Directional Stimulus Prompting: steering a black-box LLM you cannot fine-tune

The strongest LLMs are often the ones you have the least control over. You reach them through an API, you cannot touch their weights, and your only lever is the text you send in. Hand-writing one clever prompt helps, but it is a single fixed instruction applied to wildly different inputs, so it under-steers the hard cases. Directional Stimulus Prompting (Li et al., 2023) is a genuinely clever answer to this, and I built an interactive demo of the loop to make it click. The idea: train a tiny…