The simple version of this is that I have two document types and I want to cache some static field on a document after the build has completed.

For example, let's say I have tags and posts, and I want a tag object to have a postCount attribute that caches the number of posts to which the tag was applied.

The more complex example is to be able to "hydrate" references without needing to write my own transformer function.

In the example above, posts would have a tags field reference. But I'd love if what were returned was of type Tag[] rather than string[].

Having both together would be ideal.