Claude Code で Nano Banana Pro を使う：画像を生成・編集するスキル

export SEEDROUTER_API_KEY="your-key"

#!/usr/bin/env python3
import argparse
import json
import os
import pathlib
import sys
import time
import urllib.error
import urllib.request

API = "https://api.seedrouter.ai/v1"
AGENT = "nano-banana-pro-skill/1.0"
MIME = {
    ".jpg": "image/jpeg",
    ".jpeg": "image/jpeg",
    ".png": "image/png",
    ".webp": "image/webp",
    ".heic": "image/heic",
    ".heif": "image/heif",
}
RATIOS = ["1:1", "2:3", "3:2", "3:4", "4:3", "4:5", "5:4", "9:16", "16:9", "21:9"]


def call(method, path, body=None):
    request = urllib.request.Request(
        API + path,
        data=None if body is None else json.dumps(body).encode(),
        method=method,
        headers={
            "Authorization": "Bearer " + os.environ["SEEDROUTER_API_KEY"],
            "Content-Type": "application/json",
            "User-Agent": AGENT,
        },
    )
    try:
        with urllib.request.urlopen(request, timeout=60) as response:
            return json.load(response)
    except urllib.error.HTTPError as error:
        sys.exit(f"HTTP {error.code}: {error.read().decode()}")


def submit(args):
    parts = [{"text": args.prompt}]
    for url in args.ref:
        suffix = pathlib.PurePosixPath(url.split("?")[0]).suffix.lower()
        if suffix not in MIME:
            sys.exit(f"Cannot tell the image type of {url}; use a .jpg, .png, .webp, .heic or .heif URL.")
        parts.append({"fileData": {"mimeType": MIME[suffix], "fileUri": url}})
    image_config = {}
    if args.ratio:
        image_config["aspectRatio"] = args.ratio
    if args.size:
        image_config["imageSize"] = args.size
    generation_config = {"responseModalities": ["IMAGE"]}
    if image_config:
        generation_config["imageConfig"] = image_config
    body = {
        "model": args.model,
        "contents": [{"role": "user", "parts": parts}],
        "generationConfig": generation_config,
    }
    return call("POST", "/images/generations", body)["id"]


def wait(task_id, out_dir, timeout):
    deadline = time.monotonic() + timeout
    while time.monotonic() < deadline:
        task = call("GET", "/tasks/" + task_id)
        if task["status"] == "completed":
            out_dir.mkdir(parents=True, exist_ok=True)
            extension = "jpg" if task["output"]["output_format"] == "jpeg" else task["output"]["output_format"]
            for index, image in enumerate(task["output"]["data"]):
                path = out_dir / f"{task_id}-{index}.{extension}"
                download = urllib.request.Request(image["url"], headers={"User-Agent": AGENT})
                with urllib.request.urlopen(download, timeout=120) as response:
                    path.write_bytes(response.read())
                print(path)
            return
        if task["status"] == "failed":
            sys.exit(f"Task {task_id} failed: {task['error']['message']}")
        time.sleep(3)
    sys.exit(f"Task {task_id} is still processing. Resume with --resume {task_id}")


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--prompt")
    parser.add_argument("--ref", action="append", default=[])
    parser.add_argument("--ratio", choices=RATIOS)
    parser.add_argument("--size", choices=["1K", "2K", "4K"])
    parser.add_argument("--model", default="gemini-3-pro-image",
                        choices=["gemini-3-pro-image", "gemini-3-pro-image-official"])
    parser.add_argument("--out", default="images")
    parser.add_argument("--timeout", type=int, default=600)
    parser.add_argument("--resume")
    args = parser.parse_args()
    if args.resume:
        task_id = args.resume
    elif args.prompt:
        task_id = submit(args)
        print(f"task {task_id}", file=sys.stderr)
    else:
        parser.error("--prompt or --resume is required")
    wait(task_id, pathlib.Path(args.out), args.timeout)


if __name__ == "__main__":
    main()

python3 scripts/nano_banana_pro.py --prompt "A ceramic teapot on a linen tablecloth, soft window light" --ratio 16:9 --size 2K

---
name: nano-banana-pro
description: Generate or edit an image with Nano Banana Pro (gemini-3-pro-image) through the SeedRouter API and save it into the project. Use when the user asks for an image, illustration, icon, poster or edit of an existing image.
argument-hint: "[what the image should show]"
disable-model-invocation: true
---

Create an image for this request: $ARGUMENTS

1. Write one prompt in full sentences: subject, framing, action, setting and style. Put any text that must appear in the image in double quotes and say where it goes. For an edit, say what changes and what must stay the same.
2. Choose --ratio from 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9 and --size from 1K, 2K, 4K (4K only for print).
3. Reference images must be public HTTPS URLs ending in .jpg, .png, .webp, .heic or .heif, passed with --ref. If the user points to a local file, ask for a public URL instead. Never send base64.
4. Show the user the prompt and options, and wait for approval. Each run is a paid request.
5. Run: python3 ${CLAUDE_SKILL_DIR}/scripts/nano_banana_pro.py --prompt "..." [--ratio R] [--size S] [--ref URL]
6. If it stops with "still processing", run it again with --resume and the same task ID. Never submit the same request twice.
7. Report the saved file paths. If the task failed, explain the reason and suggest a change to the prompt.

nano-banana-pro/
├── SKILL.md
└── scripts/
    └── nano_banana_pro.py

/nano-banana-pro a 16:9 hero image for the pricing page: a calm desk with a laptop, a notebook and a cup of tea, soft morning light, muted green palette, no text

/nano-banana-pro edit the last image: keep the desk and the laptop, change the tea cup to a glass of water, and make the light warmer