The growing decentralization of energy systems requires scalable, flexible coordination of distributed generation, energy storage, and demand-side flexibility among local energy communities. This work builds upon the agent-based scheduling framework MASSIVE, extending its capabilities to operate in real-world settings. Within the extensive framework, agents participate in the local electricity market by submitting bids based on operational constraints and preferences of local energy components or aggregates, such as a campus. Optimized setpoints derived from market clearing are sent as control signals to physical or simulated assets. To enable the transmission to be modular, interoperable, and responsive in real time, we extend the MASSIVE framework with a lightweight, MQTT-based layer. We validate the applicability of these control signals through a series of experiments involving real hardware and technical and safety constraints. Additionally, a geographically distant battery system was incorporated in real time and it effectively followed market-driven setpoints. The results confirm that a decentralized, agent-based market coordination model facilitates flexible integration of physical energy systems. Plug-and-play functionality, heterogeneous control strategies, and interconnection across regions are collectively offered by the framework, thereby providing a robust path to smart energy communities.