feat(app): offline-кэш GET-запросов на дашборде — фаза 5

CacheInterceptor кэширует каждый успешный GET по путь+параметры в drift
(sqlite нативно, wasm+OPFS в браузере) и подменяет им сетевую ошибку;
провайдер отдаёт Cached<T>, экран показывает баннер «данные на …».
Контракт для остальных экранов — docs/ai/offline-cache.md.

flake.nix: libsecret/pkg-config для линуксовой сборки, jq/curl для
just app-web-assets (сборка sqlite3.wasm + drift_worker.js).

AGENTS.md

@@ -36,6 +36,7 @@ just revision "msg"         # новая alembic-миграция из изме
 | Модель данных / миграции (`models/`, `alembic/`) | architecture.md §Домен, [conventions.md](docs/ai/conventions.md) |
 | Аналитика / метрики | architecture.md §Аналитика, [conventions.md](docs/ai/conventions.md) §Деньги |
 | API / Flutter-клиент | architecture.md §API, `openapi/openapi.json` |
+| Offline-кэш экрана (фаза 5) | [offline-cache.md](docs/ai/offline-cache.md) — контракт `Cached<T>` + `CacheInterceptor` |
 | Деплой | `docker-compose.yml`, `deploy/Caddyfile`, [ops.md](docs/ai/ops.md) |
 
 ## Обязательные ограничения

app/lib/core/api/api_client.dart

@@ -3,9 +3,22 @@ import 'package:fintracker_api/fintracker_api.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../auth/auth_controller.dart';
+import '../cache/cache_interceptor.dart';
+import '../cache/response_cache.dart';
 import '../config.dart';
 
-/// Authenticated client: bearer header on every call, one transparent refresh on 401.
+/// 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(),
@@ -14,6 +27,7 @@ final apiProvider = Provider<FintrackerApi>((ref) {
   ));
   dio.interceptors.add(DateQueryInterceptor());
   dio.interceptors.add(_AuthInterceptor(ref));
+  dio.interceptors.add(CacheInterceptor(ref.watch(responseCacheDbProvider)));
   return FintrackerApi(dio: dio, interceptors: const []);
 });
 

app/lib/core/cache/cache_interceptor.dart

@@ -0,0 +1,63 @@
+import 'dart:async';
+
+import 'package:dio/dio.dart';
+
+import 'response_cache.dart';
+
+/// Persists every successful GET body by endpoint+params, and serves the last
+/// one back when the network itself is unreachable — see
+/// `docs/ai/offline-cache.md` for the whole contract.
+///
+/// Mutations (anything but GET) are never cached and never served stale: a
+/// failed POST/PATCH/DELETE must surface as an error, not as an invented
+/// success. A response resolved from the cache carries `extra['fetchedAt']`
+/// (a [DateTime]); a live response carries no such key. That is the one flag
+/// a screen needs to decide whether to show a [StaleBanner].
+class CacheInterceptor extends Interceptor {
+  CacheInterceptor(this._db);
+
+  final ResponseCacheDatabase _db;
+
+  /// Failure shapes that mean "no network", as opposed to a real server error
+  /// (4xx/5xx) or a bug in this client — those must keep failing loudly.
+  static const _offlineTypes = {
+    DioExceptionType.connectionError,
+    DioExceptionType.connectionTimeout,
+    DioExceptionType.receiveTimeout,
+    DioExceptionType.sendTimeout,
+  };
+
+  @override
+  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));
+    }
+    handler.next(response);
+  }
+
+  @override
+  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));
+    if (cached == null) return handler.next(err);
+    handler.resolve(
+      Response<dynamic>(
+        requestOptions: err.requestOptions,
+        data: cached.body,
+        statusCode: 200,
+        extra: {'fetchedAt': cached.fetchedAt},
+      ),
+    );
+  }
+
+  /// `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 query = params.map((e) => '${e.key}=${e.value}').join('&');
+    return '${options.path}?$query';
+  }
+}

app/lib/core/cache/cached.dart

@@ -0,0 +1,31 @@
+import 'package:dio/dio.dart';
+
+/// A value from the API, or the last one [CacheInterceptor] had on file for the
+/// same endpoint+params when the live request failed. `fetchedAt` is null for
+/// a live answer — that is the one bit a screen needs to decide whether to
+/// show a `StaleBanner`. See `docs/ai/offline-cache.md`.
+class Cached<T> {
+  const Cached(this.data, {this.fetchedAt});
+
+  final T data;
+  final DateTime? fetchedAt;
+}
+
+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?);
+}
+
+/// The oldest of several fetch times, or null if none of them is stale.
+/// Screens with several cached providers show one banner for the lot rather
+/// than one per tile.
+DateTime? oldestFetch(Iterable<DateTime?> fetchedAt) {
+  DateTime? oldest;
+  for (final at in fetchedAt) {
+    if (at == null) continue;
+    if (oldest == null || at.isBefore(oldest)) oldest = at;
+  }
+  return oldest;
+}

app/lib/core/cache/response_cache.dart

@@ -0,0 +1,71 @@
+import 'dart:convert';
+
+import 'package:drift/drift.dart';
+import 'package:drift_flutter/drift_flutter.dart';
+
+part 'response_cache.g.dart';
+
+/// The last successful body of one GET, keyed by endpoint+params exactly as
+/// [CacheInterceptor] builds the key. See `docs/ai/offline-cache.md` for the
+/// whole contract this table is part of.
+class CachedResponses extends Table {
+  TextColumn get requestKey => text()();
+  TextColumn get body => text()();
+  DateTimeColumn get fetchedAt => dateTime()();
+
+  @override
+  Set<Column> get primaryKey => {requestKey};
+}
+
+/// A cached body plus when it was fetched — what [CacheInterceptor] needs to
+/// rebuild a synthetic [Response] when the network itself is unreachable.
+///
+/// Not named `CachedResponse`: drift already generates a row class with that
+/// name for the `CachedResponses` table above.
+class CacheEntry {
+  const CacheEntry(this.body, this.fetchedAt);
+  final Object? body;
+  final DateTime fetchedAt;
+}
+
+@DriftDatabase(tables: [CachedResponses])
+class ResponseCacheDatabase extends _$ResponseCacheDatabase {
+  ResponseCacheDatabase() : super(_openConnection());
+  ResponseCacheDatabase.forTesting(super.executor);
+
+  @override
+  int get schemaVersion => 1;
+
+  /// Replaces whatever was cached for [requestKey] — one row per endpoint+params,
+  /// never a history.
+  Future<void> put(String requestKey, Object? body) => into(cachedResponses).insertOnConflictUpdate(
+        CachedResponsesCompanion.insert(
+          requestKey: requestKey,
+          body: jsonEncode(body),
+          fetchedAt: DateTime.now(),
+        ),
+      );
+
+  /// 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 {
+    final row = await (select(
+      cachedResponses,
+    )..where((t) => t.requestKey.equals(requestKey))).getSingleOrNull();
+    if (row == null) return null;
+    return CacheEntry(jsonDecode(row.body), row.fetchedAt);
+  }
+}
+
+/// One sqlite file via native FFI on Android/iOS/desktop; wasm+OPFS (falling
+/// back to IndexedDB) on web — `driftDatabase` from `package:drift_flutter`
+/// picks the right backend, `web/sqlite3.wasm` and `web/drift_worker.js` are
+/// 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'),
+      ),
+    );

