## What
Adds [Databáze knih](https://www.databazeknih.cz), the Czech and Slovak
community book catalog, as a metadata provider. It follows the Moly.hu
provider (#1172): HTML scraping, no API key, disabled by default, and a
settings tab with an enable checkbox and a Test Connection button.
## Why
Hardcover, Open Library and Google Books cover Czech and Slovak editions
poorly. Databáze knih is the de facto catalog for them, including Czech
and Slovak translations of foreign works. With this provider, Universal
mode works end to end for Czech and Slovak titles: the localized title
and author from Databáze knih feed the release search.
## How
- HTML scraping with BeautifulSoup, which is already a dependency. Book
pages carry schema.org JSON-LD, so most fields come from structured data
rather than CSS selectors.
- **Title search** uses `/vyhledavani/knihy`, with the site's pagination
(`page`) and language filter (`lang` for cs/sk/en/de). A search with a
single match redirects straight to the book page, and that case is
handled.
- **Author search:** the site search only matches titles, so an
author-only search finds the author (accent- and word-order-insensitive)
and lists their books page, which is also paginated. Title + author
filters the title results on the author.
- **ISBN search** follows the site's redirect from `/search?q=<isbn>` to
the book page.
- **`get_book`** reads the full description (the JSON-LD one is
truncated), ISBN-10/13, publisher, edition year, language, genres, cover
(placeholder images dropped), series with id and position, and rating
and rating count. It also reads the page count and original title from
the more-info fragment.
- The `RateLimiter` from Open Library (30 requests/min) and the standard
`@cacheable` decorators. Fetch failures return `None`, so they are not
cached.
- `docs/environment-variables.md`: added the `DATABAZEKNIH_ENABLED`
section.
## Testing
- `tests/metadata/test_databazeknih_parse.py`: offline tests with
shortened copies of real pages. They cover search parsing, pagination
and language parameters, redirect-to-book, author listing, title +
author filtering, uncached failures, book details, ISBN resolution and
helpers.
- `uv run pytest tests/metadata` is green (89 passed), and `ruff check`
and `ruff format --check` are clean.
- Verified live against databazeknih.cz: connection test, title search
(pages 1 and 2), author books, title + author, `get_book`, and ISBN
lookup.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
