Cheaper LLM labelling

I learned for this project that a logistic regression can be trained by streaming it one label at a time, and using gradient descent to nudge its weights toward a better fit. I haven’t fully worked through the derivation, but this is not that complicated as far as these things go. And the final result is just 3–10 lines of code depending on how you count. I wish I knew this years ago! It’s so elegant.