diff --git a/app/MindWork AI Studio/Provider/Anthropic/ChatRequest.cs b/app/MindWork AI Studio/Provider/Anthropic/ChatRequest.cs
index 7489c503..d6df3990 100644
--- a/app/MindWork AI Studio/Provider/Anthropic/ChatRequest.cs	
+++ b/app/MindWork AI Studio/Provider/Anthropic/ChatRequest.cs	
@@ -9,11 +9,14 @@ namespace AIStudio.Provider.Anthropic;
 /// <param name="Messages">The chat messages.</param>
 /// <param name="MaxTokens">The maximum number of tokens to generate.</param>
 /// <param name="Stream">Whether to stream the chat completion.</param>
+/// <param name="System">The system prompt for the chat completion.</param>
 public readonly record struct ChatRequest(
     string Model,
     IList<IMessageBase> Messages,
     int MaxTokens,
-    bool Stream)
+    bool Stream,
+    string System
+)
 {
     // Attention: The "required" modifier is not supported for [JsonExtensionData].
     [JsonExtensionData]
diff --git a/app/MindWork AI Studio/Provider/Anthropic/ProviderAnthropic.cs b/app/MindWork AI Studio/Provider/Anthropic/ProviderAnthropic.cs
index d5fd9e15..f23b8d4d 100644
--- a/app/MindWork AI Studio/Provider/Anthropic/ProviderAnthropic.cs	
+++ b/app/MindWork AI Studio/Provider/Anthropic/ProviderAnthropic.cs	
@@ -27,18 +27,18 @@ public sealed class ProviderAnthropic() : BaseProvider(LLMProviders.ANTHROPIC, "
         if(!requestedSecret.Success)
             yield break;
         
-        // Prepare the system prompt:
-        var systemPrompt = new TextMessage
-        {
-            Role = "system",
-            Content = chatThread.PrepareSystemPrompt(settingsManager, chatThread),
-        };
-        
         // Parse the API parameters:
         var apiParameters = this.ParseAdditionalApiParameters("system");
 
         // Build the list of messages:
-        var messages = await chatThread.Blocks.BuildMessagesUsingStandardRoles();
+        var messages = await chatThread.Blocks.BuildMessages(role => role switch
+        {
+            ChatRole.USER => "user",
+            ChatRole.AI => "assistant",
+            ChatRole.AGENT => "assistant",
+
+            _ => "user",
+        });
         
         // Prepare the Anthropic HTTP chat request:
         var chatRequest = JsonSerializer.Serialize(new ChatRequest
@@ -46,8 +46,9 @@ public sealed class ProviderAnthropic() : BaseProvider(LLMProviders.ANTHROPIC, "
             Model = chatModel.Id,
             
             // Build the messages:
-            Messages = [systemPrompt, ..messages],
+            Messages = [..messages],
             
+            System = chatThread.PrepareSystemPrompt(settingsManager, chatThread),
             MaxTokens = apiParameters.TryGetValue("max_tokens", out var value) && value is int intValue ? intValue : 4_096,
             
             // Right now, we only support streaming completions: