Generate a consistent asset set

Individual images are the generate-image skill. This is for families of assets that must look like they came from the same designer — which requires a shared style contract, correct sizes, and correct filenames.

Step 1 — lock the style contract

Before generating anything, write one style sentence you will paste verbatim into every prompt in the set. It must pin down: art style, palette (hex codes), stroke weight, corner treatment, background, and perspective. For example:

Flat vector, 2px uniform stroke, palette #2563EB on #FFFFFF with #94A3B8 accents, 4px rounded corners, centered, generous padding, no gradients, no shadows, front-on view.

Pull the palette from the project when one exists — check tailwind.config.*, CSS custom properties, a design tokens file, or an existing logo. Ask the user only if nothing is discoverable.

Step 2 — generate

One call per asset, style sentence repeated in each:

codex-imagegen "<subject>. <style contract>" <path>.png --size <WxH>

Generate the most important asset first (the logo mark or the hero), show it to the user, and only continue once they're happy. Regenerating a whole set after the fact wastes their quota.

For assets that must match one already generated, pass it as a reference so the model has the style in front of it, not just described:

codex-imagegen "a settings gear icon, same style as the reference" ./icons/settings.png --ref ./icons/home.png

Step 3 — derive the size variants locally

Do not regenerate for each size. Generate one large master and resample it with ImageMagick (or sips on macOS) — it's instant, free, and pixel-consistent:

magick master.png -resize 512x512 icon-512.png
magick master.png -define icon:auto-resize=16,32,48,64 favicon.ico

Standard recipes

Web favicon set — master at 1024x1024, then derive favicon.ico (16/32/48), favicon-32x32.png, apple-touch-icon.png (180x180), icon-192.png, icon-512.png.

Social / OG card — generate at 1536x1024, resample to 1200x630 (1200x630 isn't directly generatable: 630 is not a multiple of 16). Leave the centre clear if a title will be overlaid; ask whether text should be baked in — text renders reliably, but baked text can't be localised later.

iOS / Android app icon — master at 1024x1024, no transparency, no rounded corners (the OS masks them), subject centred with ~10% safe margin.

Icon family — all at 1024x1024 with the identical style sentence, downscaled to the size the UI actually uses.

Empty states / illustrations — 1536x1024, same palette as the product, generous whitespace so copy can sit alongside.

Rules

1. Verify visually. Read every generated PNG and check the set actually looks coherent side by side — not just each image on its own.
2. Name and place files conventionally: public/ or assets/ for web, kebab-case, size in the filename where a variant exists.
3. Budget honestly. A full favicon + OG + icon-family run is 8–12 generations and spends real ChatGPT quota. Say the expected count before you start and let the user trim the list.
4. Use a Bash timeout of at least 300000 ms per generation.
5. Only certain sizes are generatable: longest edge ≤ 3840, both edges multiples of 16, ratio ≤ 3:1, total pixels 655,360–8,294,400. Every standard icon size (16, 32, 180, 192, 512) is below that floor — which is exactly why you generate one large master and resample.
6. Use the path the wrapper prints. Codex avoids overwriting existing files and may write a versioned sibling (icon-v2.png); the wrapper detects that and reports the real path.

For sets larger than about four images, hand the whole brief to the codex-artist subagent so the generation loop stays out of the main conversation.