app/db/database.py

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

DATABASE_URL = os.environ.get("DATABASE_URL", "sqlite:///./arxen.db")

# Fix Supabase / Heroku postgres:// -> postgresql:// for SQLAlchemy compatibility
if DATABASE_URL.startswith("postgres://"):
    DATABASE_URL = DATABASE_URL.replace("postgres://", "postgresql://", 1)

engine = create_engine(DATABASE_URL)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()