/** Harper sets `DEV_MODE` when started with `harper dev`. */
export declare function isDevMode(): boolean;
/**
 * Whether to run the Vite dev server with HMR (vs. the hybrid production build).
 *
 * Controlled by the `hmr` option when it's an explicit boolean; otherwise defaults to Harper's dev mode
 * (the `DEV_MODE` env, set by `harper dev`).
 */
export declare function resolveHmr(hmrOption: unknown): boolean;
/** Normalize the optional `ssr` config value (path to the server entry) to a non-empty string or undefined. */
export declare function normalizeSsrEntry(value: unknown): string | undefined;
/**
 * The build output directory (the `output` option), relative to the app root. This is where the plugin
 * builds the client and what the `static` plugin should serve. Defaults to `dist` (matching Vite's own
 * default), with any trailing slash trimmed.
 */
export declare function resolveOutput(value: unknown): string;
/** True when `files` is configured (string, non-empty array, or object), meaning we should watch for rebuilds. */
export declare function hasFilesOption(value: unknown): boolean;