# Yux Nano Banana > Generate images using OpenRouter API with Gemini models. Triggers on "generate image", "create image", "draw", "nano banana", "生成图片", "画图", "信息卡片". Use when this capability is needed. - Skill: `tomevault-io/yux-nano-banana` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/yux-nano-banana` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/yux-nano-banana/raw - Safety review: pending (external: skill-scanner PASS, skillspector WARNING) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Integrations & APIs - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/yux-nano-banana --- # Nano Banana - Image Generation Generate images using OpenRouter API with Google Gemini models. ## CRITICAL: Image Data Safety Rules **Read `references/image-data-safety.md` before any API call.** It contains safety rules, the fixed API response structure, and common mistakes to avoid. ## Output Directory Save generated images to the current working directory by default. If the user specifies a custom output path, use that instead (expand `~` to home directory; create directory if it doesn't exist using `mkdir -p`). ## Step 1: Prerequisites Check ### 1.1 Verify required tools Run `which curl jq base64` to confirm all tools are available. If any are missing, inform the user and stop. ### 1.2 Verify API key Check if `$OPENROUTER_API_KEY` is set: ```bash echo "${OPENROUTER_API_KEY:+set}" ``` If empty, inform the user: "Please set `OPENROUTER_API_KEY` in your environment." and **stop immediately**. Never prompt the user to enter the key inline. ## Step 2: Parse User Intent Determine the operation type and parameters from the user's request: ### 2.1 Operation type - **Generate**: Create a new image from a text prompt (default) - **Edit**: Modify an existing image — user provides an image file path and editing instructions ### 2.2 Extract parameters - **prompt** (required): The text description for image generation/editing - **model** (optional): User-specified model shorthand (see Model Table below) - **source image** (optional, for edit): Path to an existing image file - **aspect ratio / dimensions** (optional): Include in prompt if specified by user - **style preset** (optional): A predefined style template (see Style Presets below) ## Step 2.5: Style Presets When the user's request matches a style preset, wrap their content with the preset's prompt template. The user only needs to provide the **topic/content** — the style instructions are injected automatically. ### Available Presets #### `infographic` — Hand-drawn Infographic Card **Trigger keywords**: "infographic", "info card", "信息图", "信息卡片", "科普卡片", "手绘卡片", "インフォグラフィック", "인포그래픽" **Prompt template** (wrap around the user's topic/content): ``` Create a hand-drawn style infographic card in landscape orientation (16:9 ratio). Subject: {USER_CONTENT} Style requirements: - Hand-drawn / sketch illustration style with a warm, friendly, artisanal aesthetic - Background: beige / cream color with subtle paper grain texture (NOT kraft paper, NO wrinkles or creases) - NO border or frame around the edges of the card - Clean, uncluttered layout with generous whitespace - Use hand-drawn icons, diagrams, and illustrations as the primary way to convey information - Minimal text — only short labels or annotations where necessary, the illustrations should tell the story - Color palette: warm earth tones, muted pastels, with occasional accent colors for emphasis - The overall feel should be like a beautifully illustrated notebook page — approachable and educational ``` **When this preset is detected**: 1. Extract the user's actual topic/content (the subject they want illustrated) 2. Replace `{USER_CONTENT}` in the template with their topic 3. Use the assembled prompt as the final prompt sent to the API 4. The user can still specify model choice (flash/pro) — pro is recommended for this style ## Step 3: Model Selection | Shorthand | Model ID | When to use | |-----------|----------|-------------| | flash | `google/gemini-2.5-flash-image` | User says "flash", "fast", "quick", "快速" | | pro (default) | `google/gemini-3-pro-image-preview` | Default — highest