diff --git a/alembic.ini b/alembic.ini
index d15b27c..155d434 100644
--- a/alembic.ini
+++ b/alembic.ini
@@ -55,7 +55,7 @@ version_path_separator = os  # Use os.pathsep. Default configuration used for ne
 # are written from script.py.mako
 # output_encoding = utf-8
 
-sqlalchemy.url = sqlite:///./app/storage/db/db.sqlite
+sqlalchemy.url = sqlite:///app/storage/db/db.sqlite
 
 [post_write_hooks]
 # post_write_hooks defines scripts or Python functions that are run
diff --git a/alembic/env.py b/alembic/env.py
index c04175b..3ec8c52 100644
--- a/alembic/env.py
+++ b/alembic/env.py
@@ -7,7 +7,6 @@ from alembic import context
 
 from app.core.config import settings
 from app.db.session import Base
-from app.models import User, Conversation, Message, conversation_participants
 
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.
@@ -69,10 +68,20 @@ def run_migrations_online() -> None:
     )
 
     with connectable.connect() as connection:
+        # For SQLite, we need to enable foreign keys and use batch mode for migrations
+        is_sqlite = connection.dialect.name == "sqlite"
+        
         context.configure(
-            connection=connection, target_metadata=target_metadata
+            connection=connection, 
+            target_metadata=target_metadata,
+            # This is important for SQLite to support ALTER operations properly
+            render_as_batch=is_sqlite
         )
 
+        # Enable foreign key constraints for SQLite
+        if is_sqlite:
+            connection.execute("PRAGMA foreign_keys=ON")
+
         with context.begin_transaction():
             context.run_migrations()
 
diff --git a/app/api/dependencies/auth.py b/app/api/dependencies/auth.py
index 62cd81d..d500dfa 100644
--- a/app/api/dependencies/auth.py
+++ b/app/api/dependencies/auth.py
@@ -1,4 +1,3 @@
-from typing import Generator, Optional
 
 from fastapi import Depends, HTTPException, status
 from fastapi.security import OAuth2PasswordBearer
@@ -7,7 +6,6 @@ from pydantic import ValidationError
 from sqlalchemy.orm import Session
 
 from app.core.config import settings
-from app.core.security import verify_password
 from app.db.repositories.user import user_repository
 from app.db.session import get_db
 from app.models.user import User
diff --git a/app/api/endpoints/messages.py b/app/api/endpoints/messages.py
index 39d2f80..8f1a61d 100644
--- a/app/api/endpoints/messages.py
+++ b/app/api/endpoints/messages.py
@@ -8,7 +8,7 @@ from app.db.repositories.message import message_repository
 from app.db.repositories.conversation import conversation_repository
 from app.db.session import get_db
 from app.models.user import User
-from app.schemas.message import Message, MessageCreate, MessageUpdate
+from app.schemas.message import Message, MessageCreate
 
 router = APIRouter(tags=["messages"])
 
diff --git a/app/api/endpoints/websocket.py b/app/api/endpoints/websocket.py
index acf936a..8d50b67 100644
--- a/app/api/endpoints/websocket.py
+++ b/app/api/endpoints/websocket.py
@@ -1,9 +1,8 @@
 import json
-from typing import Dict, List, Any
-import asyncio
+from typing import Dict, Any
 from datetime import datetime
 
-from fastapi import APIRouter, Depends, WebSocket, WebSocketDisconnect, HTTPException, status
+from fastapi import APIRouter, Depends, WebSocket, WebSocketDisconnect
 from sqlalchemy.orm import Session
 from jose import jwt, JWTError
 
