Function params_version 

pub fn params_version(params: &InferenceParams) -> u64

A stable hash of the parameters that change a model’s output for the same input — currently the candidate label set. Computed once per batch (all rows in a batch share parameters), not per row.

Maintenance contract: every field of InferenceParams that can change the output must be folded in here. It is hashed field-by-field rather than via a derived Hash because parameters added later (e.g. an f32 temperature) are not Hash; fold those in explicitly (e.g. to_bits()).