Steven J Gold wrote:Will they remain forever (or at least until replaced by another one-time capture?)
This is the correct answer. They will remain forever ... unless recaptured or manually deleted.
or will they be deleted from the archive by a future rolling merge?
They can never be deleted or replaced by capturing something else.
The fundamental, conceptual, model of QRecall is that each layer captures just what has changed
in the captured items. And merging layers
containing the same items combines them into a single set of changes, essentially creating a single layer as if the earlier captures had not happened.
In the case of an archive with two non-overlapping items, there's nothing to merge[1]. So recapturing your home folder will never combine with or replace any data captured in your /Applications folder, or items captured from another volume, or items captured by another owner. Those items are in other branches of the archive.
Let us know if that helps clarify the concept.
Footnote [1]: That's not, technically, true although it's conceptually true. If you capture /Applications you have a layer with /Applications. Then if you capture your home folder you now have a second layer with just your home folder. When these layers are merged, you end up with a single layer containing both /Applications
and your home folder, just as if you had performed a single capture of those two items. But since these items don't overlap, no items are combined. Again, the same thing happens when you merge layers with items captured from different volumes.