UIFallbackParity renders one scene through both binding models and
compares the frames. It starts itself twice, once as is and once with
CRAFTER_GRAPHICS_NO_DESCRIPTOR_HEAP, so the fallback cannot drift from
the heap path on a machine that never takes it. The scene reaches what
HelloUI does not: the four standalone kernels next to the fused one, a
sampled image with two samplers indexed per item, an image slot and a
sampler slot that are freed and registered again, a resize, an image
created with ImageVulkan::Create's default consumer stage, and a
generic Dispatch whose push payload is not a whole number of words.
On a driver without the heap both runs take the fallback, and the test
then only checks that the scene renders. Validation errors raised
while rendering fail a run, which only bites when
CRAFTER_GRAPHICS_VALIDATION is set. They are counted before the frame
capture because Window::SaveFrame raises one itself (#157).
UIFusedShader now also compiles and validates the descriptor-set build
of the fused kernel and pins its push-constant layout: both builds are
fed the same UIFusedHeader bytes.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>