4ee75d0042
Real data has steps with up to ~37 secondaries, but the n_sec head only has K_MAX+1=16 classes. The unclamped label occasionally overflowed cross_entropy's valid range and crashed CUDA training with "unique_by_key: failed to synchronize: cudaErrorAssert". The continuous secondary targets were already truncated to K_MAX slots; only this label was missed. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>