Codex Imagegen

Claude directs and reviews; Codex only generates. Use the user's Codex subscription; never use a separately billed image API. Requires Python 3.9+, macOS/Linux, and logged-in Codex CLI 0.164.0+ (codex login). Resolve <SKILL_DIR> from this file.

Route by intent

Do not load every reference, repository documentation, or launcher source. Reuse answers and relevant project style facts already in context. Read DESIGN.md only when matching this project's style. Do not run Codex to interview, plan, or judge.

Make the brief

Use the user's language. Specify intended use, subject, medium, framing, light, palette, and constraints only where they affect this image. Preserve detailed user direction; omit irrelevant fields. For styled or illustrated images, set value contrast, palette roles, and one focal subject first (prompting-guide.md). Aim for 80–180 words for a normal image, shorter for a local edit; exact copy and necessary preservation rules take priority.

Asset: website hero for a notes app, landscape 16:9, one image
Request: an open notebook and a few index cards on a clean desk
Look: editorial product photograph; soft window light from the left;
matte paper texture, natural shadows; warm ivory and ink-blue palette
Composition: subject in the right third; quiet empty left half for page copy
Constraints: no readable writing, logos, watermark, border, or extra objects

Quote exact text with its placement and one occurrence. For references add Image 1: base to edit; Image 2: material reference only in attachment order. Send only this final brief and necessary images to Codex, never the conversation, interview answers, research, this skill, or a whole design document.

Generate and inspect

Write a UTF-8 brief using the host's file-write tool, then start in the background:

python3 "<SKILL_DIR>/scripts/image_project.py" --prompt-file "<BRIEF>" --out-dir "<NEW_DIR>" --background
# Attach inputs with --image "<BASE.png>" (repeat in reference order).

This returns a job directory immediately. Continue independent requested work; check later with image_project.py --out-dir "<DIR>" --status (no Codex call). Do not poll repeatedly or claim completion while queued/running. If images are the only work, wait with the host's background-task mechanism. Read completed paths from the manifest, then inspect them. Multi-image plans: directions.md. For foreground execution use run_codex_imagegen.py.

The default and recommended relay is gpt-6-luna with reasoning none, compact instructions, no skills catalog, and unrelated tools disabled. Both scripts accept --model and --reasoning-effort to change it; that is the text relay, NOT an image model. Codex's server picks the image model, quality, and size; no flag, brief wording, or output metadata selects or reveals it. Never call an output a specific GPT Image version or variant; if asked, say Codex chose the model server-side. Do not claim an API quality setting, native 4K, or pixel-perfect preservation.

Copy only completed manifest images (or launcher-printed paths) to the user's destination or output/imagegen/<purpose>/. Preserve originals; version edits. Keep the final brief as output/imagegen/<purpose>/<image-name>.md, even when the PNG goes elsewhere. Never write briefs into the user's destination; asset folders such as public/ are often served. Skip confidential briefs. Inspect the image using Claude's image-reading tool at full view and relevant detail. Check intent, composition, literal text, anatomy/product geometry, preserved details, and edges. A valid path is not a quality pass. State any visible unresolved defect.

If transparency is requested, describe only the isolated subject and say "transparent background" (the relay then sets the tool's transparent_background flag). A described backdrop, floor, or scene can override the flag. Then run:

python3 "<SKILL_DIR>/scripts/verify_png_alpha.py" "<PNG>"  # add --require-transparent-corners for isolated cutouts

If the subject must be fully solid (alpha is often 250–254), write a copy with scripts/solidify_png_alpha.py <PNG> <OUT.png>. Do not mistake checkerboard pixels for alpha. A cutout of an existing photo is re-rendered: compare labels, text, and framing with the source (editing.md). Measure actual dimensions before export; codex-cli 0.153.2–0.166.0 returned ≈1.57 MP, which is not a resolution guarantee. Resize proportionally; crop/pad intentionally, never stretch. Label upscaling honestly.

Generate only the requested count. Allow at most one targeted repair per rejected image; do not automatically polish accepted work, retry timeouts, or rerun a whole set. User-requested revisions begin a new edit. Return previews, usable file paths, and one useful next step, such as “pick 2 and tell me what to change.”