fix: ensure unpublished event is backwards compatible

Set _track to None AFTER the unpublished event is fired to be 100%
backwards compatible

Author: 1egoman

livekit-rtc/livekit/rtc/room.py

@@ -759,15 +759,21 @@ def _on_room_event(self, event: proto_room.RoomEvent) -> None:
             unpublished = self.local_participant._track_publications.get(sid)
             if unpublished is not None:
                 del self.local_participant._track_publications[sid]
-                if unpublished.track is not None:
-                    unpublished.track._set_room(None)
-                    # Mirror track_unsubscribed: drop the publication's track
-                    # reference. This also makes unpublish_track's own
-                    # _set_room(None) a no-op when it loses the race (its
-                    # `publication._track is not None` guard short-circuits),
-                    # avoiding a redundant clear.
-                    unpublished._track = None
+                track = unpublished.track
+                if track is not None:
+                    track._set_room(None)
+                # Emit while `publication.track` is still set, preserving the
+                # pre-existing payload for callbacks. This handler is synchronous
+                # and emit() invokes listeners synchronously, so nulling the track
+                # right after still completes before any other coroutine (e.g.
+                # unpublish_track) can interleave.
                 self.emit("local_track_unpublished", unpublished)
+                # Mirror track_unsubscribed: drop the publication's track
+                # reference. This also makes unpublish_track's own _set_room(None)
+                # a no-op when it loses the race (its `publication._track is not
+                # None` guard short-circuits), avoiding a redundant clear.
+                if track is not None:
+                    unpublished._track = None
             else:
                 logging.debug("local_track_unpublished for untracked publication sid %s", sid)
         elif which == "local_track_republished":

livekit-rtc/tests/test_audio_stream_room_lifecycle.py

@@ -649,6 +649,40 @@ def test_local_track_unpublished_event_nulls_publication_track() -> None:
     assert publication.track is None
 
 
+def test_local_track_unpublished_callback_still_sees_track() -> None:
+    """Backwards-compat: `publication._track` is nulled AFTER the
+    `local_track_unpublished` event is emitted, so a callback that reads
+    `publication.track` during the event still observes the track (matching
+    pre-PR behavior), while the reference is dropped once the handler returns.
+    """
+    room = _make_room(name="room-1", token="tok-1", url="wss://r")
+    local = _make_local_participant("agent")
+    room._local_participant = local
+
+    track = _make_track(sid="TR_1")
+    publication = _make_local_publication(sid="TR_1")
+    publication._track = track
+    local._track_publications["TR_1"] = publication
+    track._set_room(room)
+
+    seen_track: list[Optional[rtc.Track]] = []
+
+    @room.on("local_track_unpublished")
+    def _on_unpublished(pub: rtc.LocalTrackPublication) -> None:
+        seen_track.append(pub.track)
+
+    room._on_room_event(
+        proto_room.RoomEvent(
+            local_track_unpublished=proto_room.LocalTrackUnpublished(publication_sid="TR_1"),
+        )
+    )
+
+    # the callback saw the track (backwards-compatible payload) ...
+    assert seen_track == [track]
+    # ... and the reference is dropped once the handler returns
+    assert publication.track is None
+
+
 def test_token_refresh_listener_only_removed_by_set_room_none() -> None:
     """The `token_refreshed` listener a Track registers on its
     Room is only ever removed by `_set_room(None)`. `Room.disconnect()` does not