refactor: Address technical debt in auth refresh implementation

backend/src/ea_chatbot/api/routers/auth.py

@@ -2,7 +2,7 @@ from typing import Optional
 from fastapi import APIRouter, Depends, HTTPException, status, Response, Request
 from fastapi.responses import RedirectResponse
 from fastapi.security import OAuth2PasswordRequestForm
-from ea_chatbot.api.utils import create_access_token, create_refresh_token, settings
+from ea_chatbot.api.utils import create_access_token, create_refresh_token, decode_access_token, settings
 from ea_chatbot.api.dependencies import history_manager, oidc_client, get_current_user
 from ea_chatbot.history.models import User as UserDB
 from ea_chatbot.api.schemas import Token, UserCreate, UserResponse, ThemeUpdate
@@ -101,7 +101,6 @@ async def refresh(request: Request, response: Response):
             detail="Refresh token missing"
         )
     
-    from ea_chatbot.api.utils import decode_access_token # Using decode_access_token for both
     payload = decode_access_token(refresh_token)
     
     if not payload:

backend/tests/api/test_auth_refresh.py

@@ -18,11 +18,17 @@ def test_refresh_token_success(client):
     # 2. Set the cookie manually in the client
     client.cookies.set("refresh_token", refresh_token)
     
-    import time
-    time.sleep(1.1) # Wait to ensure iat is different
-    
     # 3. Call the refresh endpoint with mock
-    with patch("ea_chatbot.api.routers.auth.history_manager") as mock_hm:
+    with patch("ea_chatbot.api.routers.auth.history_manager") as mock_hm, \
+         patch("ea_chatbot.api.utils.datetime") as mock_datetime:
+        
+        # Mock datetime to ensure the second token has a different timestamp
+        from datetime import datetime, timezone, timedelta
+        base_now = datetime.now(timezone.utc)
+        # First call (inside refresh) gets base_now + 1 second
+        mock_datetime.now.return_value = base_now + timedelta(seconds=1)
+        mock_datetime.side_effect = lambda *args, **kwargs: datetime(*args, **kwargs)
+        
         mock_hm.get_user_by_id.return_value = User(id=user_id, username="test@test.com")
         
         response = client.post("/api/v1/auth/refresh")