feat(compression): adaptive auto transcript compactor

crates/owlen-core/src/conversation.rs

@@ -353,6 +353,26 @@ impl ConversationManager {
         id
     }
 
+    /// Replace the active conversation messages and rebuild internal indexes.
+    pub fn replace_active_messages(&mut self, mut messages: Vec<Message>) {
+        let now = std::time::SystemTime::now();
+        for message in &mut messages {
+            // Ensure message timestamps are not in the far past when rewired.
+            message.timestamp = now;
+        }
+        self.active.messages = messages;
+        self.active.updated_at = now;
+        self.rebuild_index();
+        self.stream_reset();
+    }
+
+    fn rebuild_index(&mut self) {
+        self.message_index.clear();
+        for (idx, message) in self.active.messages.iter().enumerate() {
+            self.message_index.insert(message.id, idx);
+        }
+    }
+
     fn stream_reset(&mut self) {
         self.streaming.clear();
     }