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Several engines answer the same questions and return the same answer shapes. A diffusion read seeds a canvas and denoises it once. A generative read writes the answer template under a grammar. Nothing is parsed. An answer cannot be off-schema. Each id also accepts its Hugging Face spelling, such as Qwen/Qwen3.8-27B.
Generative reads are experimental: The diffusion engine reads probabilities straight off the canvas. The shape is guaranteed. The calibration is not. On the smaller engines, measured probabilities sit much closer to uniform. A confident-looking answer can still be wrong. Treat confidence from a generative read as a weak signal. Validate on your own labelled data before you threshold on it. Prefer google/diffusiongemma-26b-a4b-it wherever the decision matters.

Naming a model

There is no catch-all alias: Name the model you want. An id the deployment does not serve is a 404. Override the TypeSafe SDK’s jev-latest default. See TypeSafe SDK Compatibility.
Which engines a deployment serves varies. A decision reports the id that answered it. Read the live list: GET /typesafe/v1/models. Do not hard-code an id.

Which one to reach for

reasoning_effort applies to generative engines only. A diffusion engine rejects it with a 422. See Gateway extensions.

System One

Question types, inputs, confidence, and cost levers.

List Models

The live list for a deployment.