app/lib/core/cache/response_cache.g.dart

@@ -0,0 +1,478 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'response_cache.dart';
+
+// ignore_for_file: type=lint
+class $CachedResponsesTable extends CachedResponses
+    with TableInfo<$CachedResponsesTable, CachedResponse> {
+  @override
+  final GeneratedDatabase attachedDatabase;
+  final String? _alias;
+  $CachedResponsesTable(this.attachedDatabase, [this._alias]);
+  static const VerificationMeta _requestKeyMeta = const VerificationMeta(
+    'requestKey',
+  );
+  @override
+  late final GeneratedColumn<String> requestKey = GeneratedColumn<String>(
+    'request_key',
+    aliasedName,
+    false,
+    type: DriftSqlType.string,
+    requiredDuringInsert: true,
+  );
+  static const VerificationMeta _bodyMeta = const VerificationMeta('body');
+  @override
+  late final GeneratedColumn<String> body = GeneratedColumn<String>(
+    'body',
+    aliasedName,
+    false,
+    type: DriftSqlType.string,
+    requiredDuringInsert: true,
+  );
+  static const VerificationMeta _fetchedAtMeta = const VerificationMeta(
+    'fetchedAt',
+  );
+  @override
+  late final GeneratedColumn<DateTime> fetchedAt = GeneratedColumn<DateTime>(
+    'fetched_at',
+    aliasedName,
+    false,
+    type: DriftSqlType.dateTime,
+    requiredDuringInsert: true,
+  );
+  @override
+  List<GeneratedColumn> get $columns => [requestKey, body, fetchedAt];
+  @override
+  String get aliasedName => _alias ?? actualTableName;
+  @override
+  String get actualTableName => $name;
+  static const String $name = 'cached_responses';
+  @override
+  VerificationContext validateIntegrity(
+    Insertable<CachedResponse> instance, {
+    bool isInserting = false,
+  }) {
+    final context = VerificationContext();
+    final data = instance.toColumns(true);
+    if (data.containsKey('request_key')) {
+      context.handle(
+        _requestKeyMeta,
+        requestKey.isAcceptableOrUnknown(data['request_key']!, _requestKeyMeta),
+      );
+    } else if (isInserting) {
+      context.missing(_requestKeyMeta);
+    }
+    if (data.containsKey('body')) {
+      context.handle(
+        _bodyMeta,
+        body.isAcceptableOrUnknown(data['body']!, _bodyMeta),
+      );
+    } else if (isInserting) {
+      context.missing(_bodyMeta);
+    }
+    if (data.containsKey('fetched_at')) {
+      context.handle(
+        _fetchedAtMeta,
+        fetchedAt.isAcceptableOrUnknown(data['fetched_at']!, _fetchedAtMeta),
+      );
+    } else if (isInserting) {
+      context.missing(_fetchedAtMeta);
+    }
+    return context;
+  }
+
+  @override
+  Set<GeneratedColumn> get $primaryKey => {requestKey};
+  @override
+  CachedResponse map(Map<String, dynamic> data, {String? tablePrefix}) {
+    final effectivePrefix = tablePrefix != null ? '$tablePrefix.' : '';
+    return CachedResponse(
+      requestKey: attachedDatabase.typeMapping.read(
+        DriftSqlType.string,
+        data['${effectivePrefix}request_key'],
+      )!,
+      body: attachedDatabase.typeMapping.read(
+        DriftSqlType.string,
+        data['${effectivePrefix}body'],
+      )!,
+      fetchedAt: attachedDatabase.typeMapping.read(
+        DriftSqlType.dateTime,
+        data['${effectivePrefix}fetched_at'],
+      )!,
+    );
+  }
+
+  @override
+  $CachedResponsesTable createAlias(String alias) {
+    return $CachedResponsesTable(attachedDatabase, alias);
+  }
+}
+
+class CachedResponse extends DataClass implements Insertable<CachedResponse> {
+  final String requestKey;
+  final String body;
+  final DateTime fetchedAt;
+  const CachedResponse({
+    required this.requestKey,
+    required this.body,
+    required this.fetchedAt,
+  });
+  @override
+  Map<String, Expression> toColumns(bool nullToAbsent) {
+    final map = <String, Expression>{};
+    map['request_key'] = Variable<String>(requestKey);
+    map['body'] = Variable<String>(body);
+    map['fetched_at'] = Variable<DateTime>(fetchedAt);
+    return map;
+  }
+
+  CachedResponsesCompanion toCompanion(bool nullToAbsent) {
+    return CachedResponsesCompanion(
+      requestKey: Value(requestKey),
+      body: Value(body),
+      fetchedAt: Value(fetchedAt),
+    );
+  }
+
+  factory CachedResponse.fromJson(
+    Map<String, dynamic> json, {
+    ValueSerializer? serializer,
+  }) {
+    serializer ??= driftRuntimeOptions.defaultSerializer;
+    return CachedResponse(
+      requestKey: serializer.fromJson<String>(json['requestKey']),
+      body: serializer.fromJson<String>(json['body']),
+      fetchedAt: serializer.fromJson<DateTime>(json['fetchedAt']),
+    );
+  }
+  @override
+  Map<String, dynamic> toJson({ValueSerializer? serializer}) {
+    serializer ??= driftRuntimeOptions.defaultSerializer;
+    return <String, dynamic>{
+      'requestKey': serializer.toJson<String>(requestKey),
+      'body': serializer.toJson<String>(body),
+      'fetchedAt': serializer.toJson<DateTime>(fetchedAt),
+    };
+  }
+
+  CachedResponse copyWith({
+    String? requestKey,
+    String? body,
+    DateTime? fetchedAt,
+  }) => CachedResponse(
+    requestKey: requestKey ?? this.requestKey,
+    body: body ?? this.body,
+    fetchedAt: fetchedAt ?? this.fetchedAt,
+  );
+  CachedResponse copyWithCompanion(CachedResponsesCompanion data) {
+    return CachedResponse(
+      requestKey: data.requestKey.present
+          ? data.requestKey.value
+          : this.requestKey,
+      body: data.body.present ? data.body.value : this.body,
+      fetchedAt: data.fetchedAt.present ? data.fetchedAt.value : this.fetchedAt,
+    );
+  }
+
+  @override
+  String toString() {
+    return (StringBuffer('CachedResponse(')
+          ..write('requestKey: $requestKey, ')
+          ..write('body: $body, ')
+          ..write('fetchedAt: $fetchedAt')
+          ..write(')'))
+        .toString();
+  }
+
+  @override
+  int get hashCode => Object.hash(requestKey, body, fetchedAt);
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      (other is CachedResponse &&
+          other.requestKey == this.requestKey &&
+          other.body == this.body &&
+          other.fetchedAt == this.fetchedAt);
+}
+
+class CachedResponsesCompanion extends UpdateCompanion<CachedResponse> {
+  final Value<String> requestKey;
+  final Value<String> body;
+  final Value<DateTime> fetchedAt;
+  final Value<int> rowid;
+  const CachedResponsesCompanion({
+    this.requestKey = const Value.absent(),
+    this.body = const Value.absent(),
+    this.fetchedAt = const Value.absent(),
+    this.rowid = const Value.absent(),
+  });
+  CachedResponsesCompanion.insert({
+    required String requestKey,
+    required String body,
+    required DateTime fetchedAt,
+    this.rowid = const Value.absent(),
+  }) : requestKey = Value(requestKey),
+       body = Value(body),
+       fetchedAt = Value(fetchedAt);
+  static Insertable<CachedResponse> custom({
+    Expression<String>? requestKey,
+    Expression<String>? body,
+    Expression<DateTime>? fetchedAt,
+    Expression<int>? rowid,
+  }) {
+    return RawValuesInsertable({
+      if (requestKey != null) 'request_key': requestKey,
+      if (body != null) 'body': body,
+      if (fetchedAt != null) 'fetched_at': fetchedAt,
+      if (rowid != null) 'rowid': rowid,
+    });
+  }
+
+  CachedResponsesCompanion copyWith({
+    Value<String>? requestKey,
+    Value<String>? body,
+    Value<DateTime>? fetchedAt,
+    Value<int>? rowid,
+  }) {
+    return CachedResponsesCompanion(
+      requestKey: requestKey ?? this.requestKey,
+      body: body ?? this.body,
+      fetchedAt: fetchedAt ?? this.fetchedAt,
+      rowid: rowid ?? this.rowid,
+    );
+  }
+
+  @override
+  Map<String, Expression> toColumns(bool nullToAbsent) {
+    final map = <String, Expression>{};
+    if (requestKey.present) {
+      map['request_key'] = Variable<String>(requestKey.value);
+    }
+    if (body.present) {
+      map['body'] = Variable<String>(body.value);
+    }
+    if (fetchedAt.present) {
+      map['fetched_at'] = Variable<DateTime>(fetchedAt.value);
+    }
+    if (rowid.present) {
+      map['rowid'] = Variable<int>(rowid.value);
+    }
+    return map;
+  }
+
+  @override
+  String toString() {
+    return (StringBuffer('CachedResponsesCompanion(')
+          ..write('requestKey: $requestKey, ')
+          ..write('body: $body, ')
+          ..write('fetchedAt: $fetchedAt, ')
+          ..write('rowid: $rowid')
+          ..write(')'))
+        .toString();
+  }
+}
+
+abstract class _$ResponseCacheDatabase extends GeneratedDatabase {
+  _$ResponseCacheDatabase(QueryExecutor e) : super(e);
+  $ResponseCacheDatabaseManager get managers =>
+      $ResponseCacheDatabaseManager(this);
+  late final $CachedResponsesTable cachedResponses = $CachedResponsesTable(
+    this,
+  );
+  @override
+  Iterable<TableInfo<Table, Object?>> get allTables =>
+      allSchemaEntities.whereType<TableInfo<Table, Object?>>();
+  @override
+  List<DatabaseSchemaEntity> get allSchemaEntities => [cachedResponses];
+}
+
+typedef $$CachedResponsesTableCreateCompanionBuilder =
+    CachedResponsesCompanion Function({
+      required String requestKey,
+      required String body,
+      required DateTime fetchedAt,
+      Value<int> rowid,
+    });
+typedef $$CachedResponsesTableUpdateCompanionBuilder =
+    CachedResponsesCompanion Function({
+      Value<String> requestKey,
+      Value<String> body,
+      Value<DateTime> fetchedAt,
+      Value<int> rowid,
+    });
+
+class $$CachedResponsesTableFilterComposer
+    extends Composer<_$ResponseCacheDatabase, $CachedResponsesTable> {
+  $$CachedResponsesTableFilterComposer({
+    required super.$db,
+    required super.$table,
+    super.joinBuilder,
+    super.$addJoinBuilderToRootComposer,
+    super.$removeJoinBuilderFromRootComposer,
+  });
+  ColumnFilters<String> get requestKey => $composableBuilder(
+    column: $table.requestKey,
+    builder: (column) => ColumnFilters(column),
+  );
+
+  ColumnFilters<String> get body => $composableBuilder(
+    column: $table.body,
+    builder: (column) => ColumnFilters(column),
+  );
+
+  ColumnFilters<DateTime> get fetchedAt => $composableBuilder(
+    column: $table.fetchedAt,
+    builder: (column) => ColumnFilters(column),
+  );
+}
+
+class $$CachedResponsesTableOrderingComposer
+    extends Composer<_$ResponseCacheDatabase, $CachedResponsesTable> {
+  $$CachedResponsesTableOrderingComposer({
+    required super.$db,
+    required super.$table,
+    super.joinBuilder,
+    super.$addJoinBuilderToRootComposer,
+    super.$removeJoinBuilderFromRootComposer,
+  });
+  ColumnOrderings<String> get requestKey => $composableBuilder(
+    column: $table.requestKey,
+    builder: (column) => ColumnOrderings(column),
+  );
+
+  ColumnOrderings<String> get body => $composableBuilder(
+    column: $table.body,
+    builder: (column) => ColumnOrderings(column),
+  );
+
+  ColumnOrderings<DateTime> get fetchedAt => $composableBuilder(
+    column: $table.fetchedAt,
+    builder: (column) => ColumnOrderings(column),
+  );
+}
+
+class $$CachedResponsesTableAnnotationComposer
+    extends Composer<_$ResponseCacheDatabase, $CachedResponsesTable> {
+  $$CachedResponsesTableAnnotationComposer({
+    required super.$db,
+    required super.$table,
+    super.joinBuilder,
+    super.$addJoinBuilderToRootComposer,
+    super.$removeJoinBuilderFromRootComposer,
+  });
+  GeneratedColumn<String> get requestKey => $composableBuilder(
+    column: $table.requestKey,
+    builder: (column) => column,
+  );
+
+  GeneratedColumn<String> get body =>
+      $composableBuilder(column: $table.body, builder: (column) => column);
+
+  GeneratedColumn<DateTime> get fetchedAt =>
+      $composableBuilder(column: $table.fetchedAt, builder: (column) => column);
+}
+
+class $$CachedResponsesTableTableManager
+    extends
+        RootTableManager<
+          _$ResponseCacheDatabase,
+          $CachedResponsesTable,
+          CachedResponse,
+          $$CachedResponsesTableFilterComposer,
+          $$CachedResponsesTableOrderingComposer,
+          $$CachedResponsesTableAnnotationComposer,
+          $$CachedResponsesTableCreateCompanionBuilder,
+          $$CachedResponsesTableUpdateCompanionBuilder,
+          (
+            CachedResponse,
+            BaseReferences<
+              _$ResponseCacheDatabase,
+              $CachedResponsesTable,
+              CachedResponse
+            >,
+          ),
+          CachedResponse,
+          PrefetchHooks Function()
+        > {
+  $$CachedResponsesTableTableManager(
+    _$ResponseCacheDatabase db,
+    $CachedResponsesTable table,
+  ) : super(
+        TableManagerState(
+          db: db,
+          table: table,
+          createFilteringComposer: () =>
+              $$CachedResponsesTableFilterComposer($db: db, $table: table),
+          createOrderingComposer: () =>
+              $$CachedResponsesTableOrderingComposer($db: db, $table: table),
+          createComputedFieldComposer: () =>
+              $$CachedResponsesTableAnnotationComposer($db: db, $table: table),
+          updateCompanionCallback:
+              ({
+                Value<String> requestKey = const Value.absent(),
+                Value<String> body = const Value.absent(),
+                Value<DateTime> fetchedAt = const Value.absent(),
+                Value<int> rowid = const Value.absent(),
+              }) => CachedResponsesCompanion(
+                requestKey: requestKey,
+                body: body,
+                fetchedAt: fetchedAt,
+                rowid: rowid,
+              ),
+          createCompanionCallback:
+              ({
+                required String requestKey,
+                required String body,
+                required DateTime fetchedAt,
+                Value<int> rowid = const Value.absent(),
+              }) => CachedResponsesCompanion.insert(
+                requestKey: requestKey,
+                body: body,
+                fetchedAt: fetchedAt,
+                rowid: rowid,
+              ),
+          withReferenceMapper: (p0) => p0
+              .map(
+                (e) => (
+                  e.readTable<$CachedResponsesTable, CachedResponse>(table),
+                  BaseReferences<
+                    _$ResponseCacheDatabase,
+                    $CachedResponsesTable,
+                    CachedResponse
+                  >(db, table, e),
+                ),
+              )
+              .toList(),
+          prefetchHooksCallback: null,
+        ),
+      );
+}
+
+typedef $$CachedResponsesTableProcessedTableManager =
+    ProcessedTableManager<
+      _$ResponseCacheDatabase,
+      $CachedResponsesTable,
+      CachedResponse,
+      $$CachedResponsesTableFilterComposer,
+      $$CachedResponsesTableOrderingComposer,
+      $$CachedResponsesTableAnnotationComposer,
+      $$CachedResponsesTableCreateCompanionBuilder,
+      $$CachedResponsesTableUpdateCompanionBuilder,
+      (
+        CachedResponse,
+        BaseReferences<
+          _$ResponseCacheDatabase,
+          $CachedResponsesTable,
+          CachedResponse
+        >,
+      ),
+      CachedResponse,
+      PrefetchHooks Function()
+    >;
+
+class $ResponseCacheDatabaseManager {
+  final _$ResponseCacheDatabase _db;
+  $ResponseCacheDatabaseManager(this._db);
+  $$CachedResponsesTableTableManager get cachedResponses =>
+      $$CachedResponsesTableTableManager(_db, _db.cachedResponses);
+}

