export type ExpansionTechnique = 'synonyms' | 'abbrev' | 'related' | 'hyde';
export interface ExpansionOptions {
    techniques?: ExpansionTechnique[];
    maxTerms?: number;
    hydeModel?: string;
}
export interface ExpansionResult {
    original: string;
    expanded: string;
    techniques_used: string[];
    terms_added: string[];
    hyde_doc?: string;
    durationMs: number;
}
export declare class BrainQueryExpander {
    /** Expand a query using selected techniques; returns the densified search text. */
    expand(query: string, opts?: ExpansionOptions): Promise<ExpansionResult>;
    /**
     * Run all techniques and return the densest expansion. Best for direct use
     * by retrievers that don't want to think about technique selection.
     */
    combineAll(query: string, opts?: ExpansionOptions): Promise<ExpansionResult>;
    private lookupRelatedEntities;
    private generateHyde;
    private probeHydeModel;
    private templateHyde;
    private persist;
}
export declare function getBrainQueryExpander(): BrainQueryExpander;
export declare function resetBrainQueryExpanderForTests(): void;
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