Change to using a 'FreeStyle' boolean

osu.Game/Online/Rooms/MultiplayerPlaylistItem.cs

@@ -57,11 +57,10 @@ namespace osu.Game.Online.Rooms
         public double StarRating { get; set; }
 
         /// <summary>
-        /// A non-<c>null</c> value indicates "freestyle" mode where players are able to individually select
+        /// Indicates whether participants in the room are able to pick their own choice of beatmap difficulty and ruleset.
-        /// their own choice of beatmap (from the respective beatmap set) and ruleset to play in the room.
         /// </summary>
         [Key(11)]
-        public int? BeatmapSetID { get; set; }
+        public bool FreeStyle { get; set; }
 
         [SerializationConstructor]
         public MultiplayerPlaylistItem()

osu.Game/Online/Rooms/PlaylistItem.cs

@@ -68,11 +68,10 @@ namespace osu.Game.Online.Rooms
         }
 
         /// <summary>
-        /// A non-<c>null</c> value indicates "freestyle" mode where players are able to individually select
+        /// Indicates whether participants in the room are able to pick their own choice of beatmap difficulty and ruleset.
-        /// their own choice of beatmap (from the respective beatmap set) and ruleset to play in the room.
         /// </summary>
-        [JsonProperty("beatmapset_id")]
+        [JsonProperty("freestyle")]
-        public int? BeatmapSetId { get; set; }
+        public bool FreeStyle { get; set; }
 
         /// <summary>
         /// A beatmap representing this playlist item.
@@ -108,7 +107,7 @@ namespace osu.Game.Online.Rooms
             PlayedAt = item.PlayedAt;
             RequiredMods = item.RequiredMods.ToArray();
             AllowedMods = item.AllowedMods.ToArray();
-            BeatmapSetId = item.BeatmapSetID;
+            FreeStyle = item.FreeStyle;
         }
 
         public void MarkInvalid() => valid.Value = false;
@@ -128,8 +127,7 @@ namespace osu.Game.Online.Rooms
 
         #endregion
 
-        public PlaylistItem With(Optional<long> id = default, Optional<IBeatmapInfo> beatmap = default, Optional<ushort?> playlistOrder = default,
+        public PlaylistItem With(Optional<long> id = default, Optional<IBeatmapInfo> beatmap = default, Optional<ushort?> playlistOrder = default, Optional<int> ruleset = default)
-                                 Optional<int> ruleset = default)
         {
             return new PlaylistItem(beatmap.GetOr(Beatmap))
             {
@@ -141,19 +139,19 @@ namespace osu.Game.Online.Rooms
                 PlayedAt = PlayedAt,
                 AllowedMods = AllowedMods,
                 RequiredMods = RequiredMods,
+                FreeStyle = FreeStyle,
                 valid = { Value = Valid.Value },
-                BeatmapSetId = BeatmapSetId
             };
         }
 
         public bool Equals(PlaylistItem? other)
             => ID == other?.ID
                && Beatmap.OnlineID == other.Beatmap.OnlineID
-               && BeatmapSetId == other.BeatmapSetId
                && RulesetID == other.RulesetID
                && Expired == other.Expired
                && PlaylistOrder == other.PlaylistOrder
                && AllowedMods.SequenceEqual(other.AllowedMods)
-               && RequiredMods.SequenceEqual(other.RequiredMods);
+               && RequiredMods.SequenceEqual(other.RequiredMods)
+               && FreeStyle == other.FreeStyle;
     }
 }

osu.Game/Screens/OnlinePlay/Match/RoomSubScreen.cs

@@ -272,21 +272,9 @@ namespace osu.Game.Screens.OnlinePlay.Match
             base.LoadComplete();
 
