nano-banana-pro-openrouter by github

Nano Banana Pro OpenRouter

Overview

Generate or edit images with OpenRouter using the google/gemini-3-pro-image-preview model. Support prompt-only generation, single-image edits, and multi-image composition.

Prompt-only generation

uv run {baseDir}/scripts/generate_image.py \
  --prompt "A cinematic sunset over snow-capped mountains" \
  --filename sunset.png

Edit a single image

uv run {baseDir}/scripts/generate_image.py \
  --prompt "Replace the sky with a dramatic aurora" \
  --input-image input.jpg \
  --filename aurora.png

Compose multiple images

uv run {baseDir}/scripts/generate_image.py \
  --prompt "Combine the subjects into a single studio portrait" \
  --input-image face1.jpg \
  --input-image face2.jpg \
  --filename composite.png

Resolution

Use --resolution with 1K, 2K, or 4K.
Default is 1K if not specified.

System prompt customization

The skill reads an optional system prompt from assets/SYSTEM_TEMPLATE. This allows you to customize the image generation behavior without modifying code.

Behavior and constraints

Accept up to 3 input images via repeated --input-image.
--filename accepts relative paths (saves to current directory) or absolute paths.
If multiple images are returned, append -1, -2, etc. to the filename.
Print MEDIA: <path> for each saved image. Do not read images back into the response.

Troubleshooting

If the script exits non-zero, check stderr against these common blockers:

Symptom	Resolution
`OPENROUTER_API_KEY is not set`	Ask the user to set it. PowerShell: `$env:OPENROUTER_API_KEY = "sk-or-..."` / bash: `export OPENROUTER_API_KEY="sk-or-..."`
`uv: command not found` or not recognized	macOS/Linux: <code>curl -LsSf https://astral.sh/uv/install.sh \| sh</code>. Windows: <code>powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 \| iex"</code>. Then restart the terminal.
`AuthenticationError` / HTTP 401	Key is invalid or has no credits. Verify at https://openrouter.ai/settings/keys.

For transient errors (HTTP 429, network timeouts), retry once after 30 seconds. Do not retry the same error more than twice — surface the issue to the user instead.

Third-party checks

1 warning16d5 checks · Risk SAFE

Gen Agent Trust Hub16d
The skill is safe. It allows users to generate, edit, or composite images using the Gemini 3 Pro Image model via the OpenRouter API. Dependencies and API integrations follow standard development practices.
Socket16d
No alerts
Snyk16d
Risk: LOW · No issues
Runlayer7mo
3/3 files flagged
ZeroLeaks5mo
Score: 93/100 · 2 sections analyzed

Frequently asked

What image generation model does this skill use?

The skill uses the google/gemini-3-pro-image-preview model via OpenRouter. It supports prompt-only generation, single-image edits, and multi-image composition up to 3 images.

What output resolutions are supported?

The skill supports 1K, 2K, and 4K output resolutions via the --resolution flag. If not specified, it defaults to 1K.

Do I need to set up an API key?

Yes. You must set the OPENROUTER_API_KEY environment variable with a valid OpenRouter API key before running the skill.

Can I customize the image generation behavior?

Yes. The skill reads an optional system prompt from assets/SYSTEM_TEMPLATE to customize behavior without modifying code.

What should I do if I get an AuthenticationError?

Your API key is invalid or has no credits. Verify your key at https://openrouter.ai/settings/keys and ensure it has available balance.

Generated from the current SKILL.md. These answers refresh after source changes.

/nano-banana-pro-openrouter

SKILL.md