Ask HN: Any app that merges todolist and calendar?

I can't stand switching between 2 apps to define and know what's supposed to happen in my day.

In a typical day, there are events, there are todo actions defined at a specific time, and there are todo actions that I need to complete before the end of a the day.

Events do not require user completion and will happen no matter what, unlike todos actions.

Is there any app (macOS / web) that can manage both events and todo actions? Am I the only one to not understand why calendars and todo apps are generally splited?