From 9b74c9fd81198359330804cdd9992e9a039f1c7d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Elias=20M=C3=BCller?= <elias@elias-mueller.com>
Date: Tue, 7 Jul 2026 20:24:16 +0200
Subject: [PATCH] implemented a comprehensive client-side demo mode triggered
 by a "demo@" username prefix, serving curated fixture data for all app
 modules

---
 lib/api/demo/data/demo_breaker.dart           |   9 +
 lib/api/demo/data/demo_capabilities.dart      |  33 ++
 lib/api/demo/data/demo_files.dart             | 155 +++++++
 lib/api/demo/data/demo_holidays.dart          |  34 ++
 lib/api/demo/data/demo_marianum_dates.dart    |  54 +++
 lib/api/demo/data/demo_marianum_message.dart  |  24 +
 lib/api/demo/data/demo_talk.dart              | 429 ++++++++++++++++++
 lib/api/demo/data/demo_timetable.dart         | 202 +++++++++
 lib/api/demo/demo_marianumconnect.dart        |  54 +++
 .../demo_marianumconnect_interceptor.dart     |  35 ++
 lib/api/demo/demo_mode.dart                   |  27 ++
 lib/api/demo/demo_persona.dart                |  58 +++
 .../auth/session_validator.dart               |   3 +
 .../marianumconnect/marianumconnect_api.dart  |   2 +
 lib/model/account_data.dart                   |  26 ++
 lib/push/push_registration.dart               |   3 +
 .../data_provider/breaker_data_provider.dart  |  10 +-
 .../capabilities/bloc/capabilities_cubit.dart |   6 +
 .../data_provider/chat_data_provider.dart     |   8 +
 .../chat_list_data_provider.dart              |  23 +-
 .../data_provider/files_data_provider.dart    |  28 +-
 .../bloc/grade_averages_bloc.dart             |   8 +-
 .../repository/marianum_dates_repository.dart |   7 +-
 .../marianum_message_repository.dart          |   8 +-
 .../bloc/nextcloud_capabilities_cubit.dart    |   6 +
 .../timetable_data_provider.dart              |  39 +-
 lib/view/login/login_controller.dart          |  15 +
 .../files/sharing/share_options_sheet.dart    |   2 +
 lib/view/pages/files/sharing/share_sheet.dart |   2 +
 .../pages/files/widgets/add_file_menu.dart    |   2 +
 .../pages/files/widgets/file_element.dart     |   6 +
 .../pages/more/feedback/feedback_dialog.dart  |   2 +
 .../settings/sections/account_section.dart    |   2 +
 .../settings/widgets/push_status_sheet.dart   |   3 +
 lib/view/pages/talk/chat_list.dart            |   2 +
 .../pages/talk/data/open_direct_chat.dart     |   2 +
 lib/view/pages/talk/widgets/chat_bubble.dart  |   2 +
 .../talk/widgets/chat_bubble_reactions.dart   |   2 +
 .../widgets/chat_message_options_dialog.dart  |   6 +
 .../pages/talk/widgets/chat_textfield.dart    |   3 +
 .../custom_event_edit_dialog.dart             |   2 +
 .../details/delete_custom_event.dart          |   2 +
 lib/view/pages/timetable/timetable.dart       |   2 +
 lib/widget/demo_restricted.dart               |  21 +
 test/demo/demo_marianumconnect_test.dart      |  83 ++++
 45 files changed, 1409 insertions(+), 43 deletions(-)
 create mode 100644 lib/api/demo/data/demo_breaker.dart
 create mode 100644 lib/api/demo/data/demo_capabilities.dart
 create mode 100644 lib/api/demo/data/demo_files.dart
 create mode 100644 lib/api/demo/data/demo_holidays.dart
 create mode 100644 lib/api/demo/data/demo_marianum_dates.dart
 create mode 100644 lib/api/demo/data/demo_marianum_message.dart
 create mode 100644 lib/api/demo/data/demo_talk.dart
 create mode 100644 lib/api/demo/data/demo_timetable.dart
 create mode 100644 lib/api/demo/demo_marianumconnect.dart
 create mode 100644 lib/api/demo/demo_marianumconnect_interceptor.dart
 create mode 100644 lib/api/demo/demo_mode.dart
 create mode 100644 lib/api/demo/demo_persona.dart
 create mode 100644 lib/widget/demo_restricted.dart
 create mode 100644 test/demo/demo_marianumconnect_test.dart

