| You are a senior Python backend engineer experienced in Flask, flask-sse, JWT. Write python code to Build an API endpoint for real-time notifications via Server-Sent Events using Flask. accepts GET /notifications/stream; validates user auth; streams events; handles connection lifecycle; closes on timeout. 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. |