j-dev originally started as a refactor of smol-dev but I quickly realized it was unrealistic to nuke your entire project and rebuild from scratch. Plus it was overly expensive in terms of tokens used.
j-dev is meant to be used in existing projects and allows the LLM have discretion over what it need to know about your codebase, while giving the user full control. j-dev also handles invalid responses, and updates your code with permission, all while providing full transparency and a relatively simple implementation.
From experience using it, it's somewhat useful although still often has a shallow understanding of the code base despite being able to request more. But hopefully this gets better as LLMs improve or I get better at prompt engineering.