             SelectedItem.BindValueChanged(_ => Scheduler.AddOnce(OnSelectedItemChanged));
-
+            UserMods.BindValueChanged(_ => Scheduler.AddOnce(OnSelectedItemChanged));
-            UserMods.BindValueChanged(_ => Scheduler.AddOnce(updateMods));
+            UserBeatmap.BindValueChanged(_ => Scheduler.AddOnce(OnSelectedItemChanged));
-
+            UserRuleset.BindValueChanged(_ => Scheduler.AddOnce(OnSelectedItemChanged));
-            UserBeatmap.BindValueChanged(_ => Scheduler.AddOnce(() =>
-            {
-                updateBeatmap();
-                updateUserStyle();
-            }));
-
-            UserRuleset.BindValueChanged(_ => Scheduler.AddOnce(() =>
-            {
-                updateUserMods();
-                updateRuleset();
-                updateUserStyle();
-            }));
 
             beatmapAvailabilityTracker.SelectedItem.BindTo(SelectedItem);
             beatmapAvailabilityTracker.Availability.BindValueChanged(_ => updateBeatmap());
@@ -458,14 +446,6 @@ namespace osu.Game.Screens.OnlinePlay.Match
             if (!this.IsCurrentScreen() || SelectedItem.Value is not PlaylistItem item)
                 return;
 
-            // Reset user style if no longer valid.
-            // Todo: In the future this can be made more lenient, such as allowing a non-null ruleset as the set changes.
-            if (item.BeatmapSetId == null || item.BeatmapSetId != UserBeatmap.Value?.BeatmapSet!.OnlineID)
-            {
-                UserBeatmap.Value = null;
-                UserRuleset.Value = null;
-            }
-
             updateUserMods();
             updateBeatmap();
             updateMods();
@@ -487,10 +467,10 @@ namespace osu.Game.Screens.OnlinePlay.Match
                 UserModsSelectOverlay.IsValidMod = m => allowedMods.Any(a => a.GetType() == m.GetType());
             }
 
-            if (item.BeatmapSetId == null)
+            if (item.FreeStyle)
-                UserStyleSection?.Hide();
-            else
                 UserStyleSection?.Show();
+            else
+                UserStyleSection?.Hide();
         }
 
         private void updateUserMods()
@@ -499,8 +479,13 @@ namespace osu.Game.Screens.OnlinePlay.Match
                 return;
 
             // Remove any user mods that are no longer allowed.
-            var rulesetInstance = GetGameplayRuleset().CreateInstance();
+            Ruleset rulesetInstance = GetGameplayRuleset().CreateInstance();
-            var allowedMods = item.AllowedMods.Select(m => m.ToMod(rulesetInstance));
+            Mod[] allowedMods = item.AllowedMods.Select(m => m.ToMod(rulesetInstance)).ToArray();
+            Mod[] newUserMods = UserMods.Value.Where(m => allowedMods.Any(a => m.GetType() == a.GetType())).ToArray();
+
+            if (newUserMods.SequenceEqual(UserMods.Value))
+                return;
+
             UserMods.Value = UserMods.Value.Where(m => allowedMods.Any(a => m.GetType() == a.GetType())).ToList();
         }
 

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSongSelect.cs

@@ -83,11 +83,11 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
                 {
                     ID = itemToEdit?.ID ?? 0,
                     BeatmapID = item.Beatmap.OnlineID,
-                    BeatmapSetID = item.BeatmapSetId,
                     BeatmapChecksum = item.Beatmap.MD5Hash,
                     RulesetID = item.RulesetID,
                     RequiredMods = item.RequiredMods.ToArray(),
-                    AllowedMods = item.AllowedMods.ToArray()
+                    AllowedMods = item.AllowedMods.ToArray(),
+                    FreeStyle = item.FreeStyle
                 };
 
                 Task task = itemToEdit != null ? client.EditPlaylistItem(multiplayerItem) : client.AddPlaylistItem(multiplayerItem);

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSubScreen.cs

@@ -403,7 +403,10 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         private void updateCurrentItem()
         {
             Debug.Assert(client.Room != null);
+
             SelectedItem.Value = Room.Playlist.SingleOrDefault(i => i.ID == client.Room.Settings.PlaylistItemId);
+            UserBeatmap.Value = client.LocalUser?.BeatmapId == null ? null : UserBeatmap.Value;
+            UserRuleset.Value = client.LocalUser?.RulesetId == null ? null : UserRuleset.Value;
         }
 
         private void handleRoomLost() => Schedule(() =>

osu.Game/Screens/OnlinePlay/OnlinePlaySongSelect.cs

@@ -111,8 +111,7 @@ namespace osu.Game.Screens.OnlinePlay
                     FreeMods.Value = initialItem.AllowedMods.Select(m => m.ToMod(rulesetInstance)).ToArray();
                 }
 
