Improve project-task integration and sub-task support

- TasksApi: add getSubTasks(parentId) + parentId param to create()
- TasksRepository: expose new API methods
- app.dart: invalidate projectsProvider + projectMilestonesProvider
  after quick capture creates a task; taskNew route reads ?projectId=
  query param and passes as initialProjectId to TaskEditScreen
- project_list_screen.dart: _AddTaskRow passes projectId query param
  so the task editor pre-fills the project on navigation
- task_edit_screen.dart: fully rewritten with initialProjectId support,
  sub-task fetching/creation, and _SubTasksSection widget

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

lib/app.dart

@@ -7,7 +7,9 @@ import 'core/exceptions.dart';
 import 'providers/api_client_provider.dart';
 import 'providers/auth_provider.dart';
 import 'providers/capture_queue_provider.dart';
+import 'providers/milestones_provider.dart';
 import 'providers/notes_provider.dart';
+import 'providers/projects_provider.dart';
 import 'providers/settings_provider.dart';
 import 'providers/update_provider.dart';
 import 'providers/tasks_provider.dart';
@@ -94,7 +96,11 @@ final routerProvider = Provider<GoRouter>((ref) {
       ),
       GoRoute(
         path: Routes.taskNew,
-        builder: (_, _) => const TaskEditScreen(),
+        builder: (_, state) => TaskEditScreen(
+          initialProjectId: state.uri.queryParameters['projectId'] != null
+              ? int.tryParse(state.uri.queryParameters['projectId']!)
+              : null,
+        ),
       ),
       GoRoute(
         path: Routes.taskEdit,
@@ -347,6 +353,8 @@ class _QuickCaptureBarState extends ConsumerState<_QuickCaptureBar> {
         case 'task':
         case 'todo':
           ref.invalidate(tasksProvider);
+          ref.invalidate(projectsProvider);
+          ref.invalidate(projectMilestonesProvider);
       }
 
       final msg = result.message.isNotEmpty
@@ -398,6 +406,8 @@ class _QuickCaptureBarState extends ConsumerState<_QuickCaptureBar> {
           case 'task':
           case 'todo':
             ref.invalidate(tasksProvider);
+            ref.invalidate(projectsProvider);
+            ref.invalidate(projectMilestonesProvider);
         }
       } on NetworkException {
         break; // Still offline — stop draining.

lib/data/api/tasks_api.dart

@@ -34,6 +34,7 @@ class TasksApi {
     required TaskPriority priority,
     DateTime? dueDate,
     int? projectId,
+    int? parentId,
   }) async {
     try {
       final response = await _dio.post('/api/tasks', data: {
@@ -43,6 +44,7 @@ class TasksApi {
         'priority': priority.value,
         'due_date': dueDate?.toIso8601String(),
         if (projectId != null) 'project_id': projectId,
+        if (parentId != null) 'parent_id': parentId,
       });
       return Task.fromJson(response.data as Map<String, dynamic>);
     } on DioException catch (e) {
@@ -50,6 +52,20 @@ class TasksApi {
     }
   }
 
+  Future<List<Task>> getSubTasks(int parentId) async {
+    try {
+      final response = await _dio.get(
+        '/api/notes',
+        queryParameters: {'parent_id': parentId, 'is_task': 'true', 'limit': 100},
+      );
+      final data = response.data as Map<String, dynamic>;
+      final list = data['notes'] as List<dynamic>;
+      return list.map((e) => Task.fromJson(e as Map<String, dynamic>)).toList();
+    } on DioException catch (e) {
+      throw dioToApp(e);
+    }
+  }
+
   Future<Task> update(int id, Map<String, dynamic> fields) async {
     try {
       final response = await _dio.put('/api/tasks/$id', data: fields);

lib/data/repositories/tasks_repository.dart

@@ -15,6 +15,7 @@ class TasksRepository {
     required TaskPriority priority,
     DateTime? dueDate,
     int? projectId,
+    int? parentId,
   }) =>
       _api.create(
         title: title,
@@ -23,8 +24,11 @@ class TasksRepository {
         priority: priority,
         dueDate: dueDate,
         projectId: projectId,
+        parentId: parentId,
       );
 
