fix: reset subtasks for recurring tasks

backend/main.py

@@ -640,6 +640,7 @@ async def update_task(
     data = payload.model_dump(exclude_unset=True)
     expected_version = data.pop("version")
     recurrence = None
+    reset_subtasks = False
     if data.get("completed") is True:
         recurrence = await db.scalar(select(RecurrenceTemplate).where(
             RecurrenceTemplate.task_id == task_id, RecurrenceTemplate.user_id == user.id
@@ -656,6 +657,7 @@ async def update_task(
                 data["completed"] = False
                 data["due_at"] = next_items[0]
                 recurrence.starts_at = next_items[0]
+                reset_subtasks = True
     if "list_id" in data:
         await _owned_list(db, user.id, data["list_id"])
         if task.parent_id:
@@ -685,6 +687,18 @@ async def update_task(
         if exists_id:
             raise HTTPException(status_code=409, detail="任务已被更新，请刷新后重试")
         raise HTTPException(status_code=404, detail="任务不存在")
+    if reset_subtasks:
+        reset_at = utcnow()
+        await db.execute(
+            update(Task)
+            .where(
+                Task.parent_id == task.id,
+                Task.user_id == user.id,
+                Task.deleted_at.is_(None),
+                Task.completed.is_(True),
+            )
+            .values(completed=False, version=Task.version + 1, updated_at=reset_at)
+        )
     if "list_id" in data and task.parent_id is None:
         await db.execute(
             update(Task)