Function write_state 

pub fn write_state(
    store: &Store,
    tick_id: &str,
    rows: &[(&Ground, Verdict)],
    staleness_policy: &str,
    staleness_sha: Option<&str>,
) -> Result<()>

Write results/state/<tick_id>.json: one row per (ground, verdict) pair, the staleness reference, and the time of computation. Pairing at the boundary keeps grounds and verdicts from drifting out of alignment.