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packages/@n8n/nodes-langchain/nodes/Guardrails/actions/checks/keywords.ts

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+// Source: https://github.com/openai/openai-guardrails-js/blob/b9b99b4fb454f02a362c2836aec6285176ec40a8/src/checks/keywords.ts
+import type { CreateCheckFn, GuardrailResult } from '../types';
+
+interface KeywordsConfig {
+	keywords: string[];
+}
+
+// \p{L}|\p{N}|_ - any unicode letter, number, or underscore. Alternative to \b
+const WORD_CHAR_CLASS = '[\\p{L}\\p{N}_]';
+const isWordChar = (() => {
+	const wordCharRegex = new RegExp(WORD_CHAR_CLASS, 'u');
+	return (char: string | undefined): boolean => {
+		if (!char) return false;
+		return wordCharRegex.test(char);
+	};
+})();
+
+/**
+ * Keywords-based content filtering guardrail.
+ *
+ * Checks if any of the configured keywords appear in the input text.
+ * Can be configured to trigger tripwires on matches or just report them.
+ *
+ * @param text Input text to check
+ * @param config Configuration specifying keywords and behavior
+ * @returns GuardrailResult indicating if tripwire was triggered
+ */
+const keywordsCheck = (text: string, config: KeywordsConfig): GuardrailResult => {
+	const { keywords } = config;
+
+	// Sanitize keywords by stripping trailing punctuation
+	const sanitizedKeywords = keywords.map((k: string) => k.replace(/[.,!?;:]+$/, ''));
+
+	const keywordEntries = sanitizedKeywords
+		.map((sanitized) => ({
+			sanitized,
+			escaped: sanitized.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'),
+		}))
+		.filter(({ sanitized }) => sanitized.length > 0);
+
+	if (keywordEntries.length === 0) {
+		return {
+			guardrailName: 'keywords',
+			tripwireTriggered: false,
+			info: {
+				matchedKeywords: [],
+			},
+		};
+	}
+
+	// Apply unicode-aware word boundaries per keyword so tokens that start/end with punctuation still match.
+	const keywordPatterns = keywordEntries.map(({ sanitized, escaped }) => {
+		const keywordChars = Array.from(sanitized);
+		const firstChar = keywordChars[0];
+		const lastChar = keywordChars[keywordChars.length - 1];
+		const needsLeftBoundary = isWordChar(firstChar);
+		const needsRightBoundary = isWordChar(lastChar);
+		// not preceded by a word character
+		const leftBoundary = needsLeftBoundary ? `(?<!${WORD_CHAR_CLASS})` : '';
+		// not followed by a word character
+		const rightBoundary = needsRightBoundary ? `(?!${WORD_CHAR_CLASS})` : '';
+		return `${leftBoundary}${escaped}${rightBoundary}`;
+	});
+
+	const patternText = `(?:${keywordPatterns.join('|')})`;
+	const pattern = new RegExp(patternText, 'giu'); // case-insensitive, global, unicode aware
+
+	const matches: string[] = [];
+	let match;
+	const seen = new Set<string>();
+
+	// Find all matches and collect unique ones (case-insensitive)
+	while ((match = pattern.exec(text)) !== null) {
+		const matchedText = match[0];
+		if (!seen.has(matchedText.toLowerCase())) {
+			matches.push(matchedText);
+			seen.add(matchedText.toLowerCase());
+		}
+	}
+
+	const tripwireTriggered = matches.length > 0;
+
+	return {
+		guardrailName: 'keywords',
+		tripwireTriggered,
+		info: {
+			matchedKeywords: matches,
+		},
+	};
+};
+
+export const createKeywordsCheckFn: CreateCheckFn<KeywordsConfig> = (config) => (input: string) =>
+	keywordsCheck(input, config);