Function module_exempt_from_minimum 

pub fn module_exempt_from_minimum(chapters: i64, exercises: i64) -> bool

Whether a module of the given size is exempt from the minimum cheater threshold. Small modules can legitimately be completed fast, so for them any duration >= 0 is allowed (0 disables the duration check). This is the single source of truth for the exemption rule – both the save-time validation and the configuration UI derive their behaviour from it (the latter via get_threshold_info_for_course).