examples/periodic_test/driven_channel/tools/wall_normal_profile.py works again on current checkpoints. It looks the statistics window up in checkpoint.meta, reads the six-component Ucat_m2 payload correctly, reports the actual Reynolds shear stress, and folds the two walls. A new --wall-model-csv option takes u_tau from the wall model, and --u-tau supplies it directly. The tool does not apply to driven_duct, which has only one homogeneous direction, and that example's comment now says so.