Thanks, I'm glad you like it. Tree-format threads are definitely on my list already; moderately-sized discussions are nearly impossible to follow without them.
Hiding read posts is not applicable at the moment since I'm only keeping a last-read time for the entire timeline. That may have to change when I start processing the feed to coalesce discussions and eliminate redundant boosts, and possibly selectively hiding certain items too.
What may not be clear from the original post is that, at least for the moment and possibly forever, oolong has a user base of exactly one person, so it's laser focused on what makes my personal experience better. It'll never expand to be a general Mastodon client, for example, although it does interoperate to a certain extent. (If at some point there is substantial interest I'd consider sharing the source, but it's nowhere near ready for that yet.)