Kling 3 on Sume rejects reference_*_urls: which model takes references

If you send reference_image_urls, reference_video_urls or reference_audio_urls to the kling-3 row on Sume, the request is refused: the row supports text-to-video or start/end frames only, with no reference_*_urls. The fix is not a retry. Either drop the references and use image_url plus end_image_url, or change the model to a row whose capabilities list references.

The error text reads model kling-3 supports text-to-video or start/end frames only (no reference_*_urls). and names the model, so it is easy to confuse with a typo in the field name. It is not.

What kling-3 does take

Sume's catalog describes kling-3 as Kling Video v3 Pro. Its capabilities say text-to-video, image-to-video and end frame are on, all three reference flags are off, native audio is on, resolutions are 720p and 1080p, duration is 4 to 15 seconds, and aspect ratios are 16:9, 9:16 and 1:1.

Where references work instead

Rows with reference capabilities in the same catalog include wan-3.0, seedance-2.5, minimax-h3, minimax-h3-max and gemini-omni-flash-1.1. Their limits are not the same, so read each row before you move a prompt across.

• wan-3.0: 10 images, 5 videos, 5 audio.
• minimax-h3 and minimax-h3-max: 9 images, 3 videos, 3 audio, 12 in total.
• gemini-omni-flash-1.1: 10 images and 3 videos of 3 seconds or less, no audio references.

A quick guard in your client

Do the capability check before you call generate, so a batch does not burn calls on a known 400. This reads the catalog and keeps only rows that accept reference images.

import os
import requests

r = requests.get(
    "https://api.sume.com/v1/video-router/models",
    headers={"Authorization": f"Bearer {os.environ['SUME_API_KEY']}"},
    timeout=30,
)
r.raise_for_status()
for row in r.json()["data"]:
    caps = row.get("capabilities", {})
    if caps.get("reference_images"):
        print(row["id"])

Check before you plan

The Video Router docs tell you to read capabilities from the catalog rather than assume one envelope, and the API reference has the full schema.