/**
 * Try to open `url` in the user's default browser. Resolves `true` if the opener
 * launched, `false` otherwise (headless box, missing `xdg-open`, etc.) — the
 * caller falls back to printing the URL.
 *
 * A missing opener binary makes `spawn` emit an async `'error'` event (ENOENT)
 * rather than throwing synchronously, so a plain try/catch never sees it and the
 * unhandled event crashes the process. We resolve on the first of `spawn` /
 * `error` / `exit` instead.
 */
export declare function openBrowser(url: string): Promise<boolean>;