oficina / slides Public

swap: krilla-svg replaces the archived svg2pdf behind the same ABI

typst/svg2pdf was archived on 2026-07-10 naming krilla as its successor.
The slice 3 spike had picked svg2pdf without checking that, so core/pdf
was built on a dependency nobody maintains. A second timeboxed spike, in
a scratch copy of the crate so a failure would have cost the repository
nothing, says swap now.

krilla 0.8.2 with krilla-svg 0.8.1 over usvg 0.47, same author and the
same usvg tree underneath. It builds for wasm32-unknown-unknown with no
features turned off at all — krilla-svg has none of its own, and the
resvg, tiny-skia, usvg and fontdb defaults it drags in compile clean,
including tiny-skia's simd — with zero host imports, and it keeps every
property spec §1 ruling 13 asked for: one page per SVG at 1920x1080 pt,
text as subset embedded TrueType (Type0/CIDFontType2, FontFile2,
ToUnicode, a six-letter subset tag), raster images embedded, a bad frame
still a refusal rather than a trap.

The module grows from 3,672,407 to 5,301,002 bytes, which is the whole
cost. Against it, measured through the real host under wazero on one
machine with only the .wasm swapped: 200 pages went from 634/633/637 ms
to 216/220/221 ms, and the PDF from 1,719,771 to 140,444 bytes, because
krilla writes one font subset per document where svg2pdf wrote one per
page. A 200-slide handout that was 1.7 MB of repeated font programs is
140 KB.

The C ABI is byte-identical — slides_pdf_abi_version is still 1, abi.rs
is untouched, and so is internal/slides/pdfcore. Everything above the
module that changed is a test or a comment:

- Tests that grep PDF bytes now take a dictionary entry in either
  spelling. pdf-writer 0.12 wrote "/Type /Page"; 0.15 writes
  "/Type/Page". The object looked for is the same; only the space went.
- export_test.go's little extractor walks page content streams instead
  of form XObjects, and resolves font names through each page's own
  /Resources. krilla writes text straight into the page and calls the
  first font on every page /f0, so a document-wide name map would read
  slide 4's heading in slide 3's face.
- The memory-limit test arms its ceiling at 32 wasm pages rather than
  24: the module's own static memory is 25 pages now.

krilla's XMP metadata packet is turned off. This module has no title,
author or clock to put in one, and what it would carry instead is about
730 bytes of RDF namespace URLs — which breaks the plainer rule the
export tests hold, that a Slides PDF names nothing outside itself. An
identifier is not a link, but a rule that needs that explained is a rule
that stops being checked.

krilla-svg does decode WebP, unlike svg2pdf, so svg.go's
decode-and-re-encode-as-PNG is now belt and braces on the PDF side. It
stays: dropping it changes what the SVG encoder emits and has its own
tests, so it is a change of its own and not a side effect of swapping
the converter. The comments that said otherwise were corrected.

Spec §1 keeps ruling 13, which was true when it was written, and gains
13a beside it; §4.3 gets a dated amendment with these numbers. AGENTS.md,
PRODUCT.md and the review brief follow.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>