pi-codex-image-gen

Create and edit images without leaving Pi.

pi-codex-image-gen turns natural-language requests and reference images into PNG, JPEG, or WebP assets through Codex image generation, using your existing ChatGPT Codex login instead of a separate API key.

Features

• Generate images in conversation — describe the asset you need and let Pi create it.
• Edit from references — transform up to five local or recent conversation images.
• Save where work happens — return images inline or organize them by project, session, or custom directory.
• No separate API setup — reuse your existing ChatGPT Plus/Pro Codex authentication.

Install

pi install npm:pi-codex-image-gen

During local development from this monorepo:

pi install /path/to/pi-mono/packages/pi-codex-image-gen

For a one-off test run without installing:

pi -e /path/to/pi-mono/packages/pi-codex-image-gen

To uninstall:

pi remove npm:pi-codex-image-gen

Quick usage

In a Pi session:

> Generate a pixel-art sword icon, 32×32, with a blue blade and gold hilt

The agent will invoke codex_generate_image with your prompt, optionally include up to five local or recent conversation images for editing, stream the response from the Codex backend, and save the resulting image to disk. The model parameter controls the Codex routing model, not the image model. The backend selects the image model; backendImageModel is "unknown" unless the response explicitly reports an image model.

The tool reports generation stages and the backend's returned size, quality, background, and format in details.reportedImage. These are server-reported values, not guarantees inferred from the prompt. details.byteCount records decoded bytes; details.generationDurationMs records elapsed generation/save time. Check the actual image before using it, especially for exact dimensions or alpha transparency.

Subscription reliability and limits

• Requests identify this package with a Pi User-Agent. There is no Codex impersonation, browser-cookie import, or paid API fallback.
• One five-minute network deadline covers the connection, retries, and stream. Escape cancels network work; the remote generation may still finish.
• Prompts: 32,000 characters. References: five regular PNG/JPEG/WebP files or conversation images, at most 20 MiB each and 50 MiB combined.
• Responses: 100 MiB total, with at most one 32 MiB decoded output image. Base64 and format signatures are checked; this is not a full image decoder. Backend text and revised prompts are limited to 4,000 characters; HTTP error bodies are read only up to 16 KiB and are not displayed.
• Transient HTTP failures have bounded retries. Quota exhaustion, moderation errors, failed/incomplete streams, connection errors, and deadlines are not automatically retried. Avoid immediately repeating an ambiguous failure: the first generation may have consumed quota.
• Local save settings are checked before generation. Existing files are never overwritten; a save failure still returns the inline image and a warning.
• Cloudflare challenges are reported as connection failures, not as proof that your subscription or image model is unsupported.

Images 2.5 and API fallback

The optional skills/imagegen/scripts/image_gen.py API CLI accepts --model gpt-image-2.5-flare or --model gpt-image-2.5-sunburst, including their 2026-09-08 snapshots. Both accept --quality xhigh and --quality max in addition to the existing quality settings. The CLI default remains gpt-image-2. Both 2.5 models support --size auto and custom dimensions such as 1536x864, under the documented size constraints. Resolutions above 2560x1440 are experimental.

GPT Image 2 now supports native transparency in preview: use --model gpt-image-2 --background transparent --output-format png (or webp) in confirmed CLI mode. This uses OPENAI_API_KEY and separate API billing. The Pi tool still uses chroma-key removal because it has no background parameter.

Public API model selection does not establish support for the same options on the private Codex backend. The extension does not expose Flare/Sunburst selection or claim that your account has received the Images 2.5 rollout.

In subscription tests on September 11, 2026, the direct endpoint accepted Flare, Sunburst, and an invalid model name without reporting a served model. It also returned different size, quality, and background values than requested. The Responses route generated an image successfully. These account-specific results do not justify a guaranteed subscription model selector. See the investigation and test procedure.

Authentication

Uses your existing openai-codex login — no OPENAI_API_KEY required. If you haven't logged in yet:

> /login

Select ChatGPT Plus/Pro (Codex) and complete the OAuth flow.

Configuration

Create a JSON config file at one (or both) of these locations:

Scope	Path
Global	~/.pi/agent/extensions/codex-image-gen.json
Project	<project-root>/.pi/extensions/codex-image-gen.json

Project config overrides global config only when project trust is active. If project trust is declined or otherwise inactive, project config is ignored and global config still applies. Example:

{
  "save": "global",
  "saveDir": "~/Pictures/generated",
  "model": "gpt-5.5"
}

Config keys

Key	Type	Default	Description
save	string	"global"	Default save mode (see below).
saveDir	string	—	Directory used when save=custom.
model	string	"gpt-5.5"	Codex routing model, not the backend image model.

Environment variables

Variable	Description
PI_CODEX_IMAGE_SAVE_MODE	Overrides the save config key.
PI_CODEX_IMAGE_SAVE_DIR	Overrides the saveDir config key (custom mode).
PI_OFFLINE=1	Disables install/update telemetry.
PI_TELEMETRY=0	Disables install/update telemetry.

Save modes

Mode	Behavior
none	Image is returned inline but not written to disk.
project	Saves to <project>/.pi/generated-images/<session-id>/.
global	Saves to ~/.pi/agent/generated-images/<session-id>/.
custom	Saves to a user-specified directory (requires saveDir or env). ~ and ~/... expand to the current user's home directory.

Tool parameters

Parameter	Type	Required	Description
prompt	string	✅	The image generation prompt.
model	string	—	Override the Codex model. Defaults to config or gpt-5.5.
outputFormat	string	—	png (default), jpeg, or webp.
save	string	—	Override save mode for this call.
saveDir	string	—	Directory when save=custom. Relative paths resolve under CWD.
referencedImagePaths	string[]	—	Up to five local images to edit. Relative paths resolve under CWD.
numLastImagesToInclude	integer	—	Include the most recent one to five conversation images for editing. Mutually exclusive with referencedImagePaths.

How it works

1. Resolves auth via Pi's openai-codex provider (ChatGPT session token).
2. Sends a Codex Responses API request to the routing model (default gpt-5.5) with the image_generation tool enabled.
3. For edits, attaches the selected local or conversation images to the request.
4. The backend selects an image model to generate or edit the image.
5. Parses the SSE stream and strictly validates the returned base64 and image format.
6. Saves the image according to the active save mode; persistence failures produce a warning without discarding a valid inline image.
7. Returns the image data inline plus metadata (model, format, path, revised prompt, usage).

Troubleshooting

Symptom	Cause	Fix
"Missing openai-codex credentials"	Not logged in	Run /login and select ChatGPT Plus/Pro (Codex)
401 / 403 response	Token expired	Re-run /login for openai-codex
429 response	Rate limited	Wait and retry; the extension retries automatically with backoff
"Codex did not return an image"	Backend refused the prompt	Rephrase the prompt and try again
"save=custom requires saveDir"	Missing config	Set saveDir in config or PI_CODEX_IMAGE_SAVE_DIR env var

License

Apache-2.0. See LICENSE.

This package includes imagegen skill helper files derived from OpenAI Codex, including skills/imagegen/scripts/image_gen.py. Those files remain under the Apache License, Version 2.0. See NOTICE and skills/imagegen/LICENSE.txt.