These products are not complicated at their core — you can pretty much just drop in something like Monacopilot [1] and be 80% of the way there. But the last 20% is a real slog, and it mostly comes down to handling edge cases (bracket closing...) and optimizing prompting/context so you aren't burning cash. Whatever anyone claims about "feeling the AGI," AI isn't there yet.
[1]: https://github.com/arshad-yaseen/monacopilot