When you use an extractor to lift a planetary structure that has been upgraded (e.g. hypergate, tri-phase, trellith comm relay) does it stay in the upgraded form, or does it lose the upgrade and return to being a vanilla <whatever> ?

Legion mates have done this, and I have heard it stays the upgraded form. No personal experience though.

it comes of your planet with all your upgrade, looks same as upgrade in your cargo, but its actual structure now

Thanks, figured it would work like that but just wanted to make sure.

If it's extracted, when you rebuild, is it like before where you need to replace the base structure?

Nope, you extract the structure itself.

I tried extracting the relay one, My Extractor was lost, and no Trelith thing. I sent a ticket, got it bacl