Function build_record 

pub fn build_record(
    model: String,
    backend_kind: String,
    cases_dir: String,
    report: &EvalReport,
) -> RunRecord

Assemble a RunRecord from a finished report plus the run identity, stamping it with a single now timestamp (so a record built once can be written to disk AND uploaded sharing the same timestamp / dedup key).

backend_kind is the report’s Backend column: when empty it falls back to the report’s descriptive backend label; otherwise it overrides it. system_prompt is copied from the report so a consumer reading just the record sees it without descending into the nested report. Public so a host can build a record without driving a full persist.