Projection-Induced Chirality in Oriented Closure Lattices: A General Criterion with Application to the Quantized Dimensional Ledger

This paper develops a projection-theoretic criterion for chirality in oriented closure lattices and applies the criterion to the Quantized Dimensional Ledger (QDL). The general framework consists of a free abelian group, a closure functional, a closure sublattice, an involutive orientation map, a projection, and an equivalence relation on projected modes. Projection chirality is defined by the inequivalence of a projected mode and its orientation reverse. The central result is that chirality cannot be produced by an orientation-symmetric closure equation alone. A projected sector can be chiral only when the projection, quotient, boundary condition, representation map, operator structure, or an equivalent asymmetry-producing mechanism fails to identify at least one mode with its orientation reverse. The QDL specialization uses the typed toroidal Quantized Dimensional Cell with winding vectors in Z^5 and closure functional C_QDC(w)=2(x1+x2+x3)-3(y1+y2). Since orientation reversal w -> -w preserves the primary closure lattice, QDL chirality cannot arise from primary closure alone. The paper therefore introduces a residual-orientation projection retaining closure level, residual typed asymmetry classes, and an antisymmetric orientation sign. When the equivalence relation preserves this sign, projected chirality is realized. This record supplies the chirality gate for the QDL Standard-Model admissibility program. It distinguishes projection chirality from operator-index chirality, does not claim to evade Nielsen-Ninomiya-type constraints, and does not claim to derive the full Standard Model, three generations, masses, mixing angles, dimensionless constants, or empirical substrate proof. Downstream anomaly cancellation, electric-charge normalization, and Yukawa admissibility remain separate gates for subsequent work.