Once Format stopped failing first, the Linux runner reached the GPU tests
for the first time: its software adapter (GL) can't render Rgba32Float or
R32Float. The app already picks Rgba16Float there, but the effect-map
pipelines (R32Float/R16Float) still panicked. They are now built inside an
error scope; where they can't be, documents with layer effects use the CPU
compositor and everything else stays on the GPU.
The exact-parity tests skip on adapters without 32-bit float targets (the
app uses the CPU compositor there), like they already skip without an
adapter; the fallback-path tests build with try_new_with_format.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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