@@ -231,7 +230,7 @@ async def websocket_endpoint(websocket: WebSocket, db: Session = Depends(get_db)
         # Remove user from connected users
         if user and user.id in connected_users:
             del connected_users[user.id]
-    except Exception as e:
+    except Exception:
         # Handle any other exceptions
         if user and user.id in connected_users:
             del connected_users[user.id]
\ No newline at end of file
diff --git a/app/core/config.py b/app/core/config.py
index 340abff..087bc8e 100644
--- a/app/core/config.py
+++ b/app/core/config.py
@@ -1,3 +1,4 @@
+import os
 from pathlib import Path
 import secrets
 from typing import List
@@ -16,7 +17,9 @@ class Settings(BaseSettings):
     CORS_ORIGINS: List[str] = ["*"]
     
     # Database
-    DB_DIR = Path("/app/storage/db")
+    # Use current working directory as base by default, or app directory if in container
+    BASE_DIR = Path(os.getenv("APP_BASE_DIR", os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))))
+    DB_DIR = BASE_DIR / "app" / "storage" / "db"
     DB_DIR.mkdir(parents=True, exist_ok=True)
     SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
     
diff --git a/app/db/repositories/conversation.py b/app/db/repositories/conversation.py
index 5653059..bb7fd1e 100644
--- a/app/db/repositories/conversation.py
+++ b/app/db/repositories/conversation.py
@@ -57,7 +57,7 @@ class ConversationRepository(BaseRepository[Conversation, ConversationCreate, Co
         # Find direct conversations (not groups) where both users are participants
         conversations = (
             db.query(Conversation)
-            .filter(Conversation.is_group == False)
+            .filter(not Conversation.is_group)
             .join(conversation_participants, Conversation.id == conversation_participants.c.conversation_id)
             .filter(conversation_participants.c.user_id.in_([user_id_1, user_id_2]))
             .all()
diff --git a/app/db/repositories/message.py b/app/db/repositories/message.py
index dad5761..e1d1ef5 100644
--- a/app/db/repositories/message.py
+++ b/app/db/repositories/message.py
@@ -63,7 +63,7 @@ class MessageRepository(BaseRepository[Message, MessageCreate, MessageUpdate]):
         return (
             db.query(Message)
             .filter(Message.recipient_id == user_id)
-            .filter(Message.is_read == False)
+            .filter(not Message.is_read)
             .count()
         )
 
diff --git a/app/models/__init__.py b/app/models/__init__.py
index ed77c63..18ca039 100644
--- a/app/models/__init__.py
+++ b/app/models/__init__.py
@@ -1,3 +1,3 @@
-from app.models.user import User
-from app.models.conversation import Conversation, conversation_participants
-from app.models.message import Message
\ No newline at end of file
+from app.models.user import User  # noqa: F401
+from app.models.conversation import Conversation, conversation_participants  # noqa: F401
+from app.models.message import Message  # noqa: F401
\ No newline at end of file
diff --git a/app/schemas/__init__.py b/app/schemas/__init__.py
index 63a76a4..728c87a 100644
--- a/app/schemas/__init__.py
+++ b/app/schemas/__init__.py
@@ -1,3 +1,3 @@
-from app.schemas.user import User, UserCreate, UserUpdate, UserInDB
-from app.schemas.message import Message, MessageCreate, MessageUpdate, MessageInDB
-from app.schemas.conversation import Conversation, ConversationCreate, ConversationUpdate, ConversationInDB
\ No newline at end of file
+from app.schemas.user import User, UserCreate, UserUpdate, UserInDB  # noqa: F401
+from app.schemas.message import Message, MessageCreate, MessageUpdate, MessageInDB  # noqa: F401
+from app.schemas.conversation import Conversation, ConversationCreate, ConversationUpdate, ConversationInDB  # noqa: F401
\ No newline at end of file
diff --git a/app/schemas/user.py b/app/schemas/user.py
index 5a2a6fd..33c3978 100644
--- a/app/schemas/user.py
+++ b/app/schemas/user.py
@@ -1,7 +1,7 @@
 from datetime import datetime
-from typing import Optional, List
+from typing import Optional
 
-from pydantic import BaseModel, EmailStr, Field
+from pydantic import BaseModel, EmailStr
 
 class UserBase(BaseModel):
     username: str