Fix Drift indexes and preparation ordering

CONTEXT.md

@@ -61,6 +61,18 @@ _Avoid_: Tracking vendor, analytics SDK
 A Product Usage Event that marks completion or failure of a meaningful user workflow step.
 _Avoid_: Tap event, raw navigation log, interaction trace
 
+**Schedule**:
+A planned commitment with a target time that OnTime helps the user prepare for.
+_Avoid_: Event, appointment, alarm
+
+**Preparation**:
+The ordered set of steps a user completes before a Schedule.
+_Avoid_: Preparation chain, task list
+
+**Preparation Step**:
+One named action with an expected duration inside a Preparation.
+_Avoid_: Task, checklist item, alarm step
+
 **Provider Authentication Completed**:
 The state where the external Apple or Google account prompt has returned credentials to OnTime.
 _Avoid_: Login completed, signed in, session ready
@@ -174,6 +186,9 @@ _Avoid_: Loaded range, stream range, cached range
 - An **Analytics Event Parameter** must not contain user-authored text, direct identifiers, tokens, raw exception strings, request bodies, or response bodies.
 - A **Product Usage Event** uses a stable snake_case name and includes a schema version.
 - A changed **Product Usage Event** meaning requires a new event name or schema version.
+- A **Schedule** may have one **Preparation** for that specific commitment.
+- A **Preparation** contains zero or more **Preparation Steps** in user-defined order.
+- A user's default **Preparation** may be applied to a **Schedule** and then changed for that Schedule.
 - A **Schedule** has a **Preparation** whose **Preparation Duration** contributes to preparation-start timing.
 - **Preparation Duration**, move time, and **Schedule Spare Time** are distinct schedule timing inputs.
 - User-facing copy should call a scheduled notification a **Schedule Notification**, not an **Alarm**, unless it opens an OnTime screen without the user first tapping a notification.
@@ -245,4 +260,5 @@ _Avoid_: Loaded range, stream range, cached range
 - "Time Sensitive" was too platform-specific for default user-facing status; resolved: fallback iOS delivery should be called notification.
 - "Status label" was ambiguous across platforms; resolved: Android uses precise notification or notification status, while iOS uses alarm status only for **iOS AlarmKit Alarm**.
 - "No scheduled alarm" was too capability-specific for an empty state; resolved: use **No Scheduled Notification** across platforms.
+- "Preparation chain" describes storage reconstruction, not product language; resolved: the domain concept is an ordered **Preparation** made of **Preparation Steps**.
 - "Total duration" was ambiguous between **Preparation Duration** and the broader preparation-start timing calculation; resolved: **Preparation Duration** is steps only, while move time and **Schedule Spare Time** are separate inputs.

lib/core/database/database.dart

@@ -18,42 +18,51 @@ import 'package:uuid/uuid.dart';
 part 'database.g.dart';
 
 @Singleton()
-@DriftDatabase(tables: [
-  Places,
-  Schedules,
-  Users,
-  PreparationSchedules,
-  PreparationUsers,
-], daos: [
-  ScheduleDao,
-  PlaceDao,
-  UserDao,
-  PreparationScheduleDao,
-  PreparationUserDao
-])
+@DriftDatabase(
+  tables: [Places, Schedules, Users, PreparationSchedules, PreparationUsers],
+  daos: [
+    ScheduleDao,
+    PlaceDao,
+    UserDao,
+    PreparationScheduleDao,
+    PreparationUserDao,
+  ],
+)
 class AppDatabase extends _$AppDatabase {
   AppDatabase() : super(_openConnection());
 
   AppDatabase.forTesting(super.e);
 
   @override
-  int get schemaVersion => 3;
+  int get schemaVersion => 4;
 
   @override
   MigrationStrategy get migration => MigrationStrategy(
-        onCreate: (Migrator m) async {
-          await m.createAll();
-        },
-        onUpgrade: (Migrator m, int from, int to) async {
-          if (from == 1) {
-            await m.createTable(preparationSchedules);
-            await m.createTable(preparationUsers);
-          }
-        },
-        beforeOpen: (details) async {
-          await customStatement('PRAGMA foreign_keys = ON');
-        },
-      );
+    onCreate: (Migrator m) async {
+      await m.createAll();
+    },
+    onUpgrade: (Migrator m, int from, int to) async {
+      if (from < 3) {
+        await m.createTable(preparationSchedules);
+        await m.createTable(preparationUsers);
+      }
+      if (from < 4) {
+        await _createLookupIndexes(m);
+      }
+    },
+    beforeOpen: (details) async {
+      await customStatement('PRAGMA foreign_keys = ON');
+    },
+  );
+
+  Future<void> _createLookupIndexes(Migrator m) async {
+    await m.createIndex(schedulesScheduleTimeIdx);
+    await m.createIndex(schedulesPlaceIdIdx);
+    await m.createIndex(preparationSchedulesScheduleIdIdx);
+    await m.createIndex(preparationSchedulesNextPreparationIdIdx);
+    await m.createIndex(preparationUsersUserIdIdx);
+    await m.createIndex(preparationUsersNextPreparationIdIdx);
+  }
 
