altering improvement upkeep
Is there any way to change the upkeep for specific buildings by a specific amount? The only supported effect I found is the Adam Smith one and it's very specific in it's effect. I have two ideas I'd need that for. Hospitals are an improvement I added to grow cities above 24, with the tech Public Healthcare I would like them to make one citizen content but cost one more upkeep. I'd really like to have that in the game, because I created the tech specifically for it. The second thought was an alternative effect for the Great Library, to make Libraries and Schools cost no upkeep. I might be able to do that one if I can combine Upkeep_Free effect with a custom tag for buildings, like it works for units, but I didn't check yet if that is possible, let alone if it would work in the intended way.
On freeciv-3.2 there's Output_Bonus_Absolute (#43593) which you could use to adjust output of the central tile. That approach might reduce client side help / popups quality (those adjustments don't show up as 'building upkeep')
Oh, so I could just "add" -1 gold that way? Interesting. Not reflecting the change in the building info directly wouldn't be that much of a problem, since other effects can't do that either (like Adam Smith or Colosseum). I'd add it to the description instead. Though I would like it if those parts of the display could be made dynamic in the future, for exactly those cases and significantly more convenience and clarity.