/**
 * Returns `true` when the user prefers reduced motion.
 *
 * Safe for SSR (returns `false` when `window` is unavailable).
 *
 * The result is cached after the first call via `once`. This avoids
 * calling `matchMedia` on every render. The trade-off is that if a user
 * toggles the OS reduced-motion setting mid-session, the change will not
 * take effect until the next page load. This is acceptable because
 * toggling this system-level preference mid-session is extremely rare,
 * and a page refresh is a reasonable expectation for system accessibility
 * settings to take effect.
 */
export declare const prefersReducedMotion: () => boolean;