/**
 * Persist a user-level environment variable so NEW processes (terminal,
 * extension) inherit it. Windows-only for now; on POSIX the caller prints
 * guidance to add an export line to the shell rc.
 */
export declare function setUserEnvVar(name: string, value: string, platform?: NodeJS.Platform): void;
/** Remove a user-level environment variable (Windows: delete the registry value). */
export declare function unsetUserEnvVar(name: string, platform?: NodeJS.Platform): void;