Structural Classification of Apparent Stellar Disappearance: A Registrability-Based Analysis of Long-Duration Dimming in WOH G64

Long-duration stellar dimming and apparent “disappearance” events are frequently interpreted as evidence of rapid evolutionary transformation or imminent terminal collapse. Such interpretations often conflate loss of observability with loss of physical identity. This paper applies a structural, registrability-based classification framework to the extreme red supergiant WOH G64 in the Large Magellanic Cloud, a system that has been widely discussed as undergoing a possible transition toward a yellow hypergiant or pre-supernova state. Building on a geometry-first decision framework, the analysis enforces duration, chromatic behavior, geometric admissibility, stability constraints, recurrence, and envelope recoverability prior to interpretation. Using a structured classification worksheet and decision tree, the observed behavior of WOH G64 is shown to be consistent with a boundary-stress registrability system involving extended circumstellar structure and viewing geometry, rather than intrinsic stellar transformation or terminal collapse. Apparent disappearance and spectral variability arise naturally from changes in observational access to persistent stellar layers. Terminal registrability collapse phenomena, including supernovae, are explicitly excluded from the present analysis. The paper demonstrates how disciplined structural classification can resolve controversial dimming events without invoking premature evolutionary conclusions and provides a reproducible template for evaluating similar systems.