/**
 * vapor-chamber — HTTP response cache + request deduplication
 *
 * Internal module used by createHttpClient. Not exported publicly.
 *
 * Cache entries carry a fresh window (`freshUntil`) and, when a caller opts
 * into `cache.staleTtl`, a longer stale window (`staleUntil >= freshUntil`).
 * Inside `freshUntil` → a fresh hit (no fetch). Between the two → a stale
 * hit: served instantly while the caller attaches a background revalidation
 * (see http.ts). Past `staleUntil` → a miss, but the entry is NOT deleted —
 * `getCachedAny` still finds it as a last resort for `cache.serveStaleOnError`.
 * Only LRU size pressure or an explicit `invalidateCacheByPattern` removes it.
 */
declare const CACHE_DEFAULT_TTL = 30000;
type CacheEntry = {
    data: any;
    freshUntil: number;
    staleUntil: number;
};
export type CacheHit = {
    data: any;
    stale: boolean;
};
/** A fresh or stale hit; `null` on a plain miss. Never deletes on read. */
export declare function getCached(key: string): CacheHit | null;
/** Last-resort lookup for `cache.serveStaleOnError` — ignores freshness entirely, never evicts. */
export declare function getCachedAny(key: string): CacheEntry | null;
export declare function setCache(key: string, data: any, ttl?: number, staleTtl?: number): void;
export declare function clearAllCache(): void;
export declare function invalidateCacheByPattern(pattern: string | RegExp): void;
export { CACHE_DEFAULT_TTL };
export declare function getInflight(key: string): Promise<any> | undefined;
export declare function setInflight(key: string, promise: Promise<any>): void;
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