That is good to know and thanks for the clarification. With this operating at the message level and not the thread or level, is context still preserved to actually have a conversation with GPT?
Yes. Each time you mention @AI in a thread, all prior mentions of @AI in the same thread, as well as its prior responses (up to the token limit for GPT-3.5) are resubmitted to the OpenAI API, so that it can continue the conversation including prior context.
Only messages that actually mention @AI are sent in plaintext to us, and then to OpenAI's API. All content shared between people without invoking the AI is fully end-to-end encrypted.