I checked out the Academy for anything previous on this but didn't find my answer.
I've got a bunch of ruins on a planet that has plenty of population now (> 25 mil). Engineers have recovered some of the ruins but not all - that'll take a while.
On the wealth/trade screen, my planet says it has 0 annual production, 8 annual shortfall, nothing in the annual surplus slot, and the current import requirement is (3,12somethin'). It is in parentheses, like negative in accounting spreadsheets, whereas no other ones are listed like that.
I haven't seen any freighters trading in ancient artifacts despite other planets having an import requirement, and this seems to be a bit wonked. Am I missing something?