feat(02-01): Drift tables, DAOs, scheduling utility, domain models with tests

- Add Rooms, Tasks, TaskCompletions Drift tables with schema v2 migration
- Create RoomsDao with CRUD, watchAll, watchWithStats, cascade delete, reorder
- Create TasksDao with CRUD, watchInRoom (sorted by due), completeTask, overdue detection
- Implement calculateNextDueDate and catchUpToPresent pure scheduling functions
- Define IntervalType enum (8 types), EffortLevel enum, FrequencyInterval model
- Add formatRelativeDate German formatter and curatedRoomIcons icon list
- Enable PRAGMA foreign_keys in beforeOpen migration strategy
- All 30 unit tests passing (17 scheduling + 6 rooms DAO + 7 tasks DAO)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/core/database/database.dart

@@ -2,14 +2,75 @@ import 'package:drift/drift.dart';
 import 'package:drift_flutter/drift_flutter.dart';
 import 'package:path_provider/path_provider.dart';
 
+import '../../features/rooms/data/rooms_dao.dart';
+import '../../features/tasks/data/tasks_dao.dart';
+import '../../features/tasks/domain/effort_level.dart';
+import '../../features/tasks/domain/frequency.dart';
+
 part 'database.g.dart';
 
-@DriftDatabase(tables: [])
+/// Rooms table: each room has a name, icon, and sort order.
+class Rooms extends Table {
+  IntColumn get id => integer().autoIncrement()();
+  TextColumn get name => text().withLength(min: 1, max: 100)();
+  TextColumn get iconName => text()();
+  IntColumn get sortOrder => integer().withDefault(const Constant(0))();
+  DateTimeColumn get createdAt =>
+      dateTime().clientDefault(() => DateTime.now())();
+}
+
+/// Tasks table: each task belongs to a room and has scheduling info.
+class Tasks extends Table {
+  IntColumn get id => integer().autoIncrement()();
+  IntColumn get roomId => integer().references(Rooms, #id)();
+  TextColumn get name => text().withLength(min: 1, max: 200)();
+  TextColumn get description => text().nullable()();
+  IntColumn get intervalType => intEnum<IntervalType>()();
+  IntColumn get intervalDays =>
+      integer().withDefault(const Constant(1))();
+  IntColumn get anchorDay => integer().nullable()();
+  IntColumn get effortLevel => intEnum<EffortLevel>()();
+  DateTimeColumn get nextDueDate => dateTime()();
+  DateTimeColumn get createdAt =>
+      dateTime().clientDefault(() => DateTime.now())();
+}
+
+/// TaskCompletions table: records when a task was completed.
+class TaskCompletions extends Table {
+  IntColumn get id => integer().autoIncrement()();
+  IntColumn get taskId => integer().references(Tasks, #id)();
+  DateTimeColumn get completedAt => dateTime()();
+}
+
+@DriftDatabase(
+  tables: [Rooms, Tasks, TaskCompletions],
+  daos: [RoomsDao, TasksDao],
+)
 class AppDatabase extends _$AppDatabase {
-  AppDatabase([QueryExecutor? executor]) : super(executor ?? _openConnection());
+  AppDatabase([QueryExecutor? executor])
+      : super(executor ?? _openConnection());
 
   @override
-  int get schemaVersion => 1;
+  int get schemaVersion => 2;
+
+  @override
+  MigrationStrategy get migration {
+    return MigrationStrategy(
+      onCreate: (Migrator m) async {
+        await m.createAll();
+      },
+      onUpgrade: (Migrator m, int from, int to) async {
+        if (from < 2) {
+          await m.createTable(rooms);
+          await m.createTable(tasks);
+          await m.createTable(taskCompletions);
+        }
+      },
+      beforeOpen: (details) async {
+        await customStatement('PRAGMA foreign_keys = ON');
+      },
+    );
+  }
 
