Arc B580 lost the kill test: batch-14 mask p50 103 ms vs Torch CPU
70 ms enhance / OpenVINO CPU 5 ms. Production stays on known-good
CPU workers (tag known-good-cpu-2026-08-28). Hop stays 200 ms.
Working snapshot before the OpenVINO MetricGAN GPU spike:
thread-capped SpeechBrain DelaySum+MetricGAN on CPU, hop 200 ms,
video hold for A/V sync, Arc VAAPI H.264, headless kmssink wall.
32 tests passing. Do not treat this as a GPU audio path.