Prism's structural rebuild of airbnb.com next to the real screenshot, scored two ways. Reconstructed from extracted geometry + tokens — no product imagery is fetched, so this is an honest floor.


Structure (SSIM) measures layout match — the honest headline. Flat-area measures background/fill and is high but background-dominated. We publish both, including low ones, because no competitor publishes any. Method: pixelmatch (flat-area) + SSIM (structure, luminance) + colourFidelity (redmean ΔE approx) + colourFidelityDE (CIEDE2000 ΔE2000, Lab, perceptual) + DOM-diff RDA/GDA/SDA (WebRenderBench) + perceptual DreamSim ONNX (gestalt, opt-in --perceptual) @ 2× device scale, region-matched (zone commune) ; coverage = complétude de hauteur (axe séparé, non mélangé à la fidélité).