I’ll start with more functional, then more aesthetic idea.
Functional: Depending on the view you are currently in / the item the mouse is hovering on top of, keep that item in the center (mouse should be hovering over the same item when entering/leaving architect mode). I find that with workspace with many spaces and databases, when entering and leaving architect mode, I’m a bit lost in the side nav. Having it stick to where I am is ideal.
More aesthetic, but would also actually help understand where things are moving to:
Nice animations between the two modes. Animate the height of the items in the nav bar. Animate the extra buttons in entity view.
While these are mainly cosmetic, it does make it feel a bit nicer and polished for architect.