   static QueryExecutor _openConnection() {
     return driftDatabase(

lib/core/database/database.steps.dart

@@ -0,0 +1,247 @@
+// dart format width=80
+import 'package:drift/internal/versioned_schema.dart' as i0;
+import 'package:drift/drift.dart' as i1;
+import 'package:drift/drift.dart'; // GENERATED BY drift_dev, DO NOT MODIFY.
+
+// ignore_for_file: type=lint,unused_import
+//
+final class Schema2 extends i0.VersionedSchema {
+  Schema2({required super.database}) : super(version: 2);
+  @override
+  late final List<i1.DatabaseSchemaEntity> entities = [
+    rooms,
+    tasks,
+    taskCompletions,
+  ];
+  late final Shape0 rooms = Shape0(
+    source: i0.VersionedTable(
+      entityName: 'rooms',
+      withoutRowId: false,
+      isStrict: false,
+      tableConstraints: [],
+      columns: [_column_0, _column_1, _column_2, _column_3, _column_4],
+      attachedDatabase: database,
+    ),
+    alias: null,
+  );
+  late final Shape1 tasks = Shape1(
+    source: i0.VersionedTable(
+      entityName: 'tasks',
+      withoutRowId: false,
+      isStrict: false,
+      tableConstraints: [],
+      columns: [
+        _column_0,
+        _column_5,
+        _column_1,
+        _column_6,
+        _column_7,
+        _column_8,
+        _column_9,
+        _column_10,
+        _column_11,
+        _column_4,
+      ],
+      attachedDatabase: database,
+    ),
+    alias: null,
+  );
+  late final Shape2 taskCompletions = Shape2(
+    source: i0.VersionedTable(
+      entityName: 'task_completions',
+      withoutRowId: false,
+      isStrict: false,
+      tableConstraints: [],
+      columns: [_column_0, _column_12, _column_13],
+      attachedDatabase: database,
+    ),
+    alias: null,
+  );
+}
+
+class Shape0 extends i0.VersionedTable {
+  Shape0({required super.source, required super.alias}) : super.aliased();
+  i1.GeneratedColumn<int> get id =>
+      columnsByName['id']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<String> get name =>
+      columnsByName['name']! as i1.GeneratedColumn<String>;
+  i1.GeneratedColumn<String> get iconName =>
+      columnsByName['icon_name']! as i1.GeneratedColumn<String>;
+  i1.GeneratedColumn<int> get sortOrder =>
+      columnsByName['sort_order']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get createdAt =>
+      columnsByName['created_at']! as i1.GeneratedColumn<int>;
+}
+
+i1.GeneratedColumn<int> _column_0(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'id',
+      aliasedName,
+      false,
+      hasAutoIncrement: true,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL PRIMARY KEY AUTOINCREMENT',
+    );
+i1.GeneratedColumn<String> _column_1(String aliasedName) =>
+    i1.GeneratedColumn<String>(
+      'name',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.string,
+      $customConstraints: 'NOT NULL',
+    );
+i1.GeneratedColumn<String> _column_2(String aliasedName) =>
+    i1.GeneratedColumn<String>(
+      'icon_name',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.string,
+      $customConstraints: 'NOT NULL',
+    );
+i1.GeneratedColumn<int> _column_3(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'sort_order',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL DEFAULT 0',
+      defaultValue: const i1.CustomExpression('0'),
+    );
+i1.GeneratedColumn<int> _column_4(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'created_at',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL',
+    );
+
+class Shape1 extends i0.VersionedTable {
+  Shape1({required super.source, required super.alias}) : super.aliased();
+  i1.GeneratedColumn<int> get id =>
+      columnsByName['id']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get roomId =>
+      columnsByName['room_id']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<String> get name =>
