Built-in `imagegen` skill is available, but the `image_gen` tool is not exposed in Codex App

What version of the Codex App are you using (From “About Codex” dialog)?

26.818.41509 (build 6962)

What subscription do you have?

ChatGPT Pro

What platform is your computer?

Darwin 25.6.0 arm64 arm

What issue are you seeing?

Summary

The system-provided imagegen skill is installed and can be loaded, but the built-in image_gen tool is not exposed to the active Codex App task.

As a result, Codex cannot generate an image through the documented built-in image-generation path. It instead redirects the user to the CLI fallback and asks for a separately configured OPENAI_API_KEY.

Actual behavior

Codex discovers the system skill at:

~/.codex/skills/.system/imagegen/SKILL.md

The skill documents image_gen as its preferred built-in execution path, but image_gen is absent from the tool registry exposed to the active task.

No image is generated. Codex reports that the built-in image-generation capability is unavailable and suggests switching to the CLI fallback.

This appears to be a built-in capability-registration or task-tool-provisioning issue:

• The correct system skill is discovered.
• The request is correctly identified as an image-generation request.
• The required built-in image_gen tool is missing.
• No generated image or image-generation result is returned.

Impact

The Codex App exposes a system imagegen skill that cannot use its documented primary execution path. Users are redirected to a separate API-key-based CLI workflow even though the installed skill states that its built-in path does not require OPENAI_API_KEY.

What steps can reproduce the bug?

1. Launch Codex App on macOS.

1. Create a new projectless task.

1. Send the following exact prompt:

> 用内部的 imagegen 插件 给我生成一只可爱小猫在太空的图片

English equivalent:

> Use the internal imagegen plugin to generate an image of a cute kitten in space.

1. Codex discovers and loads the system-provided imagegen skill from:

~/.codex/skills/.system/imagegen/SKILL.md

1. The skill instructs Codex to use the built-in image_gen tool as the default execution path.

1. However, image_gen is not present in the tool registry exposed to the active task.

1. Observe that no image is generated. Codex instead reports that the built-in image-generation capability is unavailable and asks the user to use the CLI fallback, which requires a separately configured OPENAI_API_KEY.

The issue occurred in a new projectless task without any image inputs or project-specific configuration.

What is the expected behavior?

When the system-provided imagegen skill is selected, the Codex App should expose the built-in image_gen tool to the active task and allow the agent to invoke it.

For the reproduction prompt, Codex should:

1. Invoke the built-in image_gen tool.
2. Generate an image of a cute kitten in space.
3. Display the generated image directly in the Codex App.
4. Complete the request without asking the user to configure an external OPENAI_API_KEY.

This is consistent with the installed skill documentation, which states that the built-in image_gen path is the preferred default and does not require OPENAI_API_KEY.

If the built-in capability is unavailable for the current account, model, or deployment, the app should clearly report the unavailable feature state. It should not expose a system skill whose required built-in tool is missing from the task.

Additional information

Environment

• Codex App version: 26.818.41509
• Build: 6962
• Bundle identifier: com.openai.codex
• Platform: Darwin 25.6.0 arm64 arm
• Task type: Projectless task
• Request language: Chinese
• Date observed: 2026-08-23

Relevant system skill

The skill is installed at:

~/.codex/skills/.system/imagegen/SKILL.md

The installed skill documentation explicitly states:

Default built-in tool mode (preferred): built-in image_gen tool for image generation, editing, and transparent-image requests. Does not require OPENAI_API_KEY.

It also states:

Use the built-in image_gen tool by default for normal image generation and editing requests.

The skill itself is therefore available and correctly selected, but its required built-in tool is absent from the active task's tool registry.

Result

• The prompt was accepted.
• The correct imagegen skill was discovered.
• No image_gen capability was exposed.
• No image-generation call was made.
• No image was returned.
• Codex redirected the user to the CLI/API-key fallback.

Possible duplicate

GitHub suggested issue #36370 as a potential duplicate while this report was being created. Please merge or close this report if it describes the same tool-provisioning issue.

Regression status

Unknown. I have not confirmed whether image generation worked in an earlier Codex App version.

I can provide the original conversation screenshot if additional reproduction evidence is needed.