Protected subspaces are usually introduced to suppress noise. Here they are used as diagnostic filters for gravitational channel structure. The question is not whether a gravitationally motivated environment causes decoherence, but what error algebra it induces on a protected code and its nearby error shell. We first formulate a recoverability diagnostic for collective versus constituent-resolving channels. For the code =span\01, 10\, collective dephasing obeys P_ (Z₁+Z₂) P_=0, while an unmatched spin-coupled response obeys P_ (q₁Z₁+q₂Z₂) P_= (q₁-q₂) ZL. Thus matched response is protected and unmatched response becomes logical dephasing. We then work this out in a weak-field axial-torsion model drawn from the propagating-torsion sector of quadratic Poincare gauge gravity. Under an even-N CPMG sequence, the unmatched recoverability contrast samples a torsion spectral density at a tunable control frequency. A thermal or quasi-static axial background consistent with present spin-gravity and torsion bounds appears far too small for discovery, while a narrowband nonequilibrium bath remains only a conditional enhancement window. Finally, we describe three upgrade paths: n>3 hybrid-code design, a model-derived two-block axial exchange term, and a bath-commutator protocol. These are routes toward stronger nonclassicality tests, not results already achieved. The uploaded PDF contains the fully typeset abstract and mathematical notation.
Jeffrey Satinover (Sat,) studied this question.