External resource inventory

This inventory covers what the HTML declares: script, stylesheet, font, image, frame, media, and manifest references, plus the preconnect and dns-prefetch hints that name the third parties the page expects to contact early. Anything loaded by script at runtime is invisible here; a DevTools network panel or a HAR capture shows that half of the picture, and the gap between this count and DevTools is exactly the size of the runtime-loaded surface. The first-party split uses a registrable-domain approximation over a short list of common multi-label suffixes (the co.uk family, com.au, com.br and similar), not the full Public Suffix List, so unusual suffixes classify by their last two labels and can be wrong. Export the CSV or JSON to diff one run against a later one.