This paper consolidates the structural development of the Dodecahedron Linear String Field Hypothesis (DLSFH) into a minimal and internally complete framework. The admissible internal operator class is defined as the finite-dimensional A 5-equivariant self-adjoint algebra End A5 (H V). An invariant quartic variational functional selects a nontrivial stationary operator O V = µP , where P is a central projector onto a maximal isotypic component. The stationary solution is determined up to overall sign and, when the maximal rank is unique, is unique up to overall scale. The nonzero spectral magnitude exhibits rigidity, with eigenvalues fixed by the algebraic relation µ 2 = −α/(2β). The internal algebra generated by O V is shown to be two-dimensional, A int = span{Id, O V }, and closed under multiplication. Equivariance, algebra closure, and compatibility with the lifted Dirac structure jointly imply a classified coupling form C = A 0 ⊗ Id + A 1 ⊗ O V , eliminating independent portal freedom. Within the declared perturbative regime and at one-loop order, radiative corrections generate only polynomial functions of O V , which collapse back into A int. The internal operator direction and its admissible coupling structure are therefore radiatively stable within the minimal framework. An explicit internal reduction yields the low-energy effective external theory, whose interaction coefficients are determined solely by the spectral scale µ and projector rank. Parameter transparency, gravitational compatibility scope, and falsifiability conditions are stated explicitly. The resulting structure is algebraically constrained rather than phenomenologically arranged, completing the minimal DLSFH architecture.