/**
 * Duration tracking plugin (per-phase and total).
 */
import type { Middleware, MiddlewareContext, MiddlewareStore, SDKMessage } from '../types';
export interface DurationData {
    phaseSnapshots: Array<{
        phase: string;
        startTime: number;
        endTime: number;
        durationMs: number;
    }>;
    totalDurationMs: number;
}
export declare class DurationTrackerPlugin implements Middleware {
    readonly name = "duration";
    private phaseStartTime;
    private phaseSnapshots;
    onPhaseTransition(fromPhase: string, _toPhase: string, _ctx: MiddlewareContext, store: MiddlewareStore): void;
    onFinalize(_resultMessage: SDKMessage, totalDurationMs: number, ctx: MiddlewareContext, store: MiddlewareStore): void;
}
