fix: handle StaleDataError in webhook user.deleted server counter decrement

When a user is deleted from the panel, the subscription may already be
cascade-deleted by the time the webhook handler tries to decrement
server counters. This caused StaleDataError followed by
PendingRollbackError when accessing subscription.id in the error handler.

- Save subscription.id before DB operations to avoid lazy load after rollback
- Catch StaleDataError explicitly and rollback the session
- Re-fetch subscription/user after potential rollback in _handle_user_deleted
- Skip subscription cleanup if it was already cascade-deleted

app/database/crud/subscription.py

@@ -6,6 +6,7 @@ from typing import Optional
 from sqlalchemy import and_, delete, func, select
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import selectinload
+from sqlalchemy.orm.exc import StaleDataError
 
 from app.config import settings
 from app.database.crud.notification import clear_notifications
@@ -625,6 +626,9 @@ async def decrement_subscription_server_counts(
     if not subscription:
         return
 
+    # Save ID before any DB operations that might invalidate the ORM object
+    sub_id = subscription.id
+
     server_ids: set[int] = set()
 
     if subscription_servers is not None:
@@ -633,12 +637,12 @@ async def decrement_subscription_server_counts(
                 server_ids.add(sub_server.server_squad_id)
     else:
         try:
-            ids_from_links = await get_subscription_server_ids(db, subscription.id)
+            ids_from_links = await get_subscription_server_ids(db, sub_id)
             server_ids.update(ids_from_links)
         except Exception as error:
             logger.error(
                 '⚠️ Не удалось получить серверы подписки %s для уменьшения счетчика: %s',
-                subscription.id,
+                sub_id,
                 error,
             )
 
@@ -652,7 +656,7 @@ async def decrement_subscription_server_counts(
         except Exception as error:
             logger.error(
                 '⚠️ Не удалось сопоставить сквады подписки %s с серверами: %s',
-                subscription.id,
+                sub_id,
                 error,
             )
 
@@ -663,11 +667,18 @@ async def decrement_subscription_server_counts(
         from app.database.crud.server_squad import remove_user_from_servers
 
         await remove_user_from_servers(db, sorted(server_ids))
+    except StaleDataError:
+        logger.warning(
+            '⚠️ Подписка %s уже удалена (StaleDataError), пропускаем декремент серверов %s',
+            sub_id,
+            list(server_ids),
+        )
+        await db.rollback()
     except Exception as error:
         logger.error(
             '⚠️ Ошибка уменьшения счетчика пользователей серверов %s для подписки %s: %s',
             list(server_ids),
-            subscription.id,
+            sub_id,
             error,
         )
 

app/services/remnawave_webhook_service.py

@@ -574,18 +574,43 @@ class RemnaWaveWebhookService:
     async def _handle_user_deleted(
         self, db: AsyncSession, user: User, subscription: Subscription | None, data: dict
     ) -> None:
+        user_id = user.id
+        sub_id = subscription.id if subscription else None
+
         if subscription:
             self._stamp_webhook_update(subscription)
 
             # Decrement server counters BEFORE clearing connected_squads
             await decrement_subscription_server_counts(db, subscription)
 
+            # Re-fetch after potential rollback inside decrement_subscription_server_counts
+            try:
+                await db.refresh(subscription)
+            except Exception:
+                # Subscription was cascade-deleted, re-fetch user and skip subscription updates
+                logger.warning(
+                    'Webhook: subscription %s already deleted for user %s, skipping subscription cleanup',
+                    sub_id,
+                    user_id,
+                )
+                subscription = None
+                try:
+                    await db.refresh(user)
+                except Exception:
+                    from app.database.crud.user import get_user_by_id
+
+                    user = await get_user_by_id(db, user_id)
+                    if not user:
+                        logger.error('Webhook: user %s not found after rollback', user_id)
+                        return
+
+        if subscription:
             if subscription.status != SubscriptionStatus.EXPIRED.value:
                 subscription.status = SubscriptionStatus.EXPIRED.value
                 logger.info(
                     'Webhook: subscription %s marked expired (user deleted in panel) for user %s',
-                    subscription.id,
-                    user.id,
+                    sub_id,
+                    user_id,
                 )
 
             # Clear subscription data — panel user no longer exists
@@ -596,7 +621,7 @@ class RemnaWaveWebhookService:
             subscription.updated_at = datetime.now(UTC).replace(tzinfo=None)
 
             # Remove SubscriptionServer link rows
-            await db.execute(delete(SubscriptionServer).where(SubscriptionServer.subscription_id == subscription.id))
+            await db.execute(delete(SubscriptionServer).where(SubscriptionServer.subscription_id == sub_id))
 
         # Clear remnawave linkage
         if user.remnawave_uuid: