/**
 * BM25 ranking implementation — no external dependencies.
 *
 * Algorithm: Okapi BM25 with standard parameters (k1=1.5, b=0.75).
 */
interface Bm25Doc {
    id: number;
    tokens: string[];
    raw: string;
    len: number;
}
/**
 * Tokenise a string into lowercase word tokens.
 *
 * Preserves apostrophes so that identifiers like `can't` or `user's`
 * remain a single token. Underscores are treated as separators (they
 * conventionally split words in snake_case identifiers).
 */
export declare function tokenise(text: string): string[];
interface IndexableDoc {
    id: number;
    text: string;
}
/**
 * Max chars of `signature` fed to the FTS index (P1, 2026-08-30).
 *
 * `signature` stores the full printed declaration — often including the whole
 * function body, because `ts-parser`'s getSignature uses `printer.printNode`
 * (capped at 500 chars). Measured on the live 131k-row index: ts+tsx signature
 * text was ~70% of all trigram FTS input, and capping to the declaration
 * header cut FTS size 47% and insert time 20-32%. Only the FTS *input* is
 * capped; the stored `signature` column (display, embeddings fallback) is
 * untouched.
 */
export declare const FTS_SIGNATURE_MAX_CHARS = 300;
/**
 * Build indexable text for BM25 from a symbol's fields.
 * The name is split into camelCase/SnakeCase words so that queries
 * like "complex" match "complexOperation". The verbatim name is
 * also included for exact-match queries. The signature contributes
 * only its declaration header (see {@link ftsSignature}).
 */
export declare function buildIndexableText(name: string, signature: string, docComment: string): string;
export declare function buildBm25Index(docs: IndexableDoc[]): Bm25Index;
export declare class Bm25Index {
    private documents;
    private N;
    private readonly safeAvgLen;
    /** Lazily-built id→doc index so getDoc is O(1) instead of an O(D) linear find. */
    private _byId;
    constructor(documents: Bm25Doc[], N: number, avgLen: number);
    score(query: string, filter?: (id: number) => boolean): Array<{
        id: number;
        score: number;
    }>;
    getDoc(id: number): Bm25Doc | undefined;
    extractSnippet(docId: number, queryTokens: string[], radius?: number): string;
}
export {};
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