Would you use a to-do app that self-destructs?

That's literally what CIPHER does.

Complete all your tasks → server executes
Scorched Earth protocol → daemon terminates → connection severed.

The question I keep getting: "but what if

I want to keep using it?"

That's the point. You shouldn't want to.

Finishing is the exit condition.

Curious — does the self-destruct mechanic feel motivating or anxiety-inducing to you?