nx_mediafacts_gate.nx

nx_mediafacts_gate.nx -- PROVE THE MEDIA FACT EXTRACTOR MEASURES, NEVER FABRICATES, NEVER LEAKS. Teeth follow the refcorpus discipline: every capability is asserted in BOTH polarities, and the PII wall gets a structural tooth -- two JPEGs identical except their Exif CONTENT must produce identical fact arrays, proving segment content cannot flow through this lane (a witness that can only agree is not a witness; a flag that fires on presence must also stay silent on absence). Fixtures are constructed byte-for-byte from the published specs (PNG sig+IHDR, JPEG markers, RIFF/WAVE chunk layout) -- not from our own writers, so a shared misreading cannot self-validate. license_tier: ORIGINAL No hw writes (Rule 26).