From 6ec30826bab349803d586bc0e5449ad5375e03df Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Thu, 18 Dec 2025 20:39:37 +0000
Subject: [PATCH] Optimize ChatInterface re-renders

Separated the message list into a `MessageList` component wrapped with `React.memo` to prevent re-rendering the entire chat history on every keystroke in the input field. This ensures that the heavy list rendering is isolated from the frequent state updates of the text input.

Optimizations:
- Extracted `MessageList` from `ChatInterface`.
- Memoized `MessageList` to skip re-renders when props (`messages`, `isLoading`, `onSendMessage`) are unchanged.
- Kept `input` state local to `ChatInterface`.

Verification:
- Verified UI functionality with Playwright screenshot.
- Validated that typing in the input does not break the layout.
---
 .Jules/bolt.md                        |  9 +++++
 src/components/chat/ChatInterface.tsx | 39 +++++-----------------
 src/components/chat/MessageList.tsx   | 48 +++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 31 deletions(-)
 create mode 100644 .Jules/bolt.md
 create mode 100644 src/components/chat/MessageList.tsx

diff --git a/.Jules/bolt.md b/.Jules/bolt.md
new file mode 100644
index 0000000..9a47f1a
--- /dev/null
+++ b/.Jules/bolt.md
@@ -0,0 +1,9 @@
+# Bolt's Journal
+
+## 2024-05-23 - Initial Setup
+**Learning:** Bolt journal initialized.
+**Action:** Always check this file for critical learnings before starting.
+
+## 2024-05-23 - Component Separation for Performance
+**Learning:** `ChatInterface` was re-rendering the entire message list (including `ReactMarkdown` parsing inside `MessageItem`) on every keystroke because the input state was in the same component. Even with `React.memo` on `MessageItem`, the list reconciliation cost adds up.
+**Action:** Split components that handle frequent state updates (like inputs) from heavy list renderers. Created `MessageList` to isolate the list rendering from the input state.
diff --git a/src/components/chat/ChatInterface.tsx b/src/components/chat/ChatInterface.tsx
index 454fe9f..48c57cd 100644
--- a/src/components/chat/ChatInterface.tsx
+++ b/src/components/chat/ChatInterface.tsx
@@ -1,14 +1,13 @@
-import { useState, useEffect, useRef } from "react";
+import { useState } from "react";
 import { useChatStore } from "@/store/chat";
 import { Button } from "@/components/ui/button";
 import { Textarea } from "@/components/ui/textarea";
-import { Send, Bot, Loader2, RefreshCw, Terminal } from "lucide-react";
-import { MessageItem } from "./MessageItem";
+import { Send, RefreshCw, Terminal } from "lucide-react";
+import { MessageList } from "./MessageList";
 
 export function ChatInterface() {
   const { messages, sendMessage, isLoading, resetChat } = useChatStore();
   const [input, setInput] = useState("");
-  const scrollRef = useRef<HTMLDivElement>(null);
 
   const handleSend = async () => {
     if (!input.trim()) return;
@@ -24,10 +23,6 @@ export function ChatInterface() {
     }
   };
 
-  useEffect(() => {
-    scrollRef.current?.scrollIntoView({ behavior: "smooth" });
-  }, [messages, isLoading]);
-
   return (
     <div className="flex flex-col min-h-[50vh] max-h-[85vh] h-auto w-full max-w-4xl mx-auto glass-panel rounded-2xl overflow-hidden shadow-2xl transition-all duration-500 ease-in-out animate-in fade-in slide-in-from-bottom-4">
       
@@ -50,29 +45,11 @@ export function ChatInterface() {
       </div>
 
       {/* CHAT AREA */}
-      <div className="flex-1 overflow-y-auto p-4 space-y-6 scroll-smooth custom-scrollbar">
-        {messages.map((msg) => (
-          <MessageItem
-            key={msg.id}
-            message={msg}
-            onSendMessage={sendMessage}
-          />
-        ))}
-
-        {isLoading && (
-          <div className="flex gap-4 max-w-[90%] mr-auto animate-in fade-in slide-in-from-left-2">
-            <div className="h-8 w-8 rounded-full bg-violet-500/10 text-violet-400 flex items-center justify-center animate-pulse border border-violet-500/20">
-              <Bot className="h-4 w-4" />
-            </div>
-            <div className="bg-white/5 border border-white/10 p-4 rounded-2xl rounded-tl-none flex items-center gap-2 text-zinc-500 text-sm backdrop-blur-sm">
-              <Loader2 className="h-3 w-3 animate-spin" />
-              Thinking...
-            </div>
-          </div>
-        )}
-        
-        <div ref={scrollRef} />
-      </div>
+      <MessageList
+        messages={messages}
+        isLoading={isLoading}
+        onSendMessage={sendMessage}
+      />
 
       {/* INPUT AREA */}
       <div className="p-4 bg-black/20 border-t border-white/5 backdrop-blur-md">
diff --git a/src/components/chat/MessageList.tsx b/src/components/chat/MessageList.tsx
new file mode 100644
index 0000000..61d115e
--- /dev/null
+++ b/src/components/chat/MessageList.tsx
@@ -0,0 +1,48 @@
+import React, { memo, useEffect, useRef } from "react";
+import { ChatMessage } from "@/types/chat";
+import { Bot, Loader2 } from "lucide-react";
+import { MessageItem } from "./MessageItem";
+
+interface MessageListProps {
+  messages: ChatMessage[];
+  isLoading: boolean;
+  onSendMessage: (content: string) => void;
+}
+
+const MessageList = memo(({ messages, isLoading, onSendMessage }: MessageListProps) => {
+  const scrollRef = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    scrollRef.current?.scrollIntoView({ behavior: "smooth" });
+  }, [messages, isLoading]);
+
+  return (
+    <div className="flex-1 overflow-y-auto p-4 space-y-6 scroll-smooth custom-scrollbar">
+      {messages.map((msg) => (
+        <MessageItem
+          key={msg.id}
+          message={msg}
+          onSendMessage={onSendMessage}
+        />
+      ))}
+
+      {isLoading && (
+        <div className="flex gap-4 max-w-[90%] mr-auto animate-in fade-in slide-in-from-left-2">
+          <div className="h-8 w-8 rounded-full bg-violet-500/10 text-violet-400 flex items-center justify-center animate-pulse border border-violet-500/20">
+            <Bot className="h-4 w-4" />
+          </div>
+          <div className="bg-white/5 border border-white/10 p-4 rounded-2xl rounded-tl-none flex items-center gap-2 text-zinc-500 text-sm backdrop-blur-sm">
+            <Loader2 className="h-3 w-3 animate-spin" />
+            Thinking...
+          </div>
+        </div>
+      )}
+
+      <div ref={scrollRef} />
+    </div>
+  );
+});
+
+MessageList.displayName = "MessageList";
+
+export { MessageList };