nx_brand_guard.nx

nx_brand_guard.nx -- R2 brand-consistency ENFORCEMENT, tied to the design-token SSOT. Three checks, all no-float: (1) WCAG 2.x contrast ratio between two token colors -- accessibility-as-brand (2) spacing-grid conformance (space tokens are multiples of a base unit) -- visual rhythm (3) modular type-scale conformance (headings descend within a sane ratio band) -- typographic consistency REUSE (audited, not reinvented): nx_css_color_decode (hex->rgb), nx_brand_tokens (bt_lookup), and fx.nx's ACCURATE Q16.16 fx_pow for the sRGB gamma. NOTE: deliberately NOT nx_aces' pow24 -- that empirical fit carries ~30% error at mid-tones and would misclassify contrast near the 4.5 threshold (hand-verified: #767676/#fff -> 3.6 wrong vs 4.54 true). fx_pow is exp2/log2-based and matches the WCAG reference (validated in the gate, no overclaim). CONSTANTS are PUBLISHED STANDARDS: sRGB OETF (IEC 61966-2-1) + Rec.709 luma (ITU-R BT.709). Library. 100% sovereign (nx_cc->nxasm, no gcc/JS). license_tier: ORIGINAL