export interface FileBackup {
    backupFileName: string | null;
    version: number;
}
export interface Snapshot {
    checkpointId: string;
    fileBackups: Record<string, FileBackup>;
    timestamp: number;
}
export declare class CheckpointEngine {
    private sessionId;
    private dir;
    private state;
    constructor(sessionId: string);
    private statePath;
    private load;
    private save;
    private ensureDir;
    private backupName;
    private backupPath;
    trackBeforeEdit(filePath: string): void;
    private nullVersions;
    private differs;
    commit(checkpointId: string): void;
    getSessionId(): string;
    hasSnapshot(checkpointId: string): boolean;
    private findSnapshot;
    changedSince(checkpointId: string): number;
    restore(checkpointId: string): string[];
}
export declare function getCheckpointEngine(): CheckpointEngine | null;
export declare function initCheckpointEngine(sessionId: string): CheckpointEngine;
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