/**
 * In-memory BM25 over the capability index — the leg that always works.
 *
 * Deliberately not the repo's lexical retriever: that one shells out to ripgrep
 * over files on disk, and capabilities are a few hundred short strings held in
 * memory. It is also not optional. The dense leg needs a binary that may not be
 * installed and a store that may still be building, so if retrieval depended on
 * it, "find me a tool that sends email" would work on some machines and not
 * others. This leg makes the floor deterministic and dependency-free; dense is
 * strictly additive on top.
 *
 * The tokenizer does the load-bearing work here. Tool names are the query terms
 * that matter most and they arrive as `mcp_github_create_pull_request` or
 * `createPullRequest`, so a naive whitespace split would make the single most
 * common query shape — a name the model half-remembers — the one thing BM25
 * cannot match.
 */
import type { CapabilityDoc } from "./registry.js";
/**
 * Split identifiers the way a person reads them: `mcp_github_create_pr` and
 * `createPullRequest` both yield their parts, and the original token is kept so
 * an exact name still scores as an exact match.
 *
 * Singular forms are emitted *alongside* the originals rather than replacing
 * them, which is the same bargain the identifier splitting makes: an exact
 * token still matches exactly, and a near miss now matches too.
 */
export declare function tokenize(text: string): string[];
export interface LexicalHit {
    id: string;
    score: number;
}
/**
 * A built BM25 index. Cheap enough to rebuild whenever the capability set
 * changes — a few hundred short documents — so there is no invalidation story
 * to get wrong.
 */
export declare class LexicalIndex {
    private readonly postings;
    private readonly docFreq;
    private readonly avgLength;
    constructor(docs: readonly CapabilityDoc[]);
    get size(): number;
    /** Top `k` documents for `query`, best first. Documents scoring zero are omitted. */
    search(query: string, k?: number): LexicalHit[];
}
//# sourceMappingURL=lexical.d.ts.map