diff --git a/lib/api/demo/data/demo_breaker.dart b/lib/api/demo/data/demo_breaker.dart
new file mode 100644
index 0000000..27917d9
--- /dev/null
+++ b/lib/api/demo/data/demo_breaker.dart
@@ -0,0 +1,9 @@
+import '../../marianumconnect/queries/get_breakers/get_breakers_response.dart';
+
+/// Demo fixtures for the app-maintenance breaker.
+class DemoBreaker {
+  const DemoBreaker._();
+
+  /// No active rules — the demo app is never blocked.
+  static GetBreakersResponse none() => GetBreakersResponse([]);
+}
diff --git a/lib/api/demo/data/demo_capabilities.dart b/lib/api/demo/data/demo_capabilities.dart
new file mode 100644
index 0000000..d43bdf8
--- /dev/null
+++ b/lib/api/demo/data/demo_capabilities.dart
@@ -0,0 +1,33 @@
+import '../../../state/app/modules/capabilities/bloc/capabilities_state.dart';
+import '../../../state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_state.dart';
+
+/// Demo fixtures for the mobile capability flags — everything granted so the
+/// demo persona sees every feature (incl. push) as available.
+class DemoCapabilities {
+  const DemoCapabilities._();
+
+  static CapabilitiesState state() => const CapabilitiesState(
+    viewForeignTimetables: true,
+    pushNotifications: true,
+    loaded: true,
+  );
+}
+
+/// Demo fixtures for the Nextcloud `files_sharing` capabilities — a permissive
+/// "everything enabled, nothing enforced" server profile.
+class DemoNextcloudCapabilities {
+  const DemoNextcloudCapabilities._();
+
+  static NextcloudCapabilitiesState state() => const NextcloudCapabilitiesState(
+    apiEnabled: true,
+    publicEnabled: true,
+    publicMultipleLinks: true,
+    publicUploadEnabled: true,
+    publicPasswordEnforced: false,
+    publicExpireEnabled: false,
+    publicExpireEnforced: false,
+    groupEnabled: true,
+    resharing: true,
+    loaded: true,
+  );
+}
diff --git a/lib/api/demo/data/demo_files.dart b/lib/api/demo/data/demo_files.dart
new file mode 100644
index 0000000..3e7437e
--- /dev/null
+++ b/lib/api/demo/data/demo_files.dart
@@ -0,0 +1,155 @@
+import '../../marianumcloud/webdav/queries/list_files/cacheable_file.dart';
+import '../../marianumcloud/webdav/queries/list_files/list_files_response.dart';
+
+/// Curated WebDAV listings for the demo mode. Everything is built on
+/// [CacheableFile] (the app-level model the file UI renders) so no `nextcloud`
+/// DAV objects need to be faked and no network is ever touched.
+///
+/// `hasPreview`/`fileId` are left null on purpose: without them the file list
+/// won't try to fetch server-side thumbnails for the fixtures.
+class DemoFiles {
+  const DemoFiles._();
+
+  /// Returns the listing for [path] as passed to `FilesDataProvider.listFiles`
+  /// (`/` or empty for the root, otherwise the joined folder display names).
+  /// Unknown folders resolve to an empty listing rather than an error.
+  static ListFilesResponse listing(String path) {
+    final key = path.replaceAll('/', '').trim();
+    switch (key) {
+      case '':
+        return _root();
+      case 'Hausaufgaben':
+        return _hausaufgaben();
+      case 'Arbeitsblätter':
+        return _arbeitsblaetter();
+      case 'Klausuren':
+        return _klausuren();
+      case 'Schuljahr 2025-26':
+        return _schuljahr();
+      default:
+        return ListFilesResponse({});
+    }
+  }
+
+  static ListFilesResponse _root() => ListFilesResponse({
+    _folder('Hausaufgaben', daysAgo: 1),
+    _folder('Arbeitsblätter', daysAgo: 3),
+    _folder('Klausuren', daysAgo: 12),
+    _folder('Schuljahr 2025-26', daysAgo: 30),
+    _file('Deutsch Lektüre.pdf', size: 2_480_000, daysAgo: 2),
+    _file('Mathe Formelsammlung.pdf', size: 890_000, daysAgo: 9),
+    _file('Bio Referat.pptx', size: 5_120_000, daysAgo: 5),
+    _file('Stundenplan.pdf', size: 145_000, daysAgo: 14),
+  });
+
+  static ListFilesResponse _hausaufgaben() => ListFilesResponse({
+    _file(
+      'Deutsch Aufsatz.docx',
+      parent: 'Hausaufgaben',
+      size: 42_000,
+      daysAgo: 1,
+    ),
+    _file(
+      'Mathe Übungen KW28.pdf',
+      parent: 'Hausaufgaben',
+      size: 310_000,
+      daysAgo: 2,
+    ),
+    _file(
+      'Englisch Vokabeln.pdf',
+      parent: 'Hausaufgaben',
+      size: 96_000,
+      daysAgo: 4,
+    ),
+  });
+
+  static ListFilesResponse _arbeitsblaetter() => ListFilesResponse({
+    _file(
+      'Physik Optik.pdf',
+      parent: 'Arbeitsblätter',
+      size: 720_000,
+      daysAgo: 6,
+    ),
+    _file(
+      'Geschichte Weimar.pdf',
+      parent: 'Arbeitsblätter',
+      size: 540_000,
+      daysAgo: 8,
+    ),
+  });
+
+  static ListFilesResponse _klausuren() => ListFilesResponse({
+    _file(
+      'Mathe Klausur 1.pdf',
+      parent: 'Klausuren',
+      size: 630_000,
+      daysAgo: 20,
+    ),
+    _file(
+      'Deutsch Klausur 1.pdf',
+      parent: 'Klausuren',
+      size: 580_000,
+      daysAgo: 34,
+    ),
+  });
+
+  static ListFilesResponse _schuljahr() => ListFilesResponse({
+    _folder('Halbjahr 1', parent: 'Schuljahr 2025-26', daysAgo: 40),
+    _file(
+      'Klassenliste 10b.pdf',
+      parent: 'Schuljahr 2025-26',
+      size: 78_000,
+      daysAgo: 60,
+    ),
+  });
+
+  static CacheableFile _folder(
+    String name, {
+    String? parent,
+    required int daysAgo,
+  }) {
+    final base = parent == null ? '' : '/$parent';
+    return CacheableFile(
+      path: '$base/$name/',
+      isDirectory: true,
+      name: name,
+      modifiedAt: _relative(daysAgo),
+      createdAt: _relative(daysAgo + 30),
+    );
+  }
+
+  static CacheableFile _file(
+    String name, {
+    String? parent,
+    required int size,
+    required int daysAgo,
+  }) {
+    final base = parent == null ? '' : '/$parent';
+    return CacheableFile(
+      path: '$base/$name',
+      isDirectory: false,
+      name: name,
+      mimeType: _mimeFor(name),
+      size: size,
+      modifiedAt: _relative(daysAgo),
+      createdAt: _relative(daysAgo + 30),
+    );
+  }
+
+  static DateTime _relative(int daysAgo) =>
+      DateTime.now().subtract(Duration(days: daysAgo, hours: 3));
+
+  static String _mimeFor(String name) {
+    final ext = name.split('.').last.toLowerCase();
+    switch (ext) {
+      case 'pdf':
+        return 'application/pdf';
+      case 'pptx':
+        return 'application/vnd.openxmlformats-officedocument.presentationml.presentation';
+      case 'docx':
+        return 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';
+      default:
+        return 'application/octet-stream';
+    }
+  }
+}
diff --git a/lib/api/demo/data/demo_holidays.dart b/lib/api/demo/data/demo_holidays.dart
new file mode 100644
index 0000000..8e9801c
--- /dev/null
+++ b/lib/api/demo/data/demo_holidays.dart
@@ -0,0 +1,34 @@
+import '../../marianumconnect/models/mc_holiday.dart';
+
+/// Demo fixtures for the holiday calendar — a couple of upcoming breaks,
+/// positioned relative to "now" so they always read as still ahead.
+class DemoHolidays {
+  const DemoHolidays._();
+
+  static List<McHoliday> upcoming() {
+    final today = DateTime.now();
+    DateTime day(int offset) =>
+        DateTime(today.year, today.month, today.day).add(Duration(days: offset));
+
+    return [
+      McHoliday(
+        shortName: 'Herbst',
+        longName: 'Herbstferien',
+        startDate: day(28),
+        endDate: day(42),
+      ),
+      McHoliday(
+        shortName: 'Weihnachten',
+        longName: 'Weihnachtsferien',
+        startDate: day(90),
+        endDate: day(104),
+      ),
+      McHoliday(
+        shortName: 'Ostern',
+        longName: 'Osterferien',
+        startDate: day(180),
+        endDate: day(194),
+      ),
+    ];
+  }
+}
diff --git a/lib/api/demo/data/demo_marianum_dates.dart b/lib/api/demo/data/demo_marianum_dates.dart
new file mode 100644
index 0000000..f7528c4
--- /dev/null
+++ b/lib/api/demo/data/demo_marianum_dates.dart
@@ -0,0 +1,54 @@
+import '../../../state/app/modules/marianum_dates/bloc/marianum_dates_state.dart';
+import '../demo_persona.dart';
+
+/// Demo fixtures for the school calendar — a handful of upcoming events built
+/// relative to "now" and consistent with the demo persona (class 10b).
+class DemoMarianumDates {
+  const DemoMarianumDates._();
+
+  static List<MarianumDate> events() {
+    final today = DateTime.now();
+    DateTime at(int offset, [int hour = 0, int minute = 0]) => DateTime(
+      today.year,
+      today.month,
+      today.day,
+      hour,
+      minute,
+    ).add(Duration(days: offset));
+
+    return [
+      MarianumDate(
+        uid: 'demo-klausur-mathe',
+        title: 'Klausur Mathematik ${DemoPersona.className}',
+        description: 'Erste Klausur bei Herr Müller. Themen: Analysis.',
+        start: at(4, 9, 45),
+        end: at(4, 11, 15),
+        isAllDay: false,
+      ),
+      MarianumDate(
+        uid: 'demo-wandertag',
+        title: 'Wandertag',
+        description: 'Gemeinsamer Ausflug der Jahrgangsstufe 10.',
+        start: at(11),
+        end: at(12),
+        isAllDay: true,
+      ),
+      MarianumDate(
+        uid: 'demo-elternsprechtag',
+        title: 'Elternsprechtag',
+        description: 'Anmeldung zu den Gesprächen über das Sekretariat.',
+        start: at(18, 14, 0),
+        end: at(18, 19, 0),
+        isAllDay: false,
+      ),
+      MarianumDate(
+        uid: 'demo-zeugniskonferenz',
+        title: 'Zeugniskonferenz',
+        description: 'Unterrichtsfrei ab der 4. Stunde.',
+        start: at(32),
+        end: at(33),
+        isAllDay: true,
+      ),
+    ];
+  }
+}
diff --git a/lib/api/demo/data/demo_marianum_message.dart b/lib/api/demo/data/demo_marianum_message.dart
new file mode 100644
index 0000000..071c8d5
--- /dev/null
+++ b/lib/api/demo/data/demo_marianum_message.dart
@@ -0,0 +1,24 @@
+import '../../../state/app/modules/marianum_message/bloc/marianum_message_state.dart';
+
+/// Demo fixtures for the info messages — a single friendly welcome entry so the
+/// section is populated rather than empty.
+class DemoMarianumMessage {
+  const DemoMarianumMessage._();
+
+  static MarianumMessageList list() {
+    final today = DateTime.now();
+    final date =
+        '${today.day.toString().padLeft(2, '0')}.${today.month.toString().padLeft(2, '0')}.${today.year}';
+
+    return MarianumMessageList(
+      base: 'https://marianum-fulda.de',
+      messages: [
+        MarianumMessage(
+          name: 'Willkommen in der Marianum-App',
+          date: date,
+          url: 'https://marianum-fulda.de',
+        ),
+      ],
+    );
+  }
+}
diff --git a/lib/api/demo/data/demo_talk.dart b/lib/api/demo/data/demo_talk.dart
new file mode 100644
index 0000000..0b045bf
--- /dev/null
+++ b/lib/api/demo/data/demo_talk.dart
@@ -0,0 +1,429 @@
+import '../../../model/account_data.dart';
+import '../../marianumcloud/talk/chat/get_chat_response.dart';
+import '../../marianumcloud/talk/room/get_room_response.dart';
+import '../demo_persona.dart';
+
+/// Fixtures for the Talk module while [DemoMode] is active: a curated set of
+/// rooms plus a believable German conversation per room. Room tokens are the
+/// join between [rooms] and [chat] — they must stay in sync.
+class DemoTalk {
+  const DemoTalk._();
+
+  static const String tokenClass = 'demo-klasse-10b';
+  static const String tokenMathLk = 'demo-mathe-lk';
+  static const String tokenWeber = 'demo-herr-weber';
+  static const String tokenWeimar = 'demo-weimar';
+  static const String tokenSv = 'demo-sv';
+
+  static GetRoomResponse rooms() {
+    return GetRoomResponse({
+      _room(
+        id: 100,
+        token: tokenClass,
+        type: GetRoomResponseObjectConversationType.group,
+        name: 'Klasse 10b',
+        displayName: 'Klasse ${DemoPersona.className}',
+        lastMessage: _lastOf(tokenClass),
+        unreadMessages: 2,
+        isFavorite: true,
+      ),
+      _room(
+        id: 200,
+        token: tokenMathLk,
+        type: GetRoomResponseObjectConversationType.group,
+        name: 'Mathe-LK',
+        displayName: 'Mathe-LK · Herr Müller',
+        lastMessage: _lastOf(tokenMathLk),
+      ),
+      _room(
+        id: 300,
+        token: tokenWeber,
+        type: GetRoomResponseObjectConversationType.oneToOne,
+        name: 'weber',
+        displayName: 'Herr Weber',
+        lastMessage: _lastOf(tokenWeber),
+        unreadMessages: 1,
+      ),
+      _room(
+        id: 400,
+        token: tokenWeimar,
+        type: GetRoomResponseObjectConversationType.group,
+        name: 'Fahrt nach Weimar',
+        displayName: 'Fahrt nach Weimar 🚌',
+        lastMessage: _lastOf(tokenWeimar),
+      ),
+      _room(
+        id: 500,
+        token: tokenSv,
