Function deterministic_run_id 

pub fn deterministic_run_id(
    domain: &str,
    size: usize,
    seed: u64,
    difficulty: &str,
    hard_neg_ratio: f64,
    singleton_master_fraction: f64,
    locale: &str,
    only_entity: Option<&str>,
    chunk_size: Option<usize>,
) -> String

Deterministic run ID derived from generation parameters, so the same (domain, size, seed, difficulty, hard_neg_ratio, singleton_master_fraction, locale) always produces the same output filename regardless of output format (IPC vs Parquet) or how many times it’s run — and, just as important, a different filename whenever any of these parameters differ, since they all affect the generated data. singleton_master_fraction and locale were missing from this list until this was flagged as a bug (BUGS.md C14/C15): two runs differing only in --singleton-master-fraction or --locale produced the exact same filename, so the second run silently overwrote the first’s output.