Here, even making that distinction of prompt-as-most-recent-user-input-only, if we use context as how it's generally been defined in "context window" then RAG and such are not then part of the context. They are just things that certain applications might use to enrich the context.

But personally I think a focus on "prompt" that refers to a specific text box in a specific application vs using it to refer to the sum total of the model input increases confusion about what's going on behind the scenes. At least when referring to products built on the OpenAI Chat Completions APIs, which is what I've used the most.

Building a simple dummy chatbot UI is very informative here for de-mystifying things and avoiding misconceptions about the model actually "learning" or having internal "memory" during your conversation. You're just supplying a message history as the model input prompt. It's your job to keep submitting the history - and you're perfectly able to change it if you like (such as rolling up older messages to keep a shorter context window).