/**
 * "Back to your message": which prompt the reader is reading the answer to, and
 * whether that prompt has scrolled out of view. Renderer-neutral geometry so
 * the web timeline (DOM rects) and native timelines (layout offsets) agree.
 */
/** How far above the viewport a prompt must be before the pill appears. */
export declare const QUESTION_NAV_HIDDEN_PX = 24;
/** Breathing room above the question when the reader jumps back to it. */
export declare const QUESTION_NAV_MARGIN_PX = 12;
export type QuestionNavPrompt = {
    key: string;
    top: number;
    bottom: number;
};
/**
 * The last prompt before the reading position (the viewport's middle) owns the
 * response in view; it is a target only once it has scrolled fully above the
 * viewport. Prompts are in document order; coordinates share one axis.
 */
export declare function questionNavTarget(prompts: readonly QuestionNavPrompt[], view: {
    top: number;
    height: number;
}): string | null;