This paper develops the categorical layer of the structural theory of atomic representations of deterministic transitions. Building on the existence of atomic normalization for SLP‑definable transitions, the work introduces the category of atomic forms and the category of SLP transitions, each equipped with structure‑preserving morphisms. The normalization procedure is shown to extend to a functor from SLP transitions to atomic forms. A universal property is established: the category of atomic forms forms a reflective subcategory of the category of SLP transitions. The results provide a categorical explanation for the canonical role of atomic normalization and clarify its structural invariance. The framework applies to deterministic transitions with fixed finite dependency structure and does not introduce new computational models.