initial commit

backend/models.py

@@ -0,0 +1,25 @@
+from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from .database import Base
+
+class ChatSession(Base):
+    __tablename__ = 'chat_sessions'
+
+    id = Column(Integer, primary_key=True, index=True)
+    session_id = Column(String(64), unique=True, index=True, nullable=False)
+    name = Column(String(100), default="New Chat", nullable=False)
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+
+    messages = relationship("ChatMessage", back_populates="session")
+
+class ChatMessage(Base):
+    __tablename__ = 'chat_messages'
+
+    id = Column(Integer, primary_key=True, index=True)
+    session_pk = Column(Integer, ForeignKey('chat_sessions.id'), nullable=False)
+    role = Column(String(16), nullable=False)  # 'user' | 'assistant'
+    content = Column(Text, nullable=False)
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+
+    session = relationship("ChatSession", back_populates="messages")