fix(rtc): avoid KeyError in local_track_unpublished handler during teardown (#692)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: tmkarthi

livekit-rtc/livekit/rtc/participant.py

@@ -826,6 +826,13 @@ async def unpublish_track(self, track_sid: str) -> None:
         Raises:
             UnpublishTrackError: If there is an error in unpublishing the track.
         """
+        # Capture the publication before the FFI round-trip. The
+        # local_track_unpublished room event races this async response and may
+        # remove it from _track_publications first; holding our own reference
+        # guarantees the track is cleared once unpublish completes, regardless
+        # of which path removes the publication from the dict.
+        publication = self._track_publications.get(track_sid)
+
         req = proto_ffi.FfiRequest()
         req.unpublish_track.local_participant_handle = self._ffi_handle.handle
         req.unpublish_track.track_sid = track_sid
@@ -841,8 +848,11 @@ async def unpublish_track(self, track_sid: str) -> None:
             if cb.unpublish_track.error:
                 raise UnpublishTrackError(cb.unpublish_track.error)
 
-            publication = self._track_publications.pop(track_sid)
-            publication._track = None
+            # Remove defensively: the room-event handler may already have done
+            # so when it processed local_track_unpublished first.
+            self._track_publications.pop(track_sid, None)
+            if publication is not None:
+                publication._track = None
             queue.task_done()
         finally:
             self._room_queue.unsubscribe(queue)

livekit-rtc/livekit/rtc/room.py

@@ -746,9 +746,20 @@ def _on_room_event(self, event: proto_room.RoomEvent) -> None:
             ltrack = lpublication.track
             self.emit("local_track_published", lpublication, ltrack)
         elif which == "local_track_unpublished":
+            # During teardown the publication may already have been removed
+            # from the participant's dict by LocalParticipant.unpublish_track
+            # (the FFI event races that async response), so the SID can be gone
+            # by the time this event is dispatched. Look it up defensively and
+            # skip the emit when it is no longer tracked, mirroring the
+            # local_track_republished and remote track_unpublished handlers,
+            # instead of raising a KeyError that _listen_task logs as an error.
             sid = event.local_track_unpublished.publication_sid
-            lpublication = self.local_participant.track_publications[sid]
-            self.emit("local_track_unpublished", lpublication)
+            unpublished = self.local_participant._track_publications.get(sid)
+            if unpublished is not None:
+                del self.local_participant._track_publications[sid]
+                self.emit("local_track_unpublished", unpublished)
+            else:
+                logging.debug("local_track_unpublished for untracked publication sid %s", sid)
         elif which == "local_track_republished":
             # The SDK auto-republished a local track during a full
             # reconnect: the underlying Track (and its bound source) is