/**
 * Result returned by npmInstall and npmUninstall.
 * The exit code from the npm subprocess; caller decides exit semantics.
 */
export interface NpmResult {
    readonly exitCode: number;
}
/**
 * Thrown when the npm binary is not found on PATH (ENOENT on spawn).
 * Callers map this to EC-31: print "npm not found on PATH; install Node.js with npm" and exit 1.
 */
export declare class NpmNotFoundError extends Error {
    constructor();
}
/**
 * Run `npm install <spec> --prefix <prefix>`.
 *
 * Resolves with NpmResult containing the exit code.
 * Rejects with NpmNotFoundError when npm is absent from PATH.
 */
export declare function npmInstall(args: {
    spec: string;
    prefix: string;
}): Promise<NpmResult>;
/**
 * Run `npm uninstall <spec> --prefix <prefix>`.
 *
 * Resolves with NpmResult containing the exit code.
 * Rejects with NpmNotFoundError when npm is absent from PATH.
 */
export declare function npmUninstall(args: {
    spec: string;
    prefix: string;
}): Promise<NpmResult>;