HIPAA-Compliant Patient Data Anonymization Middleware for GraphQL

Design a type-safe GraphQL middleware for NestJS that automatically anonymizes sensitive patient data during API transmissions. Create generic TypeScript interfaces that strip personally identifiable information (PII) while preserving medical record integrity. Implement robust type guards that ensure HIPAA compliance, with explicit handling for different data sensitivity levels (PHI, de-identified, aggregated). Include comprehensive error handling for scenarios where anonymization might fail or compromise data consistency.