In Games there’s a focus of design called Game Mechanics. It works like this: Mario jumps, that’s a mechanic. The player is pushing buttons, but that’s just how they interact with the game mechanics. In this word where Mario jumps there enemies, enemies move and have behaviors, all of these things are not game mechanics. Mario can jump on enemies, that’s a game mechanic.
Game mechanics could be said to be mental models for how your activity works.
There isn’t really anything like it for the tech industry. There’s no product mechanic for a Todo list. Just an interface, and some actions.
We design UI. Not activity. UX is trying to change this, but often lacks the understanding and even the language to do that. Maybe we should take a page out of the game design playbook and start designing Product Mechanics.