diff --git a/app/models.py b/app/models.py
new file mode 100644
index 0000000..c399487
--- /dev/null
+++ b/app/models.py
@@ -0,0 +1,135 @@
+"""数据模型"""
+from __future__ import annotations
+import uuid
+from datetime import datetime
+from sqlalchemy import Column, String, Text, Float, Integer, DateTime, ForeignKey, JSON, Boolean
+from sqlalchemy.orm import relationship
+from .database import Base
+
+
+class Agent(Base):
+    """Agent 定义"""
+    __tablename__ = "agents"
+
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    name = Column(String(255), nullable=False)
+    description = Column(Text, nullable=True)
+    system_prompt = Column(Text, nullable=True)
+    llm_provider = Column(String(100), nullable=True)
+    temperature = Column(Float, default=0.7)
+    max_tokens = Column(Integer, default=2048)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    tools = relationship("AgentTool", back_populates="agent", cascade="all, delete-orphan")
+    conversations = relationship("Conversation", back_populates="agent", cascade="all, delete-orphan")
+
+    def __repr__(self) -> str:
+        return f"<Agent(id={self.id}, name={self.name!r})>"
+
+
+class AgentTool(Base):
+    """Agent 绑定的工具"""
+    __tablename__ = "agent_tools"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    agent_id = Column(String(36), ForeignKey("agents.id", ondelete="CASCADE"), nullable=False)
+    tool_name = Column(String(255), nullable=False)
+    enabled = Column(Boolean, default=True)
+
+    agent = relationship("Agent", back_populates="tools")
+
+    def __repr__(self) -> str:
+        return f"<AgentTool(id={self.id}, agent_id={self.agent_id}, tool_name={self.tool_name!r})>"
+
+
+class Conversation(Base):
+    """对话会话"""
+    __tablename__ = "conversations"
+
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    agent_id = Column(String(36), ForeignKey("agents.id", ondelete="CASCADE"), nullable=False)
+    title = Column(String(255), nullable=True)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    agent = relationship("Agent", back_populates="conversations")
+    messages = relationship("Message", back_populates="conversation", cascade="all, delete-orphan")
+
+    def __repr__(self) -> str:
+        return f"<Conversation(id={self.id}, agent_id={self.agent_id}, title={self.title!r})>"
+
+
+class Message(Base):
+    """消息记录"""
+    __tablename__ = "messages"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    conversation_id = Column(String(36), ForeignKey("conversations.id", ondelete="CASCADE"), nullable=False)
+    role = Column(String(20), nullable=False)  # user / assistant / system / tool
+    content = Column(Text, nullable=True)
+    tool_calls = Column(JSON, nullable=True)
+    created_at = Column(DateTime, default=datetime.utcnow)
+
+    conversation = relationship("Conversation", back_populates="messages")
+
+    def __repr__(self) -> str:
+        return f"<Message(id={self.id}, conversation_id={self.conversation_id}, role={self.role!r})>"
+
+
+class Workflow(Base):
+    """工作流定义"""
+    __tablename__ = "workflows"
+
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    name = Column(String(255), nullable=False)
+    description = Column(Text, nullable=True)
+    definition = Column(JSON, nullable=True)
+    status = Column(String(50), default="draft")  # draft / active / archived
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    runs = relationship("WorkflowRun", back_populates="workflow", cascade="all, delete-orphan")
+
+    def __repr__(self) -> str:
+        return f"<Workflow(id={self.id}, name={self.name!r}, status={self.status!r})>"
+
+
+class WorkflowRun(Base):
+    """工作流执行实例"""
+    __tablename__ = "workflow_runs"
+
+    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    workflow_id = Column(String(36), ForeignKey("workflows.id", ondelete="CASCADE"), nullable=False)
+    status = Column(String(50), default="pending")  # pending / running / completed / failed
+    results = Column(JSON, nullable=True)
+    error = Column(Text, nullable=True)
+    started_at = Column(DateTime, default=datetime.utcnow)
+    completed_at = Column(DateTime, nullable=True)
+
+    workflow = relationship("Workflow", back_populates="runs")
+    steps = relationship("WorkflowStep", back_populates="run", cascade="all, delete-orphan")
+
+    def __repr__(self) -> str:
+        return f"<WorkflowRun(id={self.id}, workflow_id={self.workflow_id}, status={self.status!r})>"
+
+
+class WorkflowStep(Base):
+    """工作流步骤"""
+    __tablename__ = "workflow_steps"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    run_id = Column(String(36), ForeignKey("workflow_runs.id", ondelete="CASCADE"), nullable=False)
+    step_name = Column(String(255), nullable=False)
+    agent_id = Column(String(36), ForeignKey("agents.id"), nullable=True)
+    status = Column(String(50), default="pending")  # pending / running / completed / failed
+    input_data = Column(JSON, nullable=True)
+    output_data = Column(JSON, nullable=True)
+    started_at = Column(DateTime, default=datetime.utcnow)
+    completed_at = Column(DateTime, nullable=True)
+
+    run = relationship("WorkflowRun", back_populates="steps")
+    agent = relationship("Agent")
+
+    def __repr__(self) -> str:
+        return f"<WorkflowStep(id={self.id}, run_id={self.run_id}, step_name={self.step_name!r})>"