Replace the 20 synthetic bars with a contained WaveformVisualizer driven by the live player, pointed at the current track; add a Fill mode (CSS-only, defaults off) sizing the canvas to its container; place the lava-lamp icon to popover on the card.
Replace the TrackId-only IsActivePlayer gate with a LivePlayerTrack source that follows the playing track when it is the host track or shares the host release; single-track Mix/Session unchanged at parity.
Add GET api/track/{trackEntryKey}/waveform/high-res (+ proxy), ITrackDataService.GetTrackWaveform; rewire visualizer to resolve the current track's EntryKey and re-fetch on track change. Retire the client mix-waveform read path.
daniel-c-harvey