first add

backend/app/core/database.py

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+"""SQLModel 数据库配置"""
+from typing import Generator
+from sqlmodel import Session, create_engine
+from sqlalchemy.orm import sessionmaker
+from .config import settings
+
+
+# 创建数据库引擎
+engine = create_engine(
+    settings.DATABASE_URL,
+    echo=settings.DEBUG,
+    pool_pre_ping=True,
+    pool_size=10,
+    max_overflow=20,
+)
+
+# 创建 SessionLocal
+SessionLocal = sessionmaker(
+    autocommit=False,
+    autoflush=False,
+    bind=engine,
+    class_=Session,
+)
+
+
+def get_session() -> Generator[Session, None, None]:
+    """
+    获取数据库会话（依赖注入）
+    """
+    with SessionLocal() as session:
+        yield session
+
+
+def init_db() -> None:
+    """初始化数据库（创建所有表）"""
+    from sqlmodel import SQLModel
+    from ..models.job import Job, Step, JobLog  # noqa: F401
+
+    SQLModel.metadata.create_all(engine)
+    print("✓ Database initialized")
+
+
+def drop_db() -> None:
+    """删除所有表（开发用）"""
+    from sqlmodel import SQLModel
+
+    SQLModel.metadata.drop_all(engine)
+    print("✓ Database dropped")
+
+