feat: auto-set started_at/completed_at on task status transitions

src/fabledassistant/services/notes.py

@@ -240,6 +240,25 @@ async def update_note(user_id: int, note_id: int, **fields: object) -> Note | No
             elif key == "tags" and isinstance(value, list):
                 value = _normalize_tags(value)
             setattr(note, key, value)
+        # Auto-set lifecycle timestamps on status transitions
+        if "status" in fields:
+            _now = datetime.now(timezone.utc)
+            if note.status == TaskStatus.in_progress.value:
+                if note.started_at is None:
+                    note.started_at = _now
+            elif note.status in (TaskStatus.done.value, TaskStatus.cancelled.value):
+                note.completed_at = _now
+                if note.recurrence_rule:
+                    from fabledassistant.services.recurrence import calculate_next_due
+                    base = note.due_date or _now.date()
+                    next_due = calculate_next_due(note.recurrence_rule, base)
+                    note.recurrence_next_spawn_at = datetime(
+                        next_due.year, next_due.month, next_due.day, tzinfo=timezone.utc
+                    )
+            elif note.status == TaskStatus.todo.value:
+                note.started_at = None
+                note.completed_at = None
+                note.recurrence_next_spawn_at = None
         note.updated_at = datetime.now(timezone.utc)
         await session.commit()
         await session.refresh(note)