CMake has, for a while now, apparently has something called the "CMake file API":
CMake provides a file-based API that clients may use to get semantic information about the buildsystems CMake generates. Clients may use the API by writing query files to a specific location in a build tree to request zero or more Object Kinds. When CMake generates the buildsystem in that build tree it will read the query files and write reply files for the client to read.
I don't understand when and by whom this is supposed to be used. Consequently, I don't understand whether, as a maintainer of project employing CMake, I need to worry about this API and "cater" to satisfying requests using it. Do I?
Note: If the answer depends on which kind of CMake project I maintain - please choose a couple of examples (as I use CMake in more than one kind of project).
No - the CMake File API is meant to be used by developers of IDEs and IDE integrations.
Consequently, I don't understand whether, as a maintainer of project employing CMake, I need to worry about this API and "cater" to satisfying requests using it. Do I?
You do not.