/**
 * Lightweight semantic classifier for prompt injection detection.
 * Uses TF-IDF-like keyword scoring against known attack patterns.
 * Zero dependencies — pure TypeScript.
 */
export type SemanticResult = {
    score: number;
    category: string;
    confidence: number;
    matchedKeywords: string[];
};
/**
 * Classify the intent of an input string for prompt injection detection.
 *
 * Uses TF-IDF-like keyword scoring against known attack pattern categories.
 * No ML models or external APIs required.
 */
export declare function classifyIntent(input: string): SemanticResult;