: Text(
+              title,
+              style: TextStyle(
+                color: selected ? scheme.onSurface : scheme.onSurfaceVariant,
+                fontWeight: selected ? FontWeight.w600 : FontWeight.w400,
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+// --- panels ------------------------------------------------------------------------------
+
+/// The muted banner at the top of a panel, like Snowball's «Это ваша конфиденциальная …».
+Widget _note(BuildContext context, IconData icon, String text) {
+  final scheme = Theme.of(context).colorScheme;
+  return Container(
+    width: double.infinity,
+    padding: const EdgeInsets.all(20),
+    decoration: BoxDecoration(
+      color: scheme.surfaceContainerHigh,
+      borderRadius: BorderRadius.circular(8),
+    ),
+    child: Row(
+      children: [
+        Icon(icon, size: 18, color: scheme.onSurfaceVariant),
+        const SizedBox(width: 12),
+        Expanded(child: Text(text)),
+      ],
+    ),
+  );
+}
+
+Widget _field(
+  BuildContext context,
+  String label,
+  String value, {
+  Widget? trailing,
+}) {
+  return Column(
+    crossAxisAlignment: CrossAxisAlignment.start,
+    children: [
+      Text(label, style: Theme.of(context).textTheme.bodyMedium),
+      const SizedBox(height: 8),
+      Row(
+        children: [
+          Expanded(
+            child: TextFormField(
+              key: ValueKey('$label:$value'),
+              initialValue: value,
+              readOnly: true,
+            ),
+          ),
+          if (trailing != null) ...[const SizedBox(width: 12), trailing],
+        ],
+      ),
+    ],
+  );
+}
+
+Widget _privateData(BuildContext context, WidgetRef ref) {
+  final me = ref.watch(meProvider);
+  return Column(
+    crossAxisAlignment: CrossAxisAlignment.start,
+    children: [
+      _note(
+        context,
+        Icons.lock_outline,
+        'Это ваша конфиденциальная информация, она недоступна другим',
+      ),
+      const SizedBox(height: 20),
+      AsyncValueView(
+        value: me,
+        onRetry: () => ref.invalidate(meProvider),
+        data: (u) => _field(context, 'Email', u.email),
+      ),
+    ],
+  );
+}
+
+Widget _security(BuildContext context, WidgetRef ref) {
+  final scheme = Theme.of(context).colorScheme;
+  return Column(
+    crossAxisAlignment: CrossAxisAlignment.start,
+    children: [
+      _note(
+        context,
+        Icons.shield_outlined,
+        'Выход завершает сессию на этом устройстве и удаляет с него сохранённый токен и кэш данных',
+      ),
+      const SizedBox(height: 20),
+      FilledButton.icon(
+        style: FilledButton.styleFrom(
+          backgroundColor: scheme.error,
+          foregroundColor: scheme.onError,
+        ),
+        onPressed: () => ref.read(authControllerProvider.notifier).logout(),
+        icon: const Icon(Icons.logout),
+        label: const Text('Выйти'),
+      ),
+    ],
+  );
+}
+
+Widget _theme(BuildContext context, WidgetRef ref) {
+  final themeMode = ref.watch(themeModeProvider);
+  return Column(
+    crossAxisAlignment: CrossAxisAlignment.start,
+    children: [
+      Text('Тема оформления', style: Theme.of(context).textTheme.bodyMedium),
+      const SizedBox(height: 12),
+      SegmentedButton<ThemeMode>(
+        segments: const [
+          ButtonSegment(
+            value: ThemeMode.system,
+            label: Text('Системная'),
+            icon: Icon(Icons.brightness_auto_outlined),
+          ),
+          ButtonSegment(
+            value: ThemeMode.light,
+            label: Text('Светлая'),
+            icon: Icon(Icons.light_mode_outlined),
+          ),
+          ButtonSegment(
+            value: ThemeMode.dark,
+            label: Text('Тёмная'),
+            icon: Icon(Icons.dark_mode_outlined),
+          ),
+        ],
+        selected: {themeMode},
+        onSelectionChanged: (selection) =>
+            ref.read(themeModeProvider.notifier).setMode(selection.first),
+      ),
+    ],
+  );
+}
+
+Widget _apiAddress(BuildContext context, WidgetRef ref) {
+  return _field(
+    context,
+    'Адрес API',
+    ref.watch(apiBaseUrlProvider),
+    trailing: FilledButton.tonalIcon(
+      onPressed: () => showApiBaseUrlDialog(context),
+      icon: const Icon(Icons.edit_outlined),
+      label: const Text('Изменить'),
+    ),
+  );
+}
+
+Widget _about(BuildContext context, WidgetRef ref) =>
+    _field(context, 'Версия приложения', appVersion);

app/lib/main.dart

@@ -2,8 +2,17 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import 'app.dart';
+import 'core/config.dart';
 
