The Hidden Memory Layer OpenAI Doesn't Talk About

According to official OpenAI docs, ChatGPT memory works in two ways: chat history (the model referencing past conversations) and saved memories (explicit notes you can view or delete in settings). But there appears to be a third layer that isn’t publicly documented: the “User Knowledge Memories”, a stable AI-generated summary of your entire chat history, structured as 10 dense paragraphs. It seems to be part of the assistant’s hidden system context, helping it personalize responses. I’ve been looking into this for a while, and I’m genuinely surprised it’s rarely discussed.