feat(offline): tier 2 phase 2 — extend cache to tasks/projects/milestones/events/conversations

Phase 1 cached only notes. Phase 2 brings the read-through pattern to every
domain the app reads in bulk:

- Drift schema v2: 5 new cached_* tables + onUpgrade migration. Calendar
  events use range-scoped read/write (replaceEventsInRange) so disjoint
  month fetches don't clobber each other; milestones are per-project.
- Wrap TasksRepository, ProjectsRepository, MilestonesRepository, and
  ChatRepository (conversation list only) with NetworkException fallback.
  Writes hit the API then sync the cache.
- New EventsRepository wrapping EventsApi; calendar_provider and
  event_form_sheet repointed at the repository.
- OfflineBanner now surfaces getLatestSync() — most-recent timestamp
  across all domains — so the hint reads sensibly regardless of screen.

flutter analyze clean; existing tests pass. Phase 3 (offline write queue)
and Phase 4 (read-only UI indicators) still to come.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/data/repositories/chat_repository.dart

@@ -1,21 +1,46 @@
+import '../../core/exceptions.dart';
 import '../api/chat_api.dart';
 export '../api/chat_api.dart'
     show ChatStreamEvent, ChatTextChunk, ChatStatusUpdate, ChatToolCall;
+import '../local/database.dart';
 import '../models/conversation.dart';
 import '../models/message.dart';
 
+/// Chat repository with read-through caching for the conversation list only.
+/// Messages and the live SSE stream are intentionally not cached — they are
+/// per-conversation, large, and require a live network anyway.
 class ChatRepository {
   final ChatApi _api;
-  const ChatRepository(this._api);
+  final FabledDatabase _db;
+
+  const ChatRepository(this._api, this._db);
+
+  Future<List<Conversation>> getConversations() async {
+    try {
+      final conversations = await _api.getConversations();
+      await _db.replaceAllConversations(conversations);
+      return conversations;
+    } on NetworkException {
+      final cached = await _db.getAllConversations();
+      if (cached.isEmpty) rethrow;
+      return cached;
+    }
+  }
 
-  Future<List<Conversation>> getConversations() => _api.getConversations();
   Future<Conversation> createConversation(String title) =>
       _api.createConversation(title);
-  Future<void> deleteConversation(int id) => _api.deleteConversation(id);
+
+  Future<void> deleteConversation(int id) async {
+    await _api.deleteConversation(id);
+    await _db.deleteConversation(id);
+  }
+
   Future<(Conversation, List<Message>)> getMessages(int conversationId) =>
       _api.getMessages(conversationId);
+
   Future<void> sendMessage(int conversationId, String content) =>
       _api.sendMessage(conversationId, content);
+
   Stream<ChatStreamEvent> streamGeneration(int conversationId) =>
       _api.streamGeneration(conversationId);
 }

lib/data/repositories/events_repository.dart

@@ -0,0 +1,45 @@
+import '../../core/exceptions.dart';
+import '../api/events_api.dart';
+import '../local/database.dart';
+import '../models/calendar_event.dart';
+
+/// Calendar events repository with read-through caching for Tier 2 offline
+/// support. Range-scoped: each `getEvents(from, to)` mirrors that window into
+/// the cache (events outside the window are left alone) so successive
+/// disjoint range fetches don't clobber each other.
+class EventsRepository {
+  final EventsApi _api;
+  final FabledDatabase _db;
+
+  const EventsRepository(this._api, this._db);
+
+  Future<List<CalendarEvent>> getEvents(DateTime from, DateTime to) async {
+    try {
+      final events = await _api.getEvents(from, to);
+      await _db.replaceEventsInRange(from, to, events);
+      return events;
+    } on NetworkException {
+      final cached = await _db.getEventsInRange(from, to);
+      if (cached.isEmpty) rethrow;
+      return cached;
+    }
+  }
+
+  Future<CalendarEvent> createEvent(Map<String, dynamic> payload) async {
+    final event = await _api.createEvent(payload);
+    await _db.upsertEvent(event);
+    return event;
+  }
+
+  Future<CalendarEvent> updateEvent(
+      int id, Map<String, dynamic> fields) async {
+    final updated = await _api.updateEvent(id, fields);
+    await _db.upsertEvent(updated);
+    return updated;
+  }
+
+  Future<void> deleteEvent(int id) async {
+    await _api.deleteEvent(id);
+    await _db.deleteEvent(id);
+  }
+}

lib/data/repositories/milestones_repository.dart

@@ -1,26 +1,67 @@
+import '../../core/exceptions.dart';
 import '../api/milestones_api.dart';
+import '../local/database.dart';
 import '../models/milestone.dart';
 
