HγC O4: Narrower Comparative Calibration of Structured Near-Critical Populations in Galactic Phenomenology

This paper establishes the first narrower comparative calibration layer for structured near-critical populations in galactic phenomenology within the HγC framework. Earlier N-series work established band existence, band structure, and observational diagnostic language; O1 fixed the first explicitly galactic diagnostic morphology layer; O2 stabilized the first comparative morphology framework; and O3 introduced the first comparative estimator layer. O4 takes the next justified step by defining selective informative contrasts as the restricted domain in which narrower comparative calibration first becomes meaningful. Comparative center, breadth, asymmetry, and tail-supported persistence are carried into a first narrower calibration framework as a structured estimator bundle whose stability may be tested under selective observational use. The aim is not to replace the morphology-led framework established in the earlier O-line, but to examine whether selective narrowing sharpens or destabilizes it. On this basis, support, neutral variation, and tension are reformulated at the calibration level. Support marks cases in which selective narrowing stabilizes the shared-family reading; neutral variation marks cases that remain readable but still depend on contrast choice, weighting choice, or internal estimator emphasis; and tension marks cases in which narrowing begins to destabilize the morphology object itself. The scope of the paper is deliberately limited. O4 does not perform catalogue-level precision fitting, reconstruct galaxy-by-galaxy hidden regime-space populations, derive a unique mapping from observed residual organization to realized γ-distributions, enter the temporal reorganization sector associated with the W-series, or integrate the galactic line with the projected-profile morphology of the weak-field lensing branch. Instead, it establishes the first narrower calibration layer required before calibration consolidation and later bounded closure can become meaningful.