/**
 * Memory decay model for Iranti knowledge entries.
 *
 * Implements an Ebbinghaus-inspired forgetting curve: confidence decays
 * exponentially as a function of time since last access and a per-fact
 * stability value. Decay is opt-in (disabled by default) and controlled
 * entirely via IRANTI_DECAY_* environment variables.
 *
 * Key functions:
 *   - getDecayConfig()              — read decay settings from env
 *   - calculateRetention()          — Ebbinghaus retention fraction [0,1]
 *   - calculateDecayedConfidence()  — apply retention to a confidence score
 *   - initialStabilityFromReliability() — seed stability from source reliability
 */
export type DecayConfig = {
    enabled: boolean;
    stabilityBase: number;
    stabilityIncrement: number;
    stabilityMax: number;
    threshold: number;
};
export declare function getDecayConfig(): DecayConfig;
export declare function calculateRetention(timeSinceAccessDays: number, stability: number): number;
export declare function calculateDecayedConfidence(originalConfidence: number, timeSinceAccessDays: number, stability: number): number;
export declare function initialStabilityFromReliability(reliability: number, config?: DecayConfig): number;
export declare function readOriginalConfidence(properties: unknown, fallbackConfidence: number): number;
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