Add some commentary

Author: cpsievert

js/chat/chat.ts

@@ -232,13 +232,17 @@ class ChatContainer extends LightElement {
     return this.querySelector(CHAT_MESSAGES_TAG) as ChatMessages;
   }
 
+  // Has the user sent an input message yet?
   private hasSentInput = false;
+  // Are we currently streaming a message (i.e., append_message_stream())?
   private isStreaming = false;
+  // Throttled function to scroll to the bottom of the chat
   private requestScrollToBottom;
 
   constructor() {
     super();
 
+    // Throttle the scrolling so that, while streaming, we don't scroll too often
     this.requestScrollToBottom = throttle(
       this.#maybeScrollToBottom.bind(this),
       250