Assertions about pixels, and about the geometry the GPU actually receives. The kernel suite in selftest.html tests mathematics and runs headless; every rendering defect this project has shipped was invisible to it. Group R1 in particular exists because world UTM coordinates baked into float32 vertex buffers quantise to 0.5 m at this site's northing, which silently halved the terrain mesh's north–south resolution for three phases. Each row states the property it defends.