feat: AI patient onboarding backend and documentation

ai-patient-onboarding/app/database/database.py

@@ -0,0 +1,47 @@
+import os
+from pathlib import Path
+from dotenv import load_dotenv
+from sqlalchemy import create_engine
+from sqlalchemy.orm import DeclarativeBase, sessionmaker
+
+load_dotenv()
+
+# Ensure data directory exists relative to project root
+BASE_DIR = Path(__file__).resolve().parent.parent.parent
+DATA_DIR = BASE_DIR / "data"
+DATA_DIR.mkdir(parents=True, exist_ok=True)
+
+# Build absolute SQLite URI so it works regardless of process working directory
+DEFAULT_DB_PATH = DATA_DIR / "onboarding.db"
+env_db_url = os.getenv("DATABASE_URL")
+
+if env_db_url and not env_db_url.startswith("sqlite:///./"):
+    DATABASE_URL = env_db_url
+else:
+    # Use robust absolute path for SQLite
+    DATABASE_URL = f"sqlite:///{DEFAULT_DB_PATH.as_posix()}"
+
+engine = create_engine(
+    DATABASE_URL,
+    connect_args={
+        "check_same_thread": False
+    },
+)
+
+SessionLocal = sessionmaker(
+    bind=engine,
+    autoflush=False,
+    autocommit=False,
+)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()