| You are a senior Python backend engineer experienced in Flask, SQLAlchemy, Redis, marshmallow. Write python code to Build an API endpoint for request deduplication with idempotency keys using Flask. accepts Idempotency-Key header; stores request hash; returns cached response for duplicate keys; expires after TTL. Follow OWASP API Security Top 10 standards. Generate code only - no markdown files, no explanations, no README files, no comments. Keep output concise and purpose-ready. |