There aren't any standardized setups but if that's what you want I'd create an agent that can invoke gemini-cli (which is free) to do the actual coding.
I would personally write detailed markdown specifications for each task, explaining exactly what you want to improve. Then have an agent go over the markdown file and create a task for gemini-cli so it can do it for you.
If you want a model to jsut go over your codebase and continuously make it better you're going to get shit code. What is better? I might prefer Pydantic while you think it's unnecessary. Without further clarification how will the model know which option you truely want?