   static QueryExecutor _openConnection() {
     return driftDatabase(

lib/data/daos/preparation_schedule_dao.dart

@@ -1,4 +1,3 @@
-import 'package:collection/collection.dart';
 import 'package:drift/drift.dart';
 import 'package:on_time_front/data/mappers/domain_persistence_mappers.dart';
 import 'package:on_time_front/domain/entities/preparation_step_entity.dart';
@@ -59,29 +58,17 @@ class PreparationScheduleDao extends DatabaseAccessor<AppDatabase>
       return PreparationEntity(preparationStepList: []);
     }
 
-    final firstStep = allSteps.firstWhere(
-      (step) => allSteps.every((other) => other.nextPreparationId != step.id),
-      orElse: () => allSteps.first,
-    );
-
-    final List<PreparationStepEntity> orderedSteps = [];
-    PreparationSchedule? currentStep = firstStep;
-
-    while (currentStep != null) {
-      orderedSteps.add(
-        PreparationStepEntity(
-          id: currentStep.id,
-          preparationName: currentStep.preparationName,
-          preparationTime: Duration(minutes: currentStep.preparationTime),
-          nextPreparationId: currentStep.nextPreparationId,
-        ),
-      );
-      currentStep = allSteps.firstWhereOrNull(
-        (step) => step.id == currentStep!.nextPreparationId,
-      );
-    }
-
-    return PreparationEntity(preparationStepList: orderedSteps);
+    return PreparationEntity(
+      preparationStepList: [
+        for (final step in allSteps)
+          PreparationStepEntity(
+            id: step.id,
+            preparationName: step.preparationName,
+            preparationTime: Duration(minutes: step.preparationTime),
+            nextPreparationId: step.nextPreparationId,
+          ),
+      ],
+    ).ordered;
   }
 
   Future<PreparationStepEntity> getPreparationStepById(

lib/data/daos/preparation_user_dao.dart

@@ -1,4 +1,3 @@
-import 'package:collection/collection.dart';
 import 'package:drift/drift.dart';
 import 'package:on_time_front/data/mappers/domain_persistence_mappers.dart';
 import 'package:on_time_front/domain/entities/preparation_step_entity.dart';
@@ -49,29 +48,17 @@ class PreparationUserDao extends DatabaseAccessor<AppDatabase>
       return PreparationEntity(preparationStepList: []);
     }
 
-    final firstStep = allSteps.firstWhere(
-      (step) => allSteps.every((other) => other.nextPreparationId != step.id),
-      orElse: () => allSteps.first,
-    );
-
-    final List<PreparationStepEntity> orderedSteps = [];
-    PreparationUser? currentStep = firstStep;
-
-    while (currentStep != null) {
-      orderedSteps.add(
-        PreparationStepEntity(
-          id: currentStep.id,
-          preparationName: currentStep.preparationName,
-          preparationTime: Duration(minutes: currentStep.preparationTime),
-          nextPreparationId: currentStep.nextPreparationId,
-        ),
-      );
-      currentStep = allSteps.firstWhereOrNull(
-        (step) => step.id == currentStep!.nextPreparationId,
-      );
-    }
-
-    return PreparationEntity(preparationStepList: orderedSteps);
+    return PreparationEntity(
+      preparationStepList: [
+        for (final step in allSteps)
+          PreparationStepEntity(
+            id: step.id,
+            preparationName: step.preparationName,
+            preparationTime: Duration(minutes: step.preparationTime),
+            nextPreparationId: step.nextPreparationId,
+          ),
+      ],
+    ).ordered;
   }
 
   Future<PreparationStepEntity> getPreparationStepById(

lib/data/tables/preparation_schedule_table.dart

@@ -2,6 +2,14 @@ import 'package:drift/drift.dart';
 import 'package:on_time_front/data/tables/schedules_table.dart';
 import 'package:uuid/uuid.dart';
 
