diff --git a/DysonNetwork.Sphere/Chat/ChatController.cs b/DysonNetwork.Sphere/Chat/ChatController.cs
index ed0c634..996b74a 100644
--- a/DysonNetwork.Sphere/Chat/ChatController.cs
+++ b/DysonNetwork.Sphere/Chat/ChatController.cs
@@ -553,12 +553,13 @@ public partial class ChatController(
         if (!isMember)
             return StatusCode(403, "You are not a member of this chat room.");
 
-        var response = await cs.GetSyncDataAsync(roomId, request.LastSyncTimestamp);
+        var response = await cs.GetSyncDataAsync(roomId, request.LastSyncTimestamp, 500);
+        Response.Headers["X-Total"] = response.TotalCount.ToString();
         return Ok(response);
     }
 
-    [HttpPost("{roomId:guid}/autocomplete")]
-    public async Task<ActionResult<List<DysonNetwork.Shared.Models.Autocompletion>>> ChatAutoComplete(
+
+    public async Task<ActionResult<List<Shared.Models.Autocompletion>>> ChatAutoComplete(
         [FromBody] AutocompletionRequest request, Guid roomId)
     {
         if (HttpContext.Items["CurrentUser"] is not Account currentUser)
@@ -574,4 +575,4 @@ public partial class ChatController(
         var result = await aus.GetAutocompletion(request.Content, chatId: roomId, limit: 10);
         return Ok(result);
     }
-}
+}
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Chat/ChatService.cs b/DysonNetwork.Sphere/Chat/ChatService.cs
index 4263be1..ef97ea3 100644
--- a/DysonNetwork.Sphere/Chat/ChatService.cs
+++ b/DysonNetwork.Sphere/Chat/ChatService.cs
@@ -624,16 +624,22 @@ public partial class ChatService(
             .FirstOrDefaultAsync();
     }
 
-    public async Task<SyncResponse> GetSyncDataAsync(Guid roomId, long lastSyncTimestamp)
+    public async Task<SyncResponse> GetSyncDataAsync(Guid roomId, long lastSyncTimestamp, int limit = 500)
     {
-        var timestamp = Instant.FromUnixTimeMilliseconds(lastSyncTimestamp);
+        var lastSyncInstant = Instant.FromUnixTimeMilliseconds(lastSyncTimestamp);
 
-        // Get all messages that have been modified since the last sync
+        // Count total newer messages
+        var totalCount = await db.ChatMessages
+            .Where(m => m.ChatRoomId == roomId && m.CreatedAt > lastSyncInstant)
+            .CountAsync();
+
+        // Get up to limit messages that have been created since the last sync
         var syncMessages = await db.ChatMessages
-            .IgnoreQueryFilters()
-            .Include(m => m.Sender)
             .Where(m => m.ChatRoomId == roomId)
-            .Where(m => m.UpdatedAt > timestamp || m.DeletedAt > timestamp)
+            .Where(m => m.CreatedAt > lastSyncInstant)
+            .OrderBy(m => m.CreatedAt)
+            .Take(limit)
+            .Include(m => m.Sender)
             .ToListAsync();
 
         // Load member accounts for messages that need them
@@ -658,13 +664,14 @@ public partial class ChatService(
         }
 
         var latestTimestamp = syncMessages.Count > 0
-            ? syncMessages.Max(m => m.UpdatedAt)
+            ? syncMessages.Last().CreatedAt
             : SystemClock.Instance.GetCurrentInstant();
 
         return new SyncResponse
         {
-            Messages = syncMessages.OrderBy(m => m.UpdatedAt).ToList(),
-            CurrentTimestamp = latestTimestamp
+            Messages = syncMessages,
+            CurrentTimestamp = latestTimestamp,
+            TotalCount = totalCount
         };
     }
 
@@ -816,4 +823,5 @@ public class SyncResponse
 {
     public List<SnChatMessage> Messages { get; set; } = [];
     public Instant CurrentTimestamp { get; set; }
+    public int TotalCount { get; set; } = 0;
 }
diff --git a/DysonNetwork.Sphere/Startup/BroadcastEventHandler.cs b/DysonNetwork.Sphere/Startup/BroadcastEventHandler.cs
index d70998d..f45df45 100644
--- a/DysonNetwork.Sphere/Startup/BroadcastEventHandler.cs
+++ b/DysonNetwork.Sphere/Startup/BroadcastEventHandler.cs
@@ -217,7 +217,7 @@ public class BroadcastEventHandler(
             return;
         }
 
-        var requestData = packet.GetData<ChatController.MarkMessageReadRequest>();
+        var requestData = packet.GetData<Chat.ChatController.MarkMessageReadRequest>();
         if (requestData == null)
         {
             await SendErrorResponse(evt, "Invalid request data");
@@ -245,7 +245,7 @@ public class BroadcastEventHandler(
             return;
         }
 
-        var requestData = packet.GetData<ChatController.ChatRoomWsUniversalRequest>();
+        var requestData = packet.GetData<Chat.ChatController.ChatRoomWsUniversalRequest>();
         if (requestData == null)
         {
             await SendErrorResponse(evt, "Invalid request data");
@@ -299,7 +299,7 @@ public class BroadcastEventHandler(
             return;
         }
 
-        var requestData = packet.GetData<ChatController.ChatRoomWsUniversalRequest>();
+        var requestData = packet.GetData<Chat.ChatController.ChatRoomWsUniversalRequest>();
         if (requestData == null)
         {
             await SendErrorResponse(evt, "Invalid request data");
@@ -327,7 +327,7 @@ public class BroadcastEventHandler(
             return;
         }
 
-        var requestData = packet.GetData<ChatController.ChatRoomWsUniversalRequest>();
+        var requestData = packet.GetData<Chat.ChatController.ChatRoomWsUniversalRequest>();
         if (requestData == null)
         {
             await SendErrorResponse(evt, "Invalid request data");