import type { Message } from '../types/messages.js';
import type { SessionWriter } from '../types/session.js';
/**
 * The slice of ConversationState this module needs. Kept structural so callers
 * can pass `ctx.state` without this module depending on the core layer.
 */
export interface RewindableConversation {
    replaceMessages(messages: Message[]): void;
}
export interface ApplyRewindOptions {
    /** The live writer for the session being rewound. */
    session: SessionWriter;
    /** The live conversation to cut back. */
    state: RewindableConversation;
    /** Directory holding the session JSONL files. */
    sessionsDir: string;
    /** Checkpoint promptIndex to rewind to. */
    promptIndex: number;
    /**
     * Files the SessionRewinder just reverted, recorded on the `rewound` event.
     * Only this caller knows them: the file_snapshot events that prove what
     * changed are truncated away by this very call.
     */
    revertedFiles?: readonly string[] | undefined;
}
export interface ApplyRewindResult {
    /** Events dropped from the JSONL by the truncation. */
    removedEvents: number;
    /** Message count the live conversation was cut back to. */
    messageCount: number;
}
/**
 * Truncate the session JSONL to a checkpoint AND cut the live conversation
 * back to match.
 *
 * Truncating the log alone is not a rewind: the model keeps the rewound turns
 * in its working set, so the next prompt is answered against a history the log
 * no longer contains. Worse, the conversation journal records `message_updated`
 * by absolute index, so once the log is shorter than the live array those
 * updates fail the `index < messages.length` guard on reload and are dropped as
 * damage — the file diverges from the session permanently.
 *
 * The truncated log is the source of truth for what survives, so this reloads
 * it and replays the result into the live state rather than trying to compute
 * the cut point twice. `replaceMessages` emits `messages_replaced`, which
 * re-anchors the journal at the new length and makes the cut explicit to any
 * later reader.
 *
 * The caller is responsible for reverting files (see `SessionRewinder`); this
 * only reconciles the log with the live conversation.
 */
export declare function applyRewindToConversation(opts: ApplyRewindOptions): Promise<ApplyRewindResult>;
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