A repeat of the same query (whitespace/case-normalised, scoped by
deep-vs-shallow) returns the stored hits and skips the whole Crossref call
and DB scan. Disk-backed (survives restart), TTL'd
(CONJURER_LIBRARIAN_CACHE_TTL, default 7d; 0 disables) and size-bounded
(CONJURER_LIBRARIAN_CACHE_MAX, default 500). Reuses DiskQueue, so it's a
handful of lines. Nothing fancy - exact (normalised) match, not fuzzy.
Checked before Crossref only on a fresh search (a resume from checkpoint
still continues its scan), and stored after a completed search.
Tests: hit/miss, normalisation, deep/shallow separation, expiry, disable,
prune. Suite: 58 unit + 59 integration green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
