Per-thread version history (not just per-board)
The 90-day version history on Pro is great, but it's per-board. When I have a long-lived "Architecture" board that gets edits weekly, scrolling back to find "the version we agreed on at the API review last month" is painful.
What I'd love: name a snapshot. The board gets a "tag" (like a git tag) at the moment I name it, and the history sidebar lets me jump straight to it. Bonus points: a snapshot can be linked, so I can paste the URL in a meeting doc.
I imagine the implementation isn't trivial because of the realtime CRDT, but even an opt-in "save snapshot" button I have to click manually would be a huge improvement.