+        type: GetRoomResponseObjectConversationType.group,
+        name: 'SV',
+        displayName: 'SV – Schülervertretung',
+        lastMessage: _lastOf(tokenSv),
+      ),
+    });
+  }
+
+  static GetChatResponse chat(String token) =>
+      GetChatResponse(_messages(token).toSet());
+
+  static GetChatResponseObject _lastOf(String token) => _messages(token).last;
+
+  static List<GetChatResponseObject> _messages(String token) {
+    switch (token) {
+      case tokenClass:
+        return _classChat();
+      case tokenMathLk:
+        return _mathLkChat();
+      case tokenWeber:
+        return _weberChat();
+      case tokenWeimar:
+        return _weimarChat();
+      case tokenSv:
+        return _svChat();
+      default:
+        return _genericChat(token);
+    }
+  }
+
+  static List<GetChatResponseObject> _classChat() {
+    const token = tokenClass;
+    var base = 10000;
+    return [
+      _msg(
+        id: base + 1,
+        token: token,
+        actor: 'sophie',
+        display: 'Sophie',
+        ago: const Duration(days: 1, hours: 4),
+        message: 'Weiß jemand, was wir in Bio auf haben?',
+      ),
+      _msg(
+        id: base + 2,
+        token: token,
+        actor: 'max',
+        display: 'Max',
+        ago: const Duration(days: 1, hours: 3, minutes: 55),
+        message: 'S. 42 Nr. 3 und 4, glaube ich',
+      ),
+      _selfMsg(
+        id: base + 3,
+        token: token,
+        ago: const Duration(days: 1, hours: 3, minutes: 50),
+        message: 'Ja genau, und das Arbeitsblatt zur Zellteilung 🙌',
+        reactions: {'👍': 3},
+      ),
+      _msg(
+        id: base + 4,
+        token: token,
+        actor: 'jonas',
+        display: 'Jonas',
+        ago: const Duration(days: 1, hours: 3, minutes: 40),
+        message: 'Danke euch! 🙏',
+      ),
+      _msg(
+        id: base + 5,
+        token: token,
+        actor: 'emma',
+        display: 'Emma',
+        ago: const Duration(hours: 20),
+        message: 'Ist die Mathe-Arbeit jetzt am Donnerstag oder Freitag?',
+      ),
+      _msg(
+        id: base + 6,
+        token: token,
+        actor: 'mueller',
+        display: 'Herr Müller',
+        ago: const Duration(hours: 19, minutes: 30),
+        message: 'Die Arbeit findet am Freitag in der 3. Stunde statt.',
+      ),
+      _msg(
+        id: base + 7,
+        token: token,
+        actor: 'emma',
+        display: 'Emma',
+        ago: const Duration(hours: 19, minutes: 20),
+        message: 'Danke, Herr Müller!',
+      ),
+      _msg(
+        id: base + 8,
+        token: token,
+        actor: 'paul',
+        display: 'Paul',
+        ago: const Duration(hours: 6),
+        message: 'Wer kommt morgen mit in die Mensa?',
+      ),
+      _msg(
+        id: base + 9,
+        token: token,
+        actor: 'mia',
+        display: 'Mia',
+        ago: const Duration(hours: 5, minutes: 50),
+        message: 'Ich bin dabei 🍕',
+      ),
+      _selfMsg(
+        id: base + 10,
+        token: token,
+        ago: const Duration(hours: 5, minutes: 45),
+        message: 'Ich auch!',
+      ),
+      _msg(
+        id: base + 11,
+        token: token,
+        actor: 'sophie',
+        display: 'Sophie',
+        ago: const Duration(hours: 3),
+        message:
+            'Vergesst nicht, die Einverständniserklärung für Weimar abzugeben 🚌',
+        reactions: {'👍': 5, '🚌': 2},
+      ),
+      _msg(
+        id: base + 12,
+        token: token,
+        actor: 'ben',
+        display: 'Ben',
+        ago: const Duration(hours: 2, minutes: 10),
+        message: 'Oh stimmt, hab ich fast vergessen 😅',
+      ),
+    ];
+  }
+
+  static List<GetChatResponseObject> _mathLkChat() {
+    const token = tokenMathLk;
+    var base = 20000;
+    return [
+      _msg(
+        id: base + 1,
+        token: token,
+        actor: 'mueller',
+        display: 'Herr Müller',
+        ago: const Duration(days: 2, hours: 2),
+        message:
+            'Zur Vorbereitung auf die Arbeit findet ihr die Übungsblätter in den Dateien.',
+      ),
+      _selfMsg(
+        id: base + 2,
+        token: token,
+        ago: const Duration(days: 1, hours: 6),
+        message: 'Danke! Können wir Aufgabe 5 nächste Stunde nochmal besprechen?',
+      ),
+      _msg(
+        id: base + 3,
+        token: token,
+        actor: 'mueller',
+        display: 'Herr Müller',
+        ago: const Duration(days: 1, hours: 5, minutes: 30),
+        message: 'Klar, wir schauen uns die Kurvendiskussion gemeinsam an.',
+        reactions: {'👍': 4},
+      ),
+      _msg(
+        id: base + 4,
+        token: token,
+        actor: 'jonas',
+        display: 'Jonas',
+        ago: const Duration(hours: 8),
+        message: 'Super, danke!',
+      ),
+    ];
+  }
+
+  static List<GetChatResponseObject> _weberChat() {
+    const token = tokenWeber;
+    var base = 30000;
+    return [
+      _selfMsg(
+        id: base + 1,
+        token: token,
+        ago: const Duration(days: 1, hours: 2),
+        message:
+            'Guten Tag Herr Weber, ich war letzte Woche krank. Was muss ich in Englisch nachholen?',
+      ),
+      _msg(
+        id: base + 2,
+        token: token,
+        actor: 'weber',
+        display: 'Herr Weber',
+        ago: const Duration(hours: 4),
+        message:
+            'Hallo Lena, gute Besserung! Lies bitte Unit 4 und bereite die Vokabeln vor.',
+      ),
+      _msg(
+        id: base + 3,
+        token: token,
+        actor: 'weber',
+        display: 'Herr Weber',
+        ago: const Duration(hours: 3, minutes: 58),
+        message: 'Die Präsentation kannst du nächste Woche nachholen.',
+      ),
+    ];
+  }
+
+  static List<GetChatResponseObject> _weimarChat() {
+    const token = tokenWeimar;
+    var base = 40000;
+    return [
+      _msg(
+        id: base + 1,
+        token: token,
+        actor: 'wagner',
+        display: 'Frau Wagner',
+        ago: const Duration(days: 3),
+        message:
+            'Wir treffen uns am Montag um 7:45 Uhr am Haupteingang. Bitte pünktlich sein!',
+        reactions: {'👍': 8},
+      ),
+      _msg(
+        id: base + 2,
+        token: token,
+        actor: 'paul',
+        display: 'Paul',
+        ago: const Duration(days: 2, hours: 20),
+        message: 'Wie lange sind wir ungefähr unterwegs?',
+      ),
+      _msg(
+        id: base + 3,
+        token: token,
+        actor: 'wagner',
+        display: 'Frau Wagner',
+        ago: const Duration(days: 2, hours: 19),
+        message: 'Etwa zwei Stunden mit dem Bus. Denkt an Verpflegung!',
+      ),
+      _selfMsg(
+        id: base + 4,
+        token: token,
+        ago: const Duration(hours: 12),
+        message: 'Freue mich schon! 🎉',
+        reactions: {'🎉': 6},
+      ),
+    ];
+  }
+
+  static List<GetChatResponseObject> _svChat() {
+    const token = tokenSv;
+    var base = 50000;
+    return [
+      _msg(
+        id: base + 1,
+        token: token,
+        actor: 'ben',
+        display: 'Ben',
+        ago: const Duration(days: 2, hours: 5),
+        message: 'Nächste SV-Sitzung ist am Mittwoch in der großen Pause.',
+      ),
+      _msg(
+        id: base + 2,
+        token: token,
+        actor: 'mia',
+        display: 'Mia',
+        ago: const Duration(days: 1, hours: 8),
+        message: 'Können wir über den Ablauf vom Sommerfest sprechen?',
+      ),
+      _selfMsg(
+        id: base + 3,
+        token: token,
+        ago: const Duration(hours: 9),
+        message: 'Gute Idee, ich sammle schon mal Vorschläge.',
+        reactions: {'👍': 3},
+      ),
+    ];
+  }
+
+  static List<GetChatResponseObject> _genericChat(String token) {
+    return [
+      _msg(
+        id: 90001,
+        token: token,
+        actor: 'info',
+        display: 'MarianumConnect',
+        ago: const Duration(hours: 1),
+        message: 'Willkommen im Demo-Chat 👋',
+      ),
+    ];
+  }
+
+  static GetChatResponseObject _selfMsg({
+    required int id,
+    required String token,
+    required Duration ago,
+    required String message,
+    Map<String, int>? reactions,
+  }) => _msg(
+    id: id,
+    token: token,
+    actor: AccountData().getUsername(),
+    display: DemoPersona.studentName,
+    ago: ago,
+    message: message,
+    reactions: reactions,
+  );
+
+  static GetChatResponseObject _msg({
+    required int id,
+    required String token,
+    required String actor,
+    required String display,
+    required Duration ago,
+    required String message,
+    Map<String, int>? reactions,
+  }) => GetChatResponseObject(
+    id,
+    token,
+    GetRoomResponseObjectMessageActorType.user,
+    actor,
+    display,
+    _epoch(ago),
+    '',
+    GetRoomResponseObjectMessageType.comment,
+    true,
+    'demo-ref-$id',
+    message,
+    null,
+    reactions,
+    null,
+    null,
+  );
+
+  static GetRoomResponseObject _room({
+    required int id,
+    required String token,
+    required GetRoomResponseObjectConversationType type,
+    required String name,
+    required String displayName,
+    required GetChatResponseObject lastMessage,
+    int unreadMessages = 0,
+    bool isFavorite = false,
+  }) => GetRoomResponseObject(
+    id,
+    token,
+    type,
+    name,
+    displayName,
+    '',
+    3,
+    0,
+    0,
+    0,
+    0,
+    'demo-session-$id',
+    false,
+    false,
+    0,
+    false,
+    false,
+    true,
+    lastMessage.timestamp,
+    isFavorite,
+    GetRoomResponseObjectParticipantNotificationLevel.defaultLevel,
+    unreadMessages,
+    false,
+    false,
+    lastMessage.id - unreadMessages,
+    lastMessage.id,
+    lastMessage,
+    null,
+    null,
+    null,
+  );
+
+  static int _epoch(Duration ago) =>
+      DateTime.now().subtract(ago).millisecondsSinceEpoch ~/ 1000;
+}
diff --git a/lib/api/demo/data/demo_timetable.dart b/lib/api/demo/data/demo_timetable.dart
new file mode 100644
index 0000000..96efea0
--- /dev/null
+++ b/lib/api/demo/data/demo_timetable.dart
@@ -0,0 +1,202 @@
+import '../../marianumconnect/queries/timetable_get_holidays/timetable_get_holidays_response.dart';
+import '../../marianumconnect/queries/timetable_get_rooms/timetable_get_rooms_response.dart';
+import '../../marianumconnect/queries/timetable_get_schoolyear/timetable_get_schoolyear_response.dart';
+import '../../marianumconnect/queries/timetable_get_subjects/timetable_get_subjects_response.dart';
+import '../../marianumconnect/queries/timetable_get_timegrid/timetable_get_timegrid_response.dart';
+import '../../marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
+import '../../mhsl/custom_timetable_event/get/get_custom_timetable_event_response.dart';
+import '../demo_persona.dart';
+
+/// Curated timetable fixtures for the demo mode. Everything is derived from
+/// [DemoPersona] so subjects, teachers and rooms line up with the rest of the
+/// demo app, and every week is generated relative to the requested range so
+/// navigating forward/backward always lands on a populated 10b schedule.
+class DemoTimetable {
+  const DemoTimetable._();
+
+  /// Period → (startHour, startMinute, endHour, endMinute).
+  static const Map<int, (int, int, int, int)> _periods = {
+    1: (7, 55, 8, 40),
+    2: (8, 40, 9, 25),
+    3: (9, 45, 10, 30),
+    4: (10, 30, 11, 15),
+    5: (11, 35, 12, 20),
+    6: (12, 20, 13, 5),
+    7: (13, 50, 14, 35),
+    8: (14, 35, 15, 20),
+  };
+
+  /// Weekday (DateTime.monday..friday) → period → subject short code.
+  static const Map<int, Map<int, String>> _plan = {
+    DateTime.monday: {1: 'M', 2: 'M', 3: 'D', 4: 'E', 5: 'BIO', 6: 'GE', 7: 'SP', 8: 'SP'},
+    DateTime.tuesday: {1: 'E', 2: 'E', 3: 'PH', 4: 'M', 5: 'D', 6: 'REL', 7: 'GE'},
+    DateTime.wednesday: {1: 'BIO', 2: 'BIO', 3: 'M', 4: 'D', 5: 'E', 6: 'PH'},
+    DateTime.thursday: {1: 'D', 2: 'GE', 3: 'M', 4: 'M', 5: 'REL', 6: 'BIO', 7: 'SP', 8: 'SP'},
+    DateTime.friday: {1: 'PH', 2: 'PH', 3: 'E', 4: 'M', 5: 'D', 6: 'GE'},
+  };
+
+  static const Map<String, String> _roomBySubject = {
+    'M': 'A101',
+    'D': 'A101',
+    'E': 'A102',
+    'BIO': 'B201',
+    'PH': 'B203',
+    'GE': 'A101',
+    'SP': 'Turnhalle 1',
+    'REL': 'C305',
+  };
+
+  static TimetableGetWeekResponse week(DateTime from, DateTime until) {
+    final monday = _mondayOf(from);
+    final entries = <McTimetableEntry>[];
+    var id = 1;
+
+    for (final weekday in _plan.keys) {
+      final date = monday.add(Duration(days: weekday - DateTime.monday));
+      final day = _plan[weekday]!;
+      for (final entry in day.entries) {
+        entries.add(_entry(id++, date, weekday, entry.key, entry.value));
+      }
+    }
+
