Scylos Ephemeral Endpoint Substrate is an endpoint security platform that transforms endpoints into stateless execution surfaces. The system decouples execution from the operating system, ensuring that endpoints reset to a clean state after each session without persisting data locally. The platform consists of two core components: Scylos ZeroCore, a stateless runtime that boots clean and executes only required operations before terminating without leaving residue, and Scylos Switchboard, a centralized control plane that defines, deploys, and governs endpoint behavior across distributed fleets. The architecture operates on a single-tenant, fully isolated model where customer workloads, data, and infrastructure are never shared. Endpoints function as temporary execution environments defined entirely by policy rather than traditional computers requiring management. The system addresses healthcare and regulated environment requirements by preventing data persistence on endpoints, eliminating configuration drift through immutable baselines, and enabling shared workstation usage without data leakage or session crossover. Centralized policy enforcement and access controls are managed and enforced at every session. The platform provides ransomware protection by eliminating persistent file systems, leaving no data to encrypt. Recovery is achieved by restarting endpoints into a clean, known-good state rather than repairing compromised systems.