Nanobanana Image Skill

Use the bundled nanobanana.py to generate or edit images with Gemini image models. The default path targets Nano Banana 2 (gemini-3.1-flash-image-preview) with thinking summaries and Google Search grounding on, because those defaults are the main reason to use this skill instead of a generic image prompt.

Requirements

1. GEMINI_API_KEY in ~/.nanobanana.env (GEMINI_API_KEY=sk-dummy) or the shell environment.
2. Python dependencies from requirements.txt.
3. The executable is nanobanana.py in this same skill directory. Resolve its absolute path once before running it.

The CLI can print --help without credentials. It validates local input files before creating an API client and exits non-zero when the API returns no image.

Defaults

Model gemini-3.1-flash-image-preview, search grounding on, thinking summaries on at level high, resolution 1K, and no aspect ratio unless the request implies a shape. Do not make the user choose a model, search mode, or thinking mode unless they asked for that level of control.

Leaving aspect ratio unspecified is usually better for edits, because Gemini can match the input image shape. For text-only generation, set one only when the user implies a format such as poster, square post, banner, phone wallpaper, or ultrawide hero.

Worth overriding: --model gemini-3-pro-image-preview for very detail-heavy or typography-sensitive work (slower); --resolution 512px for quick ideation (Nanobanana 2 models only), 2K/4K for polished deliverables; --thinking-level low when latency beats refinement; search off when the user wants a purely imaginative result. Run python3 /absolute/path/to/nanobanana.py --help for the exact accepted values, including the full aspect-ratio and model lists.