Fourth Codex review round on #472; both findings confirmed. The first could
destroy data.
reprobeNestedRoots protected a root it found offline only for the scope being
reconciled, then discarded the result. The folder-wide membership reconcile and
the trash sweep afterwards rebuilt their protected set from the initial probe
alone, so rows under a child that dropped mid-scan — already marked missing and
past the removal grace — were hard-deleted by the very scan that noticed the
outage. Accumulate those roots in reprobedRoots, fold them into
protectedScanRoots, and reuse that set for the membership reconcile and sweep
instead of rebuilding. They now also land in ScanResult.UnreachableRoots so the
folder warning reflects the outage rather than presenting a partial scan as
clean.
Snapshot and group pruning was enabled for scopes that were never walked. The
gate was len(walkFailures) == 0, but an unreachable root gets nil walkRoots, so
it has no walk and therefore no failures — and pruning then deleted its
snapshots, observed locations and group locations even though its media rows
were protected. The same held for a suspect-empty child compacted into a
populated parent. Pruning now additionally requires that the scope was actually
walked and contains no protected path.
The new test pins that the sweep honours the protected set it is given. It does
not reproduce the mid-scan race itself: staging that needs the drop to land
between the probe and the walk, which a test cannot reach without hooks. That
path is covered by inspection, and the test comment says so rather than
implying coverage it does not have.
Quick
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