feat(监控): 完善系统监控、登录状态与访问审计能力

backend/app/models/user_login_session.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, String, func
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base_class import Base
+
+
+class UserLoginSession(Base):
+    """Server-side login activity record without storing credentials or raw IPs."""
+
+    __tablename__ = "user_login_sessions"
+
+    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True)
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    client_type: Mapped[str] = mapped_column(String(16), nullable=False, default="web")
+    client_platform: Mapped[str | None] = mapped_column(String(32), nullable=True)
+    client_version: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    client_source: Mapped[str | None] = mapped_column(String(32), nullable=True)
+    login_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    last_seen_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    ended_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    end_reason: Mapped[str | None] = mapped_column(String(32), nullable=True)