Praetor: Legion — Physical Boundaries for the Autonomous Control Plane

This paper proposes Legion, the autonomous control plane of the Praetor sovereign data fabric, around an architectural idea the operator describes as a Layer 0 supervisory GPU mesh: specialized Legion compute, hosting operational LLMs, that supervises the other Praetor meshes. Layer 0’s dedicated administrative API connections form Phase 0, a physical high-speed administration fabric to which every in-scope administrative API is bound at a designated physical port; workload, tenant, inference, and bulk-data traffic are excluded by contract. Proposed GPU peer links among Legion’s compute are a second, distinct path: they are not the API fabric and are not admitted onto it, and their supported implementation, topology, and possible instruction or workload routing require hardware and runtime validation, with an explicit unsupported disposition preserved if testing fails. Contracts—endpoint binding, authenticated bounded action, evidence with honest gaps, and independent recovery—are inherited across the Nano, Prime, and Max footprints through normalization and validated platform adapters, not presumed equivalence. The paper treats deployable iFortress envelopes and NEOS SIL/HIL segregation and defines a falsification-oriented evaluation program covering reachability, bypass, denial, outage recovery, drift, and failed evidence. Layer 0 remains an idea under development: no settled topology, cable map, measured result, accreditation, or hardware capability is claimed, and partner inputs remain explicit, owned gaps.