+      columnsByName['name']! as i1.GeneratedColumn<String>;
+  i1.GeneratedColumn<String> get description =>
+      columnsByName['description']! as i1.GeneratedColumn<String>;
+  i1.GeneratedColumn<int> get intervalType =>
+      columnsByName['interval_type']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get intervalDays =>
+      columnsByName['interval_days']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get anchorDay =>
+      columnsByName['anchor_day']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get effortLevel =>
+      columnsByName['effort_level']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get nextDueDate =>
+      columnsByName['next_due_date']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get createdAt =>
+      columnsByName['created_at']! as i1.GeneratedColumn<int>;
+}
+
+i1.GeneratedColumn<int> _column_5(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'room_id',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL REFERENCES rooms(id)',
+    );
+i1.GeneratedColumn<String> _column_6(String aliasedName) =>
+    i1.GeneratedColumn<String>(
+      'description',
+      aliasedName,
+      true,
+      type: i1.DriftSqlType.string,
+      $customConstraints: 'NULL',
+    );
+i1.GeneratedColumn<int> _column_7(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'interval_type',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL',
+    );
+i1.GeneratedColumn<int> _column_8(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'interval_days',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL DEFAULT 1',
+      defaultValue: const i1.CustomExpression('1'),
+    );
+i1.GeneratedColumn<int> _column_9(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'anchor_day',
+      aliasedName,
+      true,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NULL',
+    );
+i1.GeneratedColumn<int> _column_10(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'effort_level',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL',
+    );
+i1.GeneratedColumn<int> _column_11(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'next_due_date',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL',
+    );
+
+class Shape2 extends i0.VersionedTable {
+  Shape2({required super.source, required super.alias}) : super.aliased();
+  i1.GeneratedColumn<int> get id =>
+      columnsByName['id']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get taskId =>
+      columnsByName['task_id']! as i1.GeneratedColumn<int>;
+  i1.GeneratedColumn<int> get completedAt =>
+      columnsByName['completed_at']! as i1.GeneratedColumn<int>;
+}
+
+i1.GeneratedColumn<int> _column_12(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'task_id',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL REFERENCES tasks(id)',
+    );
+i1.GeneratedColumn<int> _column_13(String aliasedName) =>
+    i1.GeneratedColumn<int>(
+      'completed_at',
+      aliasedName,
+      false,
+      type: i1.DriftSqlType.int,
+      $customConstraints: 'NOT NULL',
+    );
+i0.MigrationStepWithVersion migrationSteps({
+  required Future<void> Function(i1.Migrator m, Schema2 schema) from1To2,
+}) {
+  return (currentVersion, database) async {
+    switch (currentVersion) {
+      case 1:
+        final schema = Schema2(database: database);
+        final migrator = i1.Migrator(database, schema);
+        await from1To2(migrator, schema);
+        return 2;
+      default:
+        throw ArgumentError.value('Unknown migration from $currentVersion');
+    }
+  };
+}
+
+i1.OnUpgrade stepByStep({
+  required Future<void> Function(i1.Migrator m, Schema2 schema) from1To2,
+}) => i0.VersionedSchema.stepByStepHelper(
+  step: migrationSteps(from1To2: from1To2),
+);