-void main() {
+Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
-  runApp(const ProviderScope(child: FinTrackerApp()));
+  final storedApiBaseUrl = await loadStoredApiBaseUrl();
+  runApp(
+    ProviderScope(
+      overrides: [
+        initialApiBaseUrlProvider.overrideWithValue(storedApiBaseUrl),
+      ],
+      child: const FinTrackerApp(),
+    ),
+  );
 }

app/test/cache_interceptor_test.dart

@@ -23,11 +23,16 @@ class _ErrorCapture extends ErrorInterceptorHandler {
   void next(DioException error) => forwarded = error;
 }
 
-RequestOptions _request(String method, String path, [Map<String, dynamic> query = const {}]) =>
-    RequestOptions(path: path, method: method, queryParameters: query);
+RequestOptions _request(
+  String method,
+  String path, [
+  Map<String, dynamic> query = const {},
+]) => RequestOptions(path: path, method: method, queryParameters: query);
 
-DioException _offline(RequestOptions options) =>
-    DioException(requestOptions: options, type: DioExceptionType.connectionError);
+DioException _offline(RequestOptions options) => DioException(
+  requestOptions: options,
+  type: DioExceptionType.connectionError,
+);
 
 void main() {
   late ResponseCacheDatabase db;
@@ -44,7 +49,11 @@ void main() {
     final options = _request('GET', '/networth/breakdown');
 
     interceptor.onResponse(
-      Response<dynamic>(requestOptions: options, statusCode: 200, data: {'totalRub': '100'}),
+      Response<dynamic>(
+        requestOptions: options,
+        statusCode: 200,
+        data: {'totalRub': '100'},
+      ),
       _ResponseCapture(),
     );
     await pumpEventQueue(); // the write is fire-and-forget
@@ -53,17 +62,20 @@ void main() {
     expect(cached?.body, {'totalRub': '100'});
   });
 
-  test('a connection error is answered from the cache, with fetchedAt set', () async {
-    final options = _request('GET', '/networth/breakdown');
-    await db.put(CacheInterceptor.requestKey(options), {'totalRub': '100'});
+  test(
+    'a connection error is answered from the cache, with fetchedAt set',
+    () async {
+      final options = _request('GET', '/networth/breakdown');
+      await db.put(CacheInterceptor.requestKey(options), {'totalRub': '100'});
 
-    final handler = _ErrorCapture();
-    await interceptor.onError(_offline(options), handler);
+      final handler = _ErrorCapture();
+      await interceptor.onError(_offline(options), handler);
 
-    expect(handler.resolvedResponse?.data, {'totalRub': '100'});
-    expect(handler.resolvedResponse?.extra['fetchedAt'], isA<DateTime>());
-    expect(handler.forwarded, isNull);
-  });
+      expect(handler.resolvedResponse?.data, {'totalRub': '100'});
+      expect(handler.resolvedResponse?.extra['fetchedAt'], isA<DateTime>());
+      expect(handler.forwarded, isNull);
+    },
+  );
 
   test('a connection error with nothing cached still fails', () async {
     final options = _request('GET', '/networth/breakdown', {'never': 'asked'});

