import type { NextFunction, Request, Response } from 'express';
export type LogLevel = 'info' | 'warn' | 'error';
export declare function log(level: LogLevel, msg: string, fields?: Record<string, unknown>): void;
export declare function loggingMiddleware(req: Request, res: Response, next: NextFunction): void;
export interface StatsBeaconFields {
    sessions: number;
    tabs: number;
    rssBytes: number;
    heapUsedBytes: number;
    uptimeSeconds: number;
    browserConnected: boolean;
}
export declare function startStatsBeacon(getFields: () => StatsBeaconFields): NodeJS.Timeout;
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