lib/features/rooms/data/rooms_dao.dart

@@ -0,0 +1,127 @@
+import 'package:drift/drift.dart';
+
+import '../../../core/database/database.dart';
+
+part 'rooms_dao.g.dart';
+
+/// Stats for a room including task counts and cleanliness ratio.
+class RoomWithStats {
+  final Room room;
+  final int totalTasks;
+  final int dueTasks;
+  final int overdueCount;
+  final double cleanlinessRatio;
+
+  const RoomWithStats({
+    required this.room,
+    required this.totalTasks,
+    required this.dueTasks,
+    required this.overdueCount,
+    required this.cleanlinessRatio,
+  });
+}
+
+@DriftAccessor(tables: [Rooms, Tasks, TaskCompletions])
+class RoomsDao extends DatabaseAccessor<AppDatabase> with _$RoomsDaoMixin {
+  RoomsDao(super.attachedDatabase);
+
+  /// Watch all rooms ordered by sortOrder.
+  Stream<List<Room>> watchAllRooms() {
+    return (select(rooms)..orderBy([(r) => OrderingTerm.asc(r.sortOrder)]))
+        .watch();
+  }
+
+  /// Watch all rooms with computed task stats.
+  ///
+  /// Cleanliness ratio = (totalTasks - overdueCount) / totalTasks.
+  /// 1.0 when no tasks are overdue, 0.0 when all are overdue.
+  /// Rooms with no tasks have ratio 1.0.
+  Stream<List<RoomWithStats>> watchRoomWithStats({DateTime? today}) {
+    final now = today ?? DateTime.now();
+    final todayDateOnly = DateTime(now.year, now.month, now.day);
+
+    return watchAllRooms().asyncMap((roomList) async {
+      final stats = <RoomWithStats>[];
+      for (final room in roomList) {
+        final taskList = await (select(tasks)
+              ..where((t) => t.roomId.equals(room.id)))
+            .get();
+
+        final totalTasks = taskList.length;
+        var overdueCount = 0;
+        var dueTasks = 0;
+
+        for (final task in taskList) {
+          final dueDate = DateTime(
+            task.nextDueDate.year,
+            task.nextDueDate.month,
+            task.nextDueDate.day,
+          );
+          if (dueDate.isBefore(todayDateOnly) ||
+              dueDate.isAtSameMomentAs(todayDateOnly)) {
+            dueTasks++;
+          }
+          if (dueDate.isBefore(todayDateOnly)) {
+            overdueCount++;
+          }
+        }
+
+        final ratio =
+            totalTasks == 0 ? 1.0 : (totalTasks - overdueCount) / totalTasks;
+
+        stats.add(RoomWithStats(
+          room: room,
+          totalTasks: totalTasks,
+          dueTasks: dueTasks,
+          overdueCount: overdueCount,
+          cleanlinessRatio: ratio,
+        ));
+      }
+      return stats;
+    });
+  }
+
+  /// Insert a new room. Returns the auto-generated id.
+  Future<int> insertRoom(RoomsCompanion room) => into(rooms).insert(room);
+
+  /// Update an existing room. Returns true if a row was updated.
+  Future<bool> updateRoom(Room room) => update(rooms).replace(room);
+
+  /// Delete a room and cascade to its tasks and completions.
+  Future<void> deleteRoom(int roomId) {
+    return transaction(() async {
+      // Get all task IDs for this room
+      final taskList = await (select(tasks)
+            ..where((t) => t.roomId.equals(roomId)))
+          .get();
+
+      // Delete completions for each task
+      for (final task in taskList) {
+        await (delete(taskCompletions)
+              ..where((c) => c.taskId.equals(task.id)))
+            .go();
+      }
+
+      // Delete tasks
+      await (delete(tasks)..where((t) => t.roomId.equals(roomId))).go();
+
+      // Delete room
+      await (delete(rooms)..where((r) => r.id.equals(roomId))).go();
+    });
+  }
+
+  /// Reorder rooms by updating sortOrder for each room in the list.
+  Future<void> reorderRooms(List<int> roomIds) {
+    return transaction(() async {
+      for (var i = 0; i < roomIds.length; i++) {
+        await (update(rooms)..where((r) => r.id.equals(roomIds[i])))
+            .write(RoomsCompanion(sortOrder: Value(i)));
+      }
+    });
+  }
+
+  /// Get a single room by its id.
+  Future<Room> getRoomById(int id) {
+    return (select(rooms)..where((r) => r.id.equals(id))).getSingle();
+  }
+}

lib/features/rooms/data/rooms_dao.g.dart

@@ -0,0 +1,25 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'rooms_dao.dart';
+
+// ignore_for_file: type=lint
+mixin _$RoomsDaoMixin on DatabaseAccessor<AppDatabase> {
+  $RoomsTable get rooms => attachedDatabase.rooms;
+  $TasksTable get tasks => attachedDatabase.tasks;
+  $TaskCompletionsTable get taskCompletions => attachedDatabase.taskCompletions;
+  RoomsDaoManager get managers => RoomsDaoManager(this);
+}
+
+class RoomsDaoManager {
+  final _$RoomsDaoMixin _db;
+  RoomsDaoManager(this._db);
+  $$RoomsTableTableManager get rooms =>
+      $$RoomsTableTableManager(_db.attachedDatabase, _db.rooms);
+  $$TasksTableTableManager get tasks =>
+      $$TasksTableTableManager(_db.attachedDatabase, _db.tasks);
+  $$TaskCompletionsTableTableManager get taskCompletions =>
+      $$TaskCompletionsTableTableManager(
+        _db.attachedDatabase,
+        _db.taskCompletions,
+      );
+}

