第二步

backend/app/models/user.py

@@ -0,0 +1,61 @@
+"""User 用户模型。"""
+
+from sqlalchemy import ForeignKey, Integer, String, Text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base, TimestampMixin, UUIDPrimaryKeyMixin
+
+
+class User(UUIDPrimaryKeyMixin, TimestampMixin, Base):
+    """用户模型。
+
+    技术审查 §2.2：users 表。
+    """
+
+    __tablename__ = "users"
+
+    username: Mapped[str] = mapped_column(
+        String(64),
+        unique=True,
+        nullable=False,
+        index=True,
+        comment="用户名",
+    )
+    email: Mapped[str] = mapped_column(
+        String(255),
+        unique=True,
+        nullable=False,
+        index=True,
+        comment="邮箱",
+    )
+    password_hash: Mapped[str] = mapped_column(
+        String(255),
+        nullable=False,
+        comment="Argon2id 密码哈希",
+    )
+    status: Mapped[str] = mapped_column(
+        String(16),
+        default="active",
+        nullable=False,
+        comment="状态 (active/disabled)",
+    )
+    plan_id: Mapped[str] = mapped_column(
+        String(32),
+        ForeignKey("plans.id"),
+        nullable=False,
+        comment="套餐 ID",
+    )
+    storage_used: Mapped[int] = mapped_column(
+        Integer,
+        default=0,
+        nullable=False,
+        comment="已用存储 (字节)",
+    )
+
+    # 关系
+    plan = relationship("Plan", back_populates="users", lazy="selectin")
+    knowledge_bases = relationship("KnowledgeBase", back_populates="user", lazy="selectin")
+    documents = relationship("Document", back_populates="user", lazy="selectin")
+
+    def __repr__(self) -> str:
+        return f"<User {self.username!r}>"