app/lib/core/widgets/stale_banner.dart

@@ -0,0 +1,36 @@
+import 'package:flutter/material.dart';
+
+import '../utils/ru_date.dart';
+
+/// "Нет соединения — данные на …": shown instead of pretending a screen built
+/// from the offline cache is current. Pass the oldest `fetchedAt` among the
+/// providers a screen watches (`core/cache/cached.dart`'s `oldestFetch`).
+class StaleBanner extends StatelessWidget {
+  const StaleBanner({required this.fetchedAt, super.key});
+
+  final DateTime fetchedAt;
+
+  @override
+  Widget build(BuildContext context) {
+    final scheme = Theme.of(context).colorScheme;
+    final at = fetchedAt.toLocal();
+    final time = '${at.hour.toString().padLeft(2, '0')}:${at.minute.toString().padLeft(2, '0')}';
+    return Container(
+      margin: const EdgeInsets.only(bottom: 12),
+      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+      decoration: BoxDecoration(color: scheme.errorContainer, borderRadius: BorderRadius.circular(8)),
+      child: Row(
+        children: [
+          Icon(Icons.cloud_off, size: 18, color: scheme.onErrorContainer),
+          const SizedBox(width: 8),
+          Expanded(
+            child: Text(
+              'Нет соединения — данные на ${ruDate(at)} $time',
+              style: TextStyle(color: scheme.onErrorContainer),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}

app/lib/features/home/home_page.dart

@@ -7,11 +7,13 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../core/auth/auth_controller.dart';
+import '../../core/cache/cached.dart';
 import '../../core/theme/chart_colors.dart';
 import '../../core/utils/ru_date.dart';
 import '../../core/widgets/async_value_view.dart';
 import '../../core/widgets/empty_state.dart';
 import '../../core/widgets/money_text.dart';
+import '../../core/widgets/stale_banner.dart';
 import '../../core/api/api_client.dart';
 import 'providers.dart';
 
