Function is_audio_only_video 

pub fn is_audio_only_video(item: &MediaItem) -> bool

A video item played through the native audio path — i.e. the background audio-only handoff, the only place a length-less progressive transcode is used. Jellyfin’s item-type taxonomy stays in Rust (CLAUDE.md).

TRACES: UR-040 | DR-129, DR-203 | UT-117, UT-200