Render committed synthetic fixtures through PdfViewer with the REAL
pdf.js loader and assert the canvas is non-blank (sampled dark-pixel
count). The CCITT (G4 fax) fixture exercises the shared jbig2.wasm
decode path — the same module pdf.js uses for JBIG2 — so it transitively
covers the JBIG2 acceptance criterion (the archive sample found zero
true JBIG2 docs and jbig2enc is unavailable to synthesize one). The
JPEG/DCTDecode fixture guards against regressing the natively-decoded
path. Verified the CCITT case goes red when wasmUrl is removed.
Fixtures are hermetic, committed assets (~2-5 KB each), generated with
ImageMagick — never fetched from staging at test time. CI browser mode.
Refs #708
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
