FLUX.2 pro has seed control: why a seed fails on Sume

fal's FLUX.2 [pro] page lists seed control to keep results consistent across variations. Sume's Image API docs say seed is part of the schema but not advertised by any model today, so sending it returns 400 unsupported_parameter. For repeatable edits on Sume, pass the image you like as an input_references item and ask for small changes.

The seed claim is from fal's FLUX.2 pro page, read 2026-10-03. Sume's behaviour is from the Image API docs.

Vendor vs Sume

On fal the page names seed control and flexible JPEG or PNG output. Sume validates against what each model advertises, so a field absent from the catalog row is refused rather than ignored.

Prove it in your own account

This call sends a seed on purpose. If the catalog changes and a model starts to advertise it, the call will succeed; until then expect a 400.

import os
import requests

key = os.environ["SUME_API_KEY"]
payload = {
    "model": "black-forest-labs/flux.2-pro",
    "prompt": "a red bicycle against a white wall",
    "seed": 42
}
resp = requests.post(
    "https://api.sume.com/v1/images",
    headers={"Authorization": f"Bearer {key}"},
    json=payload,
    timeout=60,
)
if resp.status_code == 200:
    print([item["url"] for item in resp.json()["data"]])
elif resp.status_code == 202:
    print("still running:", resp.json()["data"]["status_url"])
else:
    print(resp.status_code, resp.text)

Limits

The response body is the source of truth; this post did not run the call against your account. Without a seed, two runs of the same prompt can differ, so save the URLs of results you want to keep.