Cover art is not video; non-zero exit is the file's fault (ErrUnreadable), a missing binary / cancelled ctx / bad output is ours. WaitDelay bounds a cancelled probe whose child holds the pipe open. Checked against real ffprobe on iguana: JSON shape matches the fixtures and /etc/hosts exits 1 with 'Invalid data found when processing input'. The unit tests drive a stub process; ffprobe is not installed on koala. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>