/**
 * Cold-boot stage timing for IDB → Zero init.
 *
 * Host apps (Protocolbase) enable via:
 *   globalThis.__PB_ZERO_COLD_BENCH = 1
 * or NEXT_PUBLIC_ZERO_COLD_BENCH=1 (inlined by Next when present).
 *
 * Early-prefetch policy A/B:
 *   globalThis.__PB_ZERO_EARLY_PREFETCH_POLICY = 'done-only' | 'await-inflight'
 * Default: 'await-inflight' (app patch behavior). Fork historical default was
 * done-only only.
 *
 * Logs use `[zero:idb]` so they stay visible when `[ZERO-INIT]` is filtered.
 * Stages also land on `globalThis.__pbZeroColdStages` (ring, last 32).
 */
export type EarlyPrefetchPolicy = 'done-only' | 'await-inflight';
export type ColdIdbStageRecord = {
    at: number;
    stage: string;
    ms?: number;
    [key: string]: unknown;
};
export declare function isColdIdbBenchEnabled(): boolean;
/** Log `[zero:idb]` stages in non-production, or whenever cold-bench is on. */
export declare function shouldLogColdIdb(): boolean;
export declare function getEarlyPrefetchPolicy(): EarlyPrefetchPolicy;
export declare function nowMs(): number;
export declare function logColdIdbStage(stage: string, fields?: Record<string, unknown>): void;
/** Cheap byte estimate — only when bench enabled (JSON.stringify is not free). */
export declare function estimateJsonBytes(vals: Iterable<unknown>): number | undefined;
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