/**
 * Environment signal (C4, 1.6.0).
 *
 * Trivial but useful: current time / weekday / timezone. Lets the engine
 * ground time-sensitive prompts ("send this email tomorrow" / "what's
 * happening this week") without the user having to type the date.
 *
 * Pure-JS, no I/O, never fails. Always returns a populated signal.
 */
export interface EnvironmentSignal {
    /** ISO 8601 timestamp (UTC). e.g. '2026-04-28T18:33:00.000Z'. */
    nowIso: string;
    /** 'Mon' | 'Tue' | ... | 'Sun'. Locale-independent (English abbreviations). */
    weekday: string;
    /** IANA timezone (e.g. 'America/New_York', 'Europe/London') from the host. */
    timezone: string;
}
export declare function collectEnvironmentSignal(): EnvironmentSignal;