Synthesia Billing API credit usage vs Sume's /v1/usage ledger

Synthesia announced a Billing API endpoint on 9/9/2026 that gives a breakdown of credit usage so you can reconcile spend. Sume's counterpart is GET /v1/usage, which returns ledger entries such as reservations, captures, refunds and top-ups, and can be scoped to one thread, run or job.

Synthesia's side is only its one-line update note, read 2026-10-01; I did not see its endpoint documentation. Sume's side is from the Usage docs.

What does Synthesia say the Billing API does?

The update reads: "Get a clear breakdown of credit usage with a new Billing API endpoint, so you can reconcile spend and troubleshoot changes with confidence." The note gives no field names, so check Synthesia's API reference before building on it.

What does /v1/usage return?

How do I reconcile one run?

Add run_id and a limit to the request. The response adds a summary folded over every ledger row the scope caused, including debited_usd, which the docs call the figure to quote, plus open holds and refunds.

curl "https://api.sume.com/v1/usage?run_id=arun_...&limit=50" \
  -H "Authorization: Bearer $SUME_API_KEY"

Can the API add credit too?

No. The credits docs say the API currently exposes balance and usage reads, not a public top-up creation endpoint. For CSV export see export AI API usage to CSV.