Chosen split: reynolds. Out-of-envelope Cd-error elevation (out/in median): aoa=1.6x, reynolds=2.2x. Default is AoA on physical grounds (stall); reynolds gives the cleanest separation here.

  aoa: out-of-envelope Cd error median=0.0223 (in-envelope 0.01372); elevation 1.6x
    AoA asymmetry: out-of-envelope Cd error is higher on the low-AoA side (median 0.02876, n=111) than the high-AoA side (median 0.018, n=85); degradation concentrates on the low side. The high-side flagged cases are flagged-but-fine — reported, not dropped.
  reynolds: out-of-envelope Cd error median=0.04714 (in-envelope 0.02149); elevation 2.2x

[chosen split written to dev/build/airfrans-exp/chosen_split.txt]
