Query migrations' source file sets

Hi!

I would like to query copybara workflows to find which files they affect in the source repository.
My use case for this is that I want to write a CI job that informs change authors that their change affects exported files and that they should be aware to not put confidential information in them.

There is another angle I thought of (that has a much nicer profile in terms of "needing to search the entire repo for copybara workflows and query all of them"), which I think is not possible either:
Use an allow-list of files that may be exported, which all workflows must take a subset of. this seems impossible because of the lack of introspection features in copybara.

Is there some introspection functionality I've not seen? Has Google omitted their own solution to this problem from their copybara export from google3?