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@silverpill

- Reply management. Starting with the `replies` collection and working outward from there is probably the best way to go. I love a's idea of using `Add` and `Remove` activities (or `Approve` and `Reject` with a target) to share state with addressees. I think the `conversation` tree could be managed about the same way.

In general, I think you've got a lot of good ideas here. The ActivityPub fork idea is terrible, though.