+    return TimetableGetWeekResponse(from: from, until: until, entries: entries);
+  }
+
+  static McTimetableEntry _entry(
+    int id,
+    DateTime date,
+    int weekday,
+    int period,
+    String subjectShort,
+  ) {
+    final times = _periods[period]!;
+    final teacher = _teacherFor(subjectShort);
+
+    // A couple of recurring irregularities so the demo shows off the cancelled
+    // and substitution rendering.
+    final cancelled = weekday == DateTime.monday && period == 4;
+    final substituted = weekday == DateTime.tuesday && period == 3;
+
+    return McTimetableEntry(
+      id: id,
+      date: date,
+      startTime: DateTime(1970, 1, 1, times.$1, times.$2),
+      endTime: DateTime(1970, 1, 1, times.$3, times.$4),
+      subjects: [subjectShort],
+      teachers: [
+        if (substituted)
+          McTimetableTeacher(
+            shortName: 'MÜL',
+            displayName: 'Herr Müller',
+            originalShortName: teacher.short,
+            originalDisplayName: teacher.name,
+          )
+        else
+          McTimetableTeacher(shortName: teacher.short, displayName: teacher.name),
+      ],
+      rooms: [_roomBySubject[subjectShort] ?? DemoPersona.rooms.first],
+      classNames: [DemoPersona.className],
+      lessonType: 'LESSON',
+      status: cancelled
+          ? 'CANCELLED'
+          : substituted
+          ? 'IRREGULAR'
+          : 'REGULAR',
+      substitutionText: substituted ? 'Vertretung für ${teacher.name}' : null,
+      lessonText: null,
+      infoText: cancelled ? 'Fällt aus' : null,
+    );
+  }
+
+  static TimetableGetRoomsResponse rooms() => TimetableGetRoomsResponse(
+    result: [
+      for (var i = 0; i < DemoPersona.rooms.length; i++)
+        McRoom(id: i + 1, shortName: DemoPersona.rooms[i], longName: DemoPersona.rooms[i]),
+    ],
+  );
+
+  static TimetableGetSubjectsResponse subjects() => TimetableGetSubjectsResponse(
+    result: [
+      for (var i = 0; i < DemoPersona.subjects.length; i++)
+        McSubject(
+          id: i + 1,
+          shortName: DemoPersona.subjects[i].short,
+          longName: DemoPersona.subjects[i].name,
+        ),
+    ],
+  );
+
+  static TimetableGetTimegridResponse timegrid() {
+    final units = <McTimegridUnit>[];
+    for (final day in _weekdays) {
+      for (final period in _periods.entries) {
+        final t = period.value;
+        units.add(
+          McTimegridUnit(
+            dayOfWeek: day,
+            label: '${period.key}',
+            startTime: DateTime(1970, 1, 1, t.$1, t.$2),
+            endTime: DateTime(1970, 1, 1, t.$3, t.$4),
+          ),
+        );
+      }
+    }
+    return TimetableGetTimegridResponse(result: units);
+  }
+
+  static TimetableGetSchoolyearResponse schoolyear() {
+    final startYear = _schoolyearStart(DateTime.now());
+    return TimetableGetSchoolyearResponse(
+      id: 1,
+      name: '$startYear/${startYear + 1}',
+      startDate: DateTime(startYear, 8, 1),
+      endDate: DateTime(startYear + 1, 7, 31),
+    );
+  }
+
+  static TimetableGetHolidaysResponse holidays() {
+    final startYear = _schoolyearStart(DateTime.now());
+    return TimetableGetHolidaysResponse(
+      result: [
+        McHoliday(
+          shortName: 'Herbst',
+          longName: 'Herbstferien',
+          startDate: DateTime(startYear, 10, 20),
+          endDate: DateTime(startYear, 10, 31),
+        ),
+        McHoliday(
+          shortName: 'Weihnachten',
+          longName: 'Weihnachtsferien',
+          startDate: DateTime(startYear, 12, 22),
+          endDate: DateTime(startYear + 1, 1, 6),
+        ),
+      ],
+    );
+  }
+
+  static GetCustomTimetableEventResponse customEvents() =>
+      GetCustomTimetableEventResponse([]);
+
+  static const List<McDayOfWeek> _weekdays = [
+    McDayOfWeek.monday,
+    McDayOfWeek.tuesday,
+    McDayOfWeek.wednesday,
+    McDayOfWeek.thursday,
+    McDayOfWeek.friday,
+  ];
+
+  static DemoTeacher _teacherFor(String subjectShort) {
+    final subjectName = DemoPersona.subjects
+        .firstWhere((s) => s.short == subjectShort)
+        .name;
+    return DemoPersona.teachers.firstWhere((t) => t.subject == subjectName);
+  }
+
+  static DateTime _mondayOf(DateTime date) {
+    final day = DateTime(date.year, date.month, date.day);
+    return day.subtract(Duration(days: day.weekday - DateTime.monday));
+  }
+
+  static int _schoolyearStart(DateTime now) =>
+      now.month >= 8 ? now.year : now.year - 1;
+}
diff --git a/lib/api/demo/demo_marianumconnect.dart b/lib/api/demo/demo_marianumconnect.dart
new file mode 100644
index 0000000..b98ebf1
--- /dev/null
+++ b/lib/api/demo/demo_marianumconnect.dart
@@ -0,0 +1,54 @@
+import 'data/demo_breaker.dart';
+import 'data/demo_holidays.dart';
+import 'data/demo_timetable.dart';
+
+/// Single source of truth for the MarianumConnect demo responses. The demo
+/// interceptor asks this for the body of any MC request. Read endpoints reuse
+/// the typed fixtures and serialize them to the exact shape the matching query
+/// parses (a bare list vs. an object); write/side-effect endpoints (telemetry,
+/// client-errors, auth, push, feedback) have no consumed body and resolve to an
+/// empty success.
+class DemoMarianumConnect {
+  const DemoMarianumConnect._();
+
+  /// Body for [path] (relative to `/api/mobile/v1/`), using [query] for the
+  /// timetable date window.
+  static Object responseBody(String path, Map<String, dynamic> query) {
+    switch (path) {
+      case 'timetable/me':
+        return DemoTimetable.week(
+          _date(query['from']),
+          _date(query['until']),
+        ).toJson();
+      case 'timetable/schoolyear':
+        return DemoTimetable.schoolyear().toJson();
+      case 'timetable/rooms':
+        return DemoTimetable.rooms().result.map((e) => e.toJson()).toList();
+      case 'timetable/subjects':
+        return DemoTimetable.subjects().result.map((e) => e.toJson()).toList();
+      case 'timetable/timegrid':
+        return DemoTimetable.timegrid().result.map((e) => e.toJson()).toList();
+      case 'timetable/holidays':
+        return DemoTimetable.holidays().result.map((e) => e.toJson()).toList();
+      case 'holidays':
+        return DemoHolidays.upcoming().map((e) => e.toJson()).toList();
+      case 'breaker':
+        return DemoBreaker.none().toJson();
+      case 'timetable/elements/teachers':
+      case 'timetable/elements/students':
+      case 'timetable/elements/classes':
+        return const <dynamic>[];
+    }
+    // A foreign element's week (timetable/<type>/<id>) shows the same demo week.
+    if (path.startsWith('timetable/')) {
+      return DemoTimetable.week(
+        _date(query['from']),
+        _date(query['until']),
+      ).toJson();
+    }
+    return const <String, dynamic>{};
+  }
+
+  static DateTime _date(Object? raw) =>
+      DateTime.tryParse(raw?.toString() ?? '') ?? DateTime.now();
+}
diff --git a/lib/api/demo/demo_marianumconnect_interceptor.dart b/lib/api/demo/demo_marianumconnect_interceptor.dart
new file mode 100644
index 0000000..fd36572
--- /dev/null
+++ b/lib/api/demo/demo_marianumconnect_interceptor.dart
@@ -0,0 +1,35 @@
+import 'package:dio/dio.dart';
+
+import 'demo_marianumconnect.dart';
+import 'demo_mode.dart';
+
+/// Answers every MarianumConnect request from fixtures while a demo session is
+/// active, so the app makes no MC network calls. Installed first on the MC dio
+/// so it resolves before the auth interceptor tries to attach a (non-existent)
+/// bearer token.
+class DemoMarianumConnectInterceptor extends Interceptor {
+  static const _apiMarker = '/api/mobile/v1/';
+
+  @override
+  void onRequest(RequestOptions options, RequestInterceptorHandler handler) {
+    if (!DemoMode.active) {
+      handler.next(options);
+      return;
+    }
+    handler.resolve(
+      Response<dynamic>(
+        requestOptions: options,
+        statusCode: 200,
+        data: DemoMarianumConnect.responseBody(
+          _relativePath(options.uri),
+          options.queryParameters,
+        ),
+      ),
+    );
+  }
+
+  static String _relativePath(Uri uri) {
+    final i = uri.path.indexOf(_apiMarker);
+    return i >= 0 ? uri.path.substring(i + _apiMarker.length) : uri.path;
+  }
+}
diff --git a/lib/api/demo/demo_mode.dart b/lib/api/demo/demo_mode.dart
new file mode 100644
index 0000000..4da95d8
--- /dev/null
+++ b/lib/api/demo/demo_mode.dart
@@ -0,0 +1,27 @@
+import '../../model/account_data.dart';
+
+/// Central switch for the client-side demo mode.
+///
+/// A login whose username starts with [usernamePrefix] (the password is
+/// ignored) enters demo mode: instead of talking to the real backends, the app
+/// serves curated fixtures from `DemoData` for every feature. This lets Google
+/// Play reviewers and automated screenshot runs see a fully populated app
+/// without a real account and without any network dependency.
+///
+/// The flag is persisted through [AccountData.isDemo], so a demo session
+/// survives cold starts exactly like a normal login. It works in release builds
+/// too — reviewers run the shipped release build.
+class DemoMode {
+  const DemoMode._();
+
+  /// Usernames starting with this prefix trigger demo mode. Whatever the
+  /// reviewer types as the password is accepted.
+  static const String usernamePrefix = 'demo@';
+
+  /// Whether [username], as typed on the login screen, should enter demo mode.
+  static bool matches(String username) =>
+      username.trim().toLowerCase().startsWith(usernamePrefix);
+
+  /// True while the active session is a demo session.
+  static bool get active => AccountData().isDemo;
+}
diff --git a/lib/api/demo/demo_persona.dart b/lib/api/demo/demo_persona.dart
new file mode 100644
index 0000000..cee3cbf
--- /dev/null
+++ b/lib/api/demo/demo_persona.dart
@@ -0,0 +1,58 @@
+/// Shared identity for the demo mode so fixtures across every feature describe
+/// the same fictional student, class, teachers and rooms — the timetable, chats
+/// and grades all line up. See DemoMode.
+class DemoPersona {
+  const DemoPersona._();
+
+  static const String studentFirstName = 'Lena';
+  static const String studentName = 'Lena Hoffmann';
+  static const String className = '10b';
+
+  static const List<DemoTeacher> teachers = [
+    DemoTeacher('Herr Müller', 'MÜL', 'Mathematik'),
+    DemoTeacher('Frau Schmidt', 'SMT', 'Deutsch'),
+    DemoTeacher('Herr Weber', 'WEB', 'Englisch'),
+    DemoTeacher('Frau Becker', 'BEC', 'Biologie'),
+    DemoTeacher('Herr Hofmann', 'HOF', 'Physik'),
+    DemoTeacher('Frau Wagner', 'WAG', 'Geschichte'),
+    DemoTeacher('Herr Klein', 'KLN', 'Sport'),
+    DemoTeacher('Frau Richter', 'RIC', 'Religion'),
+  ];
+
+  static const List<DemoSubject> subjects = [
+    DemoSubject('Mathematik', 'M', 0xFF4E79A7),
+    DemoSubject('Deutsch', 'D', 0xFFE15759),
+    DemoSubject('Englisch', 'E', 0xFFF28E2B),
+    DemoSubject('Biologie', 'BIO', 0xFF59A14F),
+    DemoSubject('Physik', 'PH', 0xFF76B7B2),
+    DemoSubject('Geschichte', 'GE', 0xFFB07AA1),
+    DemoSubject('Sport', 'SP', 0xFFEDC948),
+    DemoSubject('Religion', 'REL', 0xFF9C755F),
+  ];
+
+  static const List<String> rooms = [
+    'A101',
+    'A102',
+    'B201',
+    'B203',
+    'C305',
+    'Turnhalle 1',
+    'Aula',
+  ];
+}
+
+class DemoTeacher {
+  final String name;
+  final String short;
+  final String subject;
+  const DemoTeacher(this.name, this.short, this.subject);
+}
+
+class DemoSubject {
+  final String name;
+  final String short;
+
+  /// ARGB color used where the UI colors a lesson/subject.
+  final int color;
+  const DemoSubject(this.name, this.short, this.color);
+}
diff --git a/lib/api/marianumconnect/auth/session_validator.dart b/lib/api/marianumconnect/auth/session_validator.dart
index bea519d..4280b4b 100644
--- a/lib/api/marianumconnect/auth/session_validator.dart
+++ b/lib/api/marianumconnect/auth/session_validator.dart
@@ -14,6 +14,9 @@ class SessionValidator {
     required Future<void> Function() onInvalidated,
   }) async {
     if (!AccountData().isPopulated()) return;
+    // AuthVerify uses its own dio (bypassing the demo interceptor), so a demo
+    // session must be skipped here or its missing token would 401 into a logout.
+    if (AccountData().isDemo) return;
     final username = AccountData().getUsername();
     final password = AccountData().getPassword();
     try {
diff --git a/lib/api/marianumconnect/marianumconnect_api.dart b/lib/api/marianumconnect/marianumconnect_api.dart
index 0d7c7bc..e9d226e 100644
--- a/lib/api/marianumconnect/marianumconnect_api.dart
+++ b/lib/api/marianumconnect/marianumconnect_api.dart
@@ -1,5 +1,6 @@
 import 'package:dio/dio.dart';
 
