fix(security): harden uploads and wecom binding

backend/app/models/__init__.py

@@ -10,6 +10,7 @@ from app.models.daily_note import DailyNote
 from app.models.ai_summary import AISummary
 from app.models.system_config import SystemConfig
 from app.models.leave import Leave
+from app.models.wecom_bind_token import WecomBindToken
 
 __all__ = [
     "User",
@@ -24,4 +25,5 @@ __all__ = [
     "AISummary",
     "SystemConfig",
     "Leave",
+    "WecomBindToken",
 ]

backend/app/models/wecom_bind_token.py

@@ -0,0 +1,18 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.database import Base
+
+
+class WecomBindToken(Base):
+    """A single-use, expiring binding token issued after a verified WeCom callback."""
+
+    __tablename__ = "wecom_bind_tokens"
+
+    token: Mapped[str] = mapped_column(String(64), primary_key=True)
+    wecom_userid: Mapped[str] = mapped_column(String(100), index=True)
+    expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), index=True)
+    consumed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())