/**
 * BRAIN Vector Similarity Search
 *
 * Provides vector-based KNN search against brain_embeddings vec0 table.
 * Falls back gracefully when no embedding provider is registered or
 * sqlite-vec is unavailable.
 *
 * @task T5388
 * @epic T5149
 */
export interface SimilarityResult {
    id: string;
    distance: number;
    type: string;
    title: string;
    text: string;
}
/**
 * Search for entries similar to a query string using vector similarity.
 *
 * 1. Embeds the query text via the registered embedding provider.
 * 2. Runs KNN query against brain_embeddings vec0 table.
 * 3. Joins with observation/decision/pattern/learning tables for full entries.
 *
 * Returns empty array when embedding is unavailable (graceful fallback).
 *
 * @param query - Text to find similar entries for
 * @param projectRoot - Project root directory
 * @param limit - Maximum results to return (default 10)
 * @returns Array of similar entries ranked by distance (ascending)
 */
export declare function searchSimilar(query: string, projectRoot: string, limit?: number): Promise<SimilarityResult[]>;
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