HeyGen stale_edit_version 409 vs Sume idempotency_conflict

stale_edit_version is HeyGen's 409 for a template edit based on an old copy. If you send expected_edit_version to PUT /v3/templates/{template_id}/variables and someone else changed the template, you get the 409 instead of an overwrite. Sume has no template edit, so its 409 is a different thing: idempotency_conflict.

HeyGen facts are from its API changelog. Sume facts are from Generation admission and Errors and credits, read 2026-10-01.

What does stale_edit_version protect?

The changelog says the variables call accepts expected_edit_version, and GET /v3/templates/{template_id} returns an edit_version. It is optimistic concurrency: read the version, send it back with your edit, and a mismatch fails with 409 instead of overwriting a concurrent change. The fix is to re-read and re-apply.

When does Sume return a 409?

Sume's admission table lists 409 idempotency_conflict for the same idempotency key reused for a different operation or payload. The client behavior is to reuse keys only for exact retries. Nothing in the docs ties a 409 to concurrent edits.

How should I retry a paid Sume submit?

Use Idempotency-Key for every paid submit that may be retried, and do not resubmit just because a local worker timed out. The docs also say production integrations should prefer async submit with an idempotency key. More in HeyGen idempotency vs Sume 409.

What about failures after acceptance?

Failed jobs expose public error metadata such as category, stage, retryability, retry-after seconds, public reason and next action. Read retryability before deciding to retry.