A community-maintained third-party Codex skill (MIT licensed): the Codex App in API mode has no built-in imagegen, and with this skill installed it can generate images through the OpenAI-compatible image endpoint you configure — LMU AI's gpt-image-2.

Do I have to fill in a base URL and API key separately?

No. At runtime it reads `OPENAI_API_KEY` from `~/.codex/auth.json` and the provider's `base_url` from `config.toml` — exactly the config you already set up when connecting Codex App to LMU AI. Install and use.

Image generation fails with model_not_found or 403

Your key's group doesn't expose `gpt-image-2`. Check the group's model list under "Available models" in the console, or switch to a group with image generation enabled.

Where do generated images get saved?

By default to Codex's current working directory, with names like `provider-image-20260920-153000.png`; name a path in the conversation to save them elsewhere.

Codex App image generation (api-image skill)

Install the community api-image skill in Codex App to restore image generation in API mode — zero extra config with LMU AI, just ask in plain language for text-to-image, image-to-image and inpainting.

api-image is a community skill (MIT licensed): the Codex App in API mode has no built-in imagegen, and once this skill is installed it can generate images through the OpenAI-compatible image endpoint you configure yourself. With LMU AI it's zero extra config — it reuses the key and endpoint already in your ~/.codex, and one sentence in the conversation is enough.

Third-party community skill

It runs on your machine, reads the key from ~/.codex/auth.json, and sends your prompt and reference images to the provider — make sure you're comfortable with that before installing. The author also notes compatibility varies between providers, so treat real error messages as the source of truth.

Install: one sentence to Codex

Open the Codex App and just say:

Install the skill at https://github.com/yc-duan/api-image — I want to generate images with the OpenAI image 2 standard API; see the usage instructions at https://github.com/yc-duan/api-image

Codex puts the repo into ~/.codex/skills/api-image itself (%USERPROFILE%\.codex\skills\api-image on Windows); restart the Codex App afterwards.

Manual install works too:

git clone https://github.com/yc-duan/api-image.git ~/.codex/skills/api-image

Use: still one sentence

You want	Say this
Text to image	Use api-image to generate a 2048x1152 cinematic photo: a rainy Tokyo street at night, neon reflections, realistic photography style
Image to image	Using this image's composition and pose as a reference, generate a warm illustration — keep the subject's pose, don't copy the original
Inpainting	Change the red cup in this image to green, keeping the original shape, composition and lighting
Explicit options	Use api-image to generate a 1024x1024 flat illustration, quality low, two images, saved to ./public/cover.png

The defaults are gpt-image-2, 2048x1152, quality high, one image; size, quality, count and output path can all be changed right in the conversation. Output lands in the current working directory by default (provider-image-<timestamp>.png).

Notes

Nothing to configure for LMU AI: the skill reads the auth.json (key) and config.toml (endpoint) you already set up when connecting to LMU AI, corresponding to the full endpoints https://api.lmuai.com/v1/images/generations and /v1/images/edits
model_not_found / 403: your key's group doesn't include the image model — check "Available models" in the console or switch groups
gpt-image-2 doesn't support transparent backgrounds; the upstream may normalize requested sizes, so trust the actual output

Last updated: 2026-09-20

Codex App image generation (api-image skill)

Install: one sentence to Codex

Use: still one sentence

Notes

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