fix demo issues

services/demo_session/app/models/demo_session.py

@@ -20,6 +20,7 @@ class DemoSessionStatus(enum.Enum):
     PARTIAL = "partial"      # Some services failed, others succeeded
     ACTIVE = "active"        # User is actively using the session (deprecated, use READY)
     EXPIRED = "expired"      # Session TTL exceeded
+    DESTROYING = "destroying"  # Session in the process of being destroyed
     DESTROYED = "destroyed"  # Session terminated
 
 
@@ -71,6 +72,9 @@ class DemoSession(Base):
     # Session metadata
     session_metadata = Column(JSONB, default=dict)
 
+    # Error tracking
+    error_details = Column(JSONB, default=list)  # List of error objects for failed sessions
+
     def __repr__(self):
         return f"<DemoSession(session_id={self.session_id}, status={self.status.value})>"