When an IoT platform manages thousands of automation rules across hundreds of Things, rules will conflict. Two rules targeting the same device with opposing states. One rule's output triggering another in an infinite cascade. Alert storms that generate thousands of notifications and destabilize the platform. I wrote ExMaude -- an simple Elixir library wrapping Maude's rewriting logic -- to solve this. Before any rule deploys, ExMaude reduces the full rule set through 260 lines of algebraic specification and returns a mathematical proof of conflict-freedom. Four conflict types detected. ~500us per verification. Zero conflicting rules in production. This talk covers the problem (with real IoT horror stories), the solution (Maude rewriting logic explained for Elixir developers), and the integration (how it fits into an Ash Framework IoT platform running on Nerves edge gateways and Phoenix cloud). Includes a live demo.