True for deep-link actions that START PLAYBACK (vs "open", which only navigates to the springboard). Gates the player-replacement path (a playback cast arriving over an active player tears it down first; an "open" cast just navigates) and the autoplay decision in ItemDetails. Any unknown action is NOT a playback action -> treated as "open". The verb set is the ADR-0018 contract ({play, shuffle, trailer, instantmix}); keep it in sync there.