import type { FileWordRef, ScannedFile } from '../orient.types.js';
/**
 * @purpose Build an inverted index: word -> Set of {file, source, entity?} references.
 * @invariant Words lowercased, split on non-alphanumeric boundaries, extracted from @file: value and entity @purpose text.
 * @param files Scanned files with parsed headers and exports.
 * @returns Map from normalized word to matching FileWordRef set.
 */
export declare function buildIndex(files: ScannedFile[]): Map<string, Set<FileWordRef>>;