`train_loss_f > 100` silently passes on NaN because IEEE 754 NaN
comparisons always return False. When an agent experiment produces
NaN (e.g. from an aggressive LR change), the run wastes the full
5-minute budget instead of failing fast.
`not (x <= 100)` catches both >100 and NaN with no added complexity.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>