Define specific garrisoned unit requirement

[Käpt'n Zur See]

Hi,
I think I finally understood what I can generally do with modifiers.
What I wanted to do is basically give out a e.g. production bonus when a spy is located/does a counterspy mission in one of the players own cities to the city.

I know that a spy isn't a military unit, but that aside I haven't found any Requirement in the game that somehow checks if a unit is located anywhere in your game. The only one that's close is the garrisoned unit check, which doesn't even take a specific unit as an argument.

Does that mean this idea is essentially impossible to do or is there a way I don't see?
Thank you

 

[Lear19]

The real problem here, in my opinion, is that I don't recall any good modifier that would change city yields when unit is in the city center. There's policy card that gives amenities when unit is inside of a city, but amenities are not yields.

As for your question, that policy card giving you one amenity when unit is in city center should be your answer. If it works when a spy is in that city, you're good to go. If it doesn't, you would have to find out what in a spy as a unit, from code perspective, decides about it.

But like I've said, I think the actual problem is the lack of good modifier. While it is possible to create non-existing combos of modifiers and requirements, it often doesn't work in the end.