/**
 * Test-only state and helpers for the engine cleanup-interval finalizer
 * leak-warning system. Kept in a sibling module so `index.ts` does not
 * accumulate test-only ceremony.
 */
export type EngineCleanupIntervalDisposalTracker = {
    disposed: boolean;
    cleanupInterval: ReturnType<typeof setInterval> | null;
    /**
     * The optional second-instance detector interval, tracked alongside the
     * cleanup interval so the same finalizer clears it when an engine is
     * garbage-collected without `[Symbol.dispose]()`. Null when detection is off.
     */
    secondInstanceDetectionInterval: ReturnType<typeof setInterval> | null;
    testToken: symbol | undefined;
};
export declare const engineCleanupIntervalFinalizer: FinalizationRegistry<EngineCleanupIntervalDisposalTracker>;
/** Test-only hook for the finalizer callback's synchronous warning gate. */
export declare function finalizeEngineCleanupIntervalTrackerForTesting(tracker: EngineCleanupIntervalDisposalTracker): void;
export declare function shouldEmitEngineLeakWarning(): boolean;
/** Test-only override for the engine leak-warning environment gate. */
export declare function setEngineLeakWarningOverrideForTesting(value: boolean | undefined): void;
/** Test-only marker applied to the next constructed engine leak tracker. */
export declare function setNextEngineLeakWarningTokenForTesting(value: symbol | undefined): void;
/** Read the test-only next-token marker, consuming it. */
export declare function consumeNextEngineLeakWarningTokenForTesting(): symbol | undefined;
/** Test-only count of engine cleanup finalizer observations. */
export declare function getEngineLeakCollectionCountForTesting(): number;
/** Test-only visibility into whether a tagged engine leak emitted a warning. */
export declare function hasEngineLeakWarningTokenForTesting(token: symbol): boolean;
/** Test-only cleanup for tagged leak warning observations. */
export declare function clearEngineLeakWarningTokenForTesting(token: symbol): void;
/** Test-only visibility into the engine leak-warning environment gate. */
export declare function shouldEmitEngineLeakWarningForTesting(): boolean;