nx_mediafacts_lib.nx

nx_mediafacts_lib.nx -- MEDIA FACT EXTRACTION CORE (R1 of the render-docs ingest program, knowledge/render_docs_ingest_program.txt). Turns raw media bytes into a CLOSED VOCABULARY of integer measurements -- the substrate rows the refcorpus admission contract was built for. COMPOSES INCUMBENTS, BUILDS NO NEW DECODER (the duplicate-inflate lesson, debt 1785854636: ask the corpus by capability before building): dimensions come from nx_img_dims.nx (PNG/GIF/JPEG/WebP header walk, in-tree since the media importer). The WAV walk below is NOT a copy of nx_wav_header.nx -- that parser's contract requires the WHOLE file in memory (it bounds-checks every chunk BODY, incl. the data payload). Fact extraction reads a BOUNDED HEADER WINDOW of possibly-huge files, so it needs a walk that only touches chunk HEADERS and never requires the body to be present: a different contract, not a duplicate. ★THE PII WALL IS STRUCTURAL: no byte from the input file ever flows to the output. Every fact is a computed integer or a fixed label from the enum below. EXIF/XMP are surfaced as a PRESENCE FLAG only -- the segment is never parsed, so GPS coordinates, serial numbers and embedded thumbnails are structurally unreadable through this lane. Fact slots (flat i64 array, MF_N_SLOTS): [0] format 0=unknown 1=png 2=gif 3=jpeg 4=webp 5=wav [1] width_px [2] height_px [3] exif_present (jpeg only) [4] channels [5] sample_rate_hz [6] bits_per_sample [7] duration_ms (wav only) Unfilled slots stay -1: "not measured" is DISTINCT from 0 -- a fabricated zero is the exact plausible-number failure the soft-tissue lane banked. license_tier: ORIGINAL No hw writes (Rule 26).