Python: Fix agent group chat bug related to function calling in ChatCompletionAgent (#8330)

### Motivation and Context

During a group chat, if using an OpenAIAssistantAgent, the addition of a
ChatCompletionMessage to the AssistantAgent channel was breaking because
we were including FunctionCallContent. Additionally, there needs to be
some translation of a FunctionResultContent type to a text type when
adding a ChatCompletionAgent message to an AssistantAgent thread
message. The AuthorRole can only be 'user' or 'assistant'.

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### Description

Fixes for the items mentioned above. This may not be a perfect solution,
but getting this in and I can revisit it to align more closely with how
dotnet handles the FunctionResultContent/TextContent as part of the
overall ChatMessageContent.
- This PR also adds a new sample showing mixed agent chat and a
ChatCompletionAgent using plugins.

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

Author: moonbox3

python/samples/concepts/agents/mixed_chat_agents_plugins.py

@@ -0,0 +1,118 @@
+# Copyright (c) Microsoft. All rights reserved.
+
+import asyncio
+from typing import Annotated
+
+from semantic_kernel.agents import AgentGroupChat, ChatCompletionAgent
+from semantic_kernel.agents.open_ai import OpenAIAssistantAgent
+from semantic_kernel.agents.strategies.termination.termination_strategy import TerminationStrategy
+from semantic_kernel.connectors.ai.function_choice_behavior import FunctionChoiceBehavior
+from semantic_kernel.connectors.ai.open_ai import AzureChatCompletion
+from semantic_kernel.contents.chat_message_content import ChatMessageContent
+from semantic_kernel.contents.utils.author_role import AuthorRole
+from semantic_kernel.functions.kernel_function_decorator import kernel_function
+from semantic_kernel.kernel import Kernel
+
+#####################################################################
+# The following sample demonstrates how to create an OpenAI         #
+# assistant using either Azure OpenAI or OpenAI, a chat completion  #
+# agent and have them participate in a group chat to work towards   #
+# the user's requirement. The ChatCompletionAgent uses a plugin     #
+# that is part of the agent group chat.                             #
+#####################################################################
+
+
+class ApprovalTerminationStrategy(TerminationStrategy):
+    """A strategy for determining when an agent should terminate."""
+
+    async def should_agent_terminate(self, agent, history):
+        """Check if the agent should terminate."""
+        return "approved" in history[-1].content.lower()
+
+
+REVIEWER_NAME = "ArtDirector"
+REVIEWER_INSTRUCTIONS = """
+You are an art director who has opinions about copywriting born of a love for David Ogilvy.
+The goal is to determine if the given copy is acceptable to print.
+If so, state that it is approved. Only include the word "approved" if it is so.
+If not, provide insight on how to refine suggested copy without example.
+You should always tie the conversation back to the food specials offered by the plugin.
+"""
+
+COPYWRITER_NAME = "CopyWriter"
+COPYWRITER_INSTRUCTIONS = """
+You are a copywriter with ten years of experience and are known for brevity and a dry humor.
+The goal is to refine and decide on the single best copy as an expert in the field.
+Only provide a single proposal per response.
+You're laser focused on the goal at hand.
+Don't waste time with chit chat.
+Consider suggestions when refining an idea.
+"""
+
+
+class MenuPlugin:
+    """A sample Menu Plugin used for the concept sample."""
+
+    @kernel_function(description="Provides a list of specials from the menu.")
+    def get_specials(self) -> Annotated[str, "Returns the specials from the menu."]:
+        return """
+        Special Soup: Clam Chowder
+        Special Salad: Cobb Salad
+        Special Drink: Chai Tea
+        """
+
+    @kernel_function(description="Provides the price of the requested menu item.")
+    def get_item_price(
+        self, menu_item: Annotated[str, "The name of the menu item."]
+    ) -> Annotated[str, "Returns the price of the menu item."]:
+        return "$9.99"
+
+
+def _create_kernel_with_chat_completion(service_id: str) -> Kernel:
+    kernel = Kernel()
+    kernel.add_service(AzureChatCompletion(service_id=service_id))
+    kernel.add_plugin(plugin=MenuPlugin(), plugin_name="menu")
+    return kernel
+
+
+async def main():
+    try:
+        kernel = _create_kernel_with_chat_completion("artdirector")
+        settings = kernel.get_prompt_execution_settings_from_service_id(service_id="artdirector")
+        # Configure the function choice behavior to auto invoke kernel functions
+        settings.function_choice_behavior = FunctionChoiceBehavior.Auto()
+        agent_reviewer = ChatCompletionAgent(
+            service_id="artdirector",
+            kernel=kernel,
+            name=REVIEWER_NAME,
+            instructions=REVIEWER_INSTRUCTIONS,
+            execution_settings=settings,
+        )
+
+        agent_writer = await OpenAIAssistantAgent.create(
+            service_id="copywriter",
+            kernel=Kernel(),
+            name=COPYWRITER_NAME,
+            instructions=COPYWRITER_INSTRUCTIONS,
+        )
+
+        chat = AgentGroupChat(
+            agents=[agent_writer, agent_reviewer],
+            termination_strategy=ApprovalTerminationStrategy(agents=[agent_reviewer], maximum_iterations=10),
+        )
+
+        input = "Write copy based on the food specials."
+
+        await chat.add_chat_message(ChatMessageContent(role=AuthorRole.USER, content=input))
+        print(f"# {AuthorRole.USER}: '{input}'")
+
+        async for content in chat.invoke():
+            print(f"# {content.role} - {content.name or '*'}: '{content.content}'")
+
+        print(f"# IS COMPLETE: {chat.is_complete}")
+    finally:
+        await agent_writer.delete()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())

