Image 1.0 mode vs POST /v1/images: default wait and 202 explained

POST /v1/images defaults to sync and blocks for up to 30 seconds, returning 200 with images or 202 with a job envelope. Image 1.0 lists async, sync, subscribe and webhook, and its docs call async the default behavior when omitted on most clients.

From Sume's Image API and Image 1.0 docs, read 2026-09-30.

What are the defaults?

Both routes share wait_timeout_seconds from 0 to 30.

How do I tell 200 from 202?

Check the status code, not the body shape: 200 is the image response, 202 is the job envelope with status_url and result_url. Slow configurations, such as 4K, high quality or large n, are the likeliest to degrade to 202.

What does subscribe mean?

On the Image API, subscribe is an alias of sync, not a progress stream. Native SSE is not served in v1, and stream: true returns 400 streaming_not_supported.

How do I force a job?

Ask for async and poll.

curl -X POST https://api.sume.com/v1/images \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-image-2.5",
    "prompt": "Poster with a large headline",
    "mode": "async"
  }'
curl https://api.sume.com/v1/jobs/job_123/status \
  -H "Authorization: Bearer $SUME_API_KEY"

How do I check this myself?

Write clients that handle both status codes, and never assume the body shape. For anything above a quick draft, prefer async or webhook so a timeout on your side does not look like a failed generation. The linked docs pages and the catalog endpoint show the current values, and this post reflects them as of 2026-09-30.