export type StartupTracePhase = 'config-ready' | 'setupAppRuntimePlugins' | 'route-registry' | 'server-listen' | 'first-byte' | 'first-page-browser-graph' | 'dev-client-transform' | 'first-request-ssr' | 'client-transfer' | 'client-hydration';
type PhaseRecord = {
    durationMs: number;
    wallMs: number;
};
export type StartupTraceReport = {
    generatedAt: string;
    runtime: string;
    platform: string;
    phases: Partial<Record<StartupTracePhase, PhaseRecord>>;
    firstRequest?: {
        path: string;
        bundleCount: number;
        clientBundleBytes: number;
        graphBuildCount: number;
        wallMs: number;
    };
    client?: {
        requestCount: number;
        transferredBytes: number;
        hmrConnected: boolean;
        hydrationReadyMs: number | null;
    };
};
declare class StartupTrace {
    private readonly phaseNesting;
    private readonly phases;
    private firstRequestPending;
    private firstRequestPath;
    private firstRequestBundleCount;
    private firstRequestClientBytes;
    private firstRequestGraphBuildCount;
    private firstRequestCompletedWallMs;
    private summaryEmitted;
    private firstPageBrowserGraphEmitted;
    private devClientTransformEmitted;
    private clientRequestCount;
    private clientTransferredBytes;
    private hmrConnected;
    private hydrationReadyMs;
    isEnabled(): boolean;
    markPhaseStart(phase: StartupTracePhase): void;
    markPhaseEnd(phase: StartupTracePhase): void;
    markConfigReady(): void;
    markServerListening(): void;
    beginServerListen(): void;
    markFirstByte(): void;
    beginFirstByte(): void;
    beginDevClientTransform(): void;
    endDevClientTransform(): void;
    /**
     * Records the first Page Browser Graph completion for startup tracing.
     *
     * @param graphBuildCount Session graph build counter when the first Page Browser Graph finished.
     */
    markFirstPageBrowserGraphReady(graphBuildCount?: number): void;
    recordBrowserBundle(outputs: Array<{
        path: string;
    }>): void;
    recordClientTransfer(requestCount: number, transferredBytes: number): void;
    beginClientTransfer(): void;
    recordClientHydration(durationMs: number): void;
    beginClientHydration(): void;
    recordHmrConnected(): void;
    traceFirstRequest<T>(request: Request, handler: () => Promise<T>): Promise<T>;
    private emitFirstRequestSummary;
    private writeJsonReport;
    createReport(): StartupTraceReport;
    /** Resets mutable trace state for unit tests. */
    resetForTests(): void;
    /**
     * Resets only the first-request bundle counters.
     *
     * @remarks
     * Used by tests that need to re-measure first-request browser bundle work
     * without clearing earlier startup phase records.
     */
    resetFirstRequestCounters(): void;
}
export declare const startupTrace: StartupTrace;
export {};