# `` — chassis-level theme registry _(no submodules)_ ## Purpose Mounts the active theme registry, hands it down through React context, applies the active theme's tokens to `` as inline CSS variables, listens for `prefers-reduced-motion` changes, and prevents flash-of- unstyled-content via an inline FOUC-prevention `` close tag. The `useTransition()` wrapper around `setTheme` is the reason the `isPending` flag exists on `useTheme()` — consumers that show a tiny spinner during a theme transition read that flag. The Provider tracks the previous theme name in a `useRef` so the OTel `from` attribute is accurate even when several `setTheme` calls land back-to-back.