[add] Throw out explicit error messages; Using the CST time zone

api/app/repositories/implicit_emotions_storage_repository.py

@@ -122,12 +122,17 @@ class ImplicitEmotionsStorageRepository:
         - 若 last_done <= updated_at，说明已是最新，跳过
 
         Args:
-            redis_client: 同步 redis.StrictRedis 实例（连接 CELERY_BACKEND DB）
+            redis_client: 同步 redis.StrictRedis 实例（连接 CELERY_BACKEND DB），为 None 时抛出 RuntimeError
             batch_size: 每批次加载的数量
 
+        Raises:
+            RuntimeError: redis_client 为 None 时，调用方可捕获并回退到 get_all_user_ids
+
         Yields:
             需要刷新的用户ID字符串
         """
+        if redis_client is None:
+            raise RuntimeError("get_users_needing_refresh: redis_client 不可用，无法执行时间轴筛选")
         from datetime import timezone
         offset = 0
         while True:
@@ -152,16 +157,14 @@ class ImplicitEmotionsStorageRepository:
                     try:
                         CST = timezone(timedelta(hours=8))
                         last_done = datetime.fromisoformat(raw)
-                        # 统一转为 CST naive 时间做比较
-                        if last_done.tzinfo is None:
-                            last_done = last_done.replace(tzinfo=timezone.utc).astimezone(CST).replace(tzinfo=None)
-                        else:
+                        # last_done 写入时已是 CST naive，直接使用，无需转换
+                        if last_done.tzinfo is not None:
                             last_done = last_done.astimezone(CST).replace(tzinfo=None)
 
                         if updated_at is None:
                             yield end_user_id
                             continue
-                        # updated_at 同样转为 CST naive
+                        # updated_at 数据库存的是 UTC naive，转为 CST naive 再比较
                         if updated_at.tzinfo is None:
                             updated_at_cst = updated_at.replace(tzinfo=timezone.utc).astimezone(CST).replace(tzinfo=None)
                         else: