feat: the library's albums go on the wanted list as held, once; after that the list is the truth (M502 #5567)

A one-time job in the wanted worker lists every album in the library as a
held want, one per release group, with a record that it happened
(acquisition_settings.library_listed_at). Albums whose tags name only a
release are named on MusicBrainz first, 120 a pass; what nothing names is
counted and shown on the Held tab.

Re-acquisition now wants back only albums on the list. Taking a held album
off the list leaves its files, and it is never fetched back; albums put in
the library folder by hand afterwards are not added.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/queries/wanted.sql

@@ -222,3 +222,66 @@ SELECT COUNT(*) FILTER (WHERE fulfilled_at IS NULL AND reason <> 'missing')::big
        (SELECT COUNT(*) FROM release_blocks b
          WHERE b.expires_at IS NULL OR b.expires_at > now())::bigint               AS blocked
   FROM wants;
+
+-- The one-time listing of the library (#5567). ---------------------------
+
+-- name: GetLibraryListing :one
+SELECT library_listing_started_at, library_listed_at, library_unlisted
+  FROM acquisition_settings WHERE id = true;
+
+-- name: StartLibraryListing :one
+-- Marks the listing begun, once; its time is the cutoff for which albums
+-- count as the library's.
+UPDATE acquisition_settings
+   SET library_listing_started_at = COALESCE(library_listing_started_at, now())
+ WHERE id = true
+RETURNING library_listing_started_at;
+
+-- name: ListLibraryAlbums :execrows
+-- Puts library albums on the list as held: each release group once, by the
+-- album holding the most tracks. Only albums the library had at the cutoff,
+-- and with album_id given only that album. A group already on the list is
+-- left as it is. An album with tracks already missing is held from just
+-- before the first loss, so re-acquisition still fetches it back.
+INSERT INTO wants (release_group_mbid, artist_mbid, artist_name, title, reason, album_id, wanted_at, fulfilled_at)
+SELECT DISTINCT ON (a.release_group_mbid)
+       a.release_group_mbid, ar.mbid, ar.name, a.title, 'library', a.id, now(),
+       COALESCE((SELECT MIN(t.missing_since) FROM tracks t WHERE t.album_id = a.id) - interval '1 second', now())
+  FROM albums a
+  JOIN artists ar ON ar.id = a.artist_id
+ WHERE a.release_group_mbid IS NOT NULL AND a.release_group_mbid <> ''
+   AND ar.mbid IS NOT NULL AND ar.mbid <> ''
+   AND a.created_at <= sqlc.arg(cutoff)::timestamptz
+   AND (sqlc.narg(album_id)::uuid IS NULL OR a.id = sqlc.narg(album_id)::uuid)
+   AND EXISTS (SELECT 1 FROM tracks t WHERE t.album_id = a.id)
+ ORDER BY a.release_group_mbid,
+          (SELECT COUNT(*) FROM tracks t WHERE t.album_id = a.id AND t.missing_since IS NULL) DESC, a.id
+ON CONFLICT (release_group_mbid) DO NOTHING;
+
+-- name: ListLibraryAlbumsToName :many
+-- Library albums from before the cutoff that carry a release id but no
+-- release group yet: the listing asks MusicBrainz for each. '' marks one
+-- MusicBrainz could not name, so it is asked once.
+SELECT a.id, a.title, a.mbid FROM albums a
+ WHERE a.release_group_mbid IS NULL AND a.mbid IS NOT NULL AND a.mbid <> ''
+   AND a.created_at <= sqlc.arg(cutoff)::timestamptz
+ ORDER BY a.created_at, a.id
+ LIMIT sqlc.arg(max_rows);
+
+-- name: SetAlbumReleaseGroup :exec
+UPDATE albums SET release_group_mbid = sqlc.arg(release_group_mbid)
+ WHERE id = sqlc.arg(id) AND release_group_mbid IS NULL;
+
+-- name: FinishLibraryListing :one
+-- The listing is done: count the albums from before the cutoff it could not
+-- list, because nothing names them to MusicBrainz.
+UPDATE acquisition_settings s
+   SET library_listed_at = now(),
+       library_unlisted = (
+         SELECT COUNT(*) FROM albums a
+          WHERE a.created_at <= s.library_listing_started_at
+            AND NOT EXISTS (SELECT 1 FROM wants w
+                             WHERE w.album_id = a.id
+                                OR (a.release_group_mbid <> '' AND w.release_group_mbid = a.release_group_mbid)))
+ WHERE s.id = true AND s.library_listed_at IS NULL
+RETURNING library_listed_at, library_unlisted;