I would say it depends on what kind of text the LLM returns to you and what you do with it. If you're only receiving feedback and suggestions, and making the edits yourself, I would say that the final result is your writing. If you're asking the LLM to do a rewrite, and you're checking its results before sending it off as your own, then that's a bit blurrier... Like, if you gave that task to an actual human, would they need or expect to be credited as a ghost writer?

Personally, I use LLMs for writing assistance as well, but I never ask it to generate text. I only ask it to:

1. Do basic copy editing. I give it a version of my document with prefixed line numbers, and ask it to find any typos, grammatical errors, or "hard to parse" sentences, and then generate a table of lines with issues. I make all of the fixes myself.

2. Do style and sentiment analysis. I previously worked as a tech writer (design docs, test reports, policies, etc...), so my natural style has become incredibly dry. Too dry for what I try to write these days. So I ask the LLMs for feedback on readability, voice, descriptiveness, emotion, etc... Yes, I know they're not actually "performing" reviews, but there must be enough literary and language analysis embedded within the models that they can take my text and return an appropriate response. They provide basically the same feedback that I've received from actual human readers (mostly that my writing is too dry...), but they're obviously a lot faster. I specifically ask it not to provide suggestions for changes to the actual text.

It's no different than having a human editor.

My personal opinion is that, under reasonable circumstances, if you type the words yourself (that is, if your fingers make the keyboard clack), you own them. That definition explicitly excludes copy-and-paste.

The simple act of forcing a roundtrip through your brain and muscles might seem like a small barrier, but I think it's actually a big step in terms of forcing you to interact with the text and take ownership. It's also not practical to do for large blocks of text, and likely will find you putting your stamp on and slightly rewriting even medium-length passages. Both of which are features of the definition.

I recently generated a "plain English" document out of a huge technical spec, and steering this process was the main time sink.

Opus 5.5 will make broad changes in meaning and scope, but subtly. A human copy editor would at least pause before making claims unsupported by evidence (unless they're marketing); an LLM will happily fill in the gaps. Adversarial checks are helpful but have limits.

Unfortunately, I believe most people's command of written language is simply limited (including their native tongue), so they genuinely don't notice or care.

Using a copy editor in the way you describe is sensible, but I suspect many people will just do one pass and blindly apply every suggestion.

If an LLM is involved it is LLM-generated. These things are clearly the slippery slope par excellence, if you use them in some fashion and are allowed to downplay that fashion, it will very predictably expand to fill all of the space of work it is allowed to, and increasingly it will even impinge on your morals and ethics to do work it is not allowed to and avoid reporting it has done such.

These things are literally the chess engines of rules lawyering, the only effective move to limit them is to precommit to an unreasonable bright line.

I have met a bunch of people who assure me they just use AI as an editor; almost invariably, they are incorrect about how much they let it write.

If the LLM says "the flow here is awkward, try connecting the thoughts better" and you do that by choosing words in your head and typing them, it's not LLM-generated.

But if you paste any output from the LLM into your document, or just wholesale roundtrip it through the LLM chat window, that's (at least partly) LLM-generated.