/**
 * Minimal undo manager used by engine ECS internals.
 */
export interface UndoStep<OpType> {
    redo: OpType;
    undo: OpType;
    timestamp: number;
}
export declare class UndoManager<OpType = unknown> {
    private undoStack;
    private redoStack;
    private maxDurationMs;
    push(undoOp: OpType, redoOp: OpType): void;
    private prune;
    undo(): UndoStep<OpType> | null;
    redo(): UndoStep<OpType> | null;
    clear(): void;
}
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