I guess to me, I'm looking at it from the perspective of diffing the repo between the squashed commit on main and the tip of the incoming PR. If there are merge conflicts during the rebase in files that don't appear in that diff, I consider that a hallucination, because those changes must already in the target branch and no matter what happened to those files along the way to get there, it will always be a waste of my time to see them during an interactive rebase.

I don't think we need to store any additional metadata to make the rebase just slightly more smarter and able to skip over the "obvious" commits in this way, but I'm also just a code monkey, so I'm sure there are Reasons.