A 339 KB Linear(5376, 14) probe on frozen google/gemma-4-31B-it states, scoring 0.7590 mean AUROC on the official ChestX-ray14 split against 0.7451 for the dataset authors' fine-tuned ResNet-50.

The backbone does not run here. The probe runs live on precomputed states.

Research artifact, not a diagnostic device. Detection, not early detection.