quality | If the user does not specify a model, use **pro**. ## Step 4: Build and Execute API Call ### 4.1 Detect platform ```bash uname -s ``` This determines the `base64` decode flag: `-D` on macOS (Darwin), `-d` on Linux. ### 4.2 Build request payload For **text-to-image generation**: ```bash curl -s -o /tmp/nano-banana-response.json -w "%{http_code}" \ https://openrouter.ai/api/v1/chat/completions \ -H "Content-Type: application/json" \ -H "Authorization: Bearer $OPENROUTER_API_KEY" \ -d '{ "model": "", "messages": [ { "role": "user", "content": "" } ] }' ``` For **image editing** (user provides a source image): 1. First verify the source file exists and is a valid image: ```bash ls "$SOURCE_IMAGE" && file --mime-type "$SOURCE_IMAGE" ``` If the file does not exist or is not an image, inform the user and stop. 2. Encode the source image to base64: ```bash base64 < /path/to/source.png | tr -d '\n' ``` Store the result in a variable. 3. Then build the request with the image inline: ```bash curl -s -o /tmp/nano-banana-response.json -w "%{http_code}" \ https://openrouter.ai/api/v1/chat/completions \ -H "Content-Type: application/json" \ -H "Authorization: Bearer $OPENROUTER_API_KEY" \ -d '{ "model": "", "messages": [ { "role": "user", "content": [ { "type": "image_url", "image_url": { "url": "data:;base64," } }, { "type": "text", "text": "" } ] } ] }' ``` **Important**: Always use `-o /tmp/nano-banana-response.json` to save the response to a file. The response contains base64-encoded image data that can be very large and would be truncated in stdout. Use `-w "%{http_code}"` to capture the HTTP status code in stdout. **Important**: For large base64 payloads (image editing), write the JSON body to a temp file first and use `curl -d @/tmp/nano-banana-request.json` to avoid shell argument length limits. ## Step 5: Parse Response and Save Image ### 5.1 Check HTTP status Check the HTTP status code returned by curl: - **200**: Success — continue to extract image - **401**: Authentication failed — stop - **402**: Insufficient funds — stop - **429**: Rate limited — stop - **Other non-200**: Show the raw error from response, stop ### 5.2 Validate image exists in response Validate image count (see `references/image-data-safety.md` for response structure): ```bash jq -r '.choices[0].message.images | length' /tmp/nano-banana-response.json ``` - If `0`, `null`, or fails → safety-filtered. Inform the user and stop. - If `1` or more → proceed to extraction. ### 5.3 Extract, decode, and save (single pipeline) Extract the base64 data, strip the data-URI prefix, and decode — all in one pipeline redirected to a file. **No intermediate temp file needed.** ```bash # OUTPUT_DIR defaults to "." (current directory). If user specified a custom path, expand ~ and ensure it exists: # OUTPUT_DIR=$(echo "$USER_SPECIFIED_PATH" | sed "s|^~|$HOME|") # mkdir -p "$OUTPUT_DIR" FILENAME="$OUTPUT_DIR/nano-banana-$(date +%Y%m%d-%H%M%S).png" jq -r '.choices[0].message.images[0].image_url.url' /tmp/nano-banana-response.json \ | sed 's|^data:image/[^;]*;base64,||' \ | base64 -D > "$FILENAME" # Use -d on Linux ``` Verify the file was created and has reasonable size (should be >100KB for a real image): ```bash wc -c < "$FILENAME" ``` If the file is 0 bytes or very small, extraction failed — inform the user and stop. ### 5.4 Cleanup ```bash rm -f /tmp/nano-banana-response.json /tmp/nano-banana-request.json ``` ## Step 6: Output Results Display the result: ``` === Image Generated === File: /path/to/nano-banana-20260329-143022.png Size: 256 KB Model: google/gemini-3-pro-image-preview ``` ## Error Handling Summary | HTTP Code | Error | Action | |-----------|-------|--------| | 401 | Invalid API key | Inform user, stop | | 402 | Insufficient funds | Inform user, stop | | 429 | Rate limited | Inform user, stop | | 200 but no image | Safety filter | Inform user, stop. Do NOT explore alternative jq paths — the response structure is fixed | | Network failure | Connection error | Inform user, stop | --- > Source: [wuyuxiangx/yux-claude-hub](https://github.com/wuyuxiangx/yux-claude-hub) — distributed by [TomeVault](https://tomevault.io).