/** Small generation-scoped LRU used by the detached index server. */
export declare class GenerationLruCache<T> {
    private readonly maxEntries;
    private readonly entries;
    constructor(maxEntries: number);
    get(key: string, generation: number): T | undefined;
    /**
     * Read an entry regardless of which generation wrote it, without touching
     * LRU recency. Used by the project server to serve a previous-generation
     * (stale) answer while an index refresh is publishing — the caller marks the
     * response `stale` instead of failing the read.
     */
    peek(key: string): T | undefined;
    /**
     * Like {@link peek} but exposes the entry's generation, so the stale-read
     * policy can bound how far a preserved entry may lag the publishing
     * generation before it is too old to serve.
     */
    peekEntry(key: string): {
        generation: number;
        value: T;
    } | undefined;
    set(key: string, generation: number, value: T): T;
    clear(): void;
    get size(): number;
}
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