@@ -109,6 +111,17 @@ class _HomePageState extends ConsumerState<HomePage> {
     final dataQuality = ref.watch(dataQualityProvider);
     final portfolio = ref.watch(portfolioSummaryHomeProvider);
 
+    final stale = oldestFetch([
+      breakdown.valueOrNull?.fetchedAt,
+      series.valueOrNull?.fetchedAt,
+      thisMonth.valueOrNull?.fetchedAt,
+      last12.valueOrNull?.fetchedAt,
+      runway.valueOrNull?.fetchedAt,
+      status.valueOrNull?.fetchedAt,
+      dataQuality.valueOrNull?.fetchedAt,
+      portfolio.valueOrNull?.fetchedAt,
+    ]);
+
     return Scaffold(
       appBar: AppBar(
         title: const Text('Обзор'),
@@ -128,13 +141,15 @@ class _HomePageState extends ConsumerState<HomePage> {
         child: ListView(
           padding: const EdgeInsets.all(16),
           children: [
+            if (stale != null) StaleBanner(fetchedAt: stale),
             Row(
               children: [
                 Expanded(
                   child: AsyncValueView(
                     value: status,
                     onRetry: () => ref.invalidate(metricsStatusProvider),
-                    data: (log) {
+                    data: (cached) {
+                      final log = cached.data;
                       final at = log?.finishedAt ?? log?.startedAt;
                       final text = at == null
                           ? 'Данные ещё не пересчитывались'
@@ -145,7 +160,9 @@ class _HomePageState extends ConsumerState<HomePage> {
                 ),
                 AsyncValueView(
                   value: dataQuality,
-                  data: (rows) => ActionChip(
+                  data: (cached) {
+                    final rows = cached.data;
+                    return ActionChip(
                       avatar: Icon(
                         rows.isEmpty ? Icons.check_circle_outline : Icons.warning_amber_outlined,
                         size: 18,
@@ -153,7 +170,8 @@ class _HomePageState extends ConsumerState<HomePage> {
                       ),
                       label: Text(rows.isEmpty ? 'ок' : '${rows.length} замечаний'),
                       onPressed: rows.isEmpty ? null : () => _showDataQuality(rows),
-                  ),
+                    );
+                  },
                 ),
               ],
             ),
@@ -161,7 +179,7 @@ class _HomePageState extends ConsumerState<HomePage> {
             AsyncValueView(
               value: breakdown,
               onRetry: () => ref.invalidate(netWorthBreakdownProvider),
-              data: (b) => _NetWorthTiles(breakdown: b),
+              data: (cached) => _NetWorthTiles(breakdown: cached.data),
             ),
             const SizedBox(height: 12),
             Row(
@@ -170,7 +188,7 @@ class _HomePageState extends ConsumerState<HomePage> {
                   child: AsyncValueView(
                     value: thisMonth,
                     onRetry: () => ref.invalidate(cashflowThisMonthProvider),
-                    data: (m) => _MonthTiles(month: m),
+                    data: (cached) => _MonthTiles(month: cached.data),
                   ),
                 ),
               ],
@@ -179,13 +197,14 @@ class _HomePageState extends ConsumerState<HomePage> {
             AsyncValueView(
               value: portfolio,
               onRetry: () => ref.invalidate(portfolioSummaryHomeProvider),
-              data: (s) => s == null ? const SizedBox.shrink() : _PortfolioTiles(summary: s),
+              data: (cached) =>
+                  cached.data == null ? const SizedBox.shrink() : _PortfolioTiles(summary: cached.data!),
             ),
             const SizedBox(height: 12),
             AsyncValueView(
               value: runway,
               onRetry: () => ref.invalidate(runwayProvider),
-              data: (r) => _RunwayTile(runway: r),
+              data: (cached) => _RunwayTile(runway: cached.data),
             ),
             const SizedBox(height: 24),
             LayoutBuilder(
@@ -196,9 +215,9 @@ class _HomePageState extends ConsumerState<HomePage> {
                   child: AsyncValueView(
                     value: series,
                     onRetry: () => ref.invalidate(netWorthSeriesProvider),
-                    data: (rows) => rows.isEmpty
+                    data: (cached) => cached.data.isEmpty
                         ? const EmptyState(icon: Icons.show_chart, message: 'Пока нет данных.')
-                        : _NetWorthChart(rows: rows),
+                        : _NetWorthChart(rows: cached.data),
                   ),
                 );
                 final cashflowChart = _ChartCard(
@@ -206,9 +225,9 @@ class _HomePageState extends ConsumerState<HomePage> {
                   child: AsyncValueView(
                     value: last12,
                     onRetry: () => ref.invalidate(cashflowLast12Provider),
-                    data: (rows) => rows.isEmpty
+                    data: (cached) => cached.data.isEmpty
                         ? const EmptyState(icon: Icons.bar_chart, message: 'Пока нет данных.')
-                        : _IncomeExpenseChart(rows: rows),
+                        : _IncomeExpenseChart(rows: cached.data),
                   ),
                 );
                 if (wide) {

app/lib/features/home/providers.dart

@@ -3,54 +3,58 @@ import 'package:fintracker_api/fintracker_api.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../core/api/api_client.dart';
+import '../../core/cache/cached.dart';
 
-final netWorthBreakdownProvider = FutureProvider.autoDispose<NetWorthBreakdown>((ref) async {
+/// Every provider below returns `Cached<T>`, not `T`: `HomePage` reads
+/// `.data` for the tiles and `.fetchedAt` (via `oldestFetch`) for the one
+/// offline banner at the top. See `docs/ai/offline-cache.md`.
+final netWorthBreakdownProvider = FutureProvider.autoDispose<Cached<NetWorthBreakdown>>((ref) async {
   final r = await ref.watch(apiProvider).getNetworthApi().networthBreakdown();
-  return r.data!;
+  return r.cached;
 });
 
 /// Daily net worth for the last 365 days.
-final netWorthSeriesProvider = FutureProvider.autoDispose<List<NetWorthDay>>((ref) async {
+final netWorthSeriesProvider = FutureProvider.autoDispose<Cached<List<NetWorthDay>>>((ref) async {
   final now = DateTime.now();
   final r = await ref.watch(apiProvider).getNetworthApi().networthSeries(
         from: now.subtract(const Duration(days: 365)),
         to: now,
       );
-  return r.data ?? const [];
+  return Cached(r.data ?? const [], fetchedAt: r.extra['fetchedAt'] as DateTime?);
 });
 
 /// The current (partial) month's cashflow, or null before any data exists.
-final cashflowThisMonthProvider = FutureProvider.autoDispose<CashFlowMonth?>((ref) async {
+final cashflowThisMonthProvider = FutureProvider.autoDispose<Cached<CashFlowMonth?>>((ref) async {
   final r = await ref.watch(apiProvider).getCashflowApi().cashflowMonthly(months: 1);
   final rows = r.data ?? const [];
-  return rows.isEmpty ? null : rows.last;
+  return Cached(rows.isEmpty ? null : rows.last, fetchedAt: r.extra['fetchedAt'] as DateTime?);
 });
 
 /// The last 12 months, for the income-vs-expense bar chart.
-final cashflowLast12Provider = FutureProvider.autoDispose<List<CashFlowMonth>>((ref) async {
+final cashflowLast12Provider = FutureProvider.autoDispose<Cached<List<CashFlowMonth>>>((ref) async {
   final r = await ref.watch(apiProvider).getCashflowApi().cashflowMonthly(months: 12);
-  return r.data ?? const [];
+  return Cached(r.data ?? const [], fetchedAt: r.extra['fetchedAt'] as DateTime?);
 });
 
-final runwayProvider = FutureProvider.autoDispose<RunwayOut>((ref) async {
+final runwayProvider = FutureProvider.autoDispose<Cached<RunwayOut>>((ref) async {
   final r = await ref.watch(apiProvider).getCashflowApi().cashflowRunway();
-  return r.data!;
+  return r.cached;
 });
 
