The cover lookup scraped the OPF with attribute-order-sensitive regexes.
Real books serialize attributes in any order - Grand Central's '3 Days to
Live' puts href before id on manifest items and content before name on
the cover meta - so all three regex paths missed and the book fell
through to filename guessing, extracting no cover at all. Attribute
order is meaningless in XML; the regexes were never safe.
Replace them with a structured parse (encoding/xml, namespace and
attribute-order agnostic; see the new media_scanner_opf.go) and follow
Calibre's read_raster_cover resolution order:
1. manifest item with properties=cover-image (non-(X)HTML media only)
2. <meta name=cover> resolved through the manifest, same media guard
3. first spine item that is itself a raster image (store manga)
4. NEW cover-page fallback: books declaring no raster cover at all -
the classic EPUB2/Adobe cover.xhtml wrapper - are mined for
<img src> / SVG <image xlink:href> references (Calibre renders the
page with Qt; extracting the referenced image covers the practical
cases without a rendering engine)
5. existing zip filename guessing stays as the last resort, and the old
regex chain survives as findCoverInOPFLegacy for OPFs too malformed
for a real XML parse.
Hrefs are now URL-decoded and posix-normalized against the OPF's own
path (path.Join semantics), so '../art/cover.jpg' from a nested cover
page and %20-encoded names resolve correctly.
Tests: attribute-order chaos modeled on the failing Patterson book,
SVG-wrapped cover pages via guide references, image-first spines, and
path resolution edge cases. Verified live against the real
'3 Days to Live' EPUB, which previously produced no cover.
John O'Keefe
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