Three blind retries of a 30 s Seedance 720p submit can reserve $52.00

A 30 s Seedance 2.5 clip at 720p costs $17.334, so a submit that times out and is retried twice with no Idempotency-Key can book 3 x $17.334 = $52.002 for one video. The docs are direct about it: never resubmit a paid job just because the local client timed out, and a 5xx does not prove the work was refused.

Exposure by attempt

Sume reserves the provider list price times 1.25 at submit. If the first request actually created a job and the retry carries no key, each retry is a new paid job. The worst case below assumes every attempt is accepted.

With one Idempotency-Key reused on every attempt, the retry returns the original job instead, so the exposure stays at one attempt.

The same loop with one key

Generate the key once, outside the loop, and send it on every attempt. The body must stay identical: the same key with a different body returns 409 idempotency_conflict.

KEY=$(uuidgen)
BODY='{"model":"seedance-2.5","prompt":"A slow dolly shot through a neon market","duration":30,"resolution":"720p","aspect_ratio":"9:16"}'
for i in 1 2 3; do
  curl -sS -m 30 -X POST https://api.sume.com/v1/videos \
    -H "Authorization: Bearer $SUME_API_KEY" \
    -H "Idempotency-Key: $KEY" \
    -H "Content-Type: application/json" \
    -d "$BODY" && break
  sleep $((i * 5))
done

Gotchas

A 402 insufficient_credits means no job was started, so it is the one failure you can retry after a top-up with no duplicate risk. A 429 or 503 is retried with the same key. If you lose the key, list your jobs and match on the idempotency_key field that every job object carries, before you submit anything new.

The curl exit code only covers transport errors; add -w '%{http_code}' if you also want to branch on 4xx responses.