Got unwanted content to be dropped from the local repo, as well as remotes when doing the expensive scan. I kept the scan a single pass for now, need to revisit that later to drop content before transferring more. Also, when content is downloaded or uploaded, this can result in it needing to be dropped from somewhere, and the assistant handles that too.

There are some edge cases with hypothetical, very weird preferred content expressions, where the assistant won't drop content right away. (But will later in the expensive scan.) Other than those, I think I have nearly all content dropping sorted out. The only common case I know of where unwanted content is not dropped by the assistant right away is when a file is renamed (eg, put in a "Trash" directory).

In other words, repositories put into the transfer group will now work as described, only retaining content as long as is needed to distribute it to clients. Big milestone!