/**
 * @license
 * Copyright 2026 Steven Roussey <sroussey@gmail.com>
 * SPDX-License-Identifier: Apache-2.0
 */
/** How often the page asks the CLI whether it is still there. */
export declare const HEARTBEAT_MS = 1000;
/**
 * How long one probe may take before it counts as a miss.
 *
 * Longer than the interval, because a busy CLI answering slowly is still
 * alive — but bounded, or a probe against a half-open socket never settles and
 * the page waits on it forever while showing controls that cannot work.
 */
export declare const HEARTBEAT_TIMEOUT_MS = 2500;
export interface CliLiveness {
    /** The CLI answered its last probe. Everything that talks to it is gated on this. */
    readonly online: boolean;
    /** `startedAt` of the process that last answered, or undefined before the first. */
    readonly startedAt: number | undefined;
    /**
     * The CLI answered, but it is a DIFFERENT process than the one this page was
     * talking to. It is reachable, and it remembers none of the runs on screen.
     */
    readonly restarted: boolean;
}
export declare const INITIAL_LIVENESS: CliLiveness;
/**
 * Folds one probe result into the liveness state.
 *
 * Pure, so the rule that matters — what counts as a restart — can be tested
 * without a server or a timer.
 */
export declare function reduceHeartbeat(previous: CliLiveness, probe: {
    readonly ok: boolean;
    readonly startedAt?: number | undefined;
}): CliLiveness;