fix: improve settings page error handling, race condition, and metadata

app/routes/settings.tsx

@@ -1,4 +1,4 @@
-import React, { useEffect, useState } from "react";
+import { useEffect, useState } from "react";
 import Navbar from "../components/Navbar";
 import SettingsSidebar, { type SettingsSection } from "../components/SettingsSidebar";
 import LlmSettings from "../components/LlmSettings";
@@ -6,6 +6,8 @@ import TradingSettings from "../components/TradingSettings";
 import StockTable from "../components/StockTable";
 import SystemSettings from "../components/SystemSettings";
 
+export const meta = () => [{ title: "Settings - AITrader" }];
+
 interface Stock {
   id: string;
   ticker: string;
@@ -69,7 +71,7 @@ export default function SettingsPage() {
 
   const saveStockNotes = async (ticker: string, notes: string) => {
     setSaveError(null);
-    const prevStocks = [...stocks];
+    const prevNotes = stocks.find((st) => st.ticker === ticker)?.notes ?? null;
     setStocks((s) => s.map((st) => (st.ticker === ticker ? { ...st, notes } : st)));
     try {
       const fd = new FormData();
@@ -80,7 +82,7 @@ export default function SettingsPage() {
         throw new Error("Failed to save notes");
       }
     } catch (err) {
-      setStocks(prevStocks);
+      setStocks((s) => s.map((st) => (st.ticker === ticker ? { ...st, notes: prevNotes } : st)));
       setSaveError(err instanceof Error ? err.message : "Save failed");
     }
   };
@@ -117,7 +119,7 @@ export default function SettingsPage() {
       <div className="mx-auto max-w-7xl px-6 sm:px-8 lg:px-8 py-8">
         <div className="bg-white rounded-xl shadow-lg border border-gray-200 overflow-hidden">
           <div className="flex min-h-[600px]">
-            <SettingsSidebar activeSection={activeSection} onSectionChange={setActiveSection} />
+            <SettingsSidebar activeSection={activeSection} onSectionChange={(s) => { setActiveSection(s); setSaveError(null); }} />
             <main className="flex-1 p-6 overflow-y-auto">
               {renderSection()}
             </main>