{
  "slug": "use.visitor_days_7d",
  "title": "Visitor-days, trailing 7 days",
  "grade": "observed",
  "unit": "count",
  "value": 100,
  "as_of": "2026-08-14",
  "sql": "SELECT COALESCE(SUM(n),0) FROM (SELECT COUNT(DISTINCT visitor_hash) n FROM page_views WHERE visitor_hash IS NOT NULL AND ua_class IN ('browser','agent') AND ts>=datetime('now','-7 day') GROUP BY substr(ts,1,10))",
  "note": "Sum of each day's DISTINCT visitors (daily-salted hash, salt destroyed at rotation \u2014 the same person on two days counts twice by design; days are unlinkable).",
  "history": [
    {
      "period": "2026-08-15",
      "value": 64.0
    }
  ]
}