export declare function stamp<T extends object, V>(target: T, key: symbol, compute: (target: T) => V): V;
export declare function epochNext(): number;
/**
 * Marks `target` as visited for this `epoch`. Returns `true` the first time
 * it is called for a given (target, epoch) pair and `false` on every
 * subsequent call within the same epoch.
 */
export declare function once<T extends object>(target: T, epoch: number): boolean;
/**
 * Returns `true` on first entry, `false` if `target` is already on the
 * current path. A `false` return does NOT deepen the counter — callers pair
 * `exit` only with successful enters (`if (!enter(n)) bail; try {…} finally
 * { exit(n); }`), so incrementing on the cycle branch would leak depth and
 * make every later top-level walk of the same object misreport a cycle.
 */
export declare function enter<T extends object>(target: T): boolean;
export declare function exit<T extends object>(target: T): void;