Why classify at all
Without the classifier, Efficiency mode would become the loophole. Users would type calculus problems into it to bypass Learn mode, and the whole product’s stance would collapse in a week.
With the classifier, the split is enforced automatically. You don’t have to think about which mode to be in. The product does that for you.
False positives
The classifier occasionally redirects a message that felt clearly non-academic. When this happens, hit “stay in Efficiency” and the message goes through. Those decisions are training data for the next tuning pass. Users see the bypass rate for their own subjects in Settings.
We prefer false positives to false negatives. A false positive is annoying. A false negative would let a student solve homework in the wrong mode — quietly poisoning the product for the students who use it correctly.
Availability
Efficiency mode is on for Student ($9.99/mo) and above. It’s off for Free — Sonnet-class inference on every general-assistant message is the largest driver of our per-user cost, and we can’t cover it in the free tier without compromising Learn mode. The free tier gets the surface that matters most; Efficiency is the paid add-on that eliminates the reason to keep another AI subscription open in a browser tab next to Brainback.