Parity-Driven Quantum Mechanics: A Framework for Superposition, Collapse, and the Gravity-Quantum Divide

We propose a new interpretive framework for quantum mechanics in which the binary parity (odd or even) of a universe's total particle count acts as the fundamental switch governing quantum and classical behavior. In this model, particles transit between parallel universes in pairs; unpaired particles remain uncommitted to any single universe and exhibit quantum behavior (superposition, tunneling, interference), while paired particles anchor to a specific universe and become subject to classical forces including gravity. Observation is reinterpreted as a forced anchoring event that pins a particle to the observer's universe. This framework provides a unified account of seven core quantum phenomena -- superposition, wavefunction collapse, double-slit interference, quantum entanglement, tunneling, the quantum Zeno effect, and the quantum-gravity incompatibility -- from a single principle. We identify testable predictions, including parity-dependent decoherence rates in controlled particle-number systems and the outcome of proposed gravitational superposition experiments, that distinguish this framework from existing interpretations. Two companion papers are included: the conceptual framework and the complete mathematical formalism (Lagrangian, equations of motion, exact solutions, consistency checks).