You don’t need Claude Fable to build a quality app. You just need to improve the thinking process. I have been using https://github.com/tuapuikia/deepthinking-ng (I am the maintainer) to maintain my enterprise app, which is written in Java and Golang. It results in less hallucination with better code quality.
Sorry, I only use the Gemini LLM for my workload, and it is still the best LLM out there.