Ch Imagegen

CH Imagegen

Use this skill for local codex-helper image generation. It calls the proxy's OpenAI-compatible /v1/images/generations endpoint, or /v1/images/edits when reference images are passed with --image, saves the returned base64 image, and validates only the newly written file.

Rules

• Do not use the system .system/imagegen workflow for requests that explicitly ask for ch-imagegen or local codex-helper image generation.
• Require a running codex-helper proxy that exposes /v1/images/generations; reference-image mode additionally requires /v1/images/edits.
• Do not ask the user to paste provider API keys. Upstream credentials belong in codex-helper config or environment variables.
• Treat scripts/generate_image.py exit code and stdout JSON as the source of truth.
• If the script exits non-zero, report the error and stop. Do not infer success from older files.
• Default Image API model intent: gpt-image-2.
• Default Responses wrapper model: gpt-5.5, sent as the helper-only responses_model JSON field so the local bridge uses /v1/responses hosted image_generation through the same kind of mainline model path as Codex's built-in imagegen tool.
• Default resolution: 2k; default aspect ratio: 16:9; default output format: png; default quality: high.
• Use 4k only when the user explicitly needs final-resolution output. Set a tool/shell timeout longer than the script timeout plus retry buffer; do not use a 120s shell timeout for 4K images.
• Treat stdout JSON as authoritative for both success and failure. On failure the script prints ok:false with error.status, error.classification, error.request_id, error.failure_hint, error.retryable, error.attempts, and error.suggested_action.
• If error.classification is image_generation_route_failed and error.failure_hint is all_upstreams_failed or route_unavailable, report that the configured codex-helper route did not have a currently usable image-capable upstream for the requested model. Do not present that as a prompt, reference image, or resolution problem unless the error says so explicitly.
• Do not automatically fall back to the system .system/imagegen workflow after local proxy failure. It may use a different account/path; ask or use it only when the user explicitly approves that bypass.
• Save final outputs under output/imagegen/ unless the user specifies another directory.

Command

python "${CODEX_HOME:-$HOME/.codex}/skills/ch-imagegen/scripts/generate_image.py" \
  --prompt "<user prompt>" \
  --aspect "16:9" \
  --resolution "2k"

Reference image mode:

python "${CODEX_HOME:-$HOME/.codex}/skills/ch-imagegen/scripts/generate_image.py" \
  --prompt "<user prompt>" \
  --image "/path/to/reference.png" \
  --aspect "3:4" \
  --resolution "2k"

Useful overrides:

• --base-url "http://127.0.0.1:3211/v1/images/generations"
• --edits-base-url "http://127.0.0.1:3211/v1/images/edits"
• --responses-model "gpt-5.5" to choose the hosted image_generation wrapper model used by codex-helper's /v1/responses bridge
• --image "reference.png"; may be repeated; accepts local image paths, data:image/..., HTTP(S) URLs, and file_id values
• --input-fidelity "high" for reference-image edits
• --aspect "4:3" or --aspect "9:16"
• --resolution "4k" for explicit final output
• --resolution "2k"
• --fallback-resolution "2k" when trying 4K but willing to retry smaller after route/provider failures
• --size "3840x2160"
• --quality "medium"
• --retries 2
• --retry-delay 30
• --output-format "webp"
• --title "short-slug"
• --out-dir "output/imagegen"
• --dry-run

Size behavior

• 4k and 2k are pixel-budget presets. The script computes a valid model size from the requested aspect ratio.
• Explicit sizes are clamped to gpt-image-2 limits: max edge 3840, total pixels no more than 8,294,400, long-to-short ratio no more than 3:1, and 16-pixel alignment.
• Use explicit 3840x2160 for 4K landscape or 2160x3840 for 4K portrait.

Validation

After generation, report:

• endpoint used;
• Image API model intent and Responses wrapper model;
• requested size and actual local image size;
• reference image count when present;
• output path;
• revised prompt if present.

If generation fails, report the structured error block from stdout, especially classification, failure_hint, request_id, retryable, and suggested_action.

Never scan old output files to guess that generation succeeded.