FLUX UI mockup prompts: app screens and game UI via one API call

Write the prompt as a layout brief: the screen type, the sections in order, and the visual style. BFL's guide says FLUX can generate website layouts, app interfaces and game UI mockups from descriptive prompts about structure and visual style. On Sume you send that prompt to POST /v1/images with a FLUX.2 id, an aspect_ratio that fits the screen, and n for variants.

BFL's guidance is from its UI Mockups page; request fields from Sume's Image API docs, read 2026-10-01.

What should a UI mockup prompt contain?

BFL's wording is to describe the layout structure, content sections and visual style. In practice: the device or window, the top-to-bottom order of regions, the text each region shows, and a style line such as "flat, light theme, rounded cards". Treat the result as a design concept, not production art.

Which request fields matter?

What does the call look like?

const res = await fetch("https://api.sume.com/v1/images", {
  method: "POST",
  headers: {
    Authorization: "Bearer " + process.env.SUME_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "black-forest-labs/flux.2-pro",
    prompt:
      "Mobile app home screen for a habit tracker: header with date, three habit cards with progress rings, bottom tab bar. Flat, light theme.",
    aspect_ratio: "9:16",
    n: 4,
  }),
});
console.log(res.status, await res.json());

What if a generation outlasts the wait?

Sume caps a blocking wait at 30 seconds; slower generations return a job envelope with 202 and you read the images from the job result. For ratio rules see image API aspect ratios and custom sizes.