[Metadata Source Plugin] [RELEASE]BiblioMeta v.1.2 (es, en)

[LudoLudovico]

Hi everyone,
I'm releasing BiblioMeta, a Calibre metadata source plugin designed for large libraries with books in Spanish and/or English. It retrieves bibliographic data from authoritative library sources rather than commercial or crowd-sourced databases.
Sources (no API keys required):

Biblioteca Nacional de España (BNE) — primary source for Spanish books, full MARC21 records with CDU classification
Library of Congress (LoC) — primary source for English books, full MARC21 records with LCC classification
Wikidata — fallback for classic works, contributes genre tags, series and original publication date
Open Library — fallback by ISBN when primary sources fail
Google Books — descriptions and cover images

Is this plugin for you?
BiblioMeta is built for large libraries — think thousands or tens of thousands of books — where metadata quality and consistency really matter. If you have a small collection of a few hundred books, the built-in Calibre sources (Amazon, Google Books) will likely serve you just as well with less configuration overhead. This plugin shines when:

Your library is primarily in Spanish and you want authoritative bibliographic data with proper subject classification (CDU tags)
Your library is primarily in English and you want Library of Congress quality records with LCC classification
You have a mixed-language library and want automatic language detection to route each book to the right source
You care about tags derived from real library classification systems rather than crowd-sourced genre labels

Key features:

Automatic language detection by ISBN prefix or existing identifier — no manual configuration per book
CDU classification tags translated to Spanish (e.g. Literatura española · Novela · s.XX)
LCC classification tags in English (e.g. English Literature, American Literature)
Direct record lookup using bne: and loc: identifiers stored from previous downloads — no repeated searches
Parallel BNE + Google Books fetching for faster downloads
Configurable language mode: auto-detect / Spanish only / English only — useful for batch processing a single-language collection
Coverage statistics panel showing results by source

Estimated coverage:

Spanish books with Spanish ISBN (978-84): 80–90%
Latin American editions: 60–70%
English books with anglophone ISBN (978-0, 978-1): 70–80%
Public domain books without ISBN: 20–40% via Wikidata

Known limitations:

Book descriptions (comments field) coverage is limited. BNE includes synopses for some books via MARC field 520, and Google Books fills gaps where available. For broader description coverage, I recommend running kiwidude's Goodreads plugin configured to download only the comments field alongside BiblioMeta.
Latin American editions not registered in Spain have lower BNE coverage — Open Library partially compensates.
The LoC SRU server has been intermittently returning 502 errors since the Voyager→Folio migration in July 2025. The plugin handles this with automatic retry and exponential backoff.

Installation:
Download BiblioMeta.zip from the GitHub releases page and install via Preferences → Plugins → Load plugin from file.
An optional toolbar button plugin (BiblioMetaAction.zip) is also available in the same release, providing quick access to metadata download, configuration, and a session statistics panel.
Source code and documentation:
https://github.com/ludoludovico/BiblioMeta
Feedback, bug reports and suggestions welcome. If you maintain a large Spanish-language library and find gaps in CDU translation coverage, please share the untranslated codes — the dictionary grows with each version based on real library data.