/**
 * Normalize an action type string before allow-list comparison:
 * - Trim whitespace
 * - Reject empty/null/undefined
 */
export declare function normalizeActionType(type: string): string | null;
/**
 * Measure the maximum nesting depth of a value.
 * Used to prevent prototype-pollution / deep-object DoS.
 */
export declare function measureDepth(value: unknown, depth: number): number;
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