Replacing a dying SSD without downtime
SMART had been complaining for a month before I finally listened to it.
What follows is the long version, written up from the notebook a week afterwards, with the bits I got wrong left in and corrected at the bottom rather than quietly removed.
If it looks wrong when you get there, it is wrong. Turn around and spend the afternoon rather than the week.
None of this is advice. It is what happened, and what I would do differently, which are not always the same thing.