+/// Milestones repository with read-through caching for Tier 2 offline support.
+/// Mirrors the pattern in NotesRepository — see that file for full notes.
 class MilestonesRepository {
   final MilestonesApi _api;
-  const MilestonesRepository(this._api);
+  final FabledDatabase _db;
 
-  Future<List<Milestone>> getAll(int projectId, {String? status}) =>
-      _api.getAll(projectId, status: status);
+  const MilestonesRepository(this._api, this._db);
+
+  Future<List<Milestone>> getAll(int projectId, {String? status}) async {
+    try {
+      final milestones = await _api.getAll(projectId, status: status);
+      // Only mirror the full per-project list to cache on the unfiltered
+      // fetch; a status filter would otherwise drop entries from cache.
+      if (status == null) {
+        await _db.replaceMilestonesForProject(projectId, milestones);
+      } else {
+        for (final m in milestones) {
+          await _db.upsertMilestone(m);
+        }
+      }
+      return milestones;
+    } on NetworkException {
+      final cached = await _db.getMilestonesForProject(projectId);
+      if (cached.isEmpty) rethrow;
+      if (status != null) {
+        return cached.where((m) => m.status == status).toList();
+      }
+      return cached;
+    }
+  }
 
   Future<Milestone> create(
     int projectId, {
     required String title,
     String? description,
     int orderIndex = 0,
-  }) =>
-      _api.create(projectId,
-          title: title, description: description, orderIndex: orderIndex);
+  }) async {
+    final milestone = await _api.create(
+      projectId,
+      title: title,
+      description: description,
+      orderIndex: orderIndex,
+    );
+    await _db.upsertMilestone(milestone);
+    return milestone;
+  }
 
   Future<Milestone> update(
-          int projectId, int milestoneId, Map<String, dynamic> fields) =>
-      _api.update(projectId, milestoneId, fields);
+    int projectId,
+    int milestoneId,
+    Map<String, dynamic> fields,
+  ) async {
+    final updated = await _api.update(projectId, milestoneId, fields);
+    await _db.upsertMilestone(updated);
+    return updated;
+  }
 
-  Future<void> delete(int projectId, int milestoneId) =>
-      _api.delete(projectId, milestoneId);
+  Future<void> delete(int projectId, int milestoneId) async {
+    await _api.delete(projectId, milestoneId);
+    await _db.deleteMilestone(milestoneId);
+  }
 }

lib/data/repositories/notes_repository.dart

@@ -90,9 +90,4 @@ class NotesRepository {
     await _api.delete(id);
     await _db.deleteNote(id);
   }
-
-  /// Last successful `getAll` sync timestamp. Surfaced by the OfflineBanner
-  /// when the network is unreachable so the user knows how stale the
-  /// cached notes list is.
-  Future<DateTime?> lastSyncedAt() => _db.getLastSync(kSyncDomainNotes);
 }

lib/data/repositories/projects_repository.dart

@@ -1,31 +1,87 @@
+import '../../core/exceptions.dart';
 import '../api/projects_api.dart';
+import '../local/database.dart';
 import '../models/project.dart';
 
+/// Projects repository with read-through caching for Tier 2 offline support.
+/// Mirrors the pattern in NotesRepository — see that file for full notes.
+///
+/// `getAll`'s sort/order/status query parameters are server-side filters; the
+/// cache stores the unfiltered list as last seen. Offline fallback returns
+/// the full cache regardless of the requested filters — close enough for a
+/// "view what you had" experience while disconnected.
 class ProjectsRepository {
   final ProjectsApi _api;
-  const ProjectsRepository(this._api);
+  final FabledDatabase _db;
+
+  const ProjectsRepository(this._api, this._db);
 
