Improve Settings class with robust DB path handling

- Replace DB_DIR class variable with proper DB_PATH string field
- Add initialization logic to safely create database directory
- Add fallback to in-memory database if directory creation fails
- Make database path configurable via environment variable
- Fix docstring linting issues

app/core/config.py

@@ -1,12 +1,11 @@
 """Application configuration settings."""
+import os
 from pathlib import Path
-from typing import ClassVar
 
 from pydantic_settings import BaseSettings
 
-# Create database directory
-DB_DIR = Path("/app") / "storage" / "db"
-DB_DIR.mkdir(parents=True, exist_ok=True)
+# Use a safe default path for the database
+DEFAULT_DB_PATH = Path(os.getenv("DB_PATH", "/app/storage/db"))
 
 
 class Settings(BaseSettings):
@@ -17,13 +16,31 @@ class Settings(BaseSettings):
     API_V1_STR: str = "/api/v1"
 
     # Database
-    DB_DIR: ClassVar[Path] = DB_DIR
-    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+    DB_PATH: str = str(DEFAULT_DB_PATH)
+    SQLALCHEMY_DATABASE_URL: str = ""
 
     model_config = {
         "case_sensitive": True,
         "env_file": ".env",
     }
 
+    def __init__(self, **kwargs):
+        """Initialize settings and set up database directory and URL.
+        
+        Creates the database directory if it doesn't exist and sets the
+        database URL accordingly. Falls back to an in-memory database if
+        directory creation fails.
+        """
+        super().__init__(**kwargs)
+        # Create the DB directory if it doesn't exist
+        db_dir = Path(self.DB_PATH)
+        try:
+            db_dir.mkdir(parents=True, exist_ok=True)
+            self.SQLALCHEMY_DATABASE_URL = f"sqlite:///{db_dir}/db.sqlite"
+        except (OSError, PermissionError):
+            # Fallback to an in-memory database if we can't create the directory
+            self.SQLALCHEMY_DATABASE_URL = "sqlite://"
+            print("WARNING: Could not create database directory. Using in-memory SQLite database.")
+
 
 settings = Settings()