Point-in-time market-regime context for a scan date: VIX close, VIX3M,
SPY trend state, and the 5-day VIX delta — all as-of <= scan_date (the
selection point, leakage-safe), plus the engine's regime safety rail
evaluated on those values.
The rail: the engine fail-closes (no trade) when spot VIX > VIX3M
(backwardation — the market pricing imminent volatility is an adverse
regime for short-dated directional longs).
Served from the labeled substrate, which lags the live pool by ~1-2
trading days. Values are constant per scan_date.
Args:
scan_date: YYYY-MM-DD. Defaults to the latest scan date carrying
regime features.
Returns:
{scan_date, vix_at_scan, vix3m_at_enrich, spy_trend_at_scan,
vix_5d_delta_at_scan, regime_rail_pass, rail_definition}