import { type Ref } from 'vue';
export declare function formatThinkingDuration(durationMs: number | null): string | null;
export declare function useReasoningTimer(options: {
    startedAt: Readonly<Ref<Date | string>>;
    endedAt: Readonly<Ref<Date | string | null | undefined>>;
    completed: Readonly<Ref<boolean>>;
}): {
    elapsedTime: Ref<number, number>;
    thinkingDuration: import("vue").ComputedRef<number | null>;
};