I'm creating a ruleset loosely based on Civ4 and i have question related unit availability.
According to units.ruleset, the unit requirement can only be defined by a tech (tech_req), by a building (impr_req) or by a government (gov_req).
My question is if it is possible to define a specific unit availability (say, a Chariot) according to an extra availability (say, Horses) on the city or trade route. I don't seem to find a way to set this by adding effects (https://freeciv.fandom.com/wiki/Editing_Effects). Am i right in assuming this is not possible?
If it is not possible, it would be great, in future releases, to have the same flexibility as the building requirements (defined by the "reqs" array) applied to units too.
I'm thinking of other alternatives to this, like defining that a Chariot can only be built when a certain building is present on the city and then define the building requirements as "must have an extra of type horses on the city/trade route" but that is a little bit lame
Thanks in advance.