feat: Support Multiple System Messages with Better API

camel/agents/chat_agent.py

@@ -491,8 +491,8 @@ def __init__(
 
         # Set up system message and initialize messages
         self._original_system_message = (
-            BaseMessage.make_assistant_message(
-                role_name="Assistant", content=system_message
+            BaseMessage.make_system_message(
+                role_name="System", content=system_message
             )
             if isinstance(system_message, str)
             else system_message
@@ -1629,8 +1629,8 @@ def _generate_system_message_for_output_language(
             content = self._original_system_message.content + language_prompt
             return self._original_system_message.create_new_instance(content)
         else:
-            return BaseMessage.make_assistant_message(
-                role_name="Assistant",
+            return BaseMessage.make_system_message(
+                role_name="System",
                 content=language_prompt,
             )
 
@@ -1650,6 +1650,45 @@ def init_messages(self) -> None:
                 )
             )
 
+    def update_system_message(
+        self, system_message: Optional[Union[BaseMessage, str]] = None
+    ) -> None:
+        r"""Update the system message.
+        It will reset conversation with new system message.
+
+        Args:
+            system_message (Optional[Union[BaseMessage, str]]):
+                Can be either a BaseMessage object or a string.
+                If a string is provided, it will be converted
+                into a BaseMessage object.
+        """
+        self._original_system_message = (
+            BaseMessage.make_system_message(
+                role_name="System", content=system_message
+            )
+            if isinstance(system_message, str)
+            else system_message
+        )
+        self._system_message = (
+            self._generate_system_message_for_output_language()
+        )
+        self.init_messages()
+
+    def append_to_system_message(self, content: str) -> None:
+        original_content = (
+            self._original_system_message.content
+            if self._original_system_message
+            else ""
+        )
+        new_system_message = original_content + content
+        self._original_system_message = BaseMessage.make_system_message(
+            role_name="System", content=new_system_message
+        )
+        self._system_message = (
+            self._generate_system_message_for_output_language()
+        )
+        self.init_messages()
+
     def reset_to_original_system_message(self) -> None:
         r"""Reset system message to original, removing any appended context.
 

camel/messages/base.py

@@ -178,6 +178,29 @@ def make_assistant_message(
             OpenAIVisionDetailType(video_detail).value,
         )
 
+    @classmethod
+    def make_system_message(
+        cls,
+        role_name: str,
+        content: str,
+        meta_dict: Optional[Dict[str, str]] = None,
+    ) -> "BaseMessage":
+        r"""Create a new system message.
+        Args:
+            role_name (str): The name of the system role.
+            content (str): The content of the new system message.
+            meta_dict (Optional[Dict[str, str]]): Additional metadata
+                dictionary for the message.
+        Returns:
+            BaseMessage: The new system message.
+        """
+        return cls(
+            role_name,
+            RoleType.DEFAULT,
+            meta_dict,
+            content,
+        )
+
     def create_new_instance(self, content: str) -> "BaseMessage":
         r"""Create a new instance of the :obj:`BaseMessage` with updated
         content.