获取历史记录服务实例（单例模式） Returns: HistoryService: 历史记录服务实例
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| 713 | |
| 714 | |
| 715 | def get_history_service() -> HistoryService: |
| 716 | """ |
| 717 | 获取历史记录服务实例（单例模式） |
| 718 | |
| 719 | Returns: |
| 720 | HistoryService: 历史记录服务实例 |
| 721 | """ |
| 722 | global _service_instance |
| 723 | if _service_instance is None: |
| 724 | _service_instance = HistoryService() |
| 725 | return _service_instance |
no test coverage detected