Strong-Sector Rotational Nullity and Residual CP Suppression

T57 develops a structurally constrained strong-CP suppression framework within the Q5 reduction architecture. The theorem separates three layers of claim: a solid structural null result in the leading retained sector, architecture-dependent suppression mechanisms arising from mediated leakage structure, and a conditional bridge assumption relating the reduced rotational invariant to the physical strong-CP phase parameter. In the symmetric retained-support limit, the reduced rotational coefficient vanishes, \ₒₓₑ₎₍₆^ (0) = 0, that the leading reduced sector is structurally CP-null under the Q5 reduction pipeline. Residual rotational structure arises only through suppressed mediated leakage contributions associated with boundary holonomy and inaccessible transport channels. The theorem further identifies several architecture-dependent suppression factors emerging from the Q5 transport geometry, including mediated leakage scaling and reduced-sector retention effects. These produce a highly suppressed effective rotational contribution while preserving explicit separation between structural derivation and phenomenological interpretation. T57 does not claim a complete derivation of the physical strong-CP parameter or a proof of equivalence with QCD. Rather, it establishes a transport-architectural mechanism in which CP-violating rotational structure is naturally suppressed through the mediated reduction geometry. Status: solid for the leading-sector nullity result and mediated suppression structure under the stated reduction assumptions; conditional for the bridge relation between the reduced rotational invariant and the physical strong-CP phase; speculative for any direct identification with observed QCD strong-CP phenomenology.