- jobs: a table-backed queue in the same SQLite file. No Redis, no second
process, included in the same backup. claim() is a single UPDATE...RETURNING
so a job cannot run twice even with several workers. Failures back off
exponentially; a missing handler fails permanently rather than retrying a
bug.
- metadata: Provider interface plus Open Library and Google Books (both
keyless). The enricher tries providers in registration order, falls back on
empty, and continues past a provider error.
- migration 0004: metadata_fetch records the attempt, not just the match, so a
rescan does not re-hammer a rate-limited API for an item that will never
match. Errors are always retried; ok/notfound are cached for 30 days.
- enrichment writes provider_ids, updates title/year, links authors through
people/item_people, and downloads the cover as an asset. The cover download
runs outside the transaction: a slow image host must not hold a write lock.
- endpoints: queue enrichment per library, and inspect an item's matches.
- web: Enrich button per library.
Verified live against Open Library: "The Hobbit" matched /works/OL27482W,
title and year 1937 written, a 301x500 JPEG cover downloaded and served.
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