Documents why updated_at moves only on reading progress and why PUT therefore
returns the stored row, why "latest chapter" is found from the browser rather
than the backend, and its limits — a bookmark is as current as its last check,
and nothing here can be instant.
Also corrects two stale claims: asurascans.com is the current domain, and
asuracomic.net deep links now 301 to its root rather than the matching path.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>