export interface StartupProfileEvent {
    name: string;
    startMs: number;
    durationMs: number;
    phase?: string;
    kind?: "event" | "gap";
    detail?: Record<string, unknown>;
}
export interface StartupProfileSnapshot {
    enabled: boolean;
    startedAt: string;
    startedAtMs?: number;
    elapsedMs: number;
    events: StartupProfileEvent[];
}
export interface StartupProfileEventOptions {
    phase?: string;
    kind?: "event" | "gap";
    detail?: Record<string, unknown>;
}
export interface StartupProfileMergeOptions {
    gapThresholdMs?: number;
}
export interface StartupProfileFormatOptions {
    prefix?: string;
}
export interface StartupProfiler {
    readonly enabled: boolean;
    time<T>(name: string, action: () => Promise<T> | T, options?: StartupProfileEventOptions): Promise<T>;
    mark(name: string, durationMs?: number, options?: StartupProfileEventOptions): void;
    toJSON(): StartupProfileSnapshot;
}
export interface StartupProfilerOptions {
    enabled?: boolean;
    now?: () => number;
    wallClockNow?: () => number;
}
export declare function createStartupProfiler(options?: StartupProfilerOptions): StartupProfiler;
export declare function createStartupProfilerFromEnv(env: Record<string, string | undefined>): StartupProfiler;
export declare function mergeStartupProfiles(mainProfile: StartupProfileSnapshot, workerProfile: StartupProfileSnapshot, options?: StartupProfileMergeOptions): StartupProfileSnapshot;
export declare function formatStartupSummary(profile: StartupProfileSnapshot, options?: StartupProfileFormatOptions): string;
export declare function formatStartupProfile(profile: StartupProfileSnapshot, options?: StartupProfileFormatOptions): string;
export declare function writeStartupProfileJson(filePath: string, profile: StartupProfileSnapshot): void;
export declare function formatStartupDuration(value: number): string;