lib/features/rooms/domain/room_icons.dart

@@ -0,0 +1,40 @@
+import 'package:flutter/material.dart';
+
+/// Curated list of ~25 household Material Icons for the room icon picker.
+const List<({String name, IconData icon})> curatedRoomIcons = [
+  (name: 'kitchen', icon: Icons.kitchen),
+  (name: 'bathtub', icon: Icons.bathtub),
+  (name: 'bed', icon: Icons.bed),
+  (name: 'living', icon: Icons.living),
+  (name: 'weekend', icon: Icons.weekend),
+  (name: 'door_front', icon: Icons.door_front_door),
+  (name: 'desk', icon: Icons.desk),
+  (name: 'garage', icon: Icons.garage),
+  (name: 'balcony', icon: Icons.balcony),
+  (name: 'local_laundry', icon: Icons.local_laundry_service),
+  (name: 'stairs', icon: Icons.stairs),
+  (name: 'child_care', icon: Icons.child_care),
+  (name: 'single_bed', icon: Icons.single_bed),
+  (name: 'dining', icon: Icons.dining),
+  (name: 'yard', icon: Icons.yard),
+  (name: 'grass', icon: Icons.grass),
+  (name: 'home', icon: Icons.home),
+  (name: 'storage', icon: Icons.inventory_2),
+  (name: 'window', icon: Icons.window),
+  (name: 'cleaning', icon: Icons.cleaning_services),
+  (name: 'iron', icon: Icons.iron),
+  (name: 'microwave', icon: Icons.microwave),
+  (name: 'shower', icon: Icons.shower),
+  (name: 'chair', icon: Icons.chair),
+  (name: 'door_sliding', icon: Icons.door_sliding),
+];
+
+/// Map a stored icon name string back to its IconData.
+///
+/// Returns [Icons.home] as fallback if the name is not found.
+IconData mapIconName(String name) {
+  for (final entry in curatedRoomIcons) {
+    if (entry.name == name) return entry.icon;
+  }
+  return Icons.home;
+}

lib/features/tasks/data/tasks_dao.dart

@@ -0,0 +1,102 @@
+import 'package:drift/drift.dart';
+
+import '../../../core/database/database.dart';
+import '../domain/scheduling.dart';
+
+part 'tasks_dao.g.dart';
+
+@DriftAccessor(tables: [Tasks, TaskCompletions])
+class TasksDao extends DatabaseAccessor<AppDatabase> with _$TasksDaoMixin {
+  TasksDao(super.attachedDatabase);
+
+  /// Watch tasks in a room sorted by nextDueDate ascending.
+  Stream<List<Task>> watchTasksInRoom(int roomId) {
+    return (select(tasks)
+          ..where((t) => t.roomId.equals(roomId))
+          ..orderBy([(t) => OrderingTerm.asc(t.nextDueDate)]))
+        .watch();
+  }
+
+  /// Insert a new task. Returns the auto-generated id.
+  Future<int> insertTask(TasksCompanion task) => into(tasks).insert(task);
+
+  /// Update an existing task. Returns true if a row was updated.
+  Future<bool> updateTask(Task task) => update(tasks).replace(task);
+
+  /// Delete a task and its completions.
+  Future<void> deleteTask(int taskId) {
+    return transaction(() async {
+      await (delete(taskCompletions)..where((c) => c.taskId.equals(taskId)))
+          .go();
+      await (delete(tasks)..where((t) => t.id.equals(taskId))).go();
+    });
+  }
+
+  /// Mark a task as done: records completion and calculates next due date.
+  ///
+  /// Uses scheduling utility for date calculation. Next due is calculated
+  /// from the original due date (not completion date) to keep rhythm stable.
+  /// If the calculated next due is in the past, catch-up advances to present.
+  ///
+  /// [now] parameter allows injection of current time for testing.
+  Future<void> completeTask(int taskId, {DateTime? now}) {
+    return transaction(() async {
+      // 1. Get current task
+      final task =
+          await (select(tasks)..where((t) => t.id.equals(taskId))).getSingle();
+
+      final currentTime = now ?? DateTime.now();
+
+      // 2. Record completion
+      await into(taskCompletions).insert(TaskCompletionsCompanion.insert(
+        taskId: taskId,
+        completedAt: currentTime,
+      ));
+
+      // 3. Calculate next due date (from original due date, not today)
+      var nextDue = calculateNextDueDate(
+        currentDueDate: task.nextDueDate,
+        intervalType: task.intervalType,
+        intervalDays: task.intervalDays,
+        anchorDay: task.anchorDay,
+      );
+
+      // 4. Catch up if next due is still in the past
+      final todayDateOnly = DateTime(
+        currentTime.year,
+        currentTime.month,
+        currentTime.day,
+      );
+      nextDue = catchUpToPresent(
+        nextDue: nextDue,
+        today: todayDateOnly,
+        intervalType: task.intervalType,
+        intervalDays: task.intervalDays,
+        anchorDay: task.anchorDay,
+      );
+
+      // 5. Update task with new due date
+      await (update(tasks)..where((t) => t.id.equals(taskId)))
+          .write(TasksCompanion(nextDueDate: Value(nextDue)));
+    });
+  }
+
+  /// Count overdue tasks in a room (nextDueDate before today).
+  Future<int> getOverdueTaskCount(int roomId, {DateTime? today}) async {
+    final now = today ?? DateTime.now();
+    final todayDateOnly = DateTime(now.year, now.month, now.day);
+
+    final taskList = await (select(tasks)
+          ..where((t) => t.roomId.equals(roomId)))
+        .get();
+
+    return taskList.where((task) {
+      final dueDate = DateTime(
+        task.nextDueDate.year,
+        task.nextDueDate.month,
+        task.nextDueDate.day,
+      );
+      return dueDate.isBefore(todayDateOnly);
+    }).length;
+  }
+}

