E-Kilit — Smart Board Lock & Management System

E-Kilit (Smart Lock) is a full-stack smart board management platform built for schools operating under Turkey's Ministry of National Education (MoNE/MEB) network infrastructure. Because MEB networks commonly block WebSocket connections, the system is architected entirely around HTTP long-polling — achieving near real-time command delivery (< 10s latency) without WebSockets. <br/>The platform consists of two components: a Node.js/Express/MongoDB REST API server with an EJS-rendered admin panel, and a PyQt6 desktop client deployed on Pardus Linux smart boards. Teachers authenticate via QR code scanning or time-based OTP (HMAC-SHA256), while school administrators manage all boards through a responsive web dashboard with live status, usage analytics, and bulk commands. <br/>Performance optimizations include a three-layer in-process Map cache (board, announcement, teacher), fire-and-forget MongoDB writes for heartbeat updates, selective session middleware exclusion for API routes, and a 50-connection MongoDB pool — collectively supporting 100+ schools and 2,000+ concurrent boards on a single Node.js process. Security features include bcrypt password hashing, rate limiting on auth endpoints, HTTP security headers via Helmet, and atomic file writes for client configuration.