Give last bundled replay frame the frame header

osu.Game.Tests/Visual/Gameplay/TestSceneSpectator.cs

@@ -218,6 +218,22 @@ namespace osu.Game.Tests.Visual.Gameplay
             AddAssert("last received frame has time = 1000", () => spectatorClient.LastReceivedUserFrames.First().Value.Time == 1000);
         }
 
+        [Test]
+        public void TestFinalFrameInBundleHasHeader()
+        {
+            FrameDataBundle lastBundle = null;
+
+            AddStep("bind to client", () => spectatorClient.OnNewFrames += (_, bundle) => lastBundle = bundle);
+
+            start(-1234);
+            sendFrames();
+            finish();
+
+            AddUntilStep("bundle received", () => lastBundle != null);
+            AddAssert("first frame does not have header", () => lastBundle.Frames[0].Header == null);
+            AddAssert("last frame has header", () => lastBundle.Frames[^1].Header != null);
+        }
+
         private OsuFramedReplayInputHandler replayHandler =>
             (OsuFramedReplayInputHandler)Stack.ChildrenOfType<OsuInputManager>().First().ReplayInputHandler;
 

osu.Game/Online/Spectator/SpectatorClient.cs

@@ -129,6 +129,9 @@ namespace osu.Game.Online.Spectator
 
         Task ISpectatorClient.UserSentFrames(int userId, FrameDataBundle data)
         {
+            if (data.Frames.Count > 0)
+                data.Frames[^1].Header = data.Header;
+
             Schedule(() => OnNewFrames?.Invoke(userId, data));
 
             return Task.CompletedTask;

osu.Game/Rulesets/Replays/ReplayFrame.cs

@@ -1,16 +1,29 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+#nullable enable
+
 using MessagePack;
+using osu.Game.Online.Spectator;
 
 namespace osu.Game.Rulesets.Replays
 {
     [MessagePackObject]
     public class ReplayFrame
     {
+        /// <summary>
+        /// The time at which this <see cref="ReplayFrame"/> takes place.
+        /// </summary>
         [Key(0)]
         public double Time;
 
+        /// <summary>
+        /// A <see cref="FrameHeader"/> containing the state of a play after this <see cref="ReplayFrame"/> takes place.
+        /// May be omitted where exact per-frame accuracy is not required.
+        /// </summary>
+        [IgnoreMember]
+        public FrameHeader? Header;
+
         public ReplayFrame()
         {
         }

osu.Game/Screens/Play/SpectatorPlayer.cs

@@ -72,6 +72,7 @@ namespace osu.Game.Screens.Play
 
                 var convertedFrame = (ReplayFrame)convertibleFrame;
                 convertedFrame.Time = frame.Time;
+                convertedFrame.Header = frame.Header;
 
                 score.Replay.Frames.Add(convertedFrame);
             }