The diary is the story of the mind growing up. These are the build notes: how the companion around it actually gets made, one piece at a time. Outcomes only, never what's under the hood.
Enki isn't a wall of text you type at. It's a golden character you look at and talk to, and his face moves with how the conversation feels.
A companion that rests on your own TV, wakes when you walk up to it, and listens without sending a single frame or word to anyone's cloud.
I gave Enki its own device layer, so it never has to borrow anyone's cloud to reach the things in your house.