@evan @msokolov @gregprice So, an ActivityPub implementation which receives a Note which has an activitystream:replies object should have all the information it needs to fetch replies; Mastodon's implementation in particular chooses not to include reply _data_, using URLs instead, which makes filling that data in downstream costly (ie, requires fetch of each Note object), but that's an implementation detail that could be changed and still fit within ActivityPub/ActivityStreams.