initial scaffolding for inverted, custom message list

src/message-list/message-list-model.vala

@@ -0,0 +1,72 @@
+using GLib;
+using Gee;
+
+public class MessageListModel : Object, ListModel 
+{
+    public SortedSet<Message> messages {
+        owned get { return _messages.read_only_view; }
+    }
+
+    private string _conversation_guid;
+    private SortedSet<Message> _messages;
+    
+    public MessageListModel(string conversation_guid) {
+        _messages = new TreeSet<Message>((a, b) => {
+            // Sort by date in descending order (newest first)
+            return (int)(b.date - a.date);
+        });
+
+        Repository.get_instance().messages_updated.connect(got_messages_updated);
+        _conversation_guid = conversation_guid;
+    }
+    
+    public void load_messages() {
+        try {
+            Message[] messages = Repository.get_instance().get_messages(_conversation_guid);
+            
+            // Clear existing set
+            uint old_count = _messages.size;
+            _messages.clear();
+            
+            // Notify of removal
+            if (old_count > 0) {
+                items_changed(0, old_count, 0);
+            }
+            
+            // Process each conversation
+            uint position = 0;
+            
+            for (int i = 0; i < messages.length; i++) {
+                var message = messages[i];
+                _messages.add(message);
+                position++;
+            }
+            
+            // Notify of additions
+            if (position > 0) {
+                items_changed(0, 0, position);
+            }
+        } catch (Error e) {
+            warning("Failed to load messages: %s", e.message);
+        }
+    }
+
+    private void got_messages_updated(string conversation_guid) {
+        if (conversation_guid == _conversation_guid) {
+            load_messages();
+        }
+    }
+    
+    // ListModel implementation
+    public Type get_item_type() {
+        return typeof(Message);
+    }
+    
+    public uint get_n_items() {
+        return _messages.size;
+    }
+    
+    public Object? get_item(uint position) {
+        return _messages.to_array()[position];
+    }
+}