Best AI writing assistant for technical documentation?

Context: I freelance as a technical writer for software companies. Most of my work is how-to pages, API reference intros and release notes, written in Markdown in the client's repo. The things that decide whether a tool is useful for me are narrow:

• Does it invent flags, parameters or menu names that do not exist?
• Can it hold a style guide and a glossary across a whole page, not just the first paragraph?
• Does it keep numbered steps as numbered steps, with one action each?
• Is it allowed on a client's unreleased product details at all?

What I tried: I pasted an excerpt of the client's style guide and a short glossary at the top of each session, then asked for edits only, no new facts. That helped with tone and terminology. It did not stop the invented details when I asked it to write a procedure from a short description. Two of the invented menu names looked completely plausible, which is the dangerous part.

What I still want to know: how do you keep terminology consistent across forty pages when each session starts fresh, and how do you handle client NDAs? One client has no written position on AI tools, and I would rather ask before I paste anything.