added robust code to create the sqlite file

app/database.py

@@ -1,20 +1,63 @@
 # app/database.py
-#!/usr/bin/env python3
 
-from sqlalchemy import create_engine
+import os
+import logging
+
+from sqlalchemy import create_engine, exc
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
+from sqlalchemy.engine.url import make_url
+
 from app.config import settings
 
+logger = logging.getLogger(__name__)
+
 Base = declarative_base()
-engine = create_engine(settings.database_url, connect_args={"check_same_thread": False})
+
+# Parse the DATABASE_URL
+DB_URL = settings.database_url
+engine = create_engine(DB_URL, connect_args={"check_same_thread": False})
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
+
 def init_db():
-    """Call this once (e.g. on startup) to create tables if they don't exist."""
-    Base.metadata.create_all(bind=engine)
+    """
+    Ensures the SQLite database file and its parent directory exist (if using sqlite).
+    Then runs Base.metadata.create_all(bind=engine) to initialize tables.
+    Logs a message if a new SQLite DB file is created.
+    """
+    # 1. Parse the DB URL to see if it's sqlite
+    url = make_url(DB_URL)
+    if url.get_backend_name() == "sqlite":
+        # 2. Extract the database path from the URL
+        database_path = url.database  # e.g. "/workdir/db/database.db" or ":memory:"
+        
+        if database_path != ":memory:":
+            # 3. Ensure directory exists
+            db_dir = os.path.dirname(database_path)
+            if db_dir and not os.path.exists(db_dir):
+                logger.info(f"Creating directory for SQLite DB: {db_dir}")
+                os.makedirs(db_dir, exist_ok=True)
+
+            # 4. If the file does not exist, create an empty one
+            if not os.path.exists(database_path):
+                logger.info(f"Creating new SQLite database file at {database_path}")
+                open(database_path, "a").close()
+    
+    # 5. Now create tables if they don't exist yet
+    try:
+        Base.metadata.create_all(bind=engine)
+        logger.info("Database initialization complete (tables created if not exist).")
+    except exc.SQLAlchemyError as e:
+        logger.error(f"Error initializing database: {e}")
+        raise
+
 
 def get_db():
+    """
+    Dependency for FastAPI routes or general DB usage.
+    Yields a SQLAlchemy session, and closes it upon exit.
+    """
     db = SessionLocal()
     try:
         yield db