Subtle changes, bugs and feedback

Could you do 'if last post'?

There are always edge cases... what does "last post" mean? Last visible? Last if nothing is merged into the conversation? Last only when not counting things in moderation queues?

Time is the best way to do it... you have a predictable window in which errors can be corrected, afterwards the fact that you made a comment is part of the historical record but we'd let you change what you said (a history is kept for legal reasons).