ab-image-gen

A provider-neutral skill for generating images and delivering them as verified files.

It does not own model access. Whatever image-capable model your harness can already dispatch is the model it uses. The skill adds the parts that are easy to get wrong: prompt craft, candidate discipline, artifact verification, provenance and release QA.

Requirements

• Python 3.10+
• Pillow

python3 -m pip install -r requirements.txt

No endpoint or credential configuration. scripts/*.py never make a network request and never read a credential.

Use

1. Ask your harness's image-capable model to produce the image.
2. Save the payload as a verified artifact:

python3 scripts/save_image.py \
  --input response.json \
  --output out/hero.png \
  --prompt "a blue circle on white" \
  --model "<model id>"

--input accepts an images API response (data[0].b64_json), a payload with b64_json / image_base64 / b64, or a raw image file. The tool writes the image plus <image>.json provenance and refuses to overwrite unless --overwrite is passed.

If the harness reports a successful generation but never hands back the payload — nothing renders, no file appears — recover the completed result instead of generating again. Mark before the call, extract after it:

python3 scripts/recover_harness_image.py mark --create-in tmp/ab-image-gen
python3 scripts/recover_harness_image.py extract \
  --marker "/absolute/path/printed/by/mark" \
  --out-dir output/ab-image-gen --name "descriptive-name"

The recovered payload goes through save_image.py, so the artifact and its provenance are identical in kind to a delivered one. The tool reads the harness's local task logs and never modifies them. See references/artifact-delivery.md.

Tools

Tool	Purpose
scripts/save_image.py	Verify a payload; write image + provenance
scripts/recover_harness_image.py	Recover a completed result the harness never handed back (Codex adapter)
scripts/inspect_image.py	Format, dimensions, mode, size, SHA-256
scripts/make_variants.py	Deterministic crops; keeps alpha; refuses overwrite

Verify

python3 -m unittest discover -s tests -v

Tests are local and require no credential and no network.