+  Future<List<Task>> getSubTasks(int parentId) => _api.getSubTasks(parentId);
+
   Future<Task> update(int id, Map<String, dynamic> fields) =>
       _api.update(id, fields);
 

lib/screens/projects/project_list_screen.dart

@@ -493,7 +493,7 @@ class _AddTaskRow extends StatelessWidget {
     return Padding(
       padding: const EdgeInsets.fromLTRB(48, 4, 16, 8),
       child: TextButton.icon(
-        onPressed: () => context.push(Routes.taskNew),
+        onPressed: () => context.push('${Routes.taskNew}?projectId=${project.id}'),
         icon: const Icon(Icons.add, size: 16),
         label: const Text('New task'),
         style: TextButton.styleFrom(

lib/screens/tasks/task_edit_screen.dart

@@ -2,7 +2,9 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
+import '../../core/constants.dart';
 import '../../core/exceptions.dart';
+import '../../data/api/tasks_api.dart';
 import '../../data/models/task.dart';
 import '../../providers/api_client_provider.dart';
 import '../../providers/tasks_provider.dart';
@@ -10,7 +12,8 @@ import '../../widgets/project_selector.dart';
 
 class TaskEditScreen extends ConsumerStatefulWidget {
   final int? taskId;
-  const TaskEditScreen({super.key, this.taskId});
+  final int? initialProjectId;
+  const TaskEditScreen({super.key, this.taskId, this.initialProjectId});
 
   @override
   ConsumerState<TaskEditScreen> createState() => _TaskEditScreenState();
@@ -25,13 +28,14 @@ class _TaskEditScreenState extends ConsumerState<TaskEditScreen> {
   DateTime? _dueDate;
   int? _projectId;
   bool _saving = false;
+  List<Task> _subTasks = [];
 
-  // Future is created once in initState so FutureBuilder never restarts it.
   late final Future<void> _initFuture;
 
   @override
   void initState() {
     super.initState();
+    _projectId = widget.initialProjectId;
     _initFuture =
         widget.taskId != null ? _loadExisting() : Future.value();
   }
@@ -44,14 +48,18 @@ class _TaskEditScreenState extends ConsumerState<TaskEditScreen> {
   }
 
   Future<void> _loadExisting() async {
-    final task =
-        await ref.read(tasksRepositoryProvider).getOne(widget.taskId!);
+    final repo = ref.read(tasksRepositoryProvider);
+    final task = await repo.getOne(widget.taskId!);
     _titleController.text = task.title;
     _descController.text = task.description ?? '';
     _status = task.status;
     _priority = task.priority;
     _dueDate = task.dueDate;
     _projectId = task.projectId;
+    // Fetch sub-tasks
+    final api = ref.read(tasksApiProvider);
+    final subs = await api.getSubTasks(widget.taskId!);
+    setState(() => _subTasks = subs);
   }
 
   Future<void> _save() async {
@@ -124,6 +132,54 @@ class _TaskEditScreenState extends ConsumerState<TaskEditScreen> {
     if (date != null) setState(() => _dueDate = date);
   }
 
