SE-04: Context-Limited Emergent Structures — A Boundary Activation Field Hypothesis for Galactic Rotation Curves

We investigate a simple saturating correction model for galactic rotation curves of the form v² = v²_bar + C·(1 − exp(−r/r_c)), motivated by a boundary activation field hypothesis (SE-04). Per-galaxy calibration achieves strong performance across the SPARC sample (170/175 pass, median χ² ≈ 2.3). A global predictive formulation using surface-brightness-derived coefficients achieves 154/175 pass at median χ² = 13.3, demonstrating that the underlying signal survives compression to two global parameters. Failures concentrate in disturbed systems (Q=3, 66% fail rate), bulge-dominated galaxies (22% fail rate), and nearly baryon-dominated cases where any positive correction worsens fit. We present this as an exploratory hypothesis generator with documented failure modes, not an established physical theory. Further progress requires a gating criterion on the boundary correction amplitude and broader validation rather than additional tuning layers.