make theme selectable in UI, store setting in localstorage

client/src/App.tsx

@@ -29,7 +29,7 @@ import { useCallback, useEffect, useRef, useState } from "react";
 import {
   Notification,
   StdErrNotification,
-  StdErrNotificationSchema
+  StdErrNotificationSchema,
 } from "./lib/notificationTypes";
 
 import { Tabs, TabsList, TabsTrigger } from "@/components/ui/tabs";
@@ -54,7 +54,6 @@ import RootsTab from "./components/RootsTab";
 import SamplingTab, { PendingRequest } from "./components/SamplingTab";
 import Sidebar from "./components/Sidebar";
 import ToolsTab from "./components/ToolsTab";
-import useDarkModeSync from "./lib/useDarkModeSync";
 
 const DEFAULT_REQUEST_TIMEOUT_MSEC = 10000;
 
@@ -144,8 +143,6 @@ const App = () => {
   const dragStartY = useRef<number>(0);
   const dragStartHeight = useRef<number>(0);
 
-  useDarkModeSync();
-
   const handleDragStart = useCallback(
     (e: React.MouseEvent) => {
       setIsDragging(true);

client/src/components/Sidebar.tsx

@@ -1,6 +1,6 @@
 import { useState } from "react";
 
-import { Play, ChevronDown, ChevronRight, Settings } from "lucide-react";
+import { Play, ChevronDown, ChevronRight } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import {
@@ -12,6 +12,8 @@ import {
 } from "@/components/ui/select";
 import { StdErrNotification } from "@/lib/notificationTypes";
 
+import useTheme from "../lib/useTheme";
+
 interface SidebarProps {
   connectionStatus: "disconnected" | "connected" | "error";
   transportType: "stdio" | "sse";
@@ -43,13 +45,15 @@ const Sidebar = ({
   onConnect,
   stdErrNotifications,
 }: SidebarProps) => {
+  const [theme, setTheme] = useTheme();
   const [showEnvVars, setShowEnvVars] = useState(false);
 
   return (
     <div className="w-80 bg-card border-r border-border flex flex-col h-full">
-      <div className="flex items-center p-4 border-b border-gray-200">
-        <Settings className="w-6 h-6 text-gray-500" />
-        <h1 className="ml-2 text-lg font-semibold">MCP Inspector</h1>
+      <div className="flex items-center justify-between p-4 border-b border-gray-200">
+        <div className="flex items-center">
+          <h1 className="ml-2 text-lg font-semibold">MCP Inspector</h1>
+        </div>
       </div>
 
       <div className="p-4 flex-1 overflow-auto">
@@ -212,6 +216,25 @@ const Sidebar = ({
           </div>
         </div>
       </div>
+      <div className="p-4 border-t">
+        <div className="flex items-center space-x-2">
+          <Select
+            value={theme}
+            onValueChange={(value: string) =>
+              setTheme(value as "system" | "light" | "dark")
+            }
+          >
+            <SelectTrigger className="w-[120px]" id="theme-select">
+              <SelectValue />
+            </SelectTrigger>
+            <SelectContent>
+              <SelectItem value="system">System</SelectItem>
+              <SelectItem value="light">Light</SelectItem>
+              <SelectItem value="dark">Dark</SelectItem>
+            </SelectContent>
+          </Select>
+        </div>
+      </div>
     </div>
   );
 };

client/src/lib/useTheme.ts

@@ -0,0 +1,51 @@
+import { useCallback, useEffect, useState } from "react";
+
+type Theme = "light" | "dark" | "system";
+
+const useTheme = (): [Theme, (mode: Theme) => void] => {
+  const [theme, setTheme] = useState<Theme>(() => {
+    const savedTheme = localStorage.getItem("theme") as Theme;
+    return savedTheme || "system";
+  });
+
+  useEffect(() => {
+    const darkModeMediaQuery = window.matchMedia(
+      "(prefers-color-scheme: dark)",
+    );
+    const handleDarkModeChange = (e: MediaQueryListEvent) => {
+      if (theme === "system") {
+        updateDocumentTheme(e.matches ? "dark" : "light");
+      }
+    };
+
+    const updateDocumentTheme = (newTheme: "light" | "dark") => {
+      document.documentElement.classList.toggle("dark", newTheme === "dark");
+    };
+
+    // Set initial theme based on current mode
+    if (theme === "system") {
+      updateDocumentTheme(darkModeMediaQuery.matches ? "dark" : "light");
+    } else {
+      updateDocumentTheme(theme);
+    }
+
+    darkModeMediaQuery.addEventListener("change", handleDarkModeChange);
+
+    return () => {
+      darkModeMediaQuery.removeEventListener("change", handleDarkModeChange);
+    };
+  }, [theme]);
+
+  return [
+    theme,
+    useCallback((newTheme: Theme) => {
+      setTheme(newTheme);
+      localStorage.setItem("theme", newTheme);
+      if (newTheme !== "system") {
+        document.documentElement.classList.toggle("dark", newTheme === "dark");
+      }
+    }, []),
+  ];
+};
+
+export default useTheme;