Diagnose and fix critical payment system bugs in Python under time pressure. Simulation Details: Lattice is a leading fintech company focused on payment processing and notification systems, handling over 10 million transactions daily. Its platform supports both enterprise and consumer payments, with peak loads surpassing 500 transactions per second. The payment notification system, built with Python and FastAPI on AWS, is designed for scalability and reliability, using auto-scaling and distributed caching to manage high traffic. Despite its robust setup, Lattice has recently faced production incidents that revealed vulnerabilities, such as memory leaks and notification failures, which threaten its reputation and SLA commitments. With fierce competition and strict regulatory requirements, maintaining system reliability and uptime is critical for Lattice’s continued success. The payment notification system is experiencing critical defects that could disrupt operations during an anticipated surge in payment traffic. Key issues include unchecked memory growth, silent failures in background tasks, and instability in the statistics endpoint. These problems have led to missed notifications, customer complaints, and delays in reporting, putting SLAs and client trust at risk. Immediate action is required to resolve these defects and propose improvements that will strengthen the system’s resilience and scalability. As a Python Back-End Developer, your mission is to diagnose and fix urgent bugs in the payment notification system’s FastAPI codebase. You will collaborate one-on-one with Sofia Andersson, the Lead Engineer, through real-time chat. Your tasks include implementing memory management, adding robust error handling, and safeguarding statistical calculations. After each change, you will discuss your reasoning and approach with Sofia, who will provide feedback and ensure your solutions meet production standards. You are also expected to propose practical, forward-looking improvements to enhance system reliability and observability, justifying your recommendations in conversation with Sofia. - Diagnose and resolve critical defects in the FastAPI code through direct editing. - Communicate and justify your technical decisions to Sofia Andersson in real-time chat. - Receive feedback and validation from Sofia on your fixes and proposals. - Propose realistic improvements to boost system resilience and scalability. - Demonstrate proficiency in Python and technical problem-solving under pressure.