export type TailSwapCarryAssignment = {
    id: string;
    height: number;
};
export type TailSwapCarryResult = {
    carriedHeights: TailSwapCarryAssignment[];
    reserveHeight: number;
    shouldClearReserve: boolean;
    shouldSnapAfterClear: boolean;
};
export type ObserveTailSwapArgs = {
    currentIds: readonly string[];
    getHeight: (_id: string) => number | undefined;
    estimatedHeight: number;
    canCarryTailRemoval: boolean;
};
export declare const startsWithIds: (ids: readonly string[], prefix: readonly string[]) => boolean;
/**
 * Tracks the one timing-sensitive shape the height cache intentionally does
 * not own: `[...prefix, measured-tail] -> [...prefix] -> [...prefix, new-id]`.
 *
 * The component uses the returned reserve to keep bottom geometry stable
 * during the empty tick, then seeds the appended id with the removed height if
 * it arrives before the pending carry is cleared.
 */
export declare class ChatTailSwapCarry {
    #private;
    clear(): void;
    observe({ currentIds, getHeight, estimatedHeight, canCarryTailRemoval }: ObserveTailSwapArgs): TailSwapCarryResult;
}