export interface RecallWeights {
    readonly relevance?: number;
    readonly recency?: number;
    readonly confidence?: number;
}
export interface RecallRankingOptions {
    readonly weights?: RecallWeights;
    readonly recencyHalfLifeMs?: number;
    readonly candidatePool?: number;
}
export declare const DEFAULT_RECALL_WEIGHTS: {
    readonly relevance: 0.6;
    readonly recency: 0.3;
    readonly confidence: 0.1;
};
export declare const DEFAULT_RECENCY_HALF_LIFE_MS: number;
export declare const DEFAULT_CANDIDATE_POOL = 256;
/**
 * BM25-smoothed inverse document frequency. Always positive — a token present
 * in every memory (df = corpusSize) still carries a small weight rather than
 * zeroing out or going negative (as unsmoothed idf would).
 */
export declare function idf(df: number, corpusSize: number): number;
/**
 * Exponential recency decay in (0, 1]. age = referenceMs − updatedMs, clamped ≥ 0;
 * invalid/absent timestamps degrade to age 0 (decay 1). Non-positive/non-finite
 * halfLife falls back to the default.
 */
export declare function recencyDecay(updatedAt: string, referenceNow: string, halfLifeMs?: number): number;
/**
 * Composite recall score: wRel·relevance + wRec·recency + wConf·confidence.
 *
 * relevance = Σ idf(matched query tokens) / Σ idf(all query tokens) — the
 * fraction of the query's information this memory matches (0..1). Query
 * tokens matching nothing inflate only the shared denominator, so relative
 * ordering is unaffected.
 *
 * recency = 2^(−age / halfLife), age measured from `referenceNow` back to
 * `updatedAt`, clamped ≥ 0. Invalid timestamps degrade to age 0. A
 * non-positive or non-finite halfLifeMs falls back to the default.
 *
 * `queryTokens` are expected to be deduplicated, as produced by `tokenize()`.
 */
export declare function scoreMemory(args: {
    readonly memoryTokens: ReadonlySet<string>;
    readonly queryTokens: readonly string[];
    readonly dfByToken: ReadonlyMap<string, number>;
    readonly corpusSize: number;
    readonly updatedAt: string;
    readonly confidence: number;
    readonly referenceNow: string;
    readonly options?: RecallRankingOptions;
}): number;
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