Module spectral 

σ → CIE 1931 XYZ → linear sRGB — CPU oracle for canvas2d fallback and cold-path export.

WGSL twin: shaders/viewport/spectral.wgsl. HDR GPU path stays linear; display paths apply sRGB gamma encode via sigma_to_display_rgb.

Functions

sigma_to_cie_xyz

sigma_to_display_rgb

sRGB 8-bit for canvas2d / HUD (gamma-encoded display).

sigma_to_linear_rgb

xyz_to_linear_srgb