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Model Fusion answers a request with several models at once, has a judge compare their answers, and returns one response. Callers use it like any other model: one model ID, one response.

Use cases

  • Review across providers: put models from different providers on the panel and read the judge’s list of contradictions before shipping an answer or a code change.
  • High-stakes answers: the Safety preset makes the judge weigh physical, financial, legal, and medical risk, and flag it before synthesis.
  • Swap models without touching callers: the fusion owns the model ID, so changing the panel or the judge leaves client code unchanged.

Create a Model Fusion

Open AI Gateway → Model Fusion, then select Model Fusion in the page header. The list filters by Preset and Status, and the switch in the Status column turns a fusion on or off without deleting it. The detail page carries Overview telemetry, Traces, and Settings.

Use it

Pass the fusion’s Name as model through the gateway. It answers on the Responses API and on chat completions.

Synthesis modes

Presets

The preset changes what the judge weighs.

Limits

  • The panel takes 1 to 8 distinct chat models. Provider models only: another fusion cannot sit on the panel.
  • Max tool calls runs from 0 to 20 per phase. The Budget preset keeps web tools off whatever the switch says.
  • An error answers the request when every panel call fails, or when the judge or orchestrator call fails.