I played with Hise for a month last year and quickly learned that my brain doesn't have the interest and time to learn everything about scripting and development needed to create the semi complex plugins I'd like to; so I tried using LLMs with moderate success..
The most immediate issue I found has already been described here - the LLMs would continue to make the same basic scripting mistakes, assuming more standard Javascript. It can be reduced to some degree by providing the agents with strict rules and contexts, but they still revert to making an unacceptable number of the same basic mistakes that you've clearly instructed them not to, even when stating specific instructions directly within the prompts.
That's where it's been most obviously unusable for me; if I'm spending half the time reiterating the same basic Hise scripting errors back to the LLM, that's too much time and tokens wasted to achieve anything substantial. It's mostly the frustration of it that kills the motivation to continue, otherwise it has great potential!
I really hope this can be overcome to make plugin development viable for people like myself, who have the interest, but not necessarily the time and programming experience to achieve what we'd like to without the help of LLM agents.
It would be great to see Hise not only survive, but to potential thrive with AI. Hise has more going for it, that if updated with effective LLM scripting capacity would likely be worth the Hise and Juce license fees for me, over other free options.
Whoever implements AI plugin development the most efficient and appealing way will pocket our money at the end of the day.
BTW you can use the 'Recompile On File Change' Hise option along with an external editors Auto Save option to seamlessly auto compile plugins/scripts at the time you change window focus from external editor to Hise.