`middleware` and the ZFS reader were being threaded through five functions as a
pair, and the snapshot namespace was re-resolved in each of them. That is one
collaborator, not two. _Snapshots owns both, resolves the namespace lazily (so the
read-only paths do not raise over a mutation they never make), and makes the rule the
module rests on structural instead of a comment people have to remember.
Deliberately internal: apply.sh injects calls to the public functions into middlewared
itself, so their signatures are a boot-time contract with a live NAS and are not worth
churning for tidiness.
Verified on TrueNAS 26.0.0-BETA.1 after the change: 292-dataset backup, 0 orphans,
0 leaked mounts, byte-identical restore of a 4-deep child dataset.
flan
928d0d1973