Does co-authors plus fire its own HTTP request to store coauthors?

I have written a plugin that synchs blog posts from one blog to another as they are published/updated/deleted.

It uses php to hook into `save_post`. I noticed recently that it is no longer catching updates to co-author assignments, because it seems like co-authors sends its own HTTP request to store coauthors, long after `save_post` has come and gone.

This is a nuisance for me because now I have to hook in twice (now using `wp_set_object_terms`) to capture all post changes, roughly doubling my network activity.

This behavior from co-authors is counter-intuitive. The post should be done saving ... when `save_post` is done.

Should I be doing something different or thinking about this differently somehow?

Begin by tracing the WordPress save_post and wp_set_object_terms entry points described in the report, and inspect when Co-Authors Plus updates coauthor assignments. Done means establishing whether a separate HTTP request is made and documenting the supported hook or expected save lifecycle for synchronization.

Written by the indexing model from the issue text.