Worked off some more technical debt yesterday, and also added the ability to automatically (1) create the store at startup if missing, and (2) snapshot the store at disk full.
There is always enough space to snapshot as long as there were previous snapshots, since they are always the same size, and they rotate between two. Verified handling of disk full on automatic backup and store create as well.
These add to the existing ability to automatically snapshot while running, automatically detect corruption due to uncontrolled shutdown, preserve an unexpected store fault through shutdown, and automatically recover from snapshot when a fault is detected at startup.
(edited)