/**
 * Resolve the .rill/npm/ prefix path for a project directory.
 * Returns an absolute path. Does not check existence.
 */
export declare function resolvePrefix(projectDir: string): string;
/**
 * Throws BootstrapMissingError when .rill/npm/package.json is absent.
 * Used by install/uninstall/upgrade/list as a UXS-EXT-2 gate.
 */
export declare function assertBootstrapped(projectDir: string): void;
/**
 * Thrown when .rill/npm/package.json is absent.
 * Callers map this to UXT-EXT-5 and exit code 1.
 */
export declare class BootstrapMissingError extends Error {
    readonly prefix: string;
    constructor(prefix: string);
}