/**
 * Retrievers under test, including the deliberately weak baselines.
 *
 * The weak baselines exist to answer one question the headline number cannot:
 * how much of our score is the retrieval stack, and how much is a golden set
 * so easy that keyword matching nearly solves it? A small gap between
 * `bm25-only` and the real stack means the SET is uninformative, not that the
 * stack is good. See Requirement C in the item-0 brief.
 *
 * @module v1/cli/knowledge/eval/retrievers
 */
export interface EvalChunk {
    docId: string;
    chunkIndex: number;
    text: string;
}
export interface RawHit {
    docId: string;
    chunkIndex: number;
    score: number;
}
export interface Retriever {
    name: string;
    description: string;
    /** Must not make network calls. Returns chunk-level hits, best-first. */
    search(query: string, limit: number): Promise<RawHit[]>;
}
export declare class Bm25Retriever implements Retriever {
    private chunks;
    name: string;
    description: string;
    private docs;
    private df;
    private avgLen;
    constructor(chunks: EvalChunk[]);
    search(query: string, limit: number): Promise<RawHit[]>;
}
export declare class RandomRetriever implements Retriever {
    private seed;
    name: string;
    description: string;
    private docIds;
    constructor(chunks: EvalChunk[], seed?: string);
    search(query: string, limit: number): Promise<RawHit[]>;
}
/** Wraps an arbitrary async search function (the real stack) as a Retriever. */
export declare class FnRetriever implements Retriever {
    name: string;
    description: string;
    private fn;
    constructor(name: string, description: string, fn: (query: string, limit: number) => Promise<RawHit[]>);
    search(query: string, limit: number): Promise<RawHit[]>;
}
export declare class RrfRetriever implements Retriever {
    private children;
    /** RRF smoothing constant. Standard values: 10–100. */
    private rrfK;
    name: string;
    description: string;
    constructor(children: Retriever[], 
    /** RRF smoothing constant. Standard values: 10–100. */
    rrfK: number, name?: string);
    search(query: string, limit: number): Promise<RawHit[]>;
}
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