Python: Exclude conversation_id from chat completions API options (#4517)

* Python: Exclude conversation_id from chat completions options (#4315)

When a session with service_session_id is passed to an agent using the
Chat Completions client, conversation_id leaked through _prepare_options()
into AsyncCompletions.create(), causing an 'unexpected keyword argument'
error. The Responses client already excluded conversation_id but the Chat
Completions client did not.

Added conversation_id to the exclusion set in _prepare_options().

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Apply pre-commit auto-fixes

* Remove reproduction report artifact

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/packages/core/tests/openai/test_openai_chat_client.py

@@ -1161,6 +1161,21 @@ def test_prepare_options_removes_parallel_tool_calls_when_no_tools(openai_unit_t
     assert "parallel_tool_calls" not in prepared_options
 
 
+def test_prepare_options_excludes_conversation_id(openai_unit_test_env: dict[str, str]) -> None:
+    """Test that conversation_id is excluded from prepared options for chat completions."""
+    client = OpenAIChatClient()
+
+    messages = [Message(role="user", text="test")]
+    options = {"conversation_id": "12345", "temperature": 0.7}
+
+    prepared_options = client._prepare_options(messages, options)
+
+    # conversation_id is not a valid parameter for AsyncCompletions.create()
+    assert "conversation_id" not in prepared_options
+    # Other options should still be present
+    assert prepared_options["temperature"] == 0.7
+
+
 async def test_streaming_exception_handling(openai_unit_test_env: dict[str, str]) -> None:
     """Test that streaming errors are properly handled."""
     client = OpenAIChatClient()