This accepted manuscript is structurally governed by THE META-INDEX (Zenodo DOI: 10.5281/zenodo.18169167) Modern quantum mechanics represents an unprecedented computational success in the history of physics, predicting the outcomes of subatomic processes with extraordinary accuracy. Despite this mathematical precision, however, the ontological status of quantum phenomena remains unresolved. This work argues that quantum mechanics correctly describes how systems behave, but fails to explain what quantum phenomena actually are. Concepts such as uncertainty, probability, and superposition are shown to be epistemic constructs—tools that describe incomplete transitions rather than fundamental properties of reality. Through a series of thought experiments and an A–B transition framework, this paper proposes that quantum phenomena should be understood as a constrained and harmonious transition regime between potentiality (A) and realized outcome (B). In this view, quantum is not a domain of indeterminacy, but the physics of becoming: a regulated ontological interval in which outcomes have not yet formed, rather than existing in an indeterminate state. This reinterpretation offers a coherent ontological foundation for quantum mechanics without invoking intrinsic randomness or observer-dependent reality.