Internal Symmetry as Boundary-Coherence Stabilization in Finite-Resolution Physics

Framework position. This paper is a foundational contribution to the internal-symmetry branch of the Closure–Stabilization Framework. It identifies internal symmetry with the stabilizer of a Simultaneously Interlocked Boundary structure (SIB) on an already represented sector. In linear dualizable realizations, the SIB is represented by its annihilator Kμ⊥, recovering the earlier SILM formulation as a special case. The paper therefore places internal symmetry downstream of stabilization, representation, and boundary compatibility, while keeping projective/spinorial external representation sectors conceptually distinct from the internal symmetry acting on their multiplicity or species degrees of freedom. This manuscript develops the internal-symmetry layer of Finite-Resolution Physics (FRP). In FRP, mathematical representation is taken to arise only after operational closure relations stabilize under refinement. The paper asks where internal symmetry enters this architecture and what determines its admissible form. The central claim is that, on a stabilized finite-resolution plateau, admissible representation channels must satisfy joint boundary-coherence constraints across finite-resolution interfaces. These constraints define a finite-dimensional boundary constraint space. The dual annihilator of this space is identified as the algebraic space of Simultaneously Interlocked Lagrange Multipliers, or SILMs. The physical internal symmetry group is then defined as the stabilizer of the SILM space inside the group of finite-resolution-preserving unitary automorphisms that commute with the external carrier action. Thus internal symmetry is not introduced as a primitive kinematical input, nor as an arbitrary gauge group. It is a plateau-relative stabilizer of finite-resolution boundary coherence. The paper also explains how symmetry plateaux correspond to refinement ranges over which the SILM space is canonically identified, while symmetry transitions correspond to changes in the SILM structure. In the finite-dimensional Hermitian case, the resulting stabilizers reduce to products of unitary groups determined by SILM multiplicity data. A simple three-plus-two-plus-one example is discussed as an illustration of the stabilizer mechanism. The paper does not derive the Standard Model gauge group. Rather, it identifies the structural position that any Standard-Model-like internal symmetry would occupy within the FRP architecture: a compact internal stabilizer plateau compatible with a real-carrier, quantum-field-theory-like external structure.