LangChain & LlamaIndex PII Redaction Middleware for TypeScript & Node.js

import { createLangChainTransform, PrivacyScrubberEngine } from '@privacyscrubber/sdk';
import { ChatOpenAI } from '@langchain/openai';
import { PromptTemplate } from '@langchain/core/prompts';
import { StringOutputParser } from '@langchain/core/output_parsers';
import { RunnableSequence } from '@langchain/core/runnables'; // 1. Initialize persistent agent state engine
const engine = new PrivacyScrubberEngine({ profile: 'Legal', detectSecrets: true
}); // 2. Create LangChain transforms
const { preprocess, postprocess } = createLangChainTransform({ engine, profile: 'Legal'
}); // 3. Build secure LCEL chain
const prompt = PromptTemplate.fromTemplate('Analyze contract for client: {client_info}');
const model = new ChatOpenAI({ modelName: 'gpt-4o' });
const parser = new StringOutputParser(); // 4. Ingest raw data -> Preprocess (Sanitize) -> Prompt -> LLM -> Parser -> Postprocess (Restore)
const chain = RunnableSequence.from([ { client_info: (input) => preprocess(input.client_info).scrubbedText, _tokenMap: (input) => preprocess(input.client_info).tokenMap }, prompt, model, parser, (output, config) => postprocess(output, config._tokenMap).restoredText
]); const result = await chain.invoke({ client_info: 'Alice Smith (alice@corp.com, SSN: 000-12-3456)'
}); console.log('Final Restored Agent Output:', result);