But an LLM provider could very easily add a "Jev mode" to any existing model, right? LLMs already produce a probability distribution over arbitrary classes. Just tell e.g. 5.6 Luna “here is the user's question, you must respond ONLY with the words 'foo', 'bar', or 'baz',” run a single forward pass of the model, and report the normalized probabilities of 'foo' 'bar' and 'baz' tokens before the first output.
With such an approach you could even retain full reasoning capability