app/test/session_wipe_test.dart

@@ -0,0 +1,120 @@
+import 'package:drift/native.dart';
+import 'package:fintracker_app/core/auth/auth_controller.dart';
+import 'package:fintracker_app/core/auth/switch_server.dart';
+import 'package:fintracker_app/core/auth/token_store.dart';
+import 'package:fintracker_app/core/cache/response_cache.dart';
+import 'package:fintracker_app/core/cache/response_cache_provider.dart';
+import 'package:fintracker_app/core/config.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+/// No stored refresh token, so `logout()` never touches the network.
+class _NoTokenStore extends TokenStore {
+  bool cleared = false;
+
+  @override
+  Future<String?> readRefresh() async => null;
+
+  @override
+  Future<void> clear() async => cleared = true;
+}
+
+void main() {
+  late ResponseCacheDatabase db;
+  late _NoTokenStore tokens;
+
+  ProviderContainer container({String? storedUrl}) {
+    final c = ProviderContainer(
+      overrides: [
+        responseCacheDbProvider.overrideWithValue(db),
+        tokenStoreProvider.overrideWithValue(tokens),
+        initialApiBaseUrlProvider.overrideWithValue(storedUrl),
+      ],
+    );
+    addTearDown(c.dispose);
+    return c;
+  }
+
+  setUp(() async {
+    SharedPreferences.setMockInitialValues({});
+    db = ResponseCacheDatabase.forTesting(NativeDatabase.memory());
+    tokens = _NoTokenStore();
+    await db.put('/networth/breakdown', {'totalRub': '100'});
+  });
+
+  tearDown(() => db.close());
+
+  test('logout drops the token and every cached response', () async {
+    final c = container();
+
+    await c.read(authControllerProvider.notifier).logout();
+
+    expect(tokens.cleared, isTrue);
+    expect(await db.get('/networth/breakdown'), isNull);
+    expect(c.read(authControllerProvider).status, AuthStatus.signedOut);
+  });
+
+  group('API base URL', () {
+    test('a saved address wins over the default', () {
+      expect(
+        container(storedUrl: 'https://fin.example.com')
+            .read(apiBaseUrlProvider),
+        'https://fin.example.com',
+      );
+      expect(container().read(apiBaseUrlProvider), defaultApiBaseUrl());
+    });
+
+    test('normalize accepts http(s) origins and trims the trailing slash', () {
+      expect(
+        ApiBaseUrlController.normalize(' https://fin.example.com/ '),
+        'https://fin.example.com',
+      );
+      expect(
+        ApiBaseUrlController.normalize('http://10.0.0.5:8000'),
+        'http://10.0.0.5:8000',
+      );
+      expect(ApiBaseUrlController.normalize('fin.example.com'), isNull);
+      expect(ApiBaseUrlController.normalize('ftp://fin.example.com'), isNull);
+      expect(ApiBaseUrlController.normalize(''), isNull);
+    });
+
+    test(
+      'switching servers signs out, clears the cache and persists the address',
+      () async {
+        final c = container();
+
+        await switchApiBaseUrl(c, 'https://other.example.com');
+
+        expect(c.read(apiBaseUrlProvider), 'https://other.example.com');
+        expect(await loadStoredApiBaseUrl(), 'https://other.example.com');
+        expect(tokens.cleared, isTrue);
+        expect(await db.get('/networth/breakdown'), isNull);
+      },
+    );
+
+    test(
+      'saving the address already in use keeps the session and the cache',
+      () async {
+        final c = container(storedUrl: 'https://fin.example.com');
+
+        await switchApiBaseUrl(c, 'https://fin.example.com');
+
+        expect(tokens.cleared, isFalse);
+        expect(await db.get('/networth/breakdown'), isNotNull);
+      },
+    );
+
+    test(
+      'null goes back to the default and forgets the saved address',
+      () async {
+        final c = container(storedUrl: 'https://fin.example.com');
+
+        await switchApiBaseUrl(c, null);
+
+        expect(c.read(apiBaseUrlProvider), defaultApiBaseUrl());
+        expect(await loadStoredApiBaseUrl(), isNull);
+      },
+    );
+  });
+}

app/test/settings_page_test.dart

@@ -0,0 +1,75 @@
+import 'package:fintracker_api/fintracker_api.dart';
+import 'package:fintracker_app/core/api/common_providers.dart';
+import 'package:fintracker_app/features/settings/settings_page.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+Future<void> _pump(WidgetTester tester, double width) async {
+  SharedPreferences.setMockInitialValues({});
+  tester.view.physicalSize = Size(width, 900);
+  tester.view.devicePixelRatio = 1;
+  addTearDown(tester.view.reset);
+  await tester.pumpWidget(
+    ProviderScope(
+      overrides: [
+        meProvider.overrideWith(
+          (ref) async => UserOut(email: 'ada@example.com', id: 1),
+        ),
+      ],
+      child: const MaterialApp(home: Scaffold(body: SettingsPage())),
+    ),
+  );
+  await tester.pumpAndSettle();
+}
+
+void main() {
+  testWidgets('tabs along the top, the tab\'s sections in a menu on the left', (
+    tester,
+  ) async {
+    await _pump(tester, 1200);
+
+    for (final tab in ['Аккаунт', 'Отображение', 'Сервер']) {
+      expect(find.text(tab), findsOneWidget, reason: tab);
+    }
+    // the first tab opens on its first section
+    expect(find.text('Приватные данные'), findsOneWidget);
+    expect(find.text('Безопасность'), findsOneWidget);
+    expect(find.text('ada@example.com'), findsOneWidget);
+
+    await tester.tap(find.text('Безопасность'));
+    await tester.pumpAndSettle();
+    expect(find.text('Выйти'), findsOneWidget);
+    expect(find.text('ada@example.com'), findsNothing);
+  });
+
+  testWidgets('switching the tab resets to its first section', (tester) async {
+    await _pump(tester, 1200);
+
+    await tester.tap(find.text('Безопасность'));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('Сервер'));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Адрес API'), findsWidgets);
+    expect(find.text('О приложении'), findsOneWidget);
+    expect(find.text('Изменить'), findsOneWidget);
+
+    await tester.tap(find.text('Отображение'));
+    await tester.pumpAndSettle();
+    expect(find.text('Тёмная'), findsOneWidget);
+  });
+
+  testWidgets('a narrow surface turns the menu into chips above the panel', (
+    tester,
+  ) async {
+    await _pump(tester, 500);
+
+    expect(find.byType(ChoiceChip), findsNWidgets(2));
+    expect(find.text('ada@example.com'), findsOneWidget);
+    await tester.tap(find.widgetWithText(ChoiceChip, 'Безопасность'));
+    await tester.pumpAndSettle();
+    expect(find.text('Выйти'), findsOneWidget);
+  });
+}