Introduce message kinds, and handle them appropriately in user and agent chat

backend/app_mixins/chat.py

@@ -86,14 +86,15 @@ class ChatMixin:
             print(f"Added agent #{agent_id} to chat #{chat_id}")
 
     # If an integer is passed in sender, it is interpreted as an agent id
-    def send_chat_message(self, chat_id, content, sender='user', thread_id=None):
+    def send_chat_message(self, chat_id, content, sender='user', thread_id=None, kind=None, subkind=None, format=None):
         with self.sql_session() as session:
             message = db.Message()
             message.chat_id = chat_id
             message.time = int(datetime.now().timestamp())
             message.last_edit = message.time
             message.sender = sender
-            message.kind = 'text'  # default kind
+            message.kind = kind or 'message'
+            message.subkind = subkind
             message.content = content
             message.thread_id = thread_id