Implement recurring tasks functionality

Adds automatic creation of next task instance when recurring tasks are completed.

- Add calculate_next_due_date() and create_next_recurrence() methods to Task model
- Update task completion handlers in views and sync API to create next recurrence
- Add hourly Celery task to process any missed recurring tasks
- Support daily, weekly, biweekly, monthly, yearly recurrence patterns
- Respect recurrence_end_date limits

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

config/celery.py

@@ -30,6 +30,10 @@ app.conf.beat_schedule = {
         'task': 'notifications.tasks.check_overdue_tasks',
         'schedule': crontab(hour=8, minute=0),  # Daily at 8 AM
     },
+    'process-recurring-tasks': {
+        'task': 'notifications.tasks.process_recurring_tasks',
+        'schedule': crontab(minute=0),  # Every hour
+    },
 }
 
 

notifications/tasks.py

@@ -236,3 +236,51 @@ def schedule_task_reminder(task_id):
                 task=task,
                 remind_at=remind_at
             )
+
+
+@shared_task
+def process_recurring_tasks():
+    """
+    Process completed recurring tasks and create next instances.
+    This runs periodically as a safety net to catch any tasks that weren't
+    automatically handled when marked as completed.
+    Runs every hour via Celery Beat.
+    """
+    from tasks.models import Task
+
+    # Find completed recurring tasks that don't have a next instance created yet
+    # We look for tasks completed in the last 24 hours to avoid reprocessing old tasks
+    yesterday = timezone.now() - timedelta(days=1)
+
+    completed_recurring_tasks = Task.objects.filter(
+        status='completed',
+        recurrence__in=['daily', 'weekly', 'biweekly', 'monthly', 'yearly', 'custom'],
+        completed_at__gte=yesterday
+    ).exclude(recurrence='none')
+
+    tasks_created = 0
+    for task in completed_recurring_tasks:
+        # Check if a next recurrence already exists
+        # Look for pending tasks with the same title, user, and recurrence pattern
+        next_due_date = task.calculate_next_due_date()
+        if next_due_date:
+            # Check if we already created this recurrence
+            existing = Task.objects.filter(
+                user=task.user,
+                title=task.title,
+                due_date=next_due_date,
+                recurrence=task.recurrence,
+                status='pending'
+            ).exists()
+
+            if not existing:
+                # Create the next recurrence
+                new_task = task.create_next_recurrence()
+                if new_task:
+                    tasks_created += 1
+                    logger.info(f"Created recurring task: {new_task.title} (due: {new_task.due_date})")
+
+    if tasks_created > 0:
+        logger.info(f"Created {tasks_created} recurring task instances")
+
+    return tasks_created

sync/views.py

@@ -291,6 +291,9 @@ def process_time_entry_changes(user, entry_changes, last_sync_at):
 
 def update_task_from_data(task, data):
     """Update a task from sync data."""
+    # Track old status to detect completion
+    old_status = task.status
+
     task.title = data.get('title', task.title)
     task.description = data.get('description', task.description)
     task.status = data.get('status', task.status)
@@ -302,6 +305,10 @@ def update_task_from_data(task, data):
     task.recurrence_rule = data.get('recurrence_rule', task.recurrence_rule)
     task.sort_order = data.get('sort_order', task.sort_order)
 
+    # Create next recurrence if task is being marked as completed
+    if old_status != 'completed' and task.status == 'completed' and task.recurrence != 'none':
+        task.create_next_recurrence()
+
     task.save()
 
     # Handle tags

tasks/models.py

@@ -174,6 +174,79 @@ class Task(models.Model):
         secs = seconds % 60
         return f"{hours}:{minutes:02d}:{secs:02d}"
 
+    def calculate_next_due_date(self, from_date=None):
+        """
+        Calculate the next due date based on recurrence pattern.
+        Returns None if task doesn't recur or has reached end date.
+        """
+        if self.recurrence == 'none':
+            return None
+
+        from datetime import timedelta
+        from dateutil.relativedelta import relativedelta
+
+        base_date = from_date or self.due_date
+        if not base_date:
+            from django.utils import timezone
+            base_date = timezone.now().date()
+
+        # Calculate next date based on recurrence type
+        if self.recurrence == 'daily':
+            next_date = base_date + timedelta(days=1)
+        elif self.recurrence == 'weekly':
+            next_date = base_date + timedelta(weeks=1)
+        elif self.recurrence == 'biweekly':
+            next_date = base_date + timedelta(weeks=2)
+        elif self.recurrence == 'monthly':
+            next_date = base_date + relativedelta(months=1)
+        elif self.recurrence == 'yearly':
+            next_date = base_date + relativedelta(years=1)
+        elif self.recurrence == 'custom' and self.recurrence_rule:
+            # TODO: Implement RRULE parsing for custom recurrence
+            # For now, default to weekly
+            next_date = base_date + timedelta(weeks=1)
+        else:
+            return None
+
+        # Check if we've passed the end date
+        if self.recurrence_end_date and next_date > self.recurrence_end_date:
+            return None
+
+        return next_date
+
+    def create_next_recurrence(self):
+        """
+        Create the next instance of this recurring task.
+        Returns the new task or None if no recurrence should be created.
+        """
+        if self.recurrence == 'none':
+            return None
+
+        next_due_date = self.calculate_next_due_date()
+        if not next_due_date:
+            return None
+
+        # Create new task with same properties
+        new_task = Task.objects.create(
+            user=self.user,
+            parent=self.parent,
+            title=self.title,
+            description=self.description,
+            status='pending',
+            priority=self.priority,
+            due_date=next_due_date,
+            due_time=self.due_time,
+            recurrence=self.recurrence,
+            recurrence_rule=self.recurrence_rule,
+            recurrence_end_date=self.recurrence_end_date,
+            sort_order=self.sort_order,
+        )
+
+        # Copy tags
+        new_task.tags.set(self.tags.all())
+
+        return new_task
+
 
 class TimeEntry(models.Model):
     """

tasks/views.py

@@ -425,6 +425,9 @@ class TaskDetailView(View):
         task.title = request.POST.get('title', task.title)
         task.description = request.POST.get('description', '')
 
+        # Track old status to detect completion
+        old_status = task.status
+
         # Validate status against allowed choices
         status = request.POST.get('status', task.status)
         valid_statuses = [choice[0] for choice in Task.STATUS_CHOICES]
@@ -451,6 +454,10 @@ class TaskDetailView(View):
         else:
             task.recurrence = 'none'
 
+        # Create next recurrence if task is being marked as completed
+        if old_status != 'completed' and task.status == 'completed' and task.recurrence != 'none':
+            task.create_next_recurrence()
+
         task.save()
 
         # Handle tags
@@ -564,7 +571,13 @@ def task_toggle_status(request, task_id):
     if task.status == 'completed':
         task.status = 'pending'
     else:
+        # Mark as completed
         task.status = 'completed'
+
+        # Create next recurrence if this is a recurring task
+        if task.recurrence != 'none':
+            task.create_next_recurrence()
+
     task.save()
 
     next_url = request.POST.get('next', 'dashboard')