lib/features/tasks/data/tasks_dao.g.dart

@@ -0,0 +1,25 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'tasks_dao.dart';
+
+// ignore_for_file: type=lint
+mixin _$TasksDaoMixin on DatabaseAccessor<AppDatabase> {
+  $RoomsTable get rooms => attachedDatabase.rooms;
+  $TasksTable get tasks => attachedDatabase.tasks;
+  $TaskCompletionsTable get taskCompletions => attachedDatabase.taskCompletions;
+  TasksDaoManager get managers => TasksDaoManager(this);
+}
+
+class TasksDaoManager {
+  final _$TasksDaoMixin _db;
+  TasksDaoManager(this._db);
+  $$RoomsTableTableManager get rooms =>
+      $$RoomsTableTableManager(_db.attachedDatabase, _db.rooms);
+  $$TasksTableTableManager get tasks =>
+      $$TasksTableTableManager(_db.attachedDatabase, _db.tasks);
+  $$TaskCompletionsTableTableManager get taskCompletions =>
+      $$TaskCompletionsTableTableManager(
+        _db.attachedDatabase,
+        _db.taskCompletions,
+      );
+}

lib/features/tasks/domain/effort_level.dart

@@ -0,0 +1,23 @@
+/// Effort level for tasks.
+///
+/// IMPORTANT: Never reorder or remove values - intEnum stores the .index.
+/// Always add new values at the END.
+enum EffortLevel {
+  low, // 0
+  medium, // 1
+  high, // 2
+}
+
+/// German display labels for effort levels.
+extension EffortLevelLabel on EffortLevel {
+  String label() {
+    switch (this) {
+      case EffortLevel.low:
+        return 'Gering';
+      case EffortLevel.medium:
+        return 'Mittel';
+      case EffortLevel.high:
+        return 'Hoch';
+    }
+  }
+}

lib/features/tasks/domain/frequency.dart

@@ -0,0 +1,62 @@
+/// Frequency interval types for recurring tasks.
+///
+/// IMPORTANT: Never reorder or remove values - intEnum stores the .index.
+/// Always add new values at the END.
+enum IntervalType {
+  daily, // 0
+  everyNDays, // 1
+  weekly, // 2
+  biweekly, // 3
+  monthly, // 4
+  everyNMonths, // 5
+  quarterly, // 6
+  yearly, // 7
+}
+
+/// A frequency interval combining a type with an optional multiplier.
+class FrequencyInterval {
+  final IntervalType intervalType;
+  final int days;
+
+  const FrequencyInterval({required this.intervalType, this.days = 1});
+
+  /// German display label for this interval.
+  String label() {
+    switch (intervalType) {
+      case IntervalType.daily:
+        return 'Taeglich';
+      case IntervalType.everyNDays:
+        if (days == 7) return 'Woechentlich';
+        if (days == 14) return 'Alle 2 Wochen';
+        return 'Alle $days Tage';
+      case IntervalType.weekly:
+        return 'Woechentlich';
+      case IntervalType.biweekly:
+        return 'Alle 2 Wochen';
+      case IntervalType.monthly:
+        return 'Monatlich';
+      case IntervalType.everyNMonths:
+        if (days == 3) return 'Vierteljaehrlich';
+        if (days == 6) return 'Halbjaehrlich';
+        return 'Alle $days Monate';
+      case IntervalType.quarterly:
+        return 'Vierteljaehrlich';
+      case IntervalType.yearly:
+        return 'Jaehrlich';
+    }
+  }
+
+  /// All preset frequency intervals per TASK-04.
+  static const List<FrequencyInterval> presets = [
+    FrequencyInterval(intervalType: IntervalType.daily),
+    FrequencyInterval(intervalType: IntervalType.everyNDays, days: 2),
+    FrequencyInterval(intervalType: IntervalType.everyNDays, days: 3),
+    FrequencyInterval(intervalType: IntervalType.weekly),
+    FrequencyInterval(intervalType: IntervalType.biweekly),
+    FrequencyInterval(intervalType: IntervalType.monthly),
+    FrequencyInterval(intervalType: IntervalType.everyNMonths, days: 2),
+    FrequencyInterval(intervalType: IntervalType.quarterly),
+    FrequencyInterval(intervalType: IntervalType.everyNMonths, days: 6),
+    FrequencyInterval(intervalType: IntervalType.yearly),
+  ];
+}

