The cover is the first image reached by EPUB 3's cover-image property,
EPUB 2's <meta name="cover"> (by id, or by address where a converter wrote
one), the guide's cover page and the first <img> or SVG <image> on it, and
last any manifest image whose id or address says cover. A route that names
something unusable leaves a note and the next is asked.
Addresses are resolved against the document they are written in, with the
fragment off and percent-escapes undone; one that climbs out of the archive
or carries a scheme is not followed. Every member is read through a bound,
checked against the size the archive declares and enforced on the read
itself, so an understated entry stops at the cap too.
The media type is read off the bytes, now WebP as well, and a manifest that
disagrees is a note; bytes that are not an image are no cover. MAX_COVER
(16 MiB) is the cap for both formats, so a Kindle cover record larger than
that is left out as well.
Two things between a converted EPUB and its chapter titles.
The heading level taken as the chapter map was the shallowest present. Pandoc
writes the book's title as the only `#` and every real chapter as a `##`, so
the shallowest level had one heading in it and the whole book came back as a
single chapter. The dividing level is now the shallowest one used more than
once — a level used once is a title.
And an empty bracketed span survived the heading cleaner, because the pattern
wanted at least one character between the brackets. Pandoc writes an anchor
as exactly that: `## []{#link2H_INTR} Introduction`.
Gibbon's first volume, converted from the Project Gutenberg EPUB: 2 distinct
chapter titles before, 61 after, and none of them carrying an element id.
The harness compared these tools against the code they replaced — Python
imported from book-pipeline, podcast-pipeline and knowledge-mcp, and
JavaScript copied out of the podcast media server and indexer, each pinned to
a commit. All of it has since been deleted, so the live half cannot run and
the golden half pins answers against a source nobody can consult.
What was worth keeping was never the comparison. `KNOWN.md` argued, at
length, why a dozen of these tools deliberately do something a reader would
not expect: why pdfgutter measures the crop box throughout, why avplan finds
the encoder rather than reading one out of the environment, why mdscrub will
not manufacture a page boundary. Those arguments are about this code and
stand on their own, so they are now `docs/decisions.md`, rewritten to say
what each tool does and why rather than what it does differently.
Binding coverage is unaffected: the bindings carry 24 tests of their own, a
node smoke test against the built package, and a typecheck.
funkpower