Hey folks!

It is possible to have a construction available only when senate-related prerequisites are met, most laws or "propaganda" improvements from the base game actually work like this.

SupportPrerequisites allow you to check if a specific Politics is represented in the senate.

The "1" in the example below represents how strong the support must be (going from 0 to 1, shared between all present politics):

<SupportPrerequisite Flags="Prerequisite,Discard" Politics="Politics01">1</SupportPrerequisite>

This PathPrerequisite checks if the Politics01 party (Industrialists) is leading:

<PathPrerequisite Flags="Prerequisite,Discard">../ClassEmpire/ClassSenate/ClassSenator,Politics01,PrimeSenator</PathPrerequisite>

And this final PathPrerequisite checks if the law LawP01L00 (which applies the descriptor "LawEffectP01L00") is currently active:

<PathPrerequisite Flags="Prerequisite,Discard">../ClassEmpire/ClassSenate/LawEffectP01L00</PathPrerequisite>

Note that if the law/politics become invalid while the improvement is being built, it will become invalid and block the construction queue.

If you don't want this to happen, you can replace the flag "Prerequisite" with "Enqueue", which means the SupportPrerequisite/PathPrerequisite will be checked only when starting the construction, instead of when starting and when it is queued.