AVITY Across Galaxies: A Frozen-Operator Reconstruction of SPARC Rotation Curves

We present a frozen-operator reconstruction of 143 SPARC galaxy rotation curves using a two-scale AVITY saturation framework. The model applies a uniform operator structure across galaxies without galaxy-specific halo customization. Model performance is evaluated using RMS residuals in logarithmic acceleration space. Under the strict baseline configuration, 132 galaxies satisfy conservative Tier-1 tolerance criteria. The global median RMS remains stable at 0.03471, while the mean RMS decreases from 0.05295 to 0.05000. The 16th–84th percentile interval shifts from [0.01308, 0.10615] to [0.01308, 0.08747] under frozen-operator validation. A structural scaling relation between outer saturation amplitude and transition radius yields Pearson r = 0.815 (p = 3.11 × 10⁻³²) and a fitted log-slope m = 0.516 ± 0.071 across Tier-1 systems. Blind holdout validation confirms comparable performance without parameter retuning. The framework is presented as a phenomenological reconstruction method for galactic rotation curves under a constrained, globally applied scalar operator structure.