fav_core is the core library of fav, which provides the core traits needed to create an app, which fetch your remote favorite sets(lists), and pull tracked resources to local.
fav_utils provides the utilities for fav_cli, which now only support bilibili(Like Chinese Youtube).
All you need is to define data structures with protobuf like this example.
And impl traits in fav_core like Res, Set, Sets, Status, Attr to defined resources, and AuthOps, SetOps, SetsOps to operate resources.
After that, many Ext method will be available for you to use, helping you batchly operating resource, getting subset of resource, and so on.
Examples can be find here.
To derive trait for code generated by protobuf, see example.