Port a Bedrock image call to Sume /v1/images in Python

A Bedrock image call posts a task-specific JSON body and reads images from the response. Sume's call is one flat JSON body with the same fields for every model. The mapping is mostly renaming, plus three behaviour changes.

Three behaviour changes

• Results are URLs, in data[].url, not base64 strings.
• The call waits 30 seconds by default, then returns 202 with a job envelope. Handle it.
• Errors come back as an envelope with category, retryable and next_action, and failed jobs are not billed.

A wrapper with the same return type

Most Bedrock callers want bytes back. This wrapper returns bytes and raises on anything that is not a finished image, so your downstream code does not change.

import os, requests

def generate_bytes(prompt: str, source_url: str | None = None,
                   model: str = "google/nano-banana-2") -> bytes:
    body = {"model": model, "prompt": prompt}
    if source_url:
        body["input_references"] = [
            {"type": "image_url", "image_url": {"url": source_url}}]
    r = requests.post("https://api.sume.com/v1/images", json=body, timeout=90,
        headers={"Authorization": f"Bearer {os.environ['SUME_API_KEY']}"})
    if r.status_code != 200:
        raise RuntimeError(f"{r.status_code}: {r.text[:200]}")
    return requests.get(r.json()["data"][0]["url"], timeout=60).content

open("out.png", "wb").write(generate_bytes("A ceramic mug on a wooden table"))

A 202 raises in this wrapper. Add the polling loop from the timeout post when you move to higher qualities or sizes.