blankeos/crabcode/codex-imagegen

Codex Image Generation Skill

Generates or edits raster images for the current project by delegating to the official OpenAI Codex CLI via codex exec.

This skill is intentionally a subprocess bridge. Crabcode must not access Codex credentials directly, copy Codex auth headers, read ~/.codex/auth.json, or call private Codex/ChatGPT backend endpoints itself.

Top-level mode

This skill has exactly one mode:

• Codex CLI delegation mode: call the user-installed codex binary with codex exec and instruct Codex to use its own imagegen skill/tool. Codex handles authentication, model/tool access, image generation, and any subscription/quota accounting.

There is no API-key fallback in this skill.

Authentication rule

Before attempting generation, assume the user must have already run:

codex login

If codex exec fails because Codex is missing, unauthenticated, expired, or otherwise unable to access its account, respond exactly:

You must authenticate w/ `codex login`

Do not suggest OPENAI_API_KEY for this skill. Do not try to inspect or repair Codex credentials.

When to use

Use this skill when the user asks Crabcode to create, edit, transform, or derive bitmap assets, including:

• website or app hero images
• product mockups
• UI mockups or wireframes as images
• photos or photorealistic renders
• illustrations
• textures
• game sprites
• thumbnails
• icons that should be raster assets
• transparent-background or cutout-style PNGs
• variants based on an existing reference image

Do not use this skill when the task is better solved by:

• editing existing SVG/vector assets
• creating repo-native HTML/CSS/canvas
• extending an established logo/icon system in vector form
• making textual diagrams or Mermaid diagrams
• generating code instead of a bitmap file

Safety and boundary rules

• Always use the installed codex CLI as the actor that talks to OpenAI.
• Never read ~/.codex/auth.json or any Codex token store.
• Never spoof Codex headers, user agents, account IDs, or private endpoints.
• Never call https://chatgpt.com/backend-api/codex directly from Crabcode.
• Never use --dangerously-bypass-approvals-and-sandbox by default.
• Prefer --skip-git-repo-check because image output may be requested from temporary or asset folders.
• Keep the delegated prompt tightly scoped to image generation/editing and saving the output file.
• Instruct Codex not to modify unrelated files.
• After codex exec returns, verify the expected output file exists before reporting success.

Output path policy

Always establish a concrete destination path before invoking codex exec.

Path precedence:

1. If the user names a destination file, use that path.
2. If the image is intended for the current project but no path is specified, choose an appropriate path under the workspace, such as:

• assets/<descriptive-name>.png
• public/images/<descriptive-name>.png
• src/assets/<descriptive-name>.png
• output/imagegen/<descriptive-name>.png

1. If the image is only for brainstorming or preview, use output/imagegen/<descriptive-name>.png in the current workspace.

Prefer .png unless the user explicitly requests JPEG or WebP.

Create parent directories locally before calling Codex when practical.

Basic command shape

Use this pattern:

mkdir -p "$(dirname "$OUTPUT_PATH")"
codex exec --skip-git-repo-check \
  "Use your imagegen skill to generate: $IMAGE_REQUEST
 
Save or copy the final image exactly to: $ABSOLUTE_OUTPUT_PATH
Do not modify anything else.
If you are not authenticated, respond exactly: You must authenticate w/ \`codex login\`.
When done, reply with only the absolute saved path."

After the command finishes:

test -f "$OUTPUT_PATH"

If the file exists, report the saved path to the user. If it does not exist, inspect Codex stdout/stderr enough to determine whether this is an auth failure, CLI failure, or generation failure.

Prompting Codex

The delegated prompt should include:

• the exact user image request
• style, composition, aspect ratio, size, background, and format constraints from the user
• any reference image paths, if provided
• the exact absolute output path
• an instruction to not modify unrelated files
• the exact auth failure response
• an instruction to reply only with the saved path

Example delegated prompt:

Use your imagegen skill to generate a square PNG illustration of a cozy crab-shaped coding robot at a terminal, warm desk lamp, dark background, polished but playful.
 
Save or copy the final image exactly to: /absolute/path/to/public/images/crab-robot.png
Do not modify anything else.
If you are not authenticated, respond exactly: You must authenticate w/ `codex login`.
When done, reply with only the absolute saved path.

Existing image editing

If the user provides one or more reference images, pass their absolute paths in the delegated prompt and clearly describe how Codex should use them.

Example:

Use your imagegen skill to edit the reference image at /absolute/path/to/input.png.
Change the background to a clean studio gradient, preserve the object shape and colors, and export a PNG.
 
Save or copy the final image exactly to: /absolute/path/to/output/product-studio.png
Do not modify anything else.
If you are not authenticated, respond exactly: You must authenticate w/ `codex login`.
When done, reply with only the absolute saved path.

Do not embed large image files in the shell command. Prefer passing local file paths.

Transparent-background requests

For transparent-background or cutout requests, stay in Codex CLI delegation mode. Ask Codex to use its own imagegen workflow and save the final PNG to the requested path.

Example phrasing:

Use your imagegen skill to create a PNG cutout with a transparent background if your imagegen workflow supports it. If not, use the best supported workflow to produce a clean removable-background PNG.

Do not implement local chroma-key removal in this skill unless the user explicitly asks for local post-processing after generation.

Batch generation

For multiple assets, prefer one codex exec call per final asset unless the user explicitly asks for a batch in one call.

Each requested image should have a distinct output path. Verify every expected file exists.

Example paths:

output/imagegen/icon-idle.png
output/imagegen/icon-hover.png
output/imagegen/icon-active.png

Failure handling

If codex is not installed, unavailable on PATH, unauthenticated, or returns an auth/account error, respond exactly:

You must authenticate w/ `codex login`

If Codex succeeds but the expected file is missing:

• report that Codex did not create the expected output file
• include the expected path
• do not claim success
• optionally suggest rerunning with a simpler prompt or explicit output filename

If Codex creates a file at a different path and reports it clearly, move or copy it to the requested output path only if that is safe and unambiguous. Then verify the requested path exists.

Completion response

On success, keep the final response short:

Generated image saved to `<path>`.

If multiple files were generated:

Generated images:
- `<path-1>`
- `<path-2>`

Do not include Codex internals, credentials, account details, or raw base64 image data.