Another big one I wish I saw more often is "these are the circumstances under which this assumption was made and here are the steps you can take to check if tho

Another big one I wish I saw more often is "these are the circumstances under which this assumption was made and here are the steps you can take to check if those circumstances have meaningfully changed." In other words, the comment allows the author to reach into the future and co-debug with the reader, even if the author is no longer there.