+import '../demo/demo_marianumconnect_interceptor.dart';
 import 'auth/auth_interceptor.dart';
 
 /// Singleton dio instance for the Marianum-Connect mobile API. Wired with the
@@ -24,6 +25,7 @@ class MarianumConnectApi {
         contentType: 'application/json',
       ),
     );
+    dio.interceptors.add(DemoMarianumConnectInterceptor());
     dio.interceptors.add(MarianumConnectAuthInterceptor());
     return dio;
   }
diff --git a/lib/model/account_data.dart b/lib/model/account_data.dart
index c033578..8ba8a3a 100644
--- a/lib/model/account_data.dart
+++ b/lib/model/account_data.dart
@@ -18,6 +18,10 @@ class AccountData {
   // token, so two registrations need two app passwords.
   static const _appPasswordField = 'nextcloud_app_password';
   static const _appPasswordTalkField = 'nextcloud_app_password_talk';
+  // Persists the demo session across cold starts (see DemoMode).
+  static const _demoField = 'is_demo';
+  // Keeps isPopulated()/getPassword() valid; demo mode never uses a real one.
+  static const _demoPasswordPlaceholder = 'demo';
 
   static const FlutterSecureStorage _secureStorage = FlutterSecureStorage();
 
@@ -34,6 +38,10 @@ class AccountData {
   String? _password;
   String? _appPassword;
   String? _appPasswordTalk;
+  bool _isDemo = false;
+
+  /// True while the active session is a local demo session (see DemoMode).
+  bool get isDemo => _isDemo;
 
   String getUsername() {
     if (_username == null) throw Exception('Username not initialized');
@@ -65,14 +73,31 @@ class AccountData {
     if (!_populated.isCompleted) _populated.complete();
   }
 
+  /// Enters a local demo session for [username] — no real credentials or token;
+  /// every backend is served from fixtures while [isDemo] is true (see DemoMode).
+  Future<void> setDemo(String username) async {
+    await _secureStorage.write(key: _usernameField, value: username);
+    await _secureStorage.write(
+      key: _passwordField,
+      value: _demoPasswordPlaceholder,
+    );
+    await _secureStorage.write(key: _demoField, value: 'true');
+    _username = username;
+    _password = _demoPasswordPlaceholder;
+    _isDemo = true;
+    if (!_populated.isCompleted) _populated.complete();
+  }
+
   Future<void> removeData() async {
     _populated = Completer();
     _username = null;
     _password = null;
     _appPassword = null;
     _appPasswordTalk = null;
+    _isDemo = false;
     await _secureStorage.delete(key: _usernameField);
     await _secureStorage.delete(key: _passwordField);
+    await _secureStorage.delete(key: _demoField);
     await _clearAppPasswordStorage();
     await _clearAppPasswordTalkStorage();
   }
@@ -139,6 +164,7 @@ class AccountData {
     await _migrateFromLegacyStorage();
     _username = await _secureStorage.read(key: _usernameField);
     _password = await _secureStorage.read(key: _passwordField);
+    _isDemo = (await _secureStorage.read(key: _demoField)) == 'true';
     try {
       _appPassword = await pushSecureStorage.read(key: _appPasswordField);
       _appPasswordTalk = await pushSecureStorage.read(
diff --git a/lib/push/push_registration.dart b/lib/push/push_registration.dart
index 08580e4..4c98d7a 100644
--- a/lib/push/push_registration.dart
+++ b/lib/push/push_registration.dart
@@ -5,6 +5,7 @@ import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:nextcloud/notifications.dart' show generatePushTokenHash;
 import 'package:package_info_plus/package_info_plus.dart';
 
+import '../api/demo/demo_mode.dart';
 import '../api/marianumcloud/app_password/delete_app_password.dart';
 import '../api/marianumcloud/app_password/get_app_password.dart';
 import '../api/marianumconnect/marianumconnect_endpoint.dart';
@@ -93,6 +94,7 @@ class PushRegistration {
   /// transport failures are logged and swallowed so callers can
   /// fire-and-forget (and simply ignore the result).
   Future<bool> register() async {
+    if (DemoMode.active) return false;
     final String? fcmToken;
     try {
       fcmToken = await FirebaseMessaging.instance.getToken();
@@ -383,6 +385,7 @@ class PushRegistration {
   /// is called with), then clear them locally. Ordered so the proxy stops
   /// pushing before credentials are gone.
   Future<void> logoutCleanup() async {
+    if (DemoMode.active) return;
     await unregister();
     try {
       await DeleteAppPassword().run();
diff --git a/lib/state/app/modules/breaker/data_provider/breaker_data_provider.dart b/lib/state/app/modules/breaker/data_provider/breaker_data_provider.dart
index be5a131..fd22cf3 100644
--- a/lib/state/app/modules/breaker/data_provider/breaker_data_provider.dart
+++ b/lib/state/app/modules/breaker/data_provider/breaker_data_provider.dart
@@ -12,9 +12,9 @@ class BreakerDataProvider {
     bool renew = true,
     void Function(Object)? onError,
   }) => resolveFromCache<GetBreakersResponse>(
-    (onUpdate, onError) =>
-        GetBreakersCache(renew: renew, onUpdate: onUpdate, onError: onError),
-    onError: onError,
-    operationName: 'getBreakers',
-  );
+      (onUpdate, onError) =>
+          GetBreakersCache(renew: renew, onUpdate: onUpdate, onError: onError),
+      onError: onError,
+      operationName: 'getBreakers',
+    );
 }
diff --git a/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart b/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart
index 4217c9c..bd76d13 100644
--- a/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart
+++ b/lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart
@@ -2,6 +2,8 @@ import 'dart:developer';
 
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 
+import '../../../../../api/demo/data/demo_capabilities.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumconnect/queries/get_capabilities/get_capabilities.dart';
 import 'capabilities_state.dart';
 
@@ -20,6 +22,10 @@ class CapabilitiesCubit extends HydratedCubit<CapabilitiesState> {
   /// state is marked `loaded` — a failed fetch never silently grants a
   /// capability, and an offline launch keeps whatever was cached.
   Future<void> load() async {
+    if (DemoMode.active) {
+      emit(DemoCapabilities.state());
+      return;
+    }
     try {
       final response = await GetCapabilities().run();
       emit(
diff --git a/lib/state/app/modules/chat/data_provider/chat_data_provider.dart b/lib/state/app/modules/chat/data_provider/chat_data_provider.dart
index 9be4252..123baac 100644
--- a/lib/state/app/modules/chat/data_provider/chat_data_provider.dart
+++ b/lib/state/app/modules/chat/data_provider/chat_data_provider.dart
@@ -1,3 +1,5 @@
+import '../../../../../api/demo/data/demo_talk.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumcloud/talk/chat/get_chat_cache.dart';
 import '../../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
 
@@ -8,6 +10,12 @@ class ChatDataProvider {
     void Function(GetChatResponse data)? onNetworkData,
     void Function(Object)? onError,
   }) async {
+    if (DemoMode.active) {
+      final data = DemoTalk.chat(token);
+      onCacheData?.call(data);
+      onNetworkData?.call(data);
+      return;
+    }
     final cache = GetChatCache(
       chatToken: token,
       onCacheData: onCacheData,
diff --git a/lib/state/app/modules/chat_list/data_provider/chat_list_data_provider.dart b/lib/state/app/modules/chat_list/data_provider/chat_list_data_provider.dart
index 8786baa..6189bc3 100644
--- a/lib/state/app/modules/chat_list/data_provider/chat_list_data_provider.dart
+++ b/lib/state/app/modules/chat_list/data_provider/chat_list_data_provider.dart
@@ -1,3 +1,5 @@
+import '../../../../../api/demo/data/demo_talk.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumcloud/talk/create_room/create_room.dart';
 import '../../../../../api/marianumcloud/talk/create_room/create_room_params.dart';
 import '../../../../../api/marianumcloud/talk/room/get_room_cache.dart';
@@ -8,13 +10,18 @@ class ChatListDataProvider {
   Future<GetRoomResponse> getRooms({
     void Function(Object)? onError,
     bool renew = false,
-  }) => resolveFromCache<GetRoomResponse>(
-    (onUpdate, onError) =>
-        GetRoomCache(renew: renew, onUpdate: onUpdate, onError: onError),
-    onError: onError,
-    operationName: 'getRooms',
-  );
+  }) {
+    if (DemoMode.active) return Future.value(DemoTalk.rooms());
+    return resolveFromCache<GetRoomResponse>(
+      (onUpdate, onError) =>
+          GetRoomCache(renew: renew, onUpdate: onUpdate, onError: onError),
+      onError: onError,
+      operationName: 'getRooms',
+    );
+  }
 
-  Future<void> createDirectRoom(String invite) =>
-      CreateRoom(CreateRoomParams(roomType: 1, invite: invite)).run();
+  Future<void> createDirectRoom(String invite) {
+    if (DemoMode.active) return Future.value();
+    return CreateRoom(CreateRoomParams(roomType: 1, invite: invite)).run();
+  }
 }
diff --git a/lib/state/app/modules/files/data_provider/files_data_provider.dart b/lib/state/app/modules/files/data_provider/files_data_provider.dart
index e4a1d5f..17cf211 100644
--- a/lib/state/app/modules/files/data_provider/files_data_provider.dart
+++ b/lib/state/app/modules/files/data_provider/files_data_provider.dart
@@ -1,5 +1,7 @@
 import 'package:nextcloud/nextcloud.dart';
 
