/** Reset the dedup set — intended for use between tests. */
export declare function resetContrastWarnings(): void;
/**
 * DEV-only WCAG AA guardrail for caller-supplied hex pairs.
 *
 * - No-op when `import.meta.env.DEV` is false.
 * - No-op when either half of the pair is missing (the "fg missing →
 *   inherits DS token" case is a docs concern; the DS token isn't a
 *   hex at runtime so we can't check it here).
 * - No-op when either hex can't be parsed (silent — not the helper's
 *   concern to police malformed input).
 * - Deduplicated by `(bgHex, fgHex, contextLabel)` tuple so moving a
 *   ratio-bad event around the calendar doesn't spam the console.
 *
 * @param bgHex - Caller-supplied background hex (e.g. `'#c2185b'`)
 * @param fgHex - Caller-supplied foreground hex (e.g. `'#ffffff'`)
 * @param contextLabel - Short description for the warning (e.g. `'event e1'`).
 */
export declare function warnLowContrast(bgHex: string | undefined, fgHex: string | undefined, contextLabel: string): void;
export type EventInk = 'on-light' | 'on-dark';
/**
 * Pick the ink for an arbitrary opaque bg hex. Returns `null` when the
 * input can't be parsed (`#rgb` / `#rrggbb` only).
 *
 * The threshold 0.1791 is the relative luminance at which
 * `contrast(bg, #fff) === contrast(bg, #000)`; the better of the two
 * always yields ≥ 4.58:1 (the minimum, at a mid-grey ≈ `#757575`) —
 * provably WCAG AA-safe for any opaque background.
 */
export declare function resolveInk(bgHex: string): EventInk | null;
/**
 * DEV-only, one-shot warning for a caller `backgroundColor` the kit can't
 * parse (`rgb(…)`, keywords, malformed hex). The browser can still paint
 * it, but the text falls back to the token default and contrast can't be
 * verified. Deduplicated by `(bgHex, contextLabel)`.
 */
export declare function warnUnparseableBackground(bgHex: string, contextLabel: string): void;
/**
 * DEV-only, one-shot warning for a near-white `backgroundColor`
 * (relative luminance > 0.9) supplied without a `borderColor` — the
 * event may be invisible against the calendar grid. The kit warns, it
 * does not repaint (delineation is decorative under WCAG 1.4.11 and the
 * consumer owns the picker colour). Deduplicated by `(bgHex, contextLabel)`.
 */
export declare function warnLowDelineation(bgHex: string, contextLabel: string): void;
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