US09-04: Write the User Manual with Generated Screenshots (#110)

docs/stages/archive.md

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+# Archive
+
+[← Documentation index](../index.md) · [Guided first pass](../first-pass.md)
+
+![Archive locations and plans](../images/archive.png)
+
+**What it is for.** Moving a finished album out of active storage onto another disk,
+while keeping everything the library knows about it.
+
+**What you decide.** Which album, which destination, and whether to accept the
+reclaimed space in exchange for needing that medium mounted to see the originals
+again.
+
+**What it changes.** Files are copied to the archive location, verified there, and
+only then removed from the library. The asset keeps its id, its hashes, its
+decisions, its analysis, its upload history, and a durable preview thumbnail;
+`current_path` becomes null and availability becomes `archived_online` or
+`archived_offline`.
+
+**What it refuses.** Preflight blocks on: an unverified upload, a checksum that no
+longer matches the uploaded bytes, an unmounted or unwritable destination,
+insufficient free space plus the configured reserve, a destination that already
+holds unexpected paths, a missing durable thumbnail, and any conflicting job. The
+source is **never** removed before the archived copy is verified — not because Immich
+reported success, which is an ingest, not a backup.
+
+## Offline is not missing
+
+An archived photo whose medium is unplugged is `archived_offline`. It still appears
+in search, still participates in duplicate detection through its retained hashes and
+thumbnail, and is never reported as lost. If a full-resolution comparison is needed,
+the application asks you to mount the named medium rather than guessing.
+
+## Restore
+
+Restore is planned and journaled like everything else: the medium must be online, the
+bytes are copied back and verified into a collision-free destination, a new active
+path is registered, and a reconciliation scan follows. Existing safety, analysis,
+EXIF, and upload state stay valid when hashes match — and when they do not, the
+result is a visible `divergent` state rather than silent acceptance of a different
+file.
+
+Next: [diagnostics](diagnostics.md).