Runtime backend reference

Auto

D3D11 on Windows, Vulkan on Linux, Metal on macOS.

D3D11

Shipped Windows default; HLSL SM5 through FXC.

Vulkan

Selectable on Windows and default policy on Linux.

Metal

Default policy on macOS.

Backend availability is not itself evidence that a wheel rendered. See Portability and validation status for the package, install, contract, and runtime validation matrix.