Enum BaseModel 

pub enum BaseModel {
    ModernBert(ModernBert),
    Bert(BertModel),
}

An enum to abstract over different underlying BERT-based models.

This allows ColBERT to use different architectures like BertModel or ModernBert without changing the core logic.

ModernBert and BertModel have very different struct sizes (clippy::large_enum_variant would suggest boxing one), but boxing would add an indirection on the hot forward path and we hold exactly one of these per ColBERT anyway, so the size difference is immaterial.

Variants

ModernBert(ModernBert)

A variant holding a ModernBert model.

Bert(BertModel)

A variant holding a standard BertModel.