When two tokens must always agree, do not write the same value twice. Speak the other's name instead.
An alias is a $value that is exactly `{path.to.another.token}` — curly braces, dotted path, no extras.
Two semantic tokens await: `color.action.default` should alias `color.brand.primary`, and `color.action.hover` should alias `color.brand.secondary`.
When the brand changes, the action layer follows. That is the whole point.