Introduce message kinds, and handle them appropriately in user and agent chat

frontend/lib/chat_screen.dart

@@ -25,12 +25,34 @@ class Message extends ChatEntry {
 
 class ThreadHeader extends ChatEntry {
   final int threadId;
-  final int messageCount;
+  int messageCount;
   
   ThreadHeader({required this.threadId, required this.messageCount})
     : super(content: "Thread ($messageCount messages)", isFromUser: false);
 }
 
+class NoteMessage extends Message {
+  NoteMessage({sender, content, id, threadId}) :
+    super(sender: sender, content: content, id: id, threadId: threadId);
+}
+class HiddenMessage extends Message {
+  HiddenMessage({sender, content, id, threadId}) :
+    super(sender: sender, content: content, id: id, threadId: threadId);
+}
+
+Message createMessageFromData (Map<String, dynamic> data) {
+  switch (data['kind']) {
+    case 'message':
+      return Message(sender: data['sender'], content: data['content'], threadId: data['threadId']);
+      break;
+    case 'note':
+      return NoteMessage(sender: data['sender'], content: data['content'], threadId: data['threadId']);
+      break;
+    default:
+      return HiddenMessage(sender: data['sender'], content: data['content'], threadId: data['threadId']);
+  }
+}
+
 class ChatScreen extends StatefulWidget {
   final int chatId;
 
@@ -39,9 +61,7 @@ class ChatScreen extends StatefulWidget {
   static Future<List<Message>> getChatMessages(int chatId) async {
     final response = await Backend.sendAction("get-chat-messages", {'chatId': chatId});
     List<dynamic> messageObjects = response['messages'];
-    List<Message> messages = messageObjects.map((msg) =>
-      Message(sender: msg['sender'], content: msg['content'], id: msg['id'], threadId: msg['threadId'])
-    ).toList();
+    List<Message> messages = messageObjects.map((msg) => createMessageFromData(msg)).toList();
     return messages;
   }
 
@@ -58,6 +78,7 @@ class _ChatScreenState extends State<ChatScreen> {
   // UI State
   Set<int> expandedThreads = {};
   int? editingMessageId = null;
+  bool noteMode = false;
 
   // Internal Funcionality
   Offset? _longPressOffset;
@@ -70,7 +91,7 @@ class _ChatScreenState extends State<ChatScreen> {
     super.initState();
     _loadInitialData();
     _chatSubscription = Backend.chatMessages(widget.chatId).listen((data) {
-      final message = Message(sender: data['sender'], content: data['content'], threadId: data['threadId']);
+      final message = createMessageFromData(data);
       if (!message.isFromUser) {
         addMessage(message);
       }
@@ -117,8 +138,8 @@ class _ChatScreenState extends State<ChatScreen> {
 
     // Second pass: Build the display list with correct ordering
     for (var message in _messages) {
-      if (message.threadId == null) {
-        // Non-threaded messages go directly to the result
+      if (message is NoteMessage || message.threadId == null) {
+        // Non-threaded messages and notes go directly to the result
         result.add(message);
       } else {
         final threadId = message.threadId!;
@@ -164,29 +185,40 @@ class _ChatScreenState extends State<ChatScreen> {
         'chatId': widget.chatId,
         'content': content,
         'threadId': currentThreadId,
+        'kind': noteMode ? 'note' : null,
       }).then((response) {
         if (response['error'] != null) {
           print("Error sending chat message: ${response['error']}");
         }
       });
 
-      final newMessage = Message(sender: "user", content: content, threadId: currentThreadId);
+      final newMessage = noteMode ?
+        NoteMessage(sender: "user", content: content, threadId: currentThreadId) :
+        Message(sender: "user", content: content, threadId: currentThreadId);
       addMessage(newMessage);
     } else {
+      Message message = _messages.firstWhere((element) => element.id == editingMessageId!);
+
       Backend.sendAction("update-chat-message", {
         'messageId': editingMessageId,
         'content': content,
+        'kind': noteMode ? 'note' : null,
       }).then((response) {
         if (response['error'] != null) {
           print("Error updating message: ${response['error']}");
         }
       });
 
-      Message message = _messages.firstWhere((element) => element.id == editingMessageId!);
       setState(() {
         message.content = content;
       });
     }
+
+    if (noteMode) {
+      setState(() {
+        noteMode = false;
+      });
+    }
   }
 
   void createThread () async {
@@ -276,6 +308,18 @@ class _ChatScreenState extends State<ChatScreen> {
   @override
   Widget build(BuildContext context) {
     final isWideScreen = MediaQuery.of(context).size.width > 600;
+    final String? editInfo;
+    if (editingMessageId != null) {
+      if (noteMode) {
+        editInfo = 'Editing Note ${editingMessageId}';
+      } else {
+        editInfo = 'Editing ${editingMessageId}';
+      }
+    } else if (noteMode) {
+      editInfo = 'Editing Note';
+    } else {
+      editInfo = null;
+    }
 
     return Scaffold(
       appBar: AppBar(
@@ -297,6 +341,7 @@ class _ChatScreenState extends State<ChatScreen> {
                 if (entry is ThreadHeader) {
                   return _buildThreadHeader(context, entry);
                 } else if (entry is Message) {
+                  final isNote = entry is NoteMessage;
                   final message = entry as Message;
                   return GestureDetector(
                     onLongPressStart: (details) {
@@ -318,7 +363,8 @@ class _ChatScreenState extends State<ChatScreen> {
                           padding: EdgeInsets.all(10),
                           decoration: BoxDecoration(
                             color: getMessageColor(context),
-                            borderRadius: BorderRadius.circular(12),
+                            borderRadius: BorderRadius.circular(isNote ? 0 : 12),
+                            border: isNote ? Border.all(color: Colors.white) : null,
                           ),
                           child: SelectableText(
                             message.content,
@@ -343,8 +389,8 @@ class _ChatScreenState extends State<ChatScreen> {
             padding: const EdgeInsets.all(8.0),
             child: Column(
               children: [
-                if (editingMessageId!= null) ...[
-                  Text('Editing ${editingMessageId}'),
+                if (editInfo != null) ...[
+                  Text(editInfo!),
                 ],
                 Expanded(
                   child: KeyboardListener(
@@ -380,6 +426,14 @@ class _ChatScreenState extends State<ChatScreen> {
                       },
                       child: Text('Start New Topic'),
                     ),
+                    ElevatedButton(
+                      onPressed: () {
+                        setState(() {
+                          noteMode = !noteMode;
+                        });
+                      },
+                      child: Text(noteMode ? 'Switch to Message' : 'Make Note'),
+                    ),
                     if (editingMessageId!= null) ...[
                       ElevatedButton(
                         onPressed: () {