/**
 * Conversation checkpointing — persist a turn's state so it can resume.
 *
 * Phase-1 sibling of the reference engines' checkpointing. A `CheckpointStore`
 * saves and loads the conversation (the non-system messages) keyed by a
 * conversation id, so a later turn — even in a new process — can pick up where
 * the last left off. `InMemoryCheckpointStore` is the zero-dependency default.
 */
type Message = Record<string, unknown>;
export interface Checkpoint {
    conversationId: string;
    messages: Message[];
}
export interface CheckpointStore {
    save(checkpoint: Checkpoint): void;
    load(conversationId: string): Checkpoint | undefined;
}
/** A process-local checkpoint store backed by a Map. */
export declare class InMemoryCheckpointStore implements CheckpointStore {
    private readonly store;
    save(checkpoint: Checkpoint): void;
    load(conversationId: string): Checkpoint | undefined;
}
export {};
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