import type { PromptVariant } from '../types/prompts.js';
/**
 * Picks an A/B arm for a key, the same arm every time for the same key, prompt, and label.
 *
 * Without a key there is nothing to be sticky to, so the arm is chosen at random.
 */
export declare function chooseVariant(variants: readonly PromptVariant[], seed?: string): number;