Add model_context property to AssistantAgent (#6072)

AssistantAgent initiation allows one to pass in a model_context, but
there isn't a "public: way to get the existing model_context created by
default.

Author: jspv

python/packages/autogen-agentchat/src/autogen_agentchat/agents/_assistant_agent.py

@@ -702,6 +702,13 @@ def produced_message_types(self) -> Sequence[type[ChatMessage]]:
             message_types.append(ToolCallSummaryMessage)
         return tuple(message_types)
 
+    @property
+    def model_context(self) -> ChatCompletionContext:
+        """
+        The model context in use by the agent.
+        """
+        return self._model_context
+
     async def on_messages(self, messages: Sequence[ChatMessage], cancellation_token: CancellationToken) -> Response:
         async for message in self.on_messages_stream(messages, cancellation_token):
             if isinstance(message, Response):

python/packages/autogen-agentchat/tests/test_assistant_agent.py

@@ -615,6 +615,8 @@ async def test_model_context(monkeypatch: pytest.MonkeyPatch) -> None:
     ]
     await agent.run(task=messages)
 
+    # Check that the model_context property returns the correct internal context
+    assert agent.model_context == model_context
     # Check if the mock client is called with only the last two messages.
     assert len(model_client.create_calls) == 1
     # 2 message from the context + 1 system message