Skillshub nano-banana-pro-openrouter

Generate or edit images via OpenRouter with the Gemini 3 Pro Image model. Use for prompt-only image generation, image edits, and multi-image compositing; supports 1K/2K/4K output.

install

source · Clone the upstream repo

git clone https://github.com/ComeOnOliver/skillshub

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/ComeOnOliver/skillshub "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/github/awesome-copilot/nano-banana-pro-openrouter" ~/.claude/skills/comeonoliver-skillshub-nano-banana-pro-openrouter && rm -rf "$T"

manifest: skills/github/awesome-copilot/nano-banana-pro-openrouter/SKILL.md

source content

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.