Ask HN: Task system that requires ack

Like everyone else, as I grow older, I have more and more responsibilities. So I started to use calendar apps on my phone, backed up via a cloud service.

I have the uncomfortable feeling that this is not very "safe". I feel I can easily miss a notification, and miss an important task (e.g. filling tax).

I am not clear exactly on what I should implement, but I have a feeling I should have a system where I 1) acknowledge the task to be done, and 2) record it as being done. The system would be able to nag me more if I do not ack, or do not do it.

I also feel a little uncomfortable with the way that calendar/tasks app are managing recurring tasks and linked tasks. For example for filling taxes, I have a list of tasks to be performed ahead of time every year. These apps allow recurring tasks and "next task" but the way it is done does not really feel robust, and can easily be missed.

I am on iOS, which compounds the problem, as apps cannot trigger a real alarm from the clock app. At best, it is a notification, which is easily missed.

There are many smart people reading this website, and I thought I would pick their brains. I would welcome any idea, from readily available open source code, to simple specs or ideas to solve this question. Thanks!