most of the way to reconstructing the last UnionFind changes, apparently lost in a version control accident
done with most of the hard work fixing UF
convinced via whiteboard the remaining admits are solveable
tick off a few more admits
one admit left
detailed proof sketch for last admit
getting tired...
just need to dualize one last subcase...
Finally done reconstructing work lost to version control user error
remove stale todos
minor cleanup / reorg