Color alias

color-warning: amber-500 is not a colour. It is a pointer. The value still lives one layer down in the palette, and the alias is a second name laid over it so the rest of the system can say what a colour is for rather than which rung it sits on. Radix calls the practice aliasing and separates three flavours: semantic aliases such as accent or brand, use case aliases named for where the colour lands (backgrounds, borders, text), and mutable aliases that resolve to different values in light and dark.

The contrast worth holding on to is with the primitive colour token underneath. A primitive names a colour and nothing else, so amber-500 is the same hex in every theme, on every product, for as long as the scale exists. An alias names a job and points at whichever primitive currently does that job, which is why swapping a theme edits the alias table and nothing else: the scale keeps its names and its hexes, and the component keeps naming the alias rather than the value.

Aliasing pays for itself because meanings outnumber colours. One amber scale can serve as the warning colour and the pending colour at the same time, at different rungs, without either meaning owning a ramp of its own. Duplicating the scale to get a second meaning is the failure this avoids: two ramps that started identical drift, and the day someone corrects a step in one of them the other quietly disagrees. Where the scale is generated from a seed colour, the alias layer is usually the only hand written part of the palette, which is a good reason to keep it short enough to read in one screen. Any alias naming a background also implies one for the ink on top of it, which is what an on-colour is.

Three habits keep an alias layer honest. Keep the chain at two hops, because an alias pointing at an alias pointing at an alias means nobody can see the resolved value without tracing it, and print that resolved value beside the name in the tooling so the trace is never needed. Never let a component reach past the alias to the primitive: doing so removes the joint the alias exists to provide, and the theme then cannot move it. And treat a drifted alias as a bug rather than a convenience. Once color-warning has been used for anything vaguely orange, re-pointing it breaks screens nobody thought to list, which is exactly the outcome the indirection was supposed to prevent.