lib/features/tasks/domain/relative_date.dart

@@ -0,0 +1,18 @@
+/// Format a due date relative to today in German.
+///
+/// Returns labels like "Heute", "Morgen", "in X Tagen",
+/// "Uberfaellig seit 1 Tag", "Uberfaellig seit X Tagen".
+///
+/// Both [dueDate] and [today] are compared as date-only (ignoring time).
+String formatRelativeDate(DateTime dueDate, DateTime today) {
+  final diff =
+      DateTime(dueDate.year, dueDate.month, dueDate.day)
+          .difference(DateTime(today.year, today.month, today.day))
+          .inDays;
+
+  if (diff == 0) return 'Heute';
+  if (diff == 1) return 'Morgen';
+  if (diff > 1) return 'in $diff Tagen';
+  if (diff == -1) return 'Uberfaellig seit 1 Tag';
+  return 'Uberfaellig seit ${diff.abs()} Tagen';
+}

lib/features/tasks/domain/scheduling.dart

@@ -0,0 +1,66 @@
+import 'frequency.dart';
+
+/// Calculate the next due date from the current due date and interval config.
+///
+/// For calendar-anchored intervals, [anchorDay] is the original day-of-month.
+/// Day-count intervals use pure arithmetic (Duration).
+/// Calendar-anchored intervals use month arithmetic with clamping.
+DateTime calculateNextDueDate({
+  required DateTime currentDueDate,
+  required IntervalType intervalType,
+  required int intervalDays,
+  int? anchorDay,
+}) {
+  switch (intervalType) {
+    // Day-count: pure arithmetic
+    case IntervalType.daily:
+      return currentDueDate.add(const Duration(days: 1));
+    case IntervalType.everyNDays:
+      return currentDueDate.add(Duration(days: intervalDays));
+    case IntervalType.weekly:
+      return currentDueDate.add(const Duration(days: 7));
+    case IntervalType.biweekly:
+      return currentDueDate.add(const Duration(days: 14));
+    // Calendar-anchored: month arithmetic with clamping
+    case IntervalType.monthly:
+      return _addMonths(currentDueDate, 1, anchorDay);
+    case IntervalType.everyNMonths:
+      return _addMonths(currentDueDate, intervalDays, anchorDay);
+    case IntervalType.quarterly:
+      return _addMonths(currentDueDate, 3, anchorDay);
+    case IntervalType.yearly:
+      return _addMonths(currentDueDate, 12, anchorDay);
+  }
+}
+
+/// Add months with day-of-month clamping.
+/// [anchorDay] remembers the original day for correct clamping.
+DateTime _addMonths(DateTime date, int months, int? anchorDay) {
+  final targetMonth = date.month + months;
+  final targetYear = date.year + (targetMonth - 1) ~/ 12;
+  final normalizedMonth = ((targetMonth - 1) % 12) + 1;
+  final day = anchorDay ?? date.day;
+  // Last day of target month: day 0 of next month
+  final lastDay = DateTime(targetYear, normalizedMonth + 1, 0).day;
+  final clampedDay = day > lastDay ? lastDay : day;
+  return DateTime(targetYear, normalizedMonth, clampedDay);
+}
+
+/// Catch-up: if next due is in the past, keep adding intervals until future/today.
+DateTime catchUpToPresent({
+  required DateTime nextDue,
+  required DateTime today,
+  required IntervalType intervalType,
+  required int intervalDays,
+  int? anchorDay,
+}) {
+  while (nextDue.isBefore(today)) {
+    nextDue = calculateNextDueDate(
+      currentDueDate: nextDue,
+      intervalType: intervalType,
+      intervalDays: intervalDays,
+      anchorDay: anchorDay,
+    );
+  }
+  return nextDue;
+}