+  Future<void> _addSubTask() async {
+    final titleCtrl = TextEditingController();
+    final result = await showDialog<String>(
+      context: context,
+      builder: (ctx) => AlertDialog(
+        title: const Text('Add sub-task'),
+        content: TextField(
+          controller: titleCtrl,
+          autofocus: true,
+          decoration: const InputDecoration(
+            labelText: 'Title',
+            border: OutlineInputBorder(),
+          ),
+          textInputAction: TextInputAction.done,
+          onSubmitted: (v) => Navigator.pop(ctx, v.trim()),
+        ),
+        actions: [
+          TextButton(
+              onPressed: () => Navigator.pop(ctx),
+              child: const Text('Cancel')),
+          FilledButton(
+              onPressed: () =>
+                  Navigator.pop(ctx, titleCtrl.text.trim()),
+              child: const Text('Add')),
+        ],
+      ),
+    );
+    titleCtrl.dispose();
+    if (result == null || result.isEmpty || !mounted) return;
+    try {
+      final api = ref.read(tasksApiProvider);
+      final sub = await api.create(
+        title: result,
+        status: TaskStatus.todo,
+        priority: TaskPriority.none,
+        projectId: _projectId,
+        parentId: widget.taskId,
+      );
+      ref.invalidate(tasksProvider);
+      setState(() => _subTasks = [..._subTasks, sub]);
+    } on AppException catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context)
+            .showSnackBar(SnackBar(content: Text(e.message)));
+      }
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     return FutureBuilder(
@@ -160,75 +216,88 @@ class _TaskEditScreenState extends ConsumerState<TaskEditScreen> {
                       key: _formKey,
                       child: ListView(
                         padding: const EdgeInsets.all(16),
-                    children: [
-                      TextFormField(
-                        controller: _titleController,
-                        decoration: const InputDecoration(
-                          labelText: 'Title',
-                          border: OutlineInputBorder(),
-                        ),
-                        validator: (v) =>
-                            (v == null || v.trim().isEmpty) ? 'Required' : null,
+                        children: [
+                          TextFormField(
+                            controller: _titleController,
+                            decoration: const InputDecoration(
+                              labelText: 'Title',
+                              border: OutlineInputBorder(),
+                            ),
+                            validator: (v) =>
+                                (v == null || v.trim().isEmpty)
+                                    ? 'Required'
+                                    : null,
+                          ),
+                          const SizedBox(height: 16),
+                          TextFormField(
+                            controller: _descController,
+                            decoration: const InputDecoration(
+                              labelText: 'Description (optional)',
+                              border: OutlineInputBorder(),
+                            ),
+                            maxLines: 3,
+                          ),
+                          const SizedBox(height: 16),
+                          DropdownButtonFormField<TaskStatus>(
+                            value: _status,
+                            decoration: const InputDecoration(
+                              labelText: 'Status',
+                              border: OutlineInputBorder(),
+                            ),
+                            items: TaskStatus.values
+                                .map((s) => DropdownMenuItem(
+                                    value: s, child: Text(s.label)))
+                                .toList(),
+                            onChanged: (v) =>
+                                setState(() => _status = v!),
+                          ),
+                          const SizedBox(height: 16),
+                          DropdownButtonFormField<TaskPriority>(
+                            value: _priority,
+                            decoration: const InputDecoration(
+                              labelText: 'Priority',
+                              border: OutlineInputBorder(),
+                            ),
+                            items: TaskPriority.values
+                                .map((p) => DropdownMenuItem(
+                                    value: p, child: Text(p.label)))
+                                .toList(),
+                            onChanged: (v) =>
+                                setState(() => _priority = v!),
+                          ),
+                          const SizedBox(height: 16),
+                          ListTile(
+                            contentPadding: EdgeInsets.zero,
+                            title: Text(_dueDate == null
+                                ? 'No due date'
+                                : 'Due: ${_dueDate!.toLocal().toString().substring(0, 10)}'),
+                            leading: const Icon(Icons.calendar_today),
+                            trailing: _dueDate != null
+                                ? IconButton(
+                                    icon: const Icon(Icons.clear),
+                                    onPressed: () =>
+                                        setState(() => _dueDate = null),
+                                  )
+                                : null,
+                            onTap: _pickDate,
+                          ),
+                          const SizedBox(height: 16),
+                          ProjectSelector(
+                            value: _projectId,
+                            onChanged: (id) =>
+                                setState(() => _projectId = id),
+                          ),
+                          // Sub-tasks (only when editing an existing task)
+                          if (widget.taskId != null) ...[
