import type { CheckpointScope, SessionCheckpointStore } from '../../../store/checkpoint/index.js';
import type { SessionLog } from '../../../store/session-log/index.js';
import type { CheckpointId } from '../../../types/hitl/index.js';
import type { Message } from '../../../types/message/index.js';
import type { Checkpoint } from '../../../types/session/checkpoint.js';
import type { Mutation } from '../../../types/session/fork.js';
import type { TurnForkOrigin } from '../../../types/session/turn.js';
import type { Logger } from '../../../utils/logger.js';
/** Which checkpoint to fork at: an id, or the turn's newest. */
export type CheckpointSelector = CheckpointId | 'latest';
export interface PrepareForkInput {
    /** The source session's log: the checkpoint's context is its fold. */
    readonly sessionLog: SessionLog;
    /** The store the source turn's checkpoints are in. */
    readonly checkpointStore: SessionCheckpointStore;
    /** The source turn, across the full attribution. */
    readonly scope: CheckpointScope;
    /** Which checkpoint to fork at. */
    readonly fromCheckpoint: CheckpointSelector;
    /** Mutations applied at the fork point before the caller hands the state to `query()`. */
    readonly mutate?: Mutation[];
    readonly logger?: Logger;
}
export interface PreparedForkState {
    /**
     * The context at the fork point, with mutations applied: the fold of the
     * source session's log through the checkpoint. Seed a NEW session with it
     * (`query({ sessionId: <new>, messages, forkedFrom })`).
     */
    readonly messages: Message[];
    /** The checkpoint the fork starts from. */
    readonly sourceCheckpoint: Checkpoint;
    /**
     * Where the fork comes from. Pass it as `query({ forkedFrom })`: the new
     * session's `session_started.forkedFrom` names it, and the returned turn
     * carries it.
     */
    readonly forkedFrom: TurnForkOrigin;
    /** The mutations that were applied. */
    readonly mutations: readonly Mutation[];
}
/**
 * Produce what a fork needs: the context at a checkpoint of a source turn,
 * with mutations applied, and the origin the new session records. A fork is
 * always a NEW session; the source session is only read.
 *
 * The checkpoint is restored under the same rules a resume uses: its
 * document must match its `checkpoint_written` record and the log prefix it
 * covers must be intact.
 */
export declare function prepareForkState(input: PrepareForkInput): Promise<PreparedForkState>;
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