+import '../../../../../api/demo/data/demo_files.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumcloud/webdav/queries/list_files/list_files_cache.dart';
 import '../../../../../api/marianumcloud/webdav/queries/list_files/list_files_response.dart';
 import '../../../../../api/marianumcloud/webdav/webdav_api.dart';
@@ -19,20 +21,24 @@ class FilesDataProvider {
     void Function(Object)? onError,
     bool renew = false,
     void Function(int nextAttempt, int maxAttempts)? onRetry,
-  }) => resolveFromCache<ListFilesResponse>(
-    (onUpdate, onError) => ListFilesCache(
-      path: path,
-      onUpdate: onUpdate,
-      onCacheData: onCacheData,
+  }) {
+    if (DemoMode.active) return Future.value(DemoFiles.listing(path));
+    return resolveFromCache<ListFilesResponse>(
+      (onUpdate, onError) => ListFilesCache(
+        path: path,
+        onUpdate: onUpdate,
+        onCacheData: onCacheData,
+        onError: onError,
+        renew: renew,
+        onRetry: onRetry,
+      ),
       onError: onError,
-      renew: renew,
-      onRetry: onRetry,
-    ),
-    onError: onError,
-    operationName: 'listFiles',
-  );
+      operationName: 'listFiles',
+    );
+  }
 
   Future<void> createFolder(String fullPath) async {
+    if (DemoMode.active) return;
     final webdav = await WebdavApi.webdav;
     await webdav.mkcol(PathUri.parse(fullPath));
   }
diff --git a/lib/state/app/modules/grade_averages/bloc/grade_averages_bloc.dart b/lib/state/app/modules/grade_averages/bloc/grade_averages_bloc.dart
index 2d3b89b..af2ba03 100644
--- a/lib/state/app/modules/grade_averages/bloc/grade_averages_bloc.dart
+++ b/lib/state/app/modules/grade_averages/bloc/grade_averages_bloc.dart
@@ -1,15 +1,19 @@
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 
+import '../../../../../api/demo/demo_mode.dart';
 import 'grade_averages_event.dart';
 import 'grade_averages_state.dart';
 
 class GradeAveragesBloc
     extends HydratedBloc<GradeAveragesEvent, GradeAveragesState> {
+  // Seeded with a realistic spread in demo mode (average 2.0); empty otherwise.
+  static const List<int> _demoGrades = [1, 2, 2, 2, 3, 2, 1, 3, 2, 2];
+
   GradeAveragesBloc()
     : super(
-        const GradeAveragesState(
+        GradeAveragesState(
           gradingSystem: GradeAveragesGradingSystem.middleSchool,
-          grades: [],
+          grades: DemoMode.active ? _demoGrades : const [],
         ),
       ) {
     on<GradingSystemChanged>((event, emit) {
diff --git a/lib/state/app/modules/marianum_dates/repository/marianum_dates_repository.dart b/lib/state/app/modules/marianum_dates/repository/marianum_dates_repository.dart
index ead14c9..316b195 100644
--- a/lib/state/app/modules/marianum_dates/repository/marianum_dates_repository.dart
+++ b/lib/state/app/modules/marianum_dates/repository/marianum_dates_repository.dart
@@ -1,7 +1,12 @@
+import '../../../../../api/demo/data/demo_marianum_dates.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../infrastructure/repository/repository.dart';
 import '../bloc/marianum_dates_state.dart';
 import '../data_provider/marianum_dates_get_events.dart';
 
 class MarianumDatesRepository extends Repository<MarianumDatesState> {
-  Future<List<MarianumDate>> getEvents() => MarianumDatesGetEvents().run();
+  Future<List<MarianumDate>> getEvents() {
+    if (DemoMode.active) return Future.value(DemoMarianumDates.events());
+    return MarianumDatesGetEvents().run();
+  }
 }
diff --git a/lib/state/app/modules/marianum_message/repository/marianum_message_repository.dart b/lib/state/app/modules/marianum_message/repository/marianum_message_repository.dart
index 3d26cb4..faa43ee 100644
--- a/lib/state/app/modules/marianum_message/repository/marianum_message_repository.dart
+++ b/lib/state/app/modules/marianum_message/repository/marianum_message_repository.dart
@@ -1,8 +1,12 @@
+import '../../../../../api/demo/data/demo_marianum_message.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../infrastructure/repository/repository.dart';
 import '../bloc/marianum_message_state.dart';
 import '../data_provider/marianum_message_get_messages.dart';
 
 class MarianumMessageRepository extends Repository<MarianumMessageState> {
-  Future<MarianumMessageList> getMessages() =>
-      MarianumMessageGetMessages().run();
+  Future<MarianumMessageList> getMessages() {
+    if (DemoMode.active) return Future.value(DemoMarianumMessage.list());
+    return MarianumMessageGetMessages().run();
+  }
 }
diff --git a/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart b/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart
index f2c60bf..6933eab 100644
--- a/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart
+++ b/lib/state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart
@@ -2,6 +2,8 @@ import 'dart:developer';
 
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 
+import '../../../../../api/demo/data/demo_capabilities.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumcloud/capabilities/get_nextcloud_capabilities.dart';
 import 'nextcloud_capabilities_state.dart';
 
@@ -57,6 +59,10 @@ class NextcloudCapabilitiesCubit
   /// Refreshes capabilities from the server. On any failure the previously
   /// hydrated flags are kept but the state is marked `loaded`.
   Future<void> load() async {
+    if (DemoMode.active) {
+      emit(DemoNextcloudCapabilities.state());
+      return;
+    }
     try {
       final caps = await GetNextcloudCapabilities().run();
       emit(
diff --git a/lib/state/app/modules/timetable/data_provider/timetable_data_provider.dart b/lib/state/app/modules/timetable/data_provider/timetable_data_provider.dart
index c7aea5c..77287b4 100644
--- a/lib/state/app/modules/timetable/data_provider/timetable_data_provider.dart
+++ b/lib/state/app/modules/timetable/data_provider/timetable_data_provider.dart
@@ -1,3 +1,5 @@
+import '../../../../../api/demo/data/demo_timetable.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumconnect/queries/timetable_get_holidays/timetable_get_holidays.dart';
 import '../../../../../api/marianumconnect/queries/timetable_get_holidays/timetable_get_holidays_response.dart';
 import '../../../../../api/marianumconnect/queries/timetable_get_rooms/timetable_get_rooms.dart';
@@ -95,27 +97,36 @@ class TimetableDataProvider {
   Future<GetCustomTimetableEventResponse> getCustomEvents({
     bool renew = false,
     void Function(Object)? onError,
-  }) => resolveFromCache<GetCustomTimetableEventResponse>(
+  }) {
+    if (DemoMode.active) return Future.value(DemoTimetable.customEvents());
+    return resolveFromCache<GetCustomTimetableEventResponse>(
     (onUpdate, onError) => GetCustomTimetableEventCache(
       GetCustomTimetableEventParams(AccountData().getUserSecret()),
       renew: renew,
       onUpdate: onUpdate,
       onError: onError,
     ),
-    onError: onError,
-    operationName: 'getCustomEvents',
-  );
+      onError: onError,
+      operationName: 'getCustomEvents',
+    );
+  }
 
-  Future<void> addCustomEvent(CustomTimetableEvent event) =>
-      AddCustomTimetableEvent(
-        AddCustomTimetableEventParams(AccountData().getUserSecret(), event),
-      ).run();
+  Future<void> addCustomEvent(CustomTimetableEvent event) {
+    if (DemoMode.active) return Future.value();
+    return AddCustomTimetableEvent(
+      AddCustomTimetableEventParams(AccountData().getUserSecret(), event),
+    ).run();
+  }
 
-  Future<void> updateCustomEvent(String id, CustomTimetableEvent event) =>
-      UpdateCustomTimetableEvent(
-        UpdateCustomTimetableEventParams(id, event),
-      ).run();
+  Future<void> updateCustomEvent(String id, CustomTimetableEvent event) {
+    if (DemoMode.active) return Future.value();
+    return UpdateCustomTimetableEvent(
+      UpdateCustomTimetableEventParams(id, event),
+    ).run();
+  }
 
-  Future<void> removeCustomEvent(String id) =>
-      RemoveCustomTimetableEvent(RemoveCustomTimetableEventParams(id)).run();
+  Future<void> removeCustomEvent(String id) {
+    if (DemoMode.active) return Future.value();
+    return RemoveCustomTimetableEvent(RemoveCustomTimetableEventParams(id)).run();
+  }
 }
diff --git a/lib/view/login/login_controller.dart b/lib/view/login/login_controller.dart
index bae4600..83ca987 100644
--- a/lib/view/login/login_controller.dart
+++ b/lib/view/login/login_controller.dart
@@ -3,6 +3,7 @@ import 'dart:developer';
 
 import 'package:flutter/foundation.dart';
 
+import '../../api/demo/demo_mode.dart';
 import '../../api/errors/auth_exception.dart';
 import '../../api/errors/error_mapper.dart';
 import '../../api/marianumconnect/auth/device_token_name.dart';
@@ -33,6 +34,20 @@ class LoginController extends ChangeNotifier {
     notifyListeners();
 
     final user = username.trim().toLowerCase();
+
+    // Demo login: the prefix enters local demo mode, password ignored, no
+    // network (see DemoMode).
+    if (DemoMode.matches(user)) {
+      await AccountData().removeData();
+      await const MarianumConnectTokenStorage().clear();
+      await WidgetSync.clear();
+      await WidgetSync.triggerUpdate();
+      await AccountData().setDemo(user);
+      _loading = false;
+      notifyListeners();
+      return true;
+    }
+
     try {
       await AccountData().removeData();
       // Vorherigen Token revoken bevor wir einen neuen anfordern — ein altes
diff --git a/lib/view/pages/files/sharing/share_options_sheet.dart b/lib/view/pages/files/sharing/share_options_sheet.dart
index 9141682..2405c2c 100644
--- a/lib/view/pages/files/sharing/share_options_sheet.dart
+++ b/lib/view/pages/files/sharing/share_options_sheet.dart
@@ -11,6 +11,7 @@ import '../../../../state/app/modules/nextcloud_capabilities/bloc/nextcloud_capa
 import '../../../../utils/clipboard_helper.dart';
 import '../../../../widget/centered_leading.dart';
 import '../../../../widget/confirm_dialog.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/info_dialog.dart';
 import 'share_password_sheet.dart';
@@ -35,6 +36,7 @@ void showShareOptionsSheet(
   Share share, {
   required VoidCallback onChanged,
 }) {
+  if (guardDemoAction(context)) return;
   showDetailsBottomSheet(
     context,
     header: ListTile(
diff --git a/lib/view/pages/files/sharing/share_sheet.dart b/lib/view/pages/files/sharing/share_sheet.dart
index aba800d..c736259 100644
--- a/lib/view/pages/files/sharing/share_sheet.dart
+++ b/lib/view/pages/files/sharing/share_sheet.dart
@@ -13,6 +13,7 @@ import '../../../../state/app/modules/nextcloud_capabilities/bloc/nextcloud_capa
 import '../../../../utils/clipboard_helper.dart';
 import '../../../../widget/app_progress_indicator.dart';
 import '../../../../widget/centered_leading.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/info_dialog.dart';
 import '../widgets/file_leading.dart';
@@ -23,6 +24,7 @@ import 'share_password_sheet.dart';
 /// gated actions to create new ones (public link, user/group). Capability
 /// gating mirrors the Nextcloud web UI.
 void showShareSheet(BuildContext context, CacheableFile file) {
+  if (guardDemoAction(context)) return;
   showDetailsBottomSheet(
     context,
     header: ListTile(
diff --git a/lib/view/pages/files/widgets/add_file_menu.dart b/lib/view/pages/files/widgets/add_file_menu.dart
index 9f8565d..6d50052 100644
--- a/lib/view/pages/files/widgets/add_file_menu.dart
+++ b/lib/view/pages/files/widgets/add_file_menu.dart
@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 
 import '../../../../state/app/modules/files/bloc/files_bloc.dart';
 import '../../../../widget/async_action_button.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/file_pick.dart';
 