 /// When the metric tables were last rebuilt; null before the first refresh.
-final metricsStatusProvider = FutureProvider.autoDispose<RefreshLogOut?>((ref) async {
+final metricsStatusProvider = FutureProvider.autoDispose<Cached<RefreshLogOut?>>((ref) async {
   try {
     final r = await ref.watch(apiProvider).getMetricsApi().metricsStatus();
-    return r.data;
+    return r.cached;
   } on DioException catch (e) {
-    if (e.response?.statusCode == 404) return null;
+    if (e.response?.statusCode == 404) return const Cached(null);
     rethrow;
   }
 });
 
-final dataQualityProvider = FutureProvider.autoDispose<List<DataQualityRow>>((ref) async {
+final dataQualityProvider = FutureProvider.autoDispose<Cached<List<DataQualityRow>>>((ref) async {
   final r = await ref.watch(apiProvider).getMetricsApi().metricsDataQuality();
-  return r.data ?? const [];
+  return Cached(r.data ?? const [], fetchedAt: r.extra['fetchedAt'] as DateTime?);
 });
 
 /// Every dashboard provider, refreshed together after a manual
@@ -68,12 +72,12 @@ void invalidateHomeProviders(WidgetRef ref) {
 
 /// The investment side of the dashboard: one scope-wide summary, `all` by default.
 /// Null when the ledger is empty, which is the normal state before a broker sync.
-final portfolioSummaryHomeProvider = FutureProvider.autoDispose<SummaryOut?>((ref) async {
+final portfolioSummaryHomeProvider = FutureProvider.autoDispose<Cached<SummaryOut?>>((ref) async {
   try {
     final r = await ref.watch(apiProvider).getAnalyticsApi().analyticsSummary();
-    return r.data;
+    return r.cached;
   } on DioException catch (e) {
-    if (e.response?.statusCode == 404) return null;
+    if (e.response?.statusCode == 404) return const Cached(null);
     rethrow;
   }
 });

app/pubspec.lock

@@ -1,6 +1,22 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
+  _fe_analyzer_shared:
+    dependency: transitive
+    description:
+      name: _fe_analyzer_shared
+      sha256: fdcd9f70f9eb80df3bc5ed0fa67280df2595fd481948df8a9ab082e6a40ad04b
+      url: "https://pub.dev"
+    source: hosted
+    version: "108.0.0"
+  analyzer:
+    dependency: transitive
+    description:
+      name: analyzer
+      sha256: a51c769bff3b6dfbe9d60199b8606d808290702a296bef0c26a4ca391d414e46
+      url: "https://pub.dev"
+    source: hosted
+    version: "14.4.0"
   args:
     dependency: transitive
     description:
@@ -25,6 +41,54 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.2"
+  build:
+    dependency: transitive
+    description:
+      name: build
+      sha256: "8a5c5761af8e31748bba3c82f68925ace40f3225c3eea25be9beb57eca7cd7a8"
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.0.11"
+  build_config:
+    dependency: transitive
+    description:
+      name: build_config
+      sha256: d466ed2dc9c6cd1d169948879b84ee061eb5e22c64a7c6089879c6296d272a8d
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.3.3"
+  build_daemon:
+    dependency: transitive
+    description:
+      name: build_daemon
+      sha256: e1d40ef3f7934986d5da2271b1ba07794921ce263e44d622fb6c406d76589e33
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.1.6"
+  build_runner:
+    dependency: "direct dev"
+    description:
+      name: build_runner
+      sha256: "894c243f6bc32015fec466ce30a6925bd537a77a426ee5bf481120477eb3de67"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.16.1"
+  built_collection:
+    dependency: transitive
+    description:
+      name: built_collection
+      sha256: "376e3dd27b51ea877c28d525560790aee2e6fbb5f20e2f85d5081027d94e2100"
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.1.1"
+  built_value:
+    dependency: transitive
+    description:
+      name: built_value
+      sha256: f87ea98192116f7093cb214551ce1929caae0681fdba282b3d8b4462adee7bb7
+      url: "https://pub.dev"
+    source: hosted
+    version: "8.13.0"
   characters:
     dependency: transitive
     description:
@@ -33,6 +97,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.1"
+  charcode:
+    dependency: transitive
+    description:
+      name: charcode
+      sha256: fb0f1107cac15a5ea6ef0a6ef71a807b9e4267c713bb93e00e92d737cc8dbd8a
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.4.0"
+  checked_yaml:
+    dependency: transitive
+    description:
+      name: checked_yaml
+      sha256: "959525d3162f249993882720d52b7e0c833978df229be20702b33d48d91de70f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.4"
+  cli_util:
+    dependency: transitive
+    description:
+      name: cli_util
+      sha256: "71e43f1976c3eae2d9468a5b4d6600bf8cae61508b87f27fa1799228935d48ab"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.2"
   clock:
     dependency: transitive
     description:
@@ -57,6 +145,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.19.1"
+  convert:
+    dependency: transitive
+    description:
+      name: convert
+      sha256: b30acd5944035672bc15c6b7a8b47d773e41e2f17de064350988c5d02adb1c68
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.2"
   copy_with_extension:
     dependency: transitive
     description:
@@ -81,6 +177,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.0.7"
+  dart_style:
+    dependency: transitive
+    description:
+      name: dart_style
+      sha256: "82ade9fc4273f29ed673e33166944465225b4f7fc5d4aaef48605cc751c18fc1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.13"
   dbus:
     dependency: transitive
     description:
@@ -113,6 +217,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.2"
+  drift:
+    dependency: "direct main"
+    description:
+      name: drift
+      sha256: e3b6352aa02e60bed6ffc3cc9894c421578dad5fbef21b1f7f57cdc0e4edabcb
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.35.0"
+  drift_dev:
+    dependency: "direct dev"
+    description:
+      name: drift_dev
+      sha256: fbad5c1e3a73820cdb1f32161eb2f40bb5e5f03c0c1a3d236595725aec7efc6d
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.35.0"
+  drift_flutter:
+    dependency: "direct main"
+    description:
+      name: drift_flutter
+      sha256: "91acf4bee7c3c84467cba46455aa70e5292a3b889f4582645d74f2e5a8c106f2"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.3.1"
   equatable:
     dependency: transitive
     description:
@@ -160,6 +288,14 @@ packages:
       relative: true
     source: path
     version: "0.1.0"
+  fixnum:
+    dependency: transitive
+    description:
+      name: fixnum
+      sha256: b6dc7065e46c974bc7c5f143080a6764ec7a4be6da1285ececdc37be96de53be
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.1"
   fl_chart:
     dependency: "direct main"
     description:
@@ -260,6 +396,14 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  glob:
+    dependency: transitive
+    description:
+      name: glob
+      sha256: "218aeb56050c714f62a3182775320dfa04602b55074873e24e31bbd39bda96fb"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.0"
   go_router:
     dependency: "direct main"
     description:
@@ -268,6 +412,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "14.8.1"
+  graphs:
+    dependency: transitive
+    description:
+      name: graphs
+      sha256: "741bbf84165310a68ff28fe9e727332eef1407342fca52759cb21ad8177bb8d0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.2"
   hooks:
     dependency: transitive
     description:
@@ -276,6 +428,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.0.2"
+  http_multi_server:
+    dependency: transitive
+    description:
+      name: http_multi_server
+      sha256: aa6199f908078bb1c5efb8d8638d4ae191aac11b311132c3ef48ce352fb52ef8
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.2"
   http_parser:
     dependency: transitive
     description:
@@ -292,6 +452,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.20.3"
+  io:
+    dependency: transitive
+    description:
+      name: io
+      sha256: "2635216ca6a737e60de577ffa1a48a0bec76ca8a62917cfc1bb88c14c570646f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
   jni:
     dependency: transitive
     description:
@@ -404,6 +572,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.0"
+  native_toolchain_c:
+    dependency: transitive
+    description:
+      name: native_toolchain_c
+      sha256: f9c168717100ae6d9fee9ffb0be379bf1f8b26b0f6bcbd4fdddcd931993a6a72
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.19.2"
   objective_c:
     dependency: transitive
     description:
@@ -429,7 +605,7 @@ packages:
     source: hosted
     version: "1.9.1"
   path_provider:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: path_provider
       sha256: a7f4874f987173da295a61c181b8ee71dab59b332a486b391babf26a1b884825
@@ -500,6 +676,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.8"
+  pool:
+    dependency: transitive
+    description:
+      name: pool
+      sha256: "4177f68c237ea2128d1bee66ac17b2ce05ba3dbaafcbdd54c5d40a39d0b6b11c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.5.3"
   pub_semver:
     dependency: transitive
     description:
@@ -508,6 +692,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.1"
+  pubspec_parse:
+    dependency: transitive
+    description:
+      name: pubspec_parse
+      sha256: c38b81cbf34450b67e0265d73433569d12e34782e30ed769c9cc99c9d5f2e796
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.6.0"
   rational:
     dependency: transitive
     description:
@@ -516,6 +708,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.3"
+  recase:
+    dependency: transitive
+    description:
+      name: recase
+      sha256: e4eb4ec2dcdee52dcf99cb4ceabaffc631d7424ee55e56f280bc039737f89213
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.1.0"
   record_use:
     dependency: transitive
     description:
@@ -588,11 +788,35 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.4.1"
+  shelf:
+    dependency: transitive
+    description:
+      name: shelf
+      sha256: e7dd780a7ffb623c57850b33f43309312fc863fb6aa3d276a754bb299839ef12
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.4.2"
+  shelf_web_socket:
+    dependency: transitive
+    description:
+      name: shelf_web_socket
+      sha256: "3632775c8e90d6c9712f883e633716432a27758216dfb61bd86a8321c0580925"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.0.0"
   sky_engine:
     dependency: transitive
     description: flutter
     source: sdk
     version: "0.0.0"
+  source_gen:
+    dependency: transitive
+    description:
+      name: source_gen
+      sha256: "11b6047da8e4eb6c643ccac3d0fda3f9c9e11651695f7da24a85ade8aff15a44"
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.3.0"
   source_span:
     dependency: transitive
     description:
@@ -601,6 +825,38 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.10.2"
+  sqlcipher_flutter_libs:
+    dependency: transitive
+    description:
+      name: sqlcipher_flutter_libs
+      sha256: "38d62d659d2fb8739bf25a42c9a350d1fdd6c29a5a61f13a946778ec75d27929"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.0+eol"
+  sqlite3:
+    dependency: transitive
+    description:
+      name: sqlite3
+      sha256: "4c7fe79840389aaeaf05fd093f795b631b5a98e2bd28d54e555c100f4a9c7a1c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.5.2"
+  sqlite3_flutter_libs:
+    dependency: transitive
+    description:
+      name: sqlite3_flutter_libs
+      sha256: "3ed7553eee7bb368f8950f58ba29f634e06e813c029aff6a0d60862b96de8454"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.0+eol"
+  sqlparser:
+    dependency: transitive
+    description:
+      name: sqlparser
+      sha256: "772bb2f6f5bce0631a60f26b57d6e8882e1105c22345b05c163ee6ee5d7ba32d"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.45.0"
   stack_trace:
     dependency: transitive
     description:
@@ -625,6 +881,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.4"
+  stream_transform:
+    dependency: transitive
+    description:
+      name: stream_transform
+      sha256: a00e5f18bffc764f923e7dec1038527f7fe7a1791361a7117f0358193f13d53a
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.2"
   string_scanner:
     dependency: transitive
     description:
@@ -673,6 +937,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "15.3.0"
+  watcher:
+    dependency: transitive
+    description:
+      name: watcher
+      sha256: "1398c9f081a753f9226febe8900fce8f7d0a67163334e1c94a2438339d79d635"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.1"
   web:
     dependency: transitive
     description:
@@ -681,6 +953,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.1"
+  web_socket:
+    dependency: transitive
+    description:
+      name: web_socket
+      sha256: "34d64019aa8e36bf9842ac014bb5d2f5586ca73df5e4d9bf5c936975cae6982c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.1"
+  web_socket_channel:
+    dependency: transitive
+    description:
+      name: web_socket_channel
+      sha256: d645757fb0f4773d602444000a8131ff5d48c9e47adfe9772652dd1a4f2d45c8
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.0.3"
   win32:
     dependency: transitive
     description:
@@ -713,6 +1001,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.1.4"
+  yaml_edit:
+    dependency: transitive
+    description:
+      name: yaml_edit
+      sha256: "07c9e63ba42519745182b88ca12264a7ba2484d8239958778dfe4d44fe760488"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.4"
 sdks:
   dart: ">=3.13.3 <4.0.0"
   flutter: ">=3.44.0"

