fix: separate base and purchased traffic in renewal pricing

When a user has 25GB base + 100GB purchased = 125GB total,
the renewal priced it at the 250GB tier (nearest tier >= 125GB)
instead of pricing each component separately at its own tier:
base 25GB + purchased 100GB.

- Split traffic_limit_gb into base and purchased components
- Price each component at its own tier via get_traffic_price()
- Apply same discount percentage to purchased portion
- Log warning when purchased >= total (data corruption)
- Fix in both subscription_renewal_service and subscription CRUD

app/database/crud/subscription.py

@@ -1391,11 +1391,27 @@ async def get_subscription_renewal_cost(
         total_servers_discount = servers_discount_per_month * months_in_period
 
         # В режиме fixed_with_topup при продлении используем фиксированный лимит
+        purchased_traffic = subscription.purchased_traffic_gb or 0
         if settings.is_traffic_fixed():
-            renewal_traffic_gb = settings.get_fixed_traffic_limit()
+            traffic_price_per_month = settings.get_traffic_price(settings.get_fixed_traffic_limit())
+        # Separate base traffic from purchased to avoid wrong tier lookup
+        elif purchased_traffic > 0:
+            base_traffic_gb = (subscription.traffic_limit_gb or 0) - purchased_traffic
+            if base_traffic_gb <= 0:
+                logger.warning(
+                    'Purchased traffic >= total limit, pricing purchased portion only',
+                    subscription_id=subscription.id,
+                    traffic_limit_gb=subscription.traffic_limit_gb,
+                    purchased_traffic_gb=purchased_traffic,
+                )
+                traffic_price_per_month = settings.get_traffic_price(purchased_traffic)
+            else:
+                traffic_price_per_month = (
+                    settings.get_traffic_price(base_traffic_gb)
+                    + settings.get_traffic_price(purchased_traffic)
+                )
         else:
-            renewal_traffic_gb = subscription.traffic_limit_gb
-        traffic_price_per_month = settings.get_traffic_price(renewal_traffic_gb)
+            traffic_price_per_month = settings.get_traffic_price(subscription.traffic_limit_gb)
         traffic_discount_percent = _get_discount_percent(
             user,
             promo_group,

app/services/subscription_renewal_service.py

@@ -325,8 +325,22 @@ class SubscriptionRenewalService:
             await self._validate_servers_for_user_promo_group(db, user, connected_uuids)
 
         # В режиме fixed_with_topup при продлении используем фиксированный лимит
+        purchased_traffic = subscription.purchased_traffic_gb or 0
         if settings.is_traffic_fixed():
             traffic_limit = settings.get_fixed_traffic_limit()
+        # Separate base traffic from purchased to avoid wrong tier lookup
+        # e.g. 25GB base + 100GB purchased = 125GB total → would round up to 250GB tier
+        elif purchased_traffic > 0:
+            base_traffic = (subscription.traffic_limit_gb or 0) - purchased_traffic
+            if base_traffic <= 0:
+                logger.warning(
+                    'Purchased traffic >= total limit, pricing purchased portion only',
+                    subscription_id=subscription.id,
+                    traffic_limit_gb=subscription.traffic_limit_gb,
+                    purchased_traffic_gb=purchased_traffic,
+                )
+                base_traffic = settings.DEFAULT_TRAFFIC_LIMIT_GB or 0
+            traffic_limit = base_traffic
         else:
             traffic_limit = subscription.traffic_limit_gb
             if traffic_limit is None:
@@ -347,6 +361,20 @@ class SubscriptionRenewalService:
 
         months = details.get('months_in_period') or calculate_months_from_days(period_days)
 
+        # Add purchased traffic cost separately (uses its own tier price, same discount %)
+        if purchased_traffic > 0 and not settings.is_traffic_fixed():
+            purchased_price_per_month = settings.get_traffic_price(purchased_traffic)
+            traffic_discount_pct = details.get('traffic_discount_percent', 0)
+            purchased_disc_per_month = purchased_price_per_month * traffic_discount_pct // 100
+            discounted_purchased_per_month = purchased_price_per_month - purchased_disc_per_month
+            purchased_total = discounted_purchased_per_month * months
+            purchased_disc_total = purchased_disc_per_month * months
+
+            total_cost += purchased_total
+            details['traffic_price_per_month'] = details.get('traffic_price_per_month', 0) + purchased_price_per_month
+            details['total_traffic_price'] = details.get('total_traffic_price', 0) + purchased_total
+            details['traffic_discount_total'] = details.get('traffic_discount_total', 0) + purchased_disc_total
+
         base_original_total = (
             details.get('base_price_original', 0)
             + details.get('traffic_price_per_month', 0) * months