Transparent Icons

Transparent Icons

Generate flat scientific icons with transparent backgrounds, styled by the project's figures/theme.json, for use as panel elements in figures:scientific-figure, in figures:svg-primitives schematics, or on their own in posters, slides, and grants. Sister skills are invoked by their fully qualified figures:<skill> names through the host's skill-invocation mechanism. Keep host-specific command or tool syntax in the host adapter, not in shared skill instructions.

Backends

Generation goes through the shared backend in plugins/figures/lib/image_backend.py, the same one figures:ai-full-figure uses.

1. Codex CLI image_gen (default when codex is logged in). No API key needed. The model and effort come from the theme's model_preferences (default gpt-5.6-luna at xhigh), which lands good icons at the cheapest tier in one to two minutes each.
2. OpenAI Images API (--backend api) with OPENAI_API_KEY.
3. Atlas Cloud (--backend atlas) with ATLASCLOUD_API_KEY. This is explicit-only; it never changes the Codex-first auto route. The default model is black-forest-labs/flux-schnell, and the asynchronous result is polled with a bounded timeout.

The backend preflights Codex with a 10 second timeout and explains the fix when the binary hangs (approve it once from Terminal.app, or copy codex and codex-code-mode-host to a folder you own, xattr -c both, and set CODEX_BIN). --backend fake renders placeholder icons for tests.

Transparency

Icons are requested with a transparent background and the model's alpha channel is kept as is. --transparency-method auto (default) runs no local processing when the PNG already has a clean cutout, so light strokes are never eaten by a second threshold pass. If the returned image is opaque, auto falls back to threshold (Pillow near-white removal); birefnet (opt-in, --with rembg --with onnxruntime) gives cleaner edges on complex foregrounds.

Usage

Free-form subject with the project theme:

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uv run --with pillow python scripts/generate_icon.py \
    "a human brain with EEG electrodes" --theme figures/theme.json -o icons/brain_eeg.png

From the icon bible (curated templates with prompt hints):

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uv run --with pillow python scripts/generate_icon.py --template brain-eeg --theme figures/theme.json -o icons/brain_eeg.png
uv run --with pillow python scripts/generate_icon.py --list-templates
uv run --with pillow python scripts/generate_icon.py --category neuroscience --theme figures/theme.json -o icons/

Batch with a placeholder:

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uv run --with pillow python scripts/generate_icon.py "a flat icon of a {item}" \
    --batch "neuron,synapse,electrode" --theme figures/theme.json -o icons/

Other flags: --colors "teal,coral" overrides the theme palette for one run; --size 1024 (square); --backend auto|codex|api|fake|atlas; --atlas-model; --codex-bin; --timeout; --verbose; --print-prompt. A log is written next to each output as <out>.codex.log.

Atlas example (explicit opt-in):

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ATLASCLOUD_API_KEY=... uv run --with pillow python scripts/generate_icon.py \
    --template neuron --backend atlas --atlas-model black-forest-labs/flux-schnell \
    -o icons/neuron.png

Theme bible

Icons should never be generated without a theme when they need to match other figures. Invoke figures:figure-bible to scaffold and validate figures/theme.json (schema at plugins/figures/schemas/theme.schema.json). The icon prompt uses palette, stroke.weight_px, style_tokens, negative_tokens, composition, and model_preferences. examples/icon_set.py generates a small consistent set from one theme.

Quality assurance

Invoke figures:figure-qa after generation unless the user passed no-qa. Its raster branch checks the alpha channel and corners (--expect-transparent), palette compliance against the theme (--palette figures/theme.json), resolution, and dominant colours, and the vision pass judges whether the icon reads as the intended concept, which is the most common miss.

Additional resources

• references/icon-bible.md: template schema and category catalog
• references/prompt-patterns.md: prompt patterns and failure modes for icons
• scripts/generate_icon.py: CLI entry point
• scripts/icon-templates.json: bible templates loaded by --template and --category
• examples/icon_set.py: themed icon set (--smoke for a one-icon check)
• Shared code: ../../lib/image_backend.py, ../../lib/prompting.py, ../../lib/theme.py