@@ -13,6 +14,7 @@ void showAddFileSheet(
   required FilesBloc bloc,
   required Future<void> Function(List<String>? paths) onPickedFiles,
 }) {
+  if (guardDemoAction(context)) return;
   showDetailsBottomSheet(
     context,
     children: (sheetCtx) => [
diff --git a/lib/view/pages/files/widgets/file_element.dart b/lib/view/pages/files/widgets/file_element.dart
index 9b21a74..2813944 100644
--- a/lib/view/pages/files/widgets/file_element.dart
+++ b/lib/view/pages/files/widgets/file_element.dart
@@ -15,6 +15,7 @@ import '../../../../utils/file_clipboard.dart';
 import '../../../../utils/haptics.dart';
 import '../../../../widget/centered_leading.dart';
 import '../../../../widget/confirm_dialog.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/downloads/download_trigger.dart';
 import '../../../../widget/info_dialog.dart';
@@ -105,6 +106,7 @@ class _FileElementState extends State<FileElement>
       );
       return;
     }
+    if (guardDemoAction(context)) return;
     if (EndpointData().getEndpointMode() == EndpointMode.stage) {
       InfoDialog.show(
         context,
@@ -135,6 +137,7 @@ class _FileElementState extends State<FileElement>
       isDirectory ? '$folder$name/' : '$folder$name';
 
   Future<void> _rename() async {
+    if (guardDemoAction(context)) return;
     final controller = TextEditingController(text: widget.file.name);
     try {
       final newName = await showDialog<String>(
@@ -182,6 +185,7 @@ class _FileElementState extends State<FileElement>
   }
 
   void _putOnClipboard({required bool copy}) {
+    if (guardDemoAction(context)) return;
     if (copy) {
       FileClipboard.instance.copy([widget.file]);
     } else {
@@ -198,6 +202,7 @@ class _FileElementState extends State<FileElement>
   }
 
   Future<void> _delete() async {
+    if (guardDemoAction(context)) return;
     await showDialog<void>(
       context: context,
       builder: (context) => ConfirmDialog(
@@ -269,6 +274,7 @@ class _FileElementState extends State<FileElement>
             title: const Text('Im Talk-Chat versenden'),
             onTap: () {
               Navigator.of(sheetCtx).pop();
+              if (guardDemoAction(context)) return;
               AppRoutes.openInternalShareToChat(
                 context,
                 RemoteFileRef.fromCacheable(widget.file),
diff --git a/lib/view/pages/more/feedback/feedback_dialog.dart b/lib/view/pages/more/feedback/feedback_dialog.dart
index b3d10f8..15b5892 100644
--- a/lib/view/pages/more/feedback/feedback_dialog.dart
+++ b/lib/view/pages/more/feedback/feedback_dialog.dart
@@ -4,6 +4,7 @@ import 'package:flutter/material.dart';
 
 import '../../../../api/marianumconnect/queries/submit_feedback/submit_feedback.dart';
 import '../../../../widget/async_action_button.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/file_pick.dart';
 import '../../../../widget/focus_behaviour.dart';
 import '../../../../widget/info_dialog.dart';
@@ -50,6 +51,7 @@ class _FeedbackDialogState extends State<FeedbackDialog> {
   }
 
   Future<void> _submit() async {
+    if (guardDemoAction(context)) return;
     if (_feedbackInput.text.trim().isEmpty) {
       setState(() => _textFieldEmpty = true);
       return;
diff --git a/lib/view/pages/settings/sections/account_section.dart b/lib/view/pages/settings/sections/account_section.dart
index 14beb54..df33022 100644
--- a/lib/view/pages/settings/sections/account_section.dart
+++ b/lib/view/pages/settings/sections/account_section.dart
@@ -11,6 +11,7 @@ import '../../../../widget/app_progress_indicator.dart';
 import '../../../../widget/async_action_button.dart';
 import '../../../../widget/avatar_actions_sheet.dart';
 import '../../../../widget/confirm_dialog.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/large_profile_picture_view.dart';
 import '../../../../widget/user_avatar.dart';
 
@@ -51,6 +52,7 @@ class _AccountSectionState extends State<AccountSection> {
   }
 
   Future<void> _editAvatar() async {
+    if (guardDemoAction(context)) return;
     final result = await showAvatarActionsSheet(context, allowRemove: true);
     if (result == null || !mounted) return;
 
diff --git a/lib/view/pages/settings/widgets/push_status_sheet.dart b/lib/view/pages/settings/widgets/push_status_sheet.dart
index 276a618..4fa6402 100644
--- a/lib/view/pages/settings/widgets/push_status_sheet.dart
+++ b/lib/view/pages/settings/widgets/push_status_sheet.dart
@@ -12,6 +12,7 @@ import '../../../../push/push_status.dart';
 import '../../../../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
 import '../../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../../widget/app_progress_indicator.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 
 /// Opens the push status checklist: one row per link in the push chain with
@@ -92,6 +93,7 @@ class _PushStatusBodyState extends State<_PushStatusBody>
   }
 
   Future<void> _reRegister() async {
+    if (guardDemoAction(context)) return;
     if (_busy) return;
     setState(() => _busy = true);
     final messenger = ScaffoldMessenger.of(context);
@@ -111,6 +113,7 @@ class _PushStatusBodyState extends State<_PushStatusBody>
   }
 
   Future<void> _sendTest() async {
+    if (guardDemoAction(context)) return;
     if (_busy) return;
     setState(() => _busy = true);
     final messenger = ScaffoldMessenger.of(context);
diff --git a/lib/view/pages/talk/chat_list.dart b/lib/view/pages/talk/chat_list.dart
index a927c45..3199bd6 100644
--- a/lib/view/pages/talk/chat_list.dart
+++ b/lib/view/pages/talk/chat_list.dart
@@ -11,6 +11,7 @@ import '../../../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
 import '../../../state/app/modules/chat_list/bloc/chat_list_state.dart';
 import '../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../widget/confirm_dialog.dart';
+import '../../../widget/demo_restricted.dart';
 import '../../../widget/placeholder_view.dart';
 import 'join_chat.dart';
 import 'notification_permission_prompt.dart';
@@ -100,6 +101,7 @@ class _ChatListViewState extends State<_ChatListView> {
             heroTag: 'createChat',
             backgroundColor: Theme.of(context).primaryColor,
             onPressed: () {
+              if (guardDemoAction(context)) return;
               showSearch(context: context, delegate: JoinChat()).then((
                 username,
               ) {
diff --git a/lib/view/pages/talk/data/open_direct_chat.dart b/lib/view/pages/talk/data/open_direct_chat.dart
index 196dd1f..0a5ecbd 100644
--- a/lib/view/pages/talk/data/open_direct_chat.dart
+++ b/lib/view/pages/talk/data/open_direct_chat.dart
@@ -5,6 +5,7 @@ import '../../../../api/marianumcloud/talk/room/get_room_response.dart';
 import '../../../../routing/app_routes.dart';
 import '../../../../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
 import '../../../../widget/confirm_dialog.dart';
+import '../../../../widget/demo_restricted.dart';
 
 /// Opens an existing 1:1 chat with [actorId] or, after confirmation, creates
 /// one. Shared between the group-message context menu and the reactions
@@ -14,6 +15,7 @@ void openOrCreateDirectChat(
   required String actorId,
   required String actorDisplayName,
 }) {
+  if (guardDemoAction(context)) return;
   final chatListBloc = context.read<ChatListBloc>();
 
   GetRoomResponseObject? findExisting() {
diff --git a/lib/view/pages/talk/widgets/chat_bubble.dart b/lib/view/pages/talk/widgets/chat_bubble.dart
index c7712fe..ed18b1a 100644
--- a/lib/view/pages/talk/widgets/chat_bubble.dart
+++ b/lib/view/pages/talk/widgets/chat_bubble.dart
@@ -9,6 +9,7 @@ import '../../../../share_intent/remote_file_ref.dart';
 import '../../../../state/app/modules/chat/bloc/chat_bloc.dart';
 import '../../../../utils/downloads/download_job.dart';
 import '../../../../utils/haptics.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/downloads/download_trigger.dart';
 import '../data/chat_bubble_styles.dart';
 import '../data/chat_message.dart';
@@ -177,6 +178,7 @@ class _ChatBubbleState extends State<ChatBubble>
       return;
     }
     if (message.file == null) return;
+    if (guardDemoAction(context)) return;
     if (isDownloading) {
       confirmCancelDownload();
     } else {
diff --git a/lib/view/pages/talk/widgets/chat_bubble_reactions.dart b/lib/view/pages/talk/widgets/chat_bubble_reactions.dart
index 34831b0..05e6a57 100644
--- a/lib/view/pages/talk/widgets/chat_bubble_reactions.dart
+++ b/lib/view/pages/talk/widgets/chat_bubble_reactions.dart
@@ -7,6 +7,7 @@ import '../../../../api/marianumcloud/talk/react_message/react_message.dart';
 import '../../../../api/marianumcloud/talk/react_message/react_message_params.dart';
 import '../../../../api/marianumcloud/talk/room/get_room_response.dart';
 import '../../../../widget/async_action_button.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/emoji_text.dart';
 
