The strongest kingdoms are not bound to a single castle, but built to endure wherever their people must go. For much of software history, we built applications as though we were building castles. The walls gave us boundaries. We knew where the application lived, where its data lived, and which machines carried the work. Even complicated systems offered a comforting sense of geography because their important pieces occupied places engineers could identify and understand. When something failed, there was usually a server, process, database, or network connection somewhere that could be examined. Modern software has been steadily dismantling that certainty. Applications move between environments, workloads appear and disappear, and infrastructure…