/**
 * Symbol-keyed lazy memoization stamped directly onto the host object.
 *
 * Faster than a module-level `WeakMap` in V8/JSC because the symbol slot is
 * resolved through the object's hidden class instead of a side-table hash
 * lookup. The slot is defined as a non-enumerable property so the stamp
 * does not leak through `{...spread}`, `Object.keys`, `JSON.stringify`, or
 * `toEqual`-style deep equality.
 *
 * Caveats: the stamp lives as long as the host object, even after callers
 * release their references to the cached value — only use this for caches
 * whose lifetime should match the host. Frozen hosts will throw on write in
 * strict mode; callers that may receive frozen input must handle that.
 */
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. */
export declare function enter<T extends object>(target: T): boolean;
export declare function exit<T extends object>(target: T): void;