app/pubspec.yaml

@@ -22,11 +22,16 @@ dependencies:
   fl_chart: ^0.69.0
   shared_preferences: ^2.3.4
   file_picker: ^11.0.3
+  drift: ^2.35.0
+  drift_flutter: ^0.3.1
+  path_provider: ^2.1.6
 
 dev_dependencies:
   flutter_test:
     sdk: flutter
   flutter_lints: ^6.0.0
+  drift_dev: ^2.35.0
+  build_runner: ^2.16.1
 
 flutter:
   uses-material-design: true

app/test/cache_interceptor_test.dart

@@ -0,0 +1,122 @@
+import 'package:dio/dio.dart';
+import 'package:drift/native.dart';
+import 'package:fintracker_app/core/cache/cache_interceptor.dart';
+import 'package:fintracker_app/core/cache/response_cache.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+/// `onResponse`/`onError` complete synchronously in `CacheInterceptor` — no
+/// real Dio transport needed, same approach as `date_query_interceptor_test.dart`.
+class _ResponseCapture extends ResponseInterceptorHandler {
+  Response<dynamic>? passed;
+  @override
+  void next(Response response) => passed = response;
+}
+
+class _ErrorCapture extends ErrorInterceptorHandler {
+  Response<dynamic>? resolvedResponse;
+  DioException? forwarded;
+
+  @override
+  void resolve(Response response) => resolvedResponse = response;
+
+  @override
+  void next(DioException error) => forwarded = error;
+}
+
+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);
+
+void main() {
+  late ResponseCacheDatabase db;
+  late CacheInterceptor interceptor;
+
+  setUp(() {
+    db = ResponseCacheDatabase.forTesting(NativeDatabase.memory());
+    interceptor = CacheInterceptor(db);
+  });
+
+  tearDown(() => db.close());
+
+  test('a successful GET is written to the cache', () async {
+    final options = _request('GET', '/networth/breakdown');
+
+    interceptor.onResponse(
+      Response<dynamic>(requestOptions: options, statusCode: 200, data: {'totalRub': '100'}),
+      _ResponseCapture(),
+    );
+    await pumpEventQueue(); // the write is fire-and-forget
+
+    final cached = await db.get(CacheInterceptor.requestKey(options));
+    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'});
+
+    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);
+  });
+
+  test('a connection error with nothing cached still fails', () async {
+    final options = _request('GET', '/networth/breakdown', {'never': 'asked'});
+    final failure = _offline(options);
+    final handler = _ErrorCapture();
+
+    await interceptor.onError(failure, handler);
+
+    expect(handler.resolvedResponse, isNull);
+    expect(handler.forwarded, same(failure));
+  });
+
+  test('a real server error is never masked by a cached answer', () async {
+    final options = _request('GET', '/networth/breakdown');
+    await db.put(CacheInterceptor.requestKey(options), {'totalRub': '100'});
+
+    final serverError = DioException(
+      requestOptions: options,
+      type: DioExceptionType.badResponse,
+      response: Response<dynamic>(requestOptions: options, statusCode: 500),
+    );
+    final handler = _ErrorCapture();
+    await interceptor.onError(serverError, handler);
+
+    expect(handler.resolvedResponse, isNull);
+    expect(handler.forwarded, same(serverError));
+  });
+
+  test('a failed mutation is never served from the cache', () async {
+    final options = _request('POST', '/links');
+    final failure = _offline(options);
+    final handler = _ErrorCapture();
+
+    await interceptor.onError(failure, handler);
+
+    expect(handler.resolvedResponse, isNull);
+    expect(handler.forwarded, same(failure));
+  });
+
+  test('query parameters are part of the cache key', () async {
+    final page1 = _request('GET', '/events', {'page': 1});
+    final page2 = _request('GET', '/events', {'page': 2});
+    await db.put(CacheInterceptor.requestKey(page1), 'page1');
+
+    final handler = _ErrorCapture();
+    await interceptor.onError(_offline(page2), handler);
+
+    expect(handler.resolvedResponse, isNull); // page=2 was never cached
+  });
+
+  test('the key ignores query parameter order', () {
+    final a = _request('GET', '/events', {'a': 1, 'b': 2});
+    final b = _request('GET', '/events', {'b': 2, 'a': 1});
+    expect(CacheInterceptor.requestKey(a), CacheInterceptor.requestKey(b));
+  });
+}

app/test/home_page_test.dart

@@ -1,4 +1,5 @@
 import 'package:fintracker_api/fintracker_api.dart';
+import 'package:fintracker_app/core/cache/cached.dart';
 import 'package:fintracker_app/core/widgets/money_text.dart';
 import 'package:fintracker_app/features/home/home_page.dart';
 import 'package:fintracker_app/features/home/providers.dart';
@@ -6,9 +7,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-void main() {
+NetWorthBreakdown _breakdown() => NetWorthBreakdown(
-  testWidgets('Обзор renders stat tiles from a net worth breakdown', (tester) async {
-    final breakdown = NetWorthBreakdown(
       accounts: const [],
       byCurrency: const {'RUB': '123456.78'},
       d: DateTime(2026, 9, 17),
@@ -20,22 +19,33 @@ void main() {
       totalRub: '123456.78',
     );
 
