Initial commit: 浼佷笟寰俊 AI 鏈哄櫒浜哄姪鐞?MVP

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/models/session.py

@@ -0,0 +1,19 @@
+"""外部客户会话（企微单聊/群聊维度）。"""
+from datetime import datetime
+from sqlalchemy import String, DateTime, ForeignKey
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base
+
+
+class ChatSession(Base):
+    __tablename__ = "chat_sessions"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    external_user_id: Mapped[str] = mapped_column(String(128), nullable=False, index=True)  # 企微 external_userid
+    external_name: Mapped[str | None] = mapped_column(String(128), nullable=True)
+    status: Mapped[str] = mapped_column(String(32), default="open")  # open / transferred / closed
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=datetime.utcnow)
+    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    messages: Mapped[list["Message"]] = relationship("Message", back_populates="session", order_by="Message.id")