Function
Purely decorative, and hidden from assistive technology: it repeats what a visible label already says in words. Never render it on its own — pair it with a label that names what is being waited on, or the wait is silent for anyone who is not looking at it.
The arc takes its colour from currentColor, so it reads correctly on a
filled button and on a plain surface without being told which it is on. The
rotation lives in globals.css under .spinner-arc, where the global
prefers-reduced-motion block can still it.
The gold arc that turns while a request is in flight.