Worse: You may created the proof. You may have linked to the proof. But if anyone has touched any of the code involved since then, it still has no value unless someone has re-done the proof and linked that. (Worse, it has negative value, because it can mislead.)
Git blame will show the commit and the date for each line. It’s easy to verify if the snippet has changed since the comment. i use Emacs and it’s builtin vc package that color code each block.
And anything that can affect relevant state, any dependencies that may have changed, validations to input that may have been modified; it’s hard to know without knowing what assumptions the assertion is based on.
