/**
 * Extracts the base package name from a module specifier or subpath.
 * Handles scoped packages:
 *   "@nx/devkit/testing" -> "@nx/devkit"
 *   "lodash/get"         -> "lodash"
 */
export declare function extractBasePackageName(specifier: string): string | null;
/**
 * Checks whether an npm package exists.
 * 1. Checks local node_modules (instant).
 * 2. Caches results to prevent duplicate lookups.
 * 3. Falls back to registry HEAD request.
 */
export declare function verifyPackageExists(pkgName: string, adapter: any): Promise<boolean>;