python/semantic_kernel/agents/channels/open_ai_assistant_channel.py

@@ -4,6 +4,8 @@
 from collections.abc import AsyncIterable
 from typing import TYPE_CHECKING, Any
 
+from semantic_kernel.contents.function_call_content import FunctionCallContent
+
 if sys.version_info >= (3, 12):
     from typing import override  # pragma: no cover
 else:
@@ -36,6 +38,8 @@ async def receive(self, history: list["ChatMessageContent"]) -> None:
             history: The conversation messages.
         """
         for message in history:
+            if any(isinstance(item, FunctionCallContent) for item in message.items):
+                continue
             await create_chat_message(self.client, self.thread_id, message)
 
     @override

python/semantic_kernel/agents/open_ai/assistant_content_generation.py

@@ -47,7 +47,7 @@ async def create_chat_message(
     Returns:
         Message: The message.
     """
-    if message.role.value not in allowed_message_roles:
+    if message.role.value not in allowed_message_roles and message.role != AuthorRole.TOOL:
         raise AgentExecutionException(
             f"Invalid message role `{message.role.value}`. Allowed roles are {allowed_message_roles}."
         )
@@ -56,7 +56,7 @@ async def create_chat_message(
 
     return await client.beta.threads.messages.create(
         thread_id=thread_id,
-        role=message.role.value,  # type: ignore
+        role="assistant" if message.role == AuthorRole.TOOL else message.role.value,  # type: ignore
         content=message_contents,  # type: ignore
     )
 
@@ -78,6 +78,8 @@ def get_message_contents(message: "ChatMessageContent") -> list[dict[str, Any]]:
                 "type": "image_file",
                 "image_file": {"file_id": content.file_id},
             })
+        elif isinstance(content, FunctionResultContent):
+            contents.append({"type": "text", "text": content.result})
     return contents
 
 

python/tests/unit/agents/test_open_ai_assistant_base.py

@@ -810,9 +810,9 @@ async def test_add_chat_message(
 async def test_add_chat_message_invalid_role(
     azure_openai_assistant_agent, mock_chat_message_content, openai_unit_test_env
 ):
-    mock_chat_message_content.role = AuthorRole.TOOL
+    mock_chat_message_content.role = AuthorRole.SYSTEM
 
-    with pytest.raises(AgentExecutionException, match="Invalid message role `tool`"):
+    with pytest.raises(AgentExecutionException, match="Invalid message role `system`"):
         await azure_openai_assistant_agent.add_chat_message("test_thread_id", mock_chat_message_content)