Function dropping_vanished_param_values 

pub fn dropping_vanished_param_values(record: &ModelRecord) -> ModelRecord

A copy of record with parameter values for vanished parameters removed.

This is an optional at-rest cleanup, not a correctness requirement: request handling normalizes through merged/normalized_param_values on every call, so a stale stored value never reaches a runtime. A caller uses this only to tidy the persisted shelf (e.g. before displaying or re-saving a record).