-                if (initialItem.BeatmapSetId != null)
+                FreeStyle.Value = initialItem.FreeStyle;
-                    FreeStyle.Value = true;
             }
 
             Mods.BindValueChanged(onModsChanged);
@@ -162,7 +161,7 @@ namespace osu.Game.Screens.OnlinePlay
                 RulesetID = Ruleset.Value.OnlineID,
                 RequiredMods = Mods.Value.Select(m => new APIMod(m)).ToArray(),
                 AllowedMods = FreeMods.Value.Select(m => new APIMod(m)).ToArray(),
-                BeatmapSetId = FreeStyle.Value ? Beatmap.Value.BeatmapSetInfo.OnlineID : null
+                FreeStyle = FreeStyle.Value
             };
 
             return SelectItem(item);

osu.Game/Screens/OnlinePlay/OnlinePlayStyleSelect.cs

@@ -63,6 +63,7 @@ namespace osu.Game.Screens.OnlinePlay
         {
             private readonly PlaylistItem item;
             private double itemLength;
+            private int beatmapSetId;
 
             public DifficultySelectFilterControl(PlaylistItem item)
             {
@@ -71,9 +72,15 @@ namespace osu.Game.Screens.OnlinePlay
 
             [BackgroundDependencyLoader]
             private void load(RealmAccess realm)
+            {
+                realm.Run(r =>
                 {
                     int beatmapId = item.Beatmap.OnlineID;
-                itemLength = realm.Run(r => r.All<BeatmapInfo>().FirstOrDefault(b => b.OnlineID == beatmapId)?.Length ?? 0);
+                    BeatmapInfo? beatmap = r.All<BeatmapInfo>().FirstOrDefault(b => b.OnlineID == beatmapId);
+
+                    itemLength = beatmap?.Length ?? 0;
+                    beatmapSetId = beatmap?.BeatmapSet?.OnlineID ?? 0;
+                });
             }
 
             public override FilterCriteria CreateCriteria()
@@ -81,7 +88,7 @@ namespace osu.Game.Screens.OnlinePlay
                 var criteria = base.CreateCriteria();
 
                 // Must be from the same set as the playlist item.
-                criteria.BeatmapSetId = item.BeatmapSetId;
+                criteria.BeatmapSetId = beatmapSetId;
 
                 // Must be within 30s of the playlist item.
                 criteria.Length.Min = itemLength - 30000;

osu.Game/Screens/OnlinePlay/Playlists/PlaylistsRoomSubScreen.cs

@@ -67,6 +67,7 @@ namespace osu.Game.Screens.OnlinePlay.Playlists
         {
             base.LoadComplete();
 
+            SelectedItem.BindValueChanged(onSelectedItemChanged, true);
             isIdle.BindValueChanged(_ => updatePollingRate(), true);
 
             Room.PropertyChanged += onRoomPropertyChanged;
@@ -75,6 +76,13 @@ namespace osu.Game.Screens.OnlinePlay.Playlists
             updateRoomPlaylist();
         }
 
+        private void onSelectedItemChanged(ValueChangedEvent<PlaylistItem?> item)
+        {
+            // Simplest for now.
+            UserBeatmap.Value = null;
+            UserRuleset.Value = null;
+        }
+
         private void onRoomPropertyChanged(object? sender, PropertyChangedEventArgs e)
         {
             switch (e.PropertyName)

osu.Game/Screens/OnlinePlay/Playlists/PlaylistsSongSelect.cs

@@ -37,10 +37,10 @@ namespace osu.Game.Screens.OnlinePlay.Playlists
         private PlaylistItem createNewItem() => new PlaylistItem(Beatmap.Value.BeatmapInfo)
         {
             ID = room.Playlist.Count == 0 ? 0 : room.Playlist.Max(p => p.ID) + 1,
-            BeatmapSetId = FreeStyle.Value ? Beatmap.Value.BeatmapSetInfo.OnlineID : null,
             RulesetID = Ruleset.Value.OnlineID,
             RequiredMods = Mods.Value.Select(m => new APIMod(m)).ToArray(),
             AllowedMods = FreeMods.Value.Select(m => new APIMod(m)).ToArray(),
+            FreeStyle = FreeStyle.Value
         };
     }
 }