Focus input on submission and fix scroll (#441)

components/custom/chat.tsx

@@ -40,15 +40,16 @@ export function Chat({
         >
           {messages.length === 0 && <Overview />}
 
-          {messages.map((message, index) => (
+          {messages.map((message) => (
             <PreviewMessage
-              key={`${id}-${index}`}
+              key={message.id}
               role={message.role}
               content={message.content}
               attachments={message.experimental_attachments}
               toolInvocations={message.toolInvocations}
             />
           ))}
+
           <div
             ref={messagesEndRef}
             className="shrink-0 min-w-[24px] min-h-[24px]"