 /// Reactions wrap shown beneath a chat bubble. Tapping a reaction toggles
@@ -60,6 +61,7 @@ class ChatBubbleReactions extends StatelessWidget {
                     ? Theme.of(context).primaryColor
                     : null,
                 onPressed: () {
+                  if (guardDemoAction(context)) return;
                   runWithErrorDialog(context, () async {
                     if (hasSelfReacted) {
                       await DeleteReactMessage(
diff --git a/lib/view/pages/talk/widgets/chat_message_options_dialog.dart b/lib/view/pages/talk/widgets/chat_message_options_dialog.dart
index eccf7e9..c679790 100644
--- a/lib/view/pages/talk/widgets/chat_message_options_dialog.dart
+++ b/lib/view/pages/talk/widgets/chat_message_options_dialog.dart
@@ -14,6 +14,7 @@ import '../../../../widget/app_progress_indicator.dart';
 import '../../../../widget/async_action_button.dart';
 import '../../../../widget/confirm_dialog.dart';
 import '../../../../widget/debug/debug_tile.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/emoji_picker_dialog.dart';
 import '../../../../widget/emoji_text.dart';
@@ -64,6 +65,7 @@ void showChatMessageOptionsDialog(
           leading: const Icon(Icons.reply_outlined),
           title: const Text('Antworten'),
           onTap: () {
+            if (guardDemoAction(sheetCtx)) return;
             sheetCtx.read<ChatBloc>().setReferenceMessageId(bubbleData.id);
             Navigator.of(sheetCtx).pop();
           },
@@ -96,6 +98,7 @@ void showChatMessageOptionsDialog(
           leading: const Icon(Icons.cloud_outlined),
           title: const Text('In Cloud speichern'),
           onTap: () {
+            if (guardDemoAction(sheetCtx)) return;
             Navigator.of(sheetCtx).pop();
             if (!parentContext.mounted) return;
             AppRoutes.openInternalSaveToFolder(
@@ -109,6 +112,7 @@ void showChatMessageOptionsDialog(
           leading: const Icon(Icons.shortcut_outlined),
           title: const Text('Weiterleiten'),
           onTap: () {
+            if (guardDemoAction(sheetCtx)) return;
             Navigator.of(sheetCtx).pop();
             if (!parentContext.mounted) return;
             AppRoutes.openForwardMessageToChat(
@@ -143,6 +147,7 @@ void showChatMessageOptionsDialog(
           leading: const Icon(Icons.delete_outline),
           title: const Text('Nachricht löschen'),
           onTap: () {
+            if (guardDemoAction(sheetCtx)) return;
             ConfirmDialog(
               title: 'Nachricht löschen?',
               content: 'Die Nachricht wird für alle Teilnehmer gelöscht.',
@@ -189,6 +194,7 @@ class _ReactionsRowState extends State<_ReactionsRow> {
   }
 
   Future<void> _react(String emoji) async {
+    if (guardDemoAction(context)) return;
     final ok = await _controller.run(() async {
       await ReactMessage(
         chatToken: widget.chatToken,
diff --git a/lib/view/pages/talk/widgets/chat_textfield.dart b/lib/view/pages/talk/widgets/chat_textfield.dart
index 153d6c5..143f5af 100644
--- a/lib/view/pages/talk/widgets/chat_textfield.dart
+++ b/lib/view/pages/talk/widgets/chat_textfield.dart
@@ -12,6 +12,7 @@ import '../../../../api/marianumcloud/webdav/webdav_api.dart';
 import '../../../../state/app/modules/chat/bloc/chat_bloc.dart';
 import '../../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../../widget/async_action_button.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/downloads/download_tray.dart';
 import '../../../../widget/emoji_picker_dialog.dart';
@@ -125,6 +126,7 @@ class _ChatTextfieldState extends State<ChatTextfield> {
   }
 
   void _showAttachmentSheet() {
+    if (guardDemoAction(context)) return;
     showDetailsBottomSheet(
       context,
       children: (sheetCtx) => [
@@ -187,6 +189,7 @@ class _ChatTextfieldState extends State<ChatTextfield> {
 
   Future<void> _sendMessage(ChatBloc chatBloc) async {
     if (_textBoxController.text.isEmpty) return;
+    if (guardDemoAction(context)) return;
     final text = _textBoxController.text;
     final replyTo = chatBloc.state.data?.referenceMessageId?.toString();
     final ownToken = widget.sendToToken;
diff --git a/lib/view/pages/timetable/custom_events/custom_event_edit_dialog.dart b/lib/view/pages/timetable/custom_events/custom_event_edit_dialog.dart
index 1cc736b..cd401d9 100644
--- a/lib/view/pages/timetable/custom_events/custom_event_edit_dialog.dart
+++ b/lib/view/pages/timetable/custom_events/custom_event_edit_dialog.dart
@@ -10,6 +10,7 @@ import '../../../../api/mhsl/custom_timetable_event/custom_timetable_event.dart'
 import '../../../../extensions/date_time.dart';
 import '../../../../state/app/modules/timetable/bloc/timetable_bloc.dart';
 import '../../../../widget/async_action_button.dart';
+import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/focus_behaviour.dart';
 import 'custom_event_colors.dart';
 
@@ -130,6 +131,7 @@ class _CustomEventEditDialogState extends State<CustomEventEditDialog> {
       end.second == 0;
 
   Future<void> _save() async {
+    if (guardDemoAction(context)) return;
     if (_name.text.trim().isEmpty) {
       throw Exception('Bitte einen Terminnamen eingeben.');
     }
diff --git a/lib/view/pages/timetable/details/delete_custom_event.dart b/lib/view/pages/timetable/details/delete_custom_event.dart
index 33d186c..fa6f70c 100644
--- a/lib/view/pages/timetable/details/delete_custom_event.dart
+++ b/lib/view/pages/timetable/details/delete_custom_event.dart
@@ -6,12 +6,14 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import '../../../../api/mhsl/custom_timetable_event/custom_timetable_event.dart';
 import '../../../../state/app/modules/timetable/bloc/timetable_bloc.dart';
 import '../../../../widget/confirm_dialog.dart';
+import '../../../../widget/demo_restricted.dart';
 
 Completer<void> showDeleteCustomEventDialog(
   BuildContext context,
   CustomTimetableEvent event,
 ) {
   final completer = Completer<void>();
+  if (guardDemoAction(context)) return completer;
   final bloc = context.read<TimetableBloc>();
   ConfirmDialog(
     title: 'Termin löschen',
diff --git a/lib/view/pages/timetable/timetable.dart b/lib/view/pages/timetable/timetable.dart
index 6b12a72..d3da3c7 100644
--- a/lib/view/pages/timetable/timetable.dart
+++ b/lib/view/pages/timetable/timetable.dart
@@ -11,6 +11,7 @@ import '../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../state/app/modules/timetable/bloc/timetable_bloc.dart';
 import '../../../state/app/modules/timetable/bloc/timetable_state.dart';
 import '../../../utils/haptics.dart';
+import '../../../widget/demo_restricted.dart';
 import 'custom_events/custom_event_edit_dialog.dart';
 import 'details/appointment_details_dispatcher.dart';
 import 'widgets/timetable_calendar_view.dart';
@@ -42,6 +43,7 @@ class _TimetableState extends State<Timetable> {
       state.startDate == _mondayOf(_initialDisplayDate());
 
   Future<void> _openPicker() async {
+    if (guardDemoAction(context)) return;
     final ref = await AppRoutes.openElementPicker(context);
     if (!mounted || ref == null) return;
     setState(() => _selected = ref);
diff --git a/lib/widget/demo_restricted.dart b/lib/widget/demo_restricted.dart
new file mode 100644
index 0000000..81b4f74
--- /dev/null
+++ b/lib/widget/demo_restricted.dart
@@ -0,0 +1,21 @@
+import 'package:flutter/widgets.dart';
+
+import '../api/demo/demo_mode.dart';
+import 'info_dialog.dart';
+
+/// Guards an action the demo mode can't back with real data (writes, uploads,
+/// downloads, user/element lookups). Shows an info dialog and returns `true`
+/// when a demo session is active — callers abort on `true`:
+///
+/// ```dart
+/// if (guardDemoAction(context)) return;
+/// ```
+bool guardDemoAction(BuildContext context) {
+  if (!DemoMode.active) return false;
+  InfoDialog.show(
+    context,
+    'Diese Funktion steht im Demo-Modus nicht zur Verfügung.',
+    title: 'Demo-Modus',
+  );
+  return true;
+}
diff --git a/test/demo/demo_marianumconnect_test.dart b/test/demo/demo_marianumconnect_test.dart
new file mode 100644
index 0000000..80ff6e6
--- /dev/null
+++ b/test/demo/demo_marianumconnect_test.dart
@@ -0,0 +1,83 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/api/demo/demo_marianumconnect.dart';
+import 'package:marianum_mobile/api/marianumconnect/models/mc_holiday.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/get_breakers/get_breakers_response.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/timetable_get_holidays/timetable_get_holidays_response.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/timetable_get_rooms/timetable_get_rooms_response.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/timetable_get_schoolyear/timetable_get_schoolyear_response.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/timetable_get_subjects/timetable_get_subjects_response.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/timetable_get_timegrid/timetable_get_timegrid_response.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
+
+/// The demo interceptor answers MarianumConnect calls with these bodies; each
+/// must round-trip through the same parser the real query uses. A shape
+/// mismatch (bare list vs. object) would only surface at runtime otherwise.
+void main() {
+  Map<String, dynamic> asMap(String path, [Map<String, dynamic> query = const {}]) =>
+      DemoMarianumConnect.responseBody(path, query) as Map<String, dynamic>;
+
+  List<Map<String, dynamic>> asList(String path) =>
+      (DemoMarianumConnect.responseBody(path, const {}) as List)
+          .cast<Map<String, dynamic>>();
+
+  group('DemoMarianumConnect responseBody parses with the real query parser', () {
+    test('timetable/me → populated week', () {
+      final week = TimetableGetWeekResponse.fromJson(
+        asMap('timetable/me', {'from': '2026-05-04', 'until': '2026-05-10'}),
+      );
+      expect(week.entries, isNotEmpty);
+    });
+
+    test('timetable/schoolyear', () {
+      expect(
+        () => TimetableGetSchoolyearResponse.fromJson(asMap('timetable/schoolyear')),
+        returnsNormally,
+      );
+    });
+
+    test('timetable/rooms → non-empty list of McRoom', () {
+      final rooms = asList('timetable/rooms').map(McRoom.fromJson).toList();
+      expect(rooms, isNotEmpty);
+    });
+
+    test('timetable/subjects → non-empty list of McSubject', () {
+      final subjects = asList('timetable/subjects').map(McSubject.fromJson).toList();
+      expect(subjects, isNotEmpty);
+    });
+
+    test('timetable/timegrid → non-empty list of McTimegridUnit', () {
+      final units = asList('timetable/timegrid').map(McTimegridUnit.fromJson).toList();
+      expect(units, isNotEmpty);
+    });
+
+    test('timetable/holidays → list of McHoliday', () {
+      expect(
+        () => asList('timetable/holidays').map(McHoliday.fromJson).toList(),
+        returnsNormally,
+      );
+    });
+
+    test('holidays → non-empty list of McHoliday', () {
+      final holidays = asList('holidays').map(McHoliday.fromJson).toList();
+      expect(holidays, isNotEmpty);
+    });
+
+    test('breaker → GetBreakersResponse with no active rules', () {
+      final breakers = GetBreakersResponse.fromJson(asMap('breaker'));
+      expect(breakers.rules, isEmpty);
+    });
+
+    test('foreign element week (timetable/<type>/<id>) parses as a week', () {
+      expect(
+        () => TimetableGetWeekResponse.fromJson(
+          asMap('timetable/teacher/42', {'from': '2026-05-04', 'until': '2026-05-10'}),
+        ),
+        returnsNormally,
+      );
+    });
+
+    test('side-effect endpoint returns an empty map body', () {
+      expect(asMap('me/telemetry'), isEmpty);
+    });
+  });
+}