/**
 * Memory Staleness Scoring — v4.0.0
 *
 * Provides staleness awareness to memories based on age.
 * Used by search and recall to surface freshness warnings.
 */
/**
 * Days since memory was created.
 */
export declare function memoryAgeDays(createdAt: number): number;
/**
 * Human-readable age string.
 */
export declare function memoryAge(createdAt: number): string;
/**
 * Freshness score: 1.0 for today, exponentially decaying.
 * Half-life of ~7 days: score ≈ 0.5 after a week.
 */
export declare function memoryFreshnessScore(createdAt: number): number;
/**
 * Warning text for stale memories (>2 days old). Returns null for fresh memories.
 */
export declare function memoryFreshnessWarning(createdAt: number): string | null;
/**
 * Append staleness warning to a memory's content for display.
 */
export declare function appendStalenessWarning(content: string, createdAt: Date): string;
