/**
 * BM25 Text Search — Free Tier Semantic Search Alternative
 *
 * Okapi BM25 ranking function with field boosting.
 * Significantly better than naive keyword matching:
 * - Term frequency saturation (repeated terms don't dominate)
 * - Inverse document frequency (rare terms score higher)
 * - Document length normalization (short docs don't get penalized)
 * - Stemming via Porter-like suffix stripping
 *
 * Zero dependencies. ~100 lines of actual logic.
 */
/** Tokenize and stem text. Strips punctuation, lowercases, stems. */
export declare function tokenize(text: string): string[];
export interface BM25Document {
    /** Unique ID */
    id: string;
    /** Fields to index, with boost weights. Higher boost = more important. */
    fields: {
        text: string;
        boost: number;
    }[];
}
export interface BM25Result {
    id: string;
    score: number;
    /** Normalized score 0-1 for compatibility with similarity field */
    similarity: number;
}
/**
 * Score documents against a query using BM25 with field boosting.
 *
 * @param query - Search query text
 * @param docs - Documents to search
 * @param k - Max results to return
 * @returns Scored and ranked results
 */
export declare function bm25Search(query: string, docs: BM25Document[], k: number): BM25Result[];
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