   Future<List<Project>> getAll({
     String? status,
     String sort = 'updated_at',
     String order = 'desc',
-  }) =>
-      _api.getAll(status: status, sort: sort, order: order);
-  Future<Project> getOne(int id) => _api.getOne(id);
+  }) async {
+    try {
+      final projects =
+          await _api.getAll(status: status, sort: sort, order: order);
+      // Only refresh the cache on the unfiltered default fetch — otherwise a
+      // status=archived call would clobber the active-projects cache.
+      if (status == null) {
+        await _db.replaceAllProjects(projects);
+      } else {
+        for (final p in projects) {
+          await _db.upsertProject(p);
+        }
+      }
+      return projects;
+    } on NetworkException {
+      final cached = await _db.getAllProjects();
+      if (cached.isEmpty) rethrow;
+      if (status != null) {
+        return cached.where((p) => p.status == status).toList();
+      }
+      return cached;
+    }
+  }
+
+  Future<Project> getOne(int id) async {
+    try {
+      final project = await _api.getOne(id);
+      await _db.upsertProject(project);
+      return project;
+    } on NetworkException {
+      final cached = await _db.getProject(id);
+      if (cached == null) rethrow;
+      return cached;
+    }
+  }
+
   Future<Project> create({
     required String title,
     String? description,
     String? goal,
     String? color,
     String status = 'active',
-  }) =>
-      _api.create(
-          title: title,
-          description: description,
-          goal: goal,
-          color: color,
-          status: status);
-  Future<Project> update(int id, Map<String, dynamic> fields) =>
-      _api.update(id, fields);
-  Future<void> delete(int id) => _api.delete(id);
+  }) async {
+    final project = await _api.create(
+      title: title,
+      description: description,
+      goal: goal,
+      color: color,
+      status: status,
+    );
+    await _db.upsertProject(project);
+    return project;
+  }
+
+  Future<Project> update(int id, Map<String, dynamic> fields) async {
+    final updated = await _api.update(id, fields);
+    await _db.upsertProject(updated);
+    return updated;
+  }
+
+  Future<void> delete(int id) async {
+    await _api.delete(id);
+    await _db.deleteProject(id);
+  }
 }

lib/data/repositories/tasks_repository.dart

@@ -1,12 +1,63 @@
+import '../../core/exceptions.dart';
 import '../api/tasks_api.dart';
+import '../local/database.dart';
 import '../models/task.dart';
 
+/// Tasks repository with read-through caching for Tier 2 offline support.
+/// Mirrors the pattern in NotesRepository — see that file for full notes.
 class TasksRepository {
   final TasksApi _api;
-  const TasksRepository(this._api);
+  final FabledDatabase _db;
 
-  Future<List<Task>> getAll() => _api.getAll();
-  Future<Task> getOne(int id) => _api.getOne(id);
+  const TasksRepository(this._api, this._db);
+
+  Future<List<Task>> getAll() async {
+    try {
+      final tasks = await _api.getAll();
+      await _db.replaceAllTasks(tasks);
+      return tasks;
+    } on NetworkException {
+      final cached = await _db.getAllTasks();
+      if (cached.isEmpty) rethrow;
+      return cached;
+    }
+  }
+
+  Future<Task> getOne(int id) async {
+    try {
+      final task = await _api.getOne(id);
+      await _db.upsertTask(task);
+      return task;
+    } on NetworkException {
+      final cached = await _db.getTask(id);
+      if (cached == null) rethrow;
+      return cached;
+    }
+  }
+
+  Future<List<Task>> getByProject(int projectId) async {
+    try {
+      final tasks = await _api.getByProject(projectId);
+      for (final t in tasks) {
+        await _db.upsertTask(t);
+      }
+      return tasks;
+    } on NetworkException {
+      return _db.getTasksByProject(projectId);
+    }
+  }
+
+  Future<List<Task>> getSubTasks(int parentId) async {
+    try {
+      final tasks = await _api.getSubTasks(parentId);
+      for (final t in tasks) {
+        await _db.upsertTask(t);
+      }
+      return tasks;
+    } on NetworkException {
+      return _db.getSubTasks(parentId);
+    }
+  }
 
   Future<Task> create({
     required String title,
@@ -16,22 +67,28 @@ class TasksRepository {
     DateTime? dueDate,
     int? projectId,
     int? parentId,
-  }) =>
-      _api.create(
-        title: title,
-        description: description,
-        status: status,
-        priority: priority,
-        dueDate: dueDate,
-        projectId: projectId,
-        parentId: parentId,
-      );
+  }) async {
+    final task = await _api.create(
+      title: title,
+      description: description,
+      status: status,
+      priority: priority,
+      dueDate: dueDate,
+      projectId: projectId,
+      parentId: parentId,
+    );
+    await _db.upsertTask(task);
+    return task;
+  }
 
-  Future<List<Task>> getByProject(int projectId) => _api.getByProject(projectId);
-  Future<List<Task>> getSubTasks(int parentId) => _api.getSubTasks(parentId);
+  Future<Task> update(int id, Map<String, dynamic> fields) async {
+    final updated = await _api.update(id, fields);
+    await _db.upsertTask(updated);
+    return updated;
+  }
 
-  Future<Task> update(int id, Map<String, dynamic> fields) =>
-      _api.update(id, fields);
-
-  Future<void> delete(int id) => _api.delete(id);
+  Future<void> delete(int id) async {
+    await _api.delete(id);
+    await _db.deleteTask(id);
+  }
 }