convention=uniform mixture over ALL classes
target=[0.900000, 0.100000]
optimal_margin=2.197225 probability=0.900000 loss=0.325083
margin=0.000000 p_true=0.500000 loss=0.693147 gradient=-0.400000
margin=2.197225 p_true=0.900000 loss=0.325083 gradient=0.000000
margin=5.000000 p_true=0.993307 loss=0.506715 gradient=0.093307
hard_target_at_5: loss=0.006715 gradient=-0.006693
other_classes_only: target=[0.800000, 0.200000] optimal_margin=1.386294
PASS 10 checks; scalar objective only, no model training
