Runway model router cost: billed at the model it picks

A Runway Model Router generation costs the standard rate of whichever model the router selects, and the response metadata reports the model used and the realized cost in credits. Sume's sume/auto works differently on one point: responses echo sume/auto and never disclose which family ran, but usage.cost still gives the billable amount.

How does Runway bill a router generation?

The Runway Dev pricing guide says generations routed through a Model Router "are billed at the standard rate of whichever model the router selects." Credits are bought for $0.01 each, so the cost of a routed job is the selected model's credits times one cent. The guide gives the metadata promise in one sentence: the response reports the model used and the realized cost in credits. Read 2026-10-01.

What does Sume report for sume/auto?

In Sume's video generation docs, model: "sume/auto" lets Sume pick the family. The table row reads: "Responses echo sume/auto; the family that ran is never disclosed." Billing is in USD: the workspace balance is reserved on submit at provider list × 1.25, and usage.cost is the Sume billable amount. So you can audit what a job cost without learning which model produced it.

Can I see the cost before a job runs?

Through MCP, yes. Paid tools accept dry_run=true, which the tools and gates docs describe as "Admission/cost preview only; do not submit the job." An optional max_spend_usd is enforced when you provide it. If you need to know which model ran, name the model in the request instead of routing; see Runway API pricing per second for the vendor side of per-model rates.

Which approach fits which need?

If you need a per-job record of which model was used, Runway's metadata gives that. If you want one id that picks for you and a single cost field to reconcile, sume/auto with usage.cost does that. Pin a model id when the choice matters to the output.