Building an always-on, contextual AI assistant that proactively supports humans remains a central goal in Embodied AI—yet cloud-based pipelines struggle to meet due to delay, bandwidth, and privacy constraints. This demo presents EdgeMind-OS, a fully on-device intelligence system designed for embodied agents operating in real-world scenarios. Edge-Mind-OS features a hierarchical architecture combining a real-time StreamBrain, modular skill experts, and a dynamic scene-episode memory. Achieving up to 7.3× faster local processing, it enables low-latency, privacy-preserving, and plug-and-play deployment across tasks such as semantic navigation, spatial memory recall, and multimodal interaction. We demonstrate how EdgeMind-OS empowers a mobile robot with only basic locomotion capabilities to perform realtime, free-form user-robot interaction through autonomous perception, reasoning and action —without reliance on external cloud infrastructure.