+@TableIndex(
+  name: 'preparation_schedules_schedule_id_idx',
+  columns: {#scheduleId},
+)
+@TableIndex(
+  name: 'preparation_schedules_next_preparation_id_idx',
+  columns: {#nextPreparationId},
+)
 class PreparationSchedules extends Table {
   TextColumn get id => text().clientDefault(() => Uuid().v7())();
   TextColumn get scheduleId => text().references(Schedules, #id)();

lib/data/tables/preparation_user_table.dart

@@ -2,6 +2,11 @@ import 'package:drift/drift.dart';
 import 'package:on_time_front/data/tables/user_table.dart';
 import 'package:uuid/uuid.dart';
 
+@TableIndex(name: 'preparation_users_user_id_idx', columns: {#userId})
+@TableIndex(
+  name: 'preparation_users_next_preparation_id_idx',
+  columns: {#nextPreparationId},
+)
 class PreparationUsers extends Table {
   TextColumn get id => text().clientDefault(() => Uuid().v7())();
   TextColumn get userId => text().references(Users, #id)();

lib/data/tables/schedules_table.dart

@@ -3,6 +3,8 @@ import 'package:on_time_front/core/utils/json_converters/duration_json_converter
 import 'package:on_time_front/data/tables/places_table.dart';
 import 'package:uuid/uuid.dart';
 
+@TableIndex(name: 'schedules_schedule_time_idx', columns: {#scheduleTime})
+@TableIndex(name: 'schedules_place_id_idx', columns: {#placeId})
 class Schedules extends Table {
   TextColumn get id => text().clientDefault(() => Uuid().v7())();
   TextColumn get placeId => text().references(Places, #id)();

test/core/database/database_index_test.dart

@@ -0,0 +1,91 @@
+import 'package:drift/drift.dart' as drift;
+import 'package:drift/native.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:on_time_front/core/database/database.dart';
+
+void main() {
+  late AppDatabase database;
+
+  setUp(() {
+    database = AppDatabase.forTesting(NativeDatabase.memory());
+  });
+
+  tearDown(() async {
+    await database.close();
+  });
+
+  test(
+    'creates lookup indexes for schedule and preparation DAO predicates',
+    () async {
+      for (final entry in _expectedLookupIndexesByTable.entries) {
+        final indexNames = await _indexNames(database, entry.key);
+
+        expect(
+          indexNames,
+          containsAll(entry.value),
+          reason: '${entry.key} should declare indexes for DAO lookup paths',
+        );
+      }
+    },
+  );
+
+  test('adds lookup indexes when upgrading a schema 3 database', () async {
+    expect(database.schemaVersion, 4);
+
+    await _dropExpectedLookupIndexes(database);
+
+    for (final entry in _expectedLookupIndexesByTable.entries) {
+      expect(
+        await _indexNames(database, entry.key),
+        isNot(containsAll(entry.value)),
+      );
+    }
+
+    await database.migration.onUpgrade(database.createMigrator(), 3, 4);
+
+    for (final entry in _expectedLookupIndexesByTable.entries) {
+      final indexNames = await _indexNames(database, entry.key);
+
+      expect(
+        indexNames,
+        containsAll(entry.value),
+        reason: '${entry.key} indexes should be added by the 3 -> 4 migration',
+      );
+    }
+  });
+}
+
+const _expectedLookupIndexesByTable = {
+  'preparation_schedules': {
+    'preparation_schedules_schedule_id_idx',
+    'preparation_schedules_next_preparation_id_idx',
+  },
+  'preparation_users': {
+    'preparation_users_user_id_idx',
+    'preparation_users_next_preparation_id_idx',
+  },
+  'schedules': {'schedules_schedule_time_idx', 'schedules_place_id_idx'},
+};
+
+Future<Set<String>> _indexNames(AppDatabase database, String tableName) async {
+  final rows = await database
+      .customSelect(
+        '''
+      SELECT name
+      FROM sqlite_master
+      WHERE type = 'index' AND tbl_name = ?
+    ''',
+        variables: [drift.Variable.withString(tableName)],
+      )
+      .get();
+
+  return {for (final row in rows) row.read<String>('name')};
+}
+
+Future<void> _dropExpectedLookupIndexes(AppDatabase database) async {
+  for (final indexNames in _expectedLookupIndexesByTable.values) {
+    for (final indexName in indexNames) {
+      await database.customStatement('DROP INDEX IF EXISTS $indexName');
+    }
+  }
+}