Mike-Solar
c4705cbb2c
playback_display_tracks_the_playhead used a 30 s wall-clock deadline as its pass/fail criterion, so a slow or loaded machine failed the test for machine speed, not for a broken pipeline — spurious, unrelated to any race. The loop now terminates on playback-clock progress (playhead >= 120, ~5 s of playback; the transport advances independently of render speed, so termination is guaranteed) and the only judgment is the tracking invariant at that point. No Instant::now() remains. Verified green on a heavily loaded machine in 84 s.