The root cause: buildManifestIndex was discarding manifest localIdentifiers and
switching to pure filename-only matching whenever dirCount > manifest.totalCount
(which is always true when the NAS has files from other tools). If filenames didn't
match exactly, Already Safe dropped to 0 on every stale-cache reconcile.
Fix: introduce ManifestIndex(manifest:nasFilenames:totalCount:) — a hybrid that keeps
Kisani's localIdentifiers as primary keys AND adds all NAS directory filenames for
filename-fallback. Used in:
- buildManifestIndex (full reconcile)
- fast path (when dirCount > cached.entries.count, previously gated at <= 1)
- BackupEngine step 3b (so "Back up again" only uploads genuinely missing files)
Also simplify countSafe / pendingIDs / step-4 filter to always try filename fallback
(removes the isFilenameOnly gate that blocked matches when the index had IDs).
Co-Authored-By: Kutesir <kutesir@provoc.ug>
Co-Authored-By: Sentry <sentry@provoc.ug>
6ae567d008