Initial commit

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

models/v/usermod/vip_renew.go

@@ -0,0 +1,12 @@
+package usermod
+
+import "time"
+
+// RenewVIPLevel returns the level that should remain after extending VIP.
+// An active higher level must not be downgraded by a lower-level renewal.
+func RenewVIPLevel(currentExpire, now time.Time, currentLevel, renewedLevel int) int {
+	if currentExpire.After(now) && currentLevel > renewedLevel {
+		return currentLevel
+	}
+	return renewedLevel
+}