/**
 * rill upgrade: Upgrade an installed extension to a newer version.
 *
 * Constraints (FR-EXT-6, UXI-EXT-6):
 * - assertBootstrapped pre-check before any npm subprocess (EC-17)
 * - Mount existence pre-check before any npm subprocess (EC-18)
 * - Local-path mounts rejected immediately; no npm, no config edit (EC-19)
 * - npm uses --prefix so project-root package.json is never modified (NFR-EXT-6)
 * - Config edit + validation < 1s (NFR-EXT-2)
 * - applyMountEdit rolls back on validation failure (EC-21)
 */
/**
 * Upgrade an extension in the current project.
 *
 * Implements UXI-EXT-6 order of operations per spec FR-EXT-6.
 *
 * EC-21 compliance: applyMountEdit rolls back rill-config.json on validation
 * failure before re-throwing. The caller (this function) emits the
 * UXT-EXT-6-style error + rollback messages and returns 1.
 */
export declare function run(argv: string[]): Promise<number>;