GET /api/sync/koreader/resolve?sha256={hash} maps a file content hash to
the book's UUID through the shared format-aware BookResolver (primary
media_items hash, then per-format hashes so converted KEPUB/PDF files
match) without touching any progress state.
Devices need the UUID to pull metadata, but a freshly downloaded book has
none cached. The old way of learning it was to push once, which
transmitted the device's first-page position and manufactured a progress
conflict for books already mid-read from another source. A read-only
lookup lets clients link (and pull) without ever pushing bootstrap
progress: resolve, then pull, then push.
Returns 200 {book_uuid, sha256, title, author}, 400 for a missing or
malformed hash, 404 when no library item matches.
john-okeefe
6859f81144