backend/app/db.py

import os
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, declarative_base

# SQLite DB path. In Docker / HF we’ll set DB_PATH env, default is local "data/app.db"
DB_PATH = os.environ.get("DB_PATH", "data/app.db")

# Create SQLAlchemy engine
engine = create_engine(
    f"sqlite:///{DB_PATH}",
    connect_args={"check_same_thread": False},
)

# Session factory
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# Base model class
Base = declarative_base()