🧠 Image Model Selector (API Fallback)

The 🧠 Image Model Selector answers a question you'll ask five minutes after installing this pack: which Gemini model is actually drawing my images? It's a controller node from ComfyUI-Gemini3-API-Fallback that outputs a model name so you can drive the model input of every 🤖 Gemini 3 Pro Image node from one place.

The two options in the dropdown map to Google's two current image-generation models:

• gemini-3.1-pro-image-preview - the 4K flagship, the model Google rebranded as Nano Banana Pro. Native 4K output, strong multi-image reference handling, multi-language text rendering.
• Nano Banana 2 (Gemini 3.1 Flash Image) - the speed-quality hybrid, aimed at cheaper, faster generation for drafts and volume.

If you've seen the "Nano Banana" name floating around r/comfyui, this is it: Google's Gemini-native image line is one of the strongest closed image models out there, and it has no open weights - the only way it enters your ComfyUI graph is through an API node like this one.

How it works

Pick a model, and the node passes the string straight through its model output, exactly like the other selector nodes in this pack. No calls, no key, no validation. You wire the output into the model input of the Gemini 3 Pro Image nodes.

One thing worth knowing from the actual source code: on the direct Google API path, the pack currently remaps both dropdown entries to gemini-3-pro-image-preview under the hood. The two choices actually diverge when you're routing through ComfyUI credits - there, Nano Banana 2 is sent to Google as its own model ID (gemini-3.1-flash-image-preview). So don't expect a dramatic quality difference between the two options today; treat the dropdown as the lever you'll flip when the model line matures, and let the pack's mapping sort out the IDs.

The fields that matter

• model - the only input: gemini-3.1-pro-image-preview or Nano Banana 2 (Gemini 3.1 Flash Image).

Output: model, a single value that plugs into the model input of any Gemini 3 Pro Image node.

Installing it

No weights to download, no GPU - everything renders on Google's servers. ComfyUI Manager (search "ComfyUI-Gemini3-API-Fallback"), or:

cd ComfyUI/custom_nodes
git clone https://github.com/Latentnaut/ComfyUI-Gemini3-API-Fallback
python -m pip install google-genai pillow numpy requests

then restart ComfyUI. The selector needs no API key; the image node it feeds does - and that node needs billing enabled on the Google Cloud project, or image calls will come back with a Limit: 0 error.

For a single image node, just set model inside it and skip this controller. It earns its place when you're running several Gemini image nodes and want to switch the whole fleet's model with one click.