Instead of having a separate state that tracks your "active portal", you just always place a yellow portal. Whichever portal is left over (depending on which button you press) turns into the new purple portal.

Therefore the two portal buttons would
A:

• remove your yellow portal
• place a new yellow portal B:
• remove your purple portal
• turn your existing yellow portal into a purple portal
• place a new yellow portal

Tracking the "state" of your active portal is needless friction and it would be much more intuitive if the color of your portals directly conveyed the information that actually matters to the player (which button corresponds to which portal) instead of having to mentally remap them.

I find myself having keybinds for both placing an alternating portal and the classic portals. It's far nicer to do things like triple portaling with one button, but whenever I'm doing something strategic, I need to use the classic scheme. Otherwise, when I'm deciding what portal to place, I need to first see where my portals are, then look at which one is active, switch if needed, then finally place the portal. Surely this isn't a worthwhile tradeoff for the colors of the portals staying constant?