optimize+注释

backend/app/api/endpoints/delivery.py

@@ -1,4 +1,5 @@
 # 推送设置 API：管理用户的推送时间表和推送渠道
+# 关键约束：同一用户两条推送时间间隔至少 30 分钟
 from datetime import time as dt_time
 from typing import List
 
@@ -73,6 +74,7 @@ def _check_min_gap(
     existing = query.all()
     new_minutes = _time_to_minutes(new_time)
 
+    # 考虑跨午夜情况：如 23:50 与 00:10 实际只差 20 分钟
     for s in existing:
         old_minutes = _time_to_minutes(s.delivery_time)
         diff = abs(new_minutes - old_minutes)
@@ -146,7 +148,7 @@ def create_delivery_schedule(
     _ensure_self_access(user_id, current_user)
 
     parsed_time = _parse_time(payload.delivery_time)
-    _check_min_gap(db, user_id, parsed_time)
+    _check_min_gap(db, user_id, parsed_time)  # 校验与已有时间间隔
     db_obj = UserDeliverySchedule(
         user_id=user_id,
         delivery_time=parsed_time,