I really wish it was more common to use AI for augmenting than authoring. Eg i find coding with LLMs neat when you primarily "talk" to it through code, by filling out structs, funcs, fields, etc - where it would use your changes as the template and then to work to effectively autocomplete the gaps. The more you iteratively write the less it fills in, but also the less it deviates from your intent, design, etc.
I feel like writing could use a similar harness, where it attempts to minimally reword the authors sentences, perhaps just tweaking grammar, spelling, etc. In the coding example i think the human code would be near unchangeable, the LLM would pivot around it - but in the writing example i think the human writing would have to be more mutable. I imagine it would be a configurable setting.
I've not really seen a system which focuses on this human<->LLM look, but it feels interesting to me.