diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0220b9e..fc74776 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -31,5 +31,5 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: '3.11'
-      - run: pip install ruff
+      - run: pip install ruff==0.16.0
       - run: ruff check nlp-service
diff --git a/nlp-service/main.py b/nlp-service/main.py
index f81f218..c1a6a95 100644
--- a/nlp-service/main.py
+++ b/nlp-service/main.py
@@ -1,10 +1,10 @@
 import os
+
 import httpx
 from dotenv import load_dotenv
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 from pydantic import BaseModel
-from typing import Optional
 
 load_dotenv(dotenv_path=os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", ".env"))
 
@@ -44,9 +44,9 @@ def detect_abuse(req: AbuseRequest):
 
 class ChatRequest(BaseModel):
     messages: list
-    system_instruction: Optional[str] = None
-    generation_config: Optional[dict] = None
-    lessons_context: Optional[str] = None
+    system_instruction: str | None = None
+    generation_config: dict | None = None
+    lessons_context: str | None = None
 
 class ChatResponse(BaseModel):
     reply: str
@@ -86,7 +86,7 @@ async def call_gemini(prompt: str, system_instruction: str = "") -> str:
             print(f"Gemini API error: {res.status_code} - {res.text[:200]}")
             return ""
 
-    except Exception as e:
+    except (httpx.HTTPError, KeyError, ValueError, IndexError) as e:
         print(f"Gemini API exception: {e}")
         return ""
 
diff --git a/nlp-service/test_service.py b/nlp-service/test_service.py
index 2a37b5e..9ebba32 100644
--- a/nlp-service/test_service.py
+++ b/nlp-service/test_service.py
@@ -1,8 +1,9 @@
+import importlib.util
 import os
 import traceback
-import importlib.util
 
 import spacy
+
 nlp_spacy = spacy.load("xx_ent_wiki_sm")
 
 spec = importlib.util.spec_from_file_location("nlp_main", os.path.join(os.path.dirname(__file__), "main.py"))
@@ -20,21 +21,21 @@
 try:
     cleaned = mod.normalize_arabic(text)
     print(f"\nCleaned: {cleaned}")
-except Exception as e:
+except Exception as e:  # noqa: BLE001 -- diagnostic script must survive any step failure to run the rest
     print(f"\nClean error: {e}")
     traceback.print_exc()
 
 try:
     s = mod.ml_sentiment(text)
     print(f"Sentiment: {s}")
-except Exception as e:
+except Exception as e:  # noqa: BLE001 -- diagnostic script must survive any step failure to run the rest
     print(f"Sentiment error: {e}")
     traceback.print_exc()
 
 try:
     e = mod.spacy_entities(text)
     print(f"Entities: {e}")
-except Exception as e:
+except Exception as e:  # noqa: BLE001 -- diagnostic script must survive any step failure to run the rest
     print(f"Entities error: {e}")
     traceback.print_exc()