trace last message in chain

src/index.ts

@@ -60,8 +60,12 @@ class Utility extends base {
   }
 
   async saveLastMessage(session: Session) {
-    const lastMessage = new LastMessage().fromSession(session);
-    return this.aragami.set(lastMessage);
+    const message = new LastMessage().fromSession(session);
+    const previousSaving = await this.aragami.get(LastMessage, session.guildId);
+    if (previousSaving && session.userId === previousSaving.userId) {
+      message.content = previousSaving.content + '\n' + message.content;
+    }
+    return this.aragami.set(message);
   }
 
   async fetchLastMessage(session: Session) {