the players are given the data while exploring in the form of player journals and visted star cache, if you lose them you lose them.
I appreciate how proc gen works (as per your other comment just now) but somewhere a decision is made by the game as to whether you can see the map for system XYZ.
Is it really relying on the contents of visited stars cache to make this decision?
It seems like that would make it easy for players to see arbitrary system maps by putting that system in their cache.
Isn't it more likely that the client will ask, and the server will say: "ok, player id X has data for system Y, show them the system map" (or not.)
Since the visited star cache has a limited size, do you think if you visit, scan, and sell UC data for more than that number of systems, then there will be some systems which - even though you've fully scanned or mapped them - you can't see the system map for them unless you re-visit them?
I think the same would apply if I lose my visited stars cache. They might not show up as "visited" for the filter on the left side of the map, but I should still be able to access their system data if I click on them from the galaxy map.