Plex only builds the `Guid` array for the Plex Movie / Plex TV Series
agents. A library still on a legacy agent answers with the scalar `guid`
alone, so `fetchExternalIds` returned nothing for it and every consumer
went quiet: trackers logged "no external IDs" and skipped the write,
manual ratings showed "Not available", the detail screen dropped its
watchlist button, and Continue Watching stopped collapsing duplicate
copies. The reverse lookup already read that scalar; only the forward
path ignored it.
Read both shapes from the one request the method already makes, with the
array winning per field and the scalar filling the rest.
HAMA identifies anime by AniDB id and nothing else, which no id set could
carry. AniDB is the Fribb mapping's own primary key, so it now travels on
`ExternalIds` and indexes those rows directly — 7177 of them expose no
tvdb/tmdb/imdb at all and were unreachable by any other path. Only plain
`anidb-` maps: `anidb2`..`anidb9` group several AniDB entries under one
TVDB-numbered show, so the guid names the root entry only.
Two guards keep the new id where it means something. It is trusted for
season 1, because that mode puts the anime there and its specials in
season 0, while a higher season means the library is numbered by TVDB
instead. And it resolves nothing for Trakt and Simkl, which never map
anime and cannot address an AniDB id, so they keep reporting no ids
rather than failing silently further down. `hasCatalogIds` marks the
callers that can only speak IMDb/TMDB/TVDB.
close#1788
edde746