The library.json index already carries full Book objects, but the
metadata merge overlay dropped tags and readingStatus on apply, so
tagging or marking a book Finished never reached peers syncing via
WebDAV or Google Drive (the same overlay gap that hit group membership
in #4942):
- mergeBookMetadata carries tags with the metadata LWW subset (raw
assignment, so tag removal clears on peers) and merges readingStatus
on its own readingStatusUpdatedAt clock, the client-side mirror of the
native field-level server merge. This survives the asymmetric race
where one device edits metadata after a peer changes the status;
whole-book LWW alone would drop the status change.
- New shouldApplyRemoteBookMetadata reconciliation predicate triggers on
either clock; the engine's index reconcile uses it so a status-only
change propagates without a metadata edit.
- Merge-law tests (direction, removal, idempotence, asymmetric races)
plus engine-level propagation tests for both fields.
Prerequisite for gating native sync when a third-party provider is
selected (#4380): third-party sync should reach metadata parity before
it becomes the only channel.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Huang Xin
a72f535346