Environment-dependent galaxy maturity and bounded residual developmental modulation

First public release of an empirical working paper documenting a bounded residual environment–maturity signal in galaxies after standard controls. Using SDSS DR7 with Tinker-based halo-mass, satellite-probability, and assembly-bias controls, a residual density coefficient of β = 0.00070 (14.6% of the uncontrolled signal) survives the full control ladder, concentrated in satellite galaxies. A Hill-function fit strongly outperforms a linear alternative (ΔAIC = −3754.9), supporting a saturating rather than unbounded response. An independent GAMA DR4 consistency check reproduces the positive environment–maturity relation. This release documents the signal and its quantitative structure; it does not identify a specific physical mechanism. Further work on mechanism discrimination is ongoing.