-    await tester.pumpWidget(
+RunwayOut _runway() => RunwayOut(
-      ProviderScope(
-        overrides: [
-          netWorthBreakdownProvider.overrideWith((ref) => breakdown),
-          netWorthSeriesProvider.overrideWith((ref) => const <NetWorthDay>[]),
-          cashflowThisMonthProvider.overrideWith((ref) => null),
-          cashflowLast12Provider.overrideWith((ref) => const <CashFlowMonth>[]),
-          runwayProvider.overrideWith((ref) => RunwayOut(
       asOf: DateTime(2026, 9, 17),
       avgBaseline3mRub: '0',
       liquidReserveRub: '0',
       runwayMonths: null,
-              )),
+    );
-          metricsStatusProvider.overrideWith((ref) => null),
+
-          dataQualityProvider.overrideWith((ref) => const <DataQualityRow>[]),
+// Every provider HomePage watches needs an override — including
-        ],
+// portfolioSummaryHomeProvider, easy to forget since it renders nothing on an
+// empty ledger. Without it, HomePage falls through to the real apiProvider,
+// which now also opens a real ResponseCacheDatabase (see docs/ai/offline-cache.md).
+List<Override> _overrides({DateTime? staleAt}) => [
+      netWorthBreakdownProvider.overrideWith((ref) => Cached(_breakdown(), fetchedAt: staleAt)),
+      netWorthSeriesProvider.overrideWith((ref) => Cached(const <NetWorthDay>[], fetchedAt: staleAt)),
+      cashflowThisMonthProvider.overrideWith((ref) => Cached(null, fetchedAt: staleAt)),
+      cashflowLast12Provider.overrideWith((ref) => Cached(const <CashFlowMonth>[], fetchedAt: staleAt)),
+      runwayProvider.overrideWith((ref) => Cached(_runway(), fetchedAt: staleAt)),
+      metricsStatusProvider.overrideWith((ref) => Cached(null, fetchedAt: staleAt)),
+      dataQualityProvider.overrideWith((ref) => Cached(const <DataQualityRow>[], fetchedAt: staleAt)),
+      portfolioSummaryHomeProvider.overrideWith((ref) => Cached(null, fetchedAt: staleAt)),
+    ];
+
+void main() {
+  testWidgets('Обзор renders stat tiles from a net worth breakdown', (tester) async {
+    await tester.pumpWidget(
+      ProviderScope(
+        overrides: _overrides(),
         child: const MaterialApp(home: HomePage()),
       ),
     );
@@ -47,5 +57,18 @@ void main() {
     expect(find.text(MoneyText.format('3000', 'RUB')), findsOneWidget);
     expect(find.text('Долги'), findsOneWidget);
     expect(find.text(MoneyText.format('1000', 'RUB')), findsOneWidget);
+    expect(find.textContaining('Нет соединения'), findsNothing);
+  });
+
+  testWidgets('shows the offline banner when the dashboard came from the cache', (tester) async {
+    await tester.pumpWidget(
+      ProviderScope(
+        overrides: _overrides(staleAt: DateTime(2026, 9, 10, 8, 30)),
+        child: const MaterialApp(home: HomePage()),
+      ),
+    );
+    await tester.pumpAndSettle();
+
+    expect(find.textContaining('Нет соединения — данные на 10.09.2026 08:30'), findsOneWidget);
   });
 }

docs/ai/README.md

@@ -35,3 +35,5 @@ worker (APScheduler, advisory locks)                      ▼
 - [plan.md](plan.md) — фазы и чек-листы проверки.
 - [ops.md](ops.md) — деплой на VPS, бэкапы, секреты.
 - [links.md](links.md) — внешние API и референсы.
+- [offline-cache.md](offline-cache.md) — офлайн-кэш Flutter-клиента: контракт `Cached<T>`,
+  `CacheInterceptor`, баннер «данные на …» (фаза 5).

docs/ai/offline-cache.md

@@ -0,0 +1,91 @@
+# Offline-кэш (фаза 5)
+
+Контракт, по которому каждый экран Flutter-клиента получает поддержку офлайна. Реализован
+целиком на `core/cache/*` + один Dio-интерцептор — экрану достаточно поменять тип провайдера
+и один раз показать баннер, ничего не меняя в том, как он делает запросы.
+
+## Идея
+
+Кэш живёт не в провайдерах и не в экранах, а в `Dio` — на уровне HTTP-транспорта, ниже
+сгенерированного `fintracker_api`-клиента:
+
+- **`CacheInterceptor`** (`core/cache/cache_interceptor.dart`) добавлен в `apiProvider`
+  (`core/api/api_client.dart`) последним, после `DateQueryInterceptor` и `_AuthInterceptor`.
+  - `onResponse`: успешный `GET` (статус 200) пишется в кэш по ключу `путь?отсортированные_параметры`
+    (`CacheInterceptor.requestKey`) — fire-and-forget, ответ не ждёт записи.
+  - `onError`: если запрос — `GET` и ошибка сетевая (`connectionError`, `connectionTimeout`,
+    `receiveTimeout`, `sendTimeout`), интерцептор ищет последний закэшированный ответ по тому же
+    ключу и, если он есть, подменяет ошибку успешным `Response` с `extra['fetchedAt']` —
+    временем, когда этот ответ был реально получен от сервера. Если в кэше пусто — ошибка идёт
+    дальше как обычно.
+  - Мутации (не-`GET`) никогда не кэшируются и никогда не подменяются: упавший `POST/PATCH/DELETE`
+    обязан остаться ошибкой.
+  - Реальная ошибка сервера (4xx/5xx, `DioExceptionType.badResponse`) кэшем не перекрывается —
+    подменяется только сетевая недоступность.
+- **`ResponseCacheDatabase`** (`core/cache/response_cache.dart`) — таблица `drift` с одной строкой
+  на ключ (`requestKey`, `body` как JSON-строка, `fetchedAt`). `driftDatabase()` из
+  `package:drift_flutter` сам выбирает бэкенд: нативный sqlite (FFI) на Android/iOS/desktop,
+  wasm+OPFS (с падением на IndexedDB) в браузере.
+- Сгенерированный API-клиент (`app/packages/api_client`) копирует `Response.extra` в возвращаемый
+  `Response<T>` без изменений (проверено в `networth_api.dart` и остальных) — значит,
+  `extra['fetchedAt']` долетает до провайдера без единой правки в генерируемом коде.
+
+## Контракт для экрана
+
+1. **Провайдер оборачивает данные в `Cached<T>`** (`core/cache/cached.dart`) вместо голого `T`:
+
+   ```dart
+   final xProvider = FutureProvider.autoDispose<Cached<X>>((ref) async {
+     final r = await ref.watch(apiProvider).getXApi().x();
+     return r.cached; // extension: Cached(r.data as T, fetchedAt: r.extra['fetchedAt'])
+   });
+   ```
+
+   Для эндпоинтов, которые сами обрабатывают `null`/404 (см. `metricsStatusProvider`,
+   `portfolioSummaryHomeProvider` в `features/home/providers.dart`), оборачивайте вручную:
+   `Cached(value, fetchedAt: r.extra['fetchedAt'] as DateTime?)`.
+
+2. **Экран разворачивает `.data`** там, где раньше было голое значение
+   (`data: (cached) => Widget(x: cached.data)`), и считает баннер один раз на весь экран:
+
+   ```dart
+   final stale = oldestFetch([a.valueOrNull?.fetchedAt, b.valueOrNull?.fetchedAt, ...]);
+   // ...
+   if (stale != null) StaleBanner(fetchedAt: stale),
+   ```
+
+   `oldestFetch` берёт самое старое время среди тех провайдеров, что реально пришли из кэша
+   (`fetchedAt != null`); один баннер на экран — не один на плитку, иначе на дашборде из 8
+   виджетов это станет шумом. `StaleBanner` (`core/widgets/stale_banner.dart`) — тонкий
+   контейнер в цветах темы («Нет соединения — данные на 12.09.2026 10:31»), без логики.
+
+3. **В тестах экрана — оверрайдить КАЖДЫЙ провайдер**, который экран смотрит, значением
+   `Cached(...)`. Если забыть один (как было с `portfolioSummaryHomeProvider` до этой фазы),
+   тест провалится не сразу, а тихо создаст настоящий `apiProvider` → настоящий
+   `ResponseCacheDatabase` — drift выведет предупреждение "multiple databases" и тест будет
+   трогать реальный sqlite-файл вместо теста в изоляции. Смотрите `test/home_page_test.dart`
+   и `_overrides()` в нём как образец.
+
+Эталонная реализация — весь `features/home/` (провайдеры + `HomePage`). Остальные ~24 экрана
+на паттерне `AsyncValueView`/`EmptyState` переводятся по этому же рецепту, независимо друг от
+друга (можно параллельно, в отдельных worktree).
+
+## Веб: sqlite3.wasm + drift_worker.js
+
+Собранные ассеты лежат в `app/web/sqlite3.wasm` и `app/web/drift_worker.js`, закоммичены (как
+`openapi/openapi.json` и Dart-клиент). Пересобирать `just app-web-assets`, когда обновляются
+версии пакетов `drift`/`sqlite3` — recipe качает `sqlite3.wasm` с GitHub-релиза пакета
+`sqlite3.dart`, версия релиза берётся из `flutter pub deps --json`, и компилирует
+`drift_worker.js` из исходника `package:drift/web/drift_worker.dart` через `dart compile js`.
+`just build-web` вызывает это автоматически.
+
+## Что не проверено
+
+`flutter build linux --debug` на сборке нативного sqlite3 не дошёл до проверки — упал раньше,
+на несвязанной с кэшем проблеме `flutter_secure_storage_linux` (старый `nlohmann/json.hpp`,
+`-Werror=deprecated-literal-operator` на новых компиляторах; плюс сначала не хватало
+`libsecret`/`pkg-config` в `flake.nix` — это уже добавлено). Сам `sqlite3`/drift на Dart VM
+(native FFI) отработал корректно — это видно по `flutter test`, где `ResponseCacheDatabase`
+реально открывает файл через нативный бэкенд без ошибок. Кто будет делать пункт «Linux/Windows
+в CI» — начните с починки `flutter_secure_storage_linux` (обновить пакет или добавить
+`-Wno-deprecated-literal-operator` в его CMake), это отдельная от кэша проблема.

