fix: handle track cleanups

Author: lherman-cs

pulsebeam/src/participant/downstream/video.rs

@@ -49,11 +49,21 @@ impl VideoAllocator {
     }
 
     pub fn remove_track(&mut self, track_id: &Arc<TrackId>) {
-        if self.tracks.remove(track_id).is_some() {
+        if let Some(track) = self.tracks.remove(track_id) {
             tracing::info!(
                 track = %track_id,
                 "video track removed"
             );
+
+            let Some(assigned_mid) = track.assigned_mid else {
+                return;
+            };
+
+            let Some(slot) = self.slots.iter_mut().find(|s| s.mid == assigned_mid) else {
+                return;
+            };
+
+            slot.stop();
             self.rebalance();
         }
     }

pulsebeam/src/room.rs

@@ -122,6 +122,7 @@ impl actor::Actor<RoomMessageSet> for RoomActor {
                 if let Some(participant_handle) = self.state.participants.get_mut(&participant_id) {
                     // if it's closed, then the participant has exited
                     let _ = participant_handle.handle.terminate().await;
+                    self.handle_participant_left(participant_id).await;
                 }
             }
             RoomMessage::PublishTrack(track_handle) => {