Function recency_score

atomic-cli/src/commands/vault/context.rs:586–595

Recency component in [0, 1]: 1.0 for "just updated", halving every [`RECENCY_HALF_LIFE_DAYS`]. Unparseable timestamps score 0.

(updated_at: &str, now: chrono::DateTime<chrono::Utc>)

/// Recency component in [0, 1]: 1.0 for "just updated", halving every
/// [`RECENCY_HALF_LIFE_DAYS`]. Unparseable timestamps score 0.
fn recency_score(updated_at: &str, now: chrono::DateTime<chrono::Utc>) -> f64 {
    let Ok(updated) = chrono::DateTime::parse_from_rfc3339(updated_at) else {
        return 0.0;
    };
    let age_days = (now - updated.with_timezone(&chrono::Utc)).num_seconds() as f64 / 86_400.0;
    if age_days <= 0.0 {
        return 1.0;
    }
    0.5_f64.powf(age_days / RECENCY_HALF_LIFE_DAYS)
}

/// Combine the candidate score parts into the final ranking score.
fn final_score(candidate: &CandidateScore, recency: f64) -> f64 {