/**
 * conversation-rewind-host.ts, a surface answering the daemon's questions
 * about a conversation only it is holding.
 *
 * ── What was broken ───────────────────────────────────────────────────────
 *
 * Files rewind works from anywhere, because the workspace checkpoint store is
 * the daemon's. The conversation half is answerable only by the process running
 * the loop, and once the surfaces became pure clients that process is not the
 * daemon. The daemon's in-process conversation registry, which nothing outside
 * the daemon could populate, answered "0 messages to drop" for every session
 * hosted elsewhere: a confident answer to a question it could not reach.
 *
 * This module is the other end of the fix. The surface OFFERS the conversation
 * it is running; the daemon then asks that surface when a rewind touches it.
 *
 * ── Why a poll, and why it is not a poll ──────────────────────────────────
 *
 * This is a reverse call: the daemon asking a connected client and awaiting an
 * answer while a `rewind.plan` call waits on it. The delivery is a `take` that
 * the surface holds open, a long poll, not a tight loop. With nothing waiting
 * the call parks for up to the daemon's own ceiling and returns empty; with
 * work waiting it returns immediately. So the steady state is one open request,
 * not repeated requests, and an answer starts moving the instant the question
 * is raised.
 *
 * The same call renews the lease. A surface that is polling is a surface that
 * is alive, so there is no separate keepalive to get out of step with it, and
 * a crashed surface simply stops being consulted when its lease lapses, with
 * nobody cleaning up after it.
 *
 * ── Answering honestly ────────────────────────────────────────────────────
 *
 * A question about a session this process is NOT holding is answered
 * `unavailable` with the reason, never zero. That distinction is the whole
 * point: a real zero and an unreachable conversation look identical as numbers,
 * and reporting the second as the first is what made the old behaviour a lie
 * rather than a gap.
 *
 * Every failure path resolves. A request that throws while being answered is
 * answered `unavailable` with the error text rather than left to time out, so
 * the waiting `rewind.plan` gets a reason instead of a stall.
 */
import { logger } from '../../utils/index.js';
import type { RewindConversationPort } from '../../rewind/types.js';
import type { DaemonVerbCaller } from './daemon-verbs.js';
export interface ConversationRewindHostOptions {
    readonly verbs: DaemonVerbCaller;
    /** The port that answers, this process's own conversations, by session id. */
    readonly port: RewindConversationPort;
    /** Whether this process is actually holding that session's conversation. */
    readonly hosts: (sessionId: string) => boolean;
    /** How this surface names itself in the refusals a person reads. */
    readonly label?: string;
    readonly waitMs?: number;
    readonly retryBackoffMs?: number;
    readonly log?: Pick<typeof logger, 'debug' | 'info' | 'warn'>;
    /** Injectable sleep (tests). */
    readonly sleep?: (ms: number) => Promise<void>;
}
export interface ConversationRewindHostClient {
    /**
     * Name the session whose conversation this surface is holding, without
     * starting the polling loop. The registration itself happens on the first
     * `pump`, so a caller that wants to drive the cycles deterministically, a
     * test, or a one-shot check, uses `offer` + `pump` and never has two takes
     * racing on one host id.
     */
    offer(sessionId: string): void;
    /** `offer`, plus the loop that keeps taking questions. Idempotent per session. */
    start(sessionId: string): void;
    /** Withdraw the offer and stop. Idempotent; safe to call with nothing running. */
    stop(): Promise<void>;
    /** The host id the daemon issued, once registered. Null before that. */
    hostId(): string | null;
    /** One take-and-answer cycle: register if needed, take, answer each question. */
    pump(): Promise<number>;
}
export declare function createConversationRewindHost(options: ConversationRewindHostOptions): ConversationRewindHostClient;
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