import { spawn } from 'node:child_process';
/** @purpose Serialized cache structure persisted by the update-check worker. */
export type UpdateCheckCache = {
    /** @purpose ISO8601 timestamp of the most recent registry check */
    lastCheck: string;
    /** @purpose Latest version string from npm registry response */
    latestVersion: string;
};
/** @purpose Configuration driving the update-check service behaviour. */
export type UpdateCheckOptions = {
    /** @purpose Package identity — name and semver version */
    pkg: {
        name: string;
        version: string;
    };
    /** @purpose Minimum interval between checks in ms | @invariant Default 24h (86_400_000 ms) */
    interval?: number;
    /** @purpose Suppress stderr notification when stderr is not a TTY | @invariant Default true — suppresses display only, never the check */
    skipNotificationIfNoTty?: boolean;
    /** @purpose Directory for the update-check cache file | @invariant Must exist before worker spawn */
    cacheDir?: string;
    /** @purpose Inject a custom spawn implementation for testing | @invariant Test seam only — not used in production */
    _spawnFn?: typeof spawn;
};
/**
 * @purpose Orchestrate a non-blocking update check — read cache, spawn worker if stale, register deferred notification.
 * @implements {UpdateCheck} in specs/cli/update-check/update-check.spec.md#updatecheck
 * @invariant Never throws — all failure paths are silent.
 * @invariant Never blocks process.exit — spawn uses unref().
 * @param pkg Package identity with name and semver version.
 * @param [opts] Optional configuration overrides.
 * @post Returns synchronously without blocking; if stale/missing cache: detached worker spawned via unref(); if fresh cache with newer version: beforeExit hook registered.
 * @sideEffect FS: reads and writes cache directory. Subprocess: may spawn UpdateCheckWorker.
 */
export declare function checkForUpdates(pkg: {
    name: string;
    version: string;
}, opts?: Partial<UpdateCheckOptions>): void;