/** Whether `host`'s currently resolved `--lr-color-*` palette is a dark scheme -- i.e. the active
*  text color is perceptually lighter than the active surface color. True both when a consumer sets
*  `--lr-theme-color-*` explicitly and when `tokens.styles.ts`'s own `@media
*  (prefers-color-scheme: dark)` fallback is what's active, since both arrive through the exact same
*  `--lr-color-text`/`--lr-color-surface` custom properties every other themed surface reads. */
export declare function resolveIsDarkTheme(host:Element):boolean;
/** Re-invokes `onChange` whenever the resolved theme might have changed: an OS-level
*  prefers-color-scheme flip, or a class/style/data-theme/data-color-scheme attribute change
*  anywhere in `host`'s ancestor chain. A consumer re-theming via `--lr-theme-*` custom properties
*  fires no DOM event on its own -- this mirrors qr-code.class.ts's/heatmap.class.ts's/
*  chart.class.ts's own theme-reactive canvases, the established pattern in this codebase for a
*  component that can't just let CSS repaint itself. Returns a cleanup function. */
export declare function watchDarkTheme(host:HTMLElement,onChange:()=>void):()=>void;