If you’ve ever built a forex monitor, trading alert system, or real‑time currency dashboard, you’ve almost certainly run into this annoying problem: Your real‑time rate API keeps sending data on weekends… but it’s just the same stale closing price from Friday. The WebSocket stays alive, timestamps keep updating, and your system thinks it’s getting fresh data. But the market is closed. This “fake data” triggers false alerts, pollutes your logic, wastes resources, and causes unnecessary headaches. In this post, I’ll show you a lightweight, production‑ready filtering layer you can drop directly into your Python project to fix this for good. The Problem We’re Solving Many free and even commercial exchange rate APIs don’t check trading days. They just keep sending the last available price during weekends and holidays.…