/**
 * Runtime host-version compatibility check for email plugin.
 *
 * OpenClaw uses a date-based version format: YYYY.M.DD (e.g. 2026.3.22).
 * This module parses that format and validates the running host is within
 * the supported range for this plugin version.
 */
export declare const PLUGIN_VERSION = "0.6.2";
export declare const SUPPORTED_HOST_MIN = "2026.3.22";
export interface OpenClawVersion {
    year: number;
    month: number;
    day: number;
}
/**
 * Parse an OpenClaw date version string (e.g. "2026.3.22") into components.
 * Returns null for unparseable strings.
 */
export declare function parseOpenClawVersion(version: string): OpenClawVersion | null;
/**
 * Compare two parsed versions.  Returns -1 | 0 | 1.
 */
export declare function compareVersions(a: OpenClawVersion, b: OpenClawVersion): -1 | 0 | 1;
/**
 * Check whether a host version string is >= SUPPORTED_HOST_MIN.
 */
export declare function isHostVersionSupported(hostVersion: string): boolean;
/**
 * Fail-fast guard.  Call at the very start of `register()` to prevent the
 * plugin from loading on an incompatible host.
 *
 * @throws {Error} with a human-readable message when the host is out of range.
 */
export declare function assertHostCompatibility(hostVersion: string | undefined): void;