fix(growth): harden deterministic report evidence

internal/growth/aggregate.go

@@ -0,0 +1,43 @@
+package growth
+
+import (
+	"slices"
+	"time"
+)
+
+type Session struct {
+	CreatedAt  time.Time `json:"createdAt"`
+	Status     string    `json:"status"`
+	AmountRial int64     `json:"amountRial"`
+}
+
+// AggregateDaily groups already-authorized, scope-filtered sessions by Tehran
+// local day. Paid and Verified are the only successful bank-payment statuses.
+func AggregateDaily(sessions []Session, catalog []Event) []DailyPoint {
+	byDate := make(map[string]DailyPoint)
+	for _, session := range sessions {
+		local := session.CreatedAt.In(tehranLocation())
+		date := time.Date(local.Year(), local.Month(), local.Day(), 0, 0, 0, 0, tehranLocation())
+		key := dayKey(date)
+		point := byDate[key]
+		point.Date = date
+		point.SessionCount++
+		if session.Status == "Paid" || session.Status == "Verified" {
+			point.PaidSessionCount++
+			point.PaidAmountRial += session.AmountRial
+		}
+		byDate[key] = point
+	}
+	points := make([]DailyPoint, 0, len(byDate))
+	for _, point := range byDate {
+		for _, event := range catalog {
+			if !dateBefore(point.Date, event.StartDate) && !dateAfter(point.Date, event.EndDate) {
+				point.EventIDs = append(point.EventIDs, event.ID)
+			}
+		}
+		slices.Sort(point.EventIDs)
+		points = append(points, point)
+	}
+	slices.SortFunc(points, func(a, b DailyPoint) int { return a.Date.Compare(b.Date) })
+	return points
+}