Necessary Adjudicators and Reflexive Self-Model Closure (RSMC) Paper 17 (C3) of the NEMS Suite

We establish that observer-like subsystems are not accidental flukes of biology, but necessary infrastructural components of any physical universe that (i) satisfies Perfect Self-Containment (PSC) in the No External Model Selection (NEMS) sense and (ii) maintains global record stability together with nonlocal coherence across distributed contexts. Here "observer-like" means a subsystem satisfying the formal adjudication / record-coherence interface; no specifically human, biological, or phenomenological assumption is entailed at this stage. Building on the diagonal barrier (Papers 11–12), No-Emulation (Paper 15), and Relative PSC / Recursive NEMS (Paper 16), we prove a weak necessity theorem: if a PSC universe contains persistent, re-readable records and must reconcile record-truth across distributed contexts, then it must contain an internal network of subsystems (Adjudicator Nodes) that steward records, adjudicate local choice points, and propagate sufficient information to support global coherence. Crucially, we also show that if such a node is computationally rich enough to host arithmetic self-reference (diagonal capability) and robust enough to maintain semantics under self-reference and re-encoding, then it is forced to satisfy Reflexive Self-Model Closure (RSMC) —a bounded-reflection fixed-point condition serving as an operational, non-anthropic surrogate for self-awareness. All definitions and conditional theorems are formalized and machine-checked in Lean 4. Nontrivial physical premises (, , ) are stated explicitly as assumptions, separating logical implications from domain-specific instantiations. This overview presents the core NEMS theorem engine and selected applications; stronger domain-specific derivation and ontological synthesis claims belong to separate release surfaces with their own premise bundles and formal artifacts. Trust boundary. "Observer-like" means the formal adjudicator-node interface; RSMC is the stated bounded-reflection predicate. Nontrivial premises, , are explicit. Machine-checked core: nems-lean. See.