/**
 * Candidate fusion (reciprocal rank fusion) and deterministic heuristic
 * reranking. Duplicate chunks are merged, per-file diversity is enforced, exact
 * matches stay strong, and every result exposes its contributing signals.
 */
import type { HybridCandidateScore } from "./types.js";
export interface FusionCandidate {
    chunkId: string;
    file: string;
    ranking: number;
    generator: string;
    reasonCode: string;
    bonus?: number;
}
export interface FusedResult {
    chunkId: string;
    file: string;
    score: HybridCandidateScore;
    rank: number;
}
/** Fuse ranked candidate lists from multiple generators via RRF. */
export declare function fuseCandidates(generatorLists: FusionCandidate[][], opts?: {
    maxPerFile?: number;
    maximumResults?: number;
}): FusedResult[];
/** Deterministic heuristic reranker over fused results (no separate model). */
export declare function rerankHeuristic(results: FusedResult[], opts?: {
    exactTerm?: string;
    symbolMatch?: Set<string>;
}): FusedResult[];
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