One gpt-image-2 call, 9 hairstyle variants: prompt engineering for grid layouts

The first version of our hairstyle preview tool made 8 separate gpt-image-2 API calls — one per hairstyle. It worked. It was also $0.32 per preview, took 40 seconds, and the faces drifted between calls (each generation re-derived the face from the prompt + uploaded image). This post is about how we cut that to a single API call producing a 9-grid (1 reference + 8 variants) — same face, lower cost, faster, and weirdly easier to prompt. The 8-call problem Naive architecture: for ha...