diff --git a/app/MindWork AI Studio/Assistants/I18N/allTexts.lua b/app/MindWork AI Studio/Assistants/I18N/allTexts.lua
index 17788f24..06009d62 100644
--- a/app/MindWork AI Studio/Assistants/I18N/allTexts.lua	
+++ b/app/MindWork AI Studio/Assistants/I18N/allTexts.lua	
@@ -7309,6 +7309,9 @@ UI_TEXT_CONTENT["AISTUDIO::TOOLS::VALIDATION::FILEEXTENSIONVALIDATION::T29806295
 -- Images are not supported at this place
 UI_TEXT_CONTENT["AISTUDIO::TOOLS::VALIDATION::FILEEXTENSIONVALIDATION::T305247150"] = "Images are not supported at this place"
 
+-- Unsupported file type
+UI_TEXT_CONTENT["AISTUDIO::TOOLS::VALIDATION::FILEEXTENSIONVALIDATION::T4041351522"] = "Unsupported file type"
+
 -- Executables are not allowed
 UI_TEXT_CONTENT["AISTUDIO::TOOLS::VALIDATION::FILEEXTENSIONVALIDATION::T4167762413"] = "Executables are not allowed"
 
diff --git a/app/MindWork AI Studio/Chat/ContentText.cs b/app/MindWork AI Studio/Chat/ContentText.cs
index 93d0fcb2..9daeec49 100644
--- a/app/MindWork AI Studio/Chat/ContentText.cs	
+++ b/app/MindWork AI Studio/Chat/ContentText.cs	
@@ -229,11 +229,15 @@ public sealed class ContentText : IContent
 
         if(this.FileAttachments.Count > 0)
         {
+            var normalizedAttachments = this.FileAttachments
+                .Select(attachment => attachment.Normalize())
+                .ToList();
+
             // Get the list of existing documents:
-            var existingDocuments = this.FileAttachments.Where(x => x.Type is FileAttachmentType.DOCUMENT && x.Exists).ToList();
+            var existingDocuments = normalizedAttachments.Where(x => x.Type is FileAttachmentType.DOCUMENT && x.Exists).ToList();
 
             // Log warning for missing files:
-            var missingDocuments = this.FileAttachments.Except(existingDocuments).Where(x => x.Type is FileAttachmentType.DOCUMENT).ToList();
+            var missingDocuments = normalizedAttachments.Except(existingDocuments).Where(x => x.Type is FileAttachmentType.DOCUMENT).ToList();
             if (missingDocuments.Count > 0)
                 foreach (var missingDocument in missingDocuments)
                     LOGGER.LogWarning("File attachment no longer exists and will be skipped: '{MissingDocument}'.", missingDocument.FilePath);
@@ -269,7 +273,7 @@ public sealed class ContentText : IContent
                         sb.AppendLine("````");
                     }
                     
-                    var numImages = this.FileAttachments.Count(x => x is { IsImage: true, Exists: true });
+                    var numImages = normalizedAttachments.Count(x => x is { IsImage: true, Exists: true });
                     if (numImages > 0)
                     {
                         sb.AppendLine();
diff --git a/app/MindWork AI Studio/Chat/FileAttachment.cs b/app/MindWork AI Studio/Chat/FileAttachment.cs
index 10e506d8..bdc9651d 100644
--- a/app/MindWork AI Studio/Chat/FileAttachment.cs	
+++ b/app/MindWork AI Studio/Chat/FileAttachment.cs	
@@ -53,6 +53,11 @@ public record FileAttachment(FileAttachmentType Type, string FileName, string Fi
     /// </remarks>
     public bool Exists => File.Exists(this.FilePath);
 
+    /// <summary>
+    /// Rebuilds the attachment from its current file path so file type detection uses the latest rules.
+    /// </summary>
+    public FileAttachment Normalize() => FromPath(this.FilePath);
+
     /// <summary>
     /// Creates a FileAttachment from a file path by automatically determining the type,
     /// extracting the filename, and reading the file size.
diff --git a/app/MindWork AI Studio/Components/ChatComponent.razor.cs b/app/MindWork AI Studio/Components/ChatComponent.razor.cs
index f734d620..c4b30a2f 100644
--- a/app/MindWork AI Studio/Components/ChatComponent.razor.cs	
+++ b/app/MindWork AI Studio/Components/ChatComponent.razor.cs	
@@ -94,7 +94,7 @@ public partial class ChatComponent : MSGComponentBase, IAsyncDisposable
 
         // Apply template's file attachments, if any:
         foreach (var attachment in this.currentChatTemplate.FileAttachments)
-            this.chatDocumentPaths.Add(attachment);
+            this.chatDocumentPaths.Add(attachment.Normalize());
 
         //
         // Check for deferred messages of the kind 'SEND_TO_CHAT',
@@ -392,7 +392,7 @@ public partial class ChatComponent : MSGComponentBase, IAsyncDisposable
         // Apply template's file attachments (replaces existing):
         this.chatDocumentPaths.Clear();
         foreach (var attachment in this.currentChatTemplate.FileAttachments)
-            this.chatDocumentPaths.Add(attachment);
+            this.chatDocumentPaths.Add(attachment.Normalize());
 
         if(this.ChatThread is null)
             return;
@@ -538,10 +538,15 @@ public partial class ChatComponent : MSGComponentBase, IAsyncDisposable
         IContent? lastUserPrompt;
         if (!reuseLastUserPrompt)
         {
+            var normalizedAttachments = this.chatDocumentPaths
+                .Select(attachment => attachment.Normalize())
+                .Where(attachment => attachment.IsValid)
+                .ToList();
+
             lastUserPrompt = new ContentText
             {
                 Text = this.userInput,
-                FileAttachments = [..this.chatDocumentPaths.Where(x => x.IsValid)],
+                FileAttachments = normalizedAttachments,
             };
 
             //
@@ -764,7 +769,7 @@ public partial class ChatComponent : MSGComponentBase, IAsyncDisposable
         // Apply template's file attachments:
         this.chatDocumentPaths.Clear();
         foreach (var attachment in this.currentChatTemplate.FileAttachments)
-            this.chatDocumentPaths.Add(attachment);
+            this.chatDocumentPaths.Add(attachment.Normalize());
 
         // Now, we have to reset the data source options as well:
         this.ApplyStandardDataSourceOptions();
diff --git a/app/MindWork AI Studio/Dialogs/ChatTemplateDialog.razor.cs b/app/MindWork AI Studio/Dialogs/ChatTemplateDialog.razor.cs
index 0aa16ddf..cbc438cf 100644
--- a/app/MindWork AI Studio/Dialogs/ChatTemplateDialog.razor.cs	
+++ b/app/MindWork AI Studio/Dialogs/ChatTemplateDialog.razor.cs	
@@ -133,7 +133,7 @@ public partial class ChatTemplateDialog : MSGComponentBase
         SystemPrompt = this.DataSystemPrompt,
         PredefinedUserPrompt = this.PredefinedUserPrompt,
         ExampleConversation = this.dataExampleConversation,
-        FileAttachments = [..this.fileAttachments],
+        FileAttachments = this.fileAttachments.Select(attachment => attachment.Normalize()).ToList(),
         AllowProfileUsage = this.AllowProfileUsage,
         
         EnterpriseConfigurationPluginId = Guid.Empty,