Is there a legal distinction between training, post-training, fine tuning and filling up a context window?
In all of these cases an AI model is taking a copyrighted source, reading it, jumbling the bytes and storing it in its memory as vectors.
Later a query reads these vectors and outputs them in a form which may or may not be similar to the original.
The context window is quite literally not a transformation of tokens or a "jumbling of bytes," it's the exact tokens themselves. The context actually needs to get passed in on every request but it's abstracted from most LLM users by the chat interface.
Judges have previously ruled that training counts as sufficiently transformative to qualify for fair use: https://www.whitecase.com/insight-alert/two-california-distr...
I don't know of any rulings on the context window, but it's certainly possible judges would rule that would not qualify as transformative.