When a book was matched via Hardcover title search with no featured
edition and the user had not selected a specific edition, the sync
client fell back to using the Hardcover book id as the edition_id.
Hardcover's Action rejects that with a parse-failed error
("ActionWebhookErrorResponse ... key 'message' not found"), so progress
and note sync failed for those books.
Leave editionId null when no real edition is known, make the read and
journal mutations accept a nullable edition_id, and omit edition_id when
adding a book so Hardcover uses the book's default edition.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Huang Xin
4c39d769e6