docs/ai/ops.md

@@ -21,8 +21,7 @@ docker compose up -d db
 docker compose exec -T db pg_restore -U $POSTGRES_USER -d $POSTGRES_DB --clean < backups/fintracker_<ts>.dump
 docker compose up -d
 ```
-Метрики пересчитываются из raw/core: `docker compose exec worker fintracker metrics refresh`
+Метрики пересчитываются из raw/core: `docker compose exec worker fintracker metrics refresh`.
-(появится в фазе 2).
 
 ## Секреты
 

docs/ai/plan.md

@@ -523,6 +523,33 @@ backup/restore, страница здоровья (`/sync/status`, счётчи
 Проверка: приложение работает offline на кэше; APK подписывается и ставится; restore из
 ночного `pg_dump` на чистом VPS + `fintracker metrics refresh` воспроизводит все метрики.
 
+**Статус: в работе.** Готово до этой правки (не с нуля):
+адаптивные раскладки (`app_shell.dart`, breakpoints 600/1200), тёмная тема
+(`theme_controller.dart`), общий паттерн пустых/ошибочных состояний
+(`AsyncValueView` — 25 экранов, `EmptyState` — 22), backup — `pg-backup`-сайдкар в
+`docker-compose.yml` (ночной `pg_dump -Fc`, retention 14 дней) и runbook в `ops.md`.
+
+Сделано в этом заходе:
+
+- **Offline-кэш** — контракт целиком в [offline-cache.md](docs/ai/offline-cache.md):
+  `CacheInterceptor` в `apiProvider` кэширует каждый успешный `GET` по `путь+параметры` в
+  `drift` (sqlite нативно, wasm+OPFS в браузере) и подменяет им сетевую ошибку;
+  провайдер отдаёт `Cached<T>`, экран показывает один баннер «Нет соединения — данные на …».
+  Реализовано и протестировано целиком на `features/home/` (дашборд — самый частый экран);
+  остальные ~24 экрана переводятся по тому же контракту независимо друг от друга.
+  `app/web/sqlite3.wasm` + `app/web/drift_worker.js` закоммичены, пересборка —
+  `just app-web-assets`.
+- `flutter build linux --debug` не пройден до конца: `flutter_secure_storage_linux` падает на
+  устаревшем `nlohmann/json.hpp` под `-Werror=deprecated-literal-operator` современных
+  компиляторов — не связано с кэшем, чинить отдельно перед пунктом CI/Linux. `libsecret` +
+  `pkg-config` для линуксовой сборки уже добавлены в `flake.nix`.
+- `docs/ai/ops.md` поправлен: убрана ссылка на «появится в фазе 2» у `metrics refresh`.
+
+Не начато: CI-джоба для Flutter (`just app-check` в CI, сборка Linux/Windows), консолидация
+страницы здоровья (сейчас статусы синка на `/sync`, data quality — блоком на дашборде),
+Android release-подпись (нужен keystore от пользователя), off-site бэкап (см. открытый
+вопрос §7.9 — решения ещё нет).
+
 ## 7. Открытые вопросы (дефолт в скобках, можно менять по ходу)
 
 1. Хранение refresh-токена в web: `localStorage` (дефолт: да, один пользователь, TLS) или

flake.nix

@@ -24,6 +24,8 @@
         pkgs.just
         pkgs.postgresql_17 # local dev cluster (`just db-start`) and psql
         pkgs.openapi-generator-cli # `just gen-client`
+        pkgs.jq # `just app-web-assets` reads package_config.json / pub deps
+        pkgs.curl # `just app-web-assets` fetches sqlite3.wasm from GitHub releases
       ];
 
       commonHook = ''
@@ -49,7 +51,12 @@
         };
         # backend + Flutter toolchain (large download on first use)
         app = pkgs.mkShell {
-          packages = backendTools ++ [ pkgs.flutter ];
+          packages = backendTools ++ [
+            pkgs.flutter
+            # Linux desktop build: flutter_secure_storage_linux links libsecret via pkg-config
+            pkgs.pkg-config
+            pkgs.libsecret
+          ];
           shellHook = commonHook;
         };
       };

justfile

@@ -22,11 +22,22 @@ web:
 
 # --- flutter ---
 
-build-web:
+build-web: app-web-assets
     cd app && flutter pub get && flutter build web --release
 
+# fetch sqlite3.wasm + compile drift_worker.js into app/web/ (offline cache, drift/wasm+OPFS —
+# see docs/ai/offline-cache.md). Re-run whenever the drift/sqlite3 package versions change;
+# both files are committed, so this is not needed on every build.
+app-web-assets:
+    cd app && flutter pub get
+    v=$(cd app && flutter pub deps --json | jq -r '.packages[] | select(.name=="sqlite3") | .version') && \
+        curl -fL -o app/web/sqlite3.wasm "https://github.com/simolus3/sqlite3.dart/releases/download/sqlite3-$v/sqlite3.wasm"
+    d=$(jq -r '.packages[] | select(.name=="drift") | .rootUri' app/.dart_tool/package_config.json | sed 's#^file://##') && \
+        cd app && dart compile js -O2 --packages=.dart_tool/package_config.json -o web/drift_worker.js "$d/web/drift_worker.dart" && \
+        rm -f web/drift_worker.js.deps web/drift_worker.js.map
+
 app-check:
-    cd app && flutter analyze && flutter test
+    cd app && flutter pub get && flutter analyze && flutter test
 
 # one-off source sync against the local dev DB (zenmoney | cbr)
 pull SOURCE: