/**
 * Non-blocking npm update notification.
 *
 * On startup of the CLI or MCP server, fires an async GET against
 * https://registry.npmjs.org/guardvibe/latest. Result is cached for 24h
 * in ~/.cache/guardvibe/version-check.json so we never hit npm twice in
 * a day from one machine. If a newer version is available, a 5-line
 * banner is written to stderr — never stdout, so the MCP JSON-RPC stream
 * is untouched.
 *
 * Disable with GUARDVIBE_NO_UPDATE_CHECK=1, NO_UPDATE_NOTIFIER=1,
 * or CI=true (CI runners don't need version banners).
 */
/**
 * Compare two semver strings. Returns true if `latest` is strictly newer.
 * Handles plain MAJOR.MINOR.PATCH (no pre-release / build metadata).
 */
export declare function isNewer(latest: string, current: string): boolean;
/**
 * Fire-and-forget version check. Never throws, never blocks.
 *
 * Behavior:
 *   - If env var disables it → no-op.
 *   - If cache is fresh (< 24h) and indicates newer version → announce immediately.
 *   - If cache is stale → fire async fetch, update cache, announce if newer.
 */
export declare function checkForUpdate(currentVersion: string): void;