+                            const SizedBox(height: 24),
+                            _SubTasksSection(
+                              subTasks: _subTasks,
+                              onAdd: _addSubTask,
+                            ),
+                          ],
+                        ],
                       ),
-                      const SizedBox(height: 16),
-                      TextFormField(
-                        controller: _descController,
-                        decoration: const InputDecoration(
-                          labelText: 'Description (optional)',
-                          border: OutlineInputBorder(),
-                        ),
-                        maxLines: 3,
-                      ),
-                      const SizedBox(height: 16),
-                      DropdownButtonFormField<TaskStatus>(
-                        initialValue: _status,
-                        decoration: const InputDecoration(
-                          labelText: 'Status',
-                          border: OutlineInputBorder(),
-                        ),
-                        items: TaskStatus.values
-                            .map((s) => DropdownMenuItem(
-                                value: s, child: Text(s.label)))
-                            .toList(),
-                        onChanged: (v) => setState(() => _status = v!),
-                      ),
-                      const SizedBox(height: 16),
-                      DropdownButtonFormField<TaskPriority>(
-                        initialValue: _priority,
-                        decoration: const InputDecoration(
-                          labelText: 'Priority',
-                          border: OutlineInputBorder(),
-                        ),
-                        items: TaskPriority.values
-                            .map((p) => DropdownMenuItem(
-                                value: p, child: Text(p.label)))
-                            .toList(),
-                        onChanged: (v) => setState(() => _priority = v!),
-                      ),
-                      const SizedBox(height: 16),
-                      ListTile(
-                        contentPadding: EdgeInsets.zero,
-                        title: Text(_dueDate == null
-                            ? 'No due date'
-                            : 'Due: ${_dueDate!.toLocal().toString().substring(0, 10)}'),
-                        leading: const Icon(Icons.calendar_today),
-                        trailing: _dueDate != null
-                            ? IconButton(
-                                icon: const Icon(Icons.clear),
-                                onPressed: () =>
-                                    setState(() => _dueDate = null),
-                              )
-                            : null,
-                        onTap: _pickDate,
-                      ),
-                      const SizedBox(height: 16),
-                      ProjectSelector(
-                        value: _projectId,
-                        onChanged: (id) => setState(() => _projectId = id),
-                      ),
-                    ],
-                  ),
-                ),
+                    ),
                   ),
                 ),
         );
@@ -236,3 +305,91 @@ class _TaskEditScreenState extends ConsumerState<TaskEditScreen> {
     );
   }
 }
+
+// ─── Sub-tasks section ─────────────────────────────────────────────────────────
+
+class _SubTasksSection extends ConsumerWidget {
+  final List<Task> subTasks;
+  final VoidCallback onAdd;
+  const _SubTasksSection({required this.subTasks, required this.onAdd});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final colorScheme = Theme.of(context).colorScheme;
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        Row(
+          children: [
+            Text(
+              'Sub-tasks',
+              style: Theme.of(context).textTheme.titleSmall?.copyWith(
+                    color: colorScheme.onSurfaceVariant,
+                  ),
+            ),
+            const Spacer(),
+            TextButton.icon(
+              onPressed: onAdd,
+              icon: const Icon(Icons.add, size: 16),
+              label: const Text('Add'),
+              style: TextButton.styleFrom(
+                foregroundColor: colorScheme.primary,
+                padding:
+                    const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
+                textStyle: const TextStyle(fontSize: 13),
+              ),
+            ),
+          ],
+        ),
+        if (subTasks.isEmpty)
+          Padding(
+            padding: const EdgeInsets.symmetric(vertical: 8),
+            child: Text(
+              'No sub-tasks yet.',
+              style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                    color: colorScheme.outline,
+                  ),
+            ),
+          )
+        else
+          ...subTasks.map((sub) => _SubTaskTile(task: sub, ref: ref)),
+      ],
+    );
+  }
+}
+
+class _SubTaskTile extends StatelessWidget {
+  final Task task;
+  final WidgetRef ref;
+  const _SubTaskTile({required this.task, required this.ref});
+
+  @override
+  Widget build(BuildContext context) {
+    final isDone = task.status == TaskStatus.done;
+    return ListTile(
+      dense: true,
+      contentPadding: EdgeInsets.zero,
+      leading: Checkbox(
+        value: isDone,
+        onChanged: (_) async {
+          final newStatus =
+              isDone ? TaskStatus.todo : TaskStatus.done;
+          await ref.read(tasksProvider.notifier).updateTask(
+              task.id, {'status': newStatus.value});
+        },
+      ),
+      title: Text(
+        task.title,
+        style: TextStyle(
+          decoration: isDone ? TextDecoration.lineThrough : null,
+          color: isDone
+              ? Theme.of(context).colorScheme.outline
+              : null,
+        ),
+      ),
+      onTap: () => context.push(
+        Routes.taskEdit.replaceFirst(':id', '${task.id}'),
+      ),
+    );
+  }
+}