GET /mangas recomputed count(*) over FILTER_WHERE (up to five correlated
subqueries) on every page, so pagination cost scaled with catalog size. The
total doesn't change as a caller walks pages, so compute it once at offset 0
and return null thereafter (the envelope already serialises total as
Option<i64>; the frontend types it number|null and the library route ignores
it).
Bump to 0.124.7.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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