diff --git a/services/backend/api/v1/generate/views.py b/services/backend/api/v1/generate/views.py
index 1b25373..2384a4e 100644
--- a/services/backend/api/v1/generate/views.py
+++ b/services/backend/api/v1/generate/views.py
@@ -49,8 +49,12 @@ def get_generate_ad_text_result(
     if task_result.status == celery.states.PENDING:
         raise Http404
 
+    result = task_result.result
+    if task_result.status != celery.states.SUCCESS:
+        result = None
+
     return status.OK, schemas.Promise(
         task_id=task_result.task_id,
         status=task_result.status,
-        result=task_result.result,
+        result=result,
     )
diff --git a/services/backend/api/v1/time/__init__.py b/services/backend/api/v1/time/__init__.py
index dc9fd4c..e69de29 100644
--- a/services/backend/api/v1/time/__init__.py
+++ b/services/backend/api/v1/time/__init__.py
@@ -1 +0,0 @@
-# noqa: A005
diff --git a/services/backend/apps/advertiser/models.py b/services/backend/apps/advertiser/models.py
index dd93a77..b4c5161 100644
--- a/services/backend/apps/advertiser/models.py
+++ b/services/backend/apps/advertiser/models.py
@@ -41,10 +41,10 @@ class Advertiser(BaseModel):
             (
                 Decimal(str(total_clicks))
                 / Decimal(str(total_impressions))
-                * Decimal("100")
+                * Decimal(100)
             )
             if total_impressions > 0
-            else Decimal("0")
+            else Decimal(0)
         )
 
         return {
@@ -115,9 +115,9 @@ class Advertiser(BaseModel):
             conversion = (
                 Decimal(str(metrics["clicks_count"]))
                 / Decimal(str(metrics["impressions_count"]))
-                * Decimal("100")
+                * Decimal(100)
                 if metrics["impressions_count"] > 0
-                else Decimal("0")
+                else Decimal(0)
             )
 
             daily_stats.append(
diff --git a/services/backend/apps/campaign/models.py b/services/backend/apps/campaign/models.py
index 98c1d64..c53124f 100644
--- a/services/backend/apps/campaign/models.py
+++ b/services/backend/apps/campaign/models.py
@@ -256,10 +256,10 @@ class Campaign(BaseModel):
             (
                 Decimal(str(clicks_count))
                 / Decimal(str(impressions_count))
-                * Decimal("100")
+                * Decimal(100)
             )
             if impressions_count > 0
-            else Decimal("0")
+            else Decimal(0)
         )
         spent_impressions = Decimal(str(impressions.get("spent", 0) or 0))
         spent_clicks = Decimal(str(clicks.get("spent", 0) or 0))
diff --git a/services/backend/integrations/yandexai/moderation.py b/services/backend/integrations/yandexai/moderation.py
index a106ff0..9189062 100644
--- a/services/backend/integrations/yandexai/moderation.py
+++ b/services/backend/integrations/yandexai/moderation.py
@@ -1,4 +1,4 @@
-# ruff: noqa: E501, W291
+# ruff: noqa: E501
 import logging
 
 from django.conf import settings
diff --git a/services/backend/manage.py b/services/backend/manage.py
index f821d3a..2f2b54f 100755
--- a/services/backend/manage.py
+++ b/services/backend/manage.py
@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+# ruff: noqa: PLC0415
 """Django's command-line utility for administrative tasks."""
 
 import os
diff --git a/services/telegram_bot/config.py b/services/telegram_bot/config.py
index b31b586..9d15ffe 100644
--- a/services/telegram_bot/config.py
+++ b/services/telegram_bot/config.py
@@ -13,4 +13,4 @@ API_ENDPOINT = os.getenv("AIOGRAM_BACKEND_URL", "http://localhost:8080")
 
 REDIS_URI = os.getenv("REDIS_URI", "redis://localhost:6379")
 
-MINIO_URL = os.getenv('MINIO_ENDPOINT', 'http://localhost:9000')
+MINIO_URL = os.getenv("MINIO_ENDPOINT", "http://localhost:9000")