import type { OverlayComposer } from './overlay-composer.js';
export declare const TTFB_GRACE_MS = 2000;
export interface TtfbTickCtx {
    ttfbStartedAt: number | undefined;
    ttfbDone: boolean;
    lastTtfbAnnotation: string;
    isTTY: boolean;
    disposed: boolean;
    overlayComposer: OverlayComposer | null;
}
export declare function checkTtfbAnnotation(ctx: TtfbTickCtx, now: number): boolean;
export declare function applyFirstContent(isDone: boolean, setDone: () => void, overlayComposer: OverlayComposer | null): boolean;