/**
 * Foreground colour for a consumer-supplied background (INTERNAL).
 *
 * Any component that paints a surface from a colour the *consumer* chose —
 * a `DateCategory.color`, a chart series colour — has to pick the label colour
 * itself, because a semantic token cannot know what it will sit on. This module
 * owns that decision for the whole package.
 *
 * It lived in `Calendar/calendar.engine.ts` until ResourceTimeline became its
 * second caller. Importing it from there would have been a **value** import
 * across two component families, in a spot `imports:lint` is structurally blind
 * to (it only tracks PascalCase component edges), and it would have coupled a
 * component whose whole point is to add nothing to the Calendar neighbourhood
 * back onto Calendar's engine. `calendar.engine.ts` re-exports the name so
 * Calendar's own sub-components (and their tests) keep their import path.
 */
/**
 * Determine whether text on a given background color should be light or dark.
 * Supports hex (#rgb, #rrggbb), rgb(), oklch(), and CSS named colors.
 * Returns 'white' or 'black' based on perceived luminance.
 */
export declare function getContrastTextColor(bgColor: string): 'white' | 'black';