/**
 * Exponential-backoff negative caching helper.
 *
 * Storage-agnostic: takes a NegativeCacheStore interface that consumers
 * implement against Dexie (web), the filesystem (CLI), or in-memory (tests).
 */
/** Record shape stored per negative-cached key. */
export interface NegativeRecord {
    until: number;
    attempts: number;
}
/** Minimal key/value storage interface used by NegativeCacheHelper. */
export interface NegativeCacheStore {
    get(key: string): Promise<NegativeRecord | undefined>;
    set(key: string, record: NegativeRecord): Promise<void>;
    delete(key: string): Promise<void>;
}
/**
 * Tracks "this thing doesn't exist" outcomes with progressive retry delays:
 * 15m base, doubling per attempt, capped at 24h.
 */
export declare class NegativeCacheHelper {
    private store;
    constructor(store: NegativeCacheStore);
    isNegative(key: string): Promise<boolean>;
    recordNegative(key: string): Promise<void>;
    clearNegative(key: string): Promise<void>;
}
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