first reading the start of a map with a 3 minute delay to overcome the transition period from the previous map

discord_verificiation/playtime-frontend/lib/mapImpact.ts

@@ -1,5 +1,6 @@
 import { query } from '@/lib/db';
 import { parseDbDate } from '@/lib/dates';
+import { START_BASELINE_MS } from '@/lib/populationBaseline';
 
 // --- Why this exists ---------------------------------------------------
 //
@@ -120,7 +121,11 @@ async function computeMapImpactStats(): Promise<MapImpactSummary[]> {
     const durationMs = nextStartMs - startMs;
     if (durationMs < MIN_REAL_PERIOD_MS) continue; // tickrate-restart artifact, not a real occurrence
 
-    const startPlayers = populationAt(startMs);
+    // Read the starting population START_BASELINE_MS into the map rather than
+    // at the exact change instant, so players still leaving the previous map
+    // aren't counted against this one. Clamped to the occurrence's end (it is
+    // always >= 2 min long here, but may be shorter than the baseline).
+    const startPlayers = populationAt(Math.min(startMs + START_BASELINE_MS, nextStartMs));
     const endPlayers = populationAt(nextStartMs);
     const netChange = endPlayers - startPlayers;
     const retentionPct = startPlayers > 0 ? (endPlayers / startPlayers) * 100 : null;