diff --git a/apps/framework-editor/app/components/HeaderFrameworks.tsx b/apps/framework-editor/app/components/HeaderFrameworks.tsx
index 716e99dd2b..c65d20ac1a 100644
--- a/apps/framework-editor/app/components/HeaderFrameworks.tsx
+++ b/apps/framework-editor/app/components/HeaderFrameworks.tsx
@@ -1,6 +1,7 @@
 import { Skeleton } from '@trycompai/ui/skeleton';
 import Link from 'next/link';
 import { Suspense } from 'react';
+import { ThemeToggle } from './theme-toggle';
 import { UserMenu } from './user-menu';
 
 export async function Header() {
@@ -9,9 +10,12 @@ export async function Header() {
       <Link href="/frameworks" className="text-foreground hover:text-foreground/80 text-sm font-semibold tracking-tight">
         Framework Editor
       </Link>
-      <Suspense fallback={<Skeleton className="h-8 w-8 rounded-full" />}>
-        <UserMenu />
-      </Suspense>
+      <div className="flex items-center gap-2">
+        <ThemeToggle />
+        <Suspense fallback={<Skeleton className="h-8 w-8 rounded-full" />}>
+          <UserMenu />
+        </Suspense>
+      </div>
     </header>
   );
 }
diff --git a/apps/framework-editor/app/components/theme-provider.tsx b/apps/framework-editor/app/components/theme-provider.tsx
new file mode 100644
index 0000000000..3370b01bc6
--- /dev/null
+++ b/apps/framework-editor/app/components/theme-provider.tsx
@@ -0,0 +1,14 @@
+'use client';
+
+import { ThemeProvider as NextThemesProvider } from 'next-themes';
+import * as React from 'react';
+
+type ThemeProviderProps = Parameters<typeof NextThemesProvider>[0];
+
+export function ThemeProvider({ children, ...props }: ThemeProviderProps) {
+  return (
+    <NextThemesProvider {...props}>
+      <React.Suspense>{children}</React.Suspense>
+    </NextThemesProvider>
+  );
+}
diff --git a/apps/framework-editor/app/components/theme-toggle.test.tsx b/apps/framework-editor/app/components/theme-toggle.test.tsx
new file mode 100644
index 0000000000..cb9a86ad12
--- /dev/null
+++ b/apps/framework-editor/app/components/theme-toggle.test.tsx
@@ -0,0 +1,41 @@
+import { fireEvent, render, screen } from '@testing-library/react';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const { setTheme, useThemeMock } = vi.hoisted(() => ({
+  setTheme: vi.fn(),
+  useThemeMock: vi.fn(),
+}));
+
+vi.mock('next-themes', () => ({ useTheme: useThemeMock }));
+vi.mock('@trycompai/ui', () => ({
+  Button: ({
+    children,
+    variant: _v,
+    size: _s,
+    ...props
+  }: { variant?: string; size?: string } & React.ComponentProps<'button'>) => (
+    <button {...props}>{children}</button>
+  ),
+}));
+
+import { ThemeToggle } from './theme-toggle';
+
+describe('ThemeToggle', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    useThemeMock.mockReturnValue({ resolvedTheme: 'light', setTheme });
+  });
+
+  it('switches to dark when currently light', () => {
+    render(<ThemeToggle />);
+    fireEvent.click(screen.getByRole('button', { name: /toggle theme/i }));
+    expect(setTheme).toHaveBeenCalledWith('dark');
+  });
+
+  it('switches to light when currently dark', () => {
+    useThemeMock.mockReturnValue({ resolvedTheme: 'dark', setTheme });
+    render(<ThemeToggle />);
+    fireEvent.click(screen.getByRole('button', { name: /toggle theme/i }));
+    expect(setTheme).toHaveBeenCalledWith('light');
+  });
+});
diff --git a/apps/framework-editor/app/components/theme-toggle.tsx b/apps/framework-editor/app/components/theme-toggle.tsx
new file mode 100644
index 0000000000..777bb1deac
--- /dev/null
+++ b/apps/framework-editor/app/components/theme-toggle.tsx
@@ -0,0 +1,30 @@
+'use client';
+
+import { Button } from '@trycompai/ui';
+import { Moon, Sun } from 'lucide-react';
+import { useTheme } from 'next-themes';
+import { useEffect, useState } from 'react';
+
+export function ThemeToggle() {
+  const { resolvedTheme, setTheme } = useTheme();
+  const [mounted, setMounted] = useState(false);
+
+  // next-themes can't know the resolved theme during SSR; wait for mount before
+  // showing a theme-specific icon to avoid a hydration mismatch.
+  useEffect(() => setMounted(true), []);
+
+  const isDark = mounted && resolvedTheme === 'dark';
+
+  return (
+    <Button
+      variant="ghost"
+      size="icon"
+      aria-label="Toggle theme"
+      title={isDark ? 'Switch to light mode' : 'Switch to dark mode'}
+      className="h-8 w-8"
+      onClick={() => setTheme(isDark ? 'light' : 'dark')}
+    >
+      {isDark ? <Sun className="h-4 w-4" /> : <Moon className="h-4 w-4" />}
+    </Button>
+  );
+}
diff --git a/apps/framework-editor/app/layout.tsx b/apps/framework-editor/app/layout.tsx
index 3d5672c63f..46ee0df931 100644
--- a/apps/framework-editor/app/layout.tsx
+++ b/apps/framework-editor/app/layout.tsx
@@ -6,6 +6,7 @@ import { Toaster as SonnerToaster } from 'sonner';
 import { headers } from 'next/headers';
 import '../styles/globals.css';
 import { Header } from './components/HeaderFrameworks';
+import { ThemeProvider } from './components/theme-provider';
 import { auth } from './lib/auth';
 import { isInternalUser } from './lib/utils';
 
@@ -25,14 +26,21 @@ export default async function RootLayout({ children }: { children: ReactNode })
     isInternalUser(session.user.email);
 
   return (
-    <html lang="en" className="h-full">
+    <html lang="en" className="h-full" suppressHydrationWarning>
       <body className="flex h-full flex-col">
-        {hasSession && <Header />}
-        <div className="flex min-h-0 flex-1 flex-col gap-2 p-4">
-          {children}
-          <Toaster />
-          <SonnerToaster richColors position="top-right" />
-        </div>
+        <ThemeProvider
+          attribute="class"
+          defaultTheme="light"
+          enableSystem
+          disableTransitionOnChange
+        >
+          {hasSession && <Header />}
+          <div className="flex min-h-0 flex-1 flex-col gap-2 p-4">
+            {children}
+            <Toaster />
+            <SonnerToaster richColors position="top-right" />
+          </div>
+        </ThemeProvider>
       </body>
     </html>
   );
diff --git a/apps/framework-editor/package.json b/apps/framework-editor/package.json
index 9d1736d060..46c6a7754e 100644
--- a/apps/framework-editor/package.json
+++ b/apps/framework-editor/package.json
@@ -17,6 +17,7 @@
         "framer-motion": "^12.23.9",
         "lucide-react": "^1.7.0",
         "next": "^16.2.0",
+        "next-themes": "^0.4.4",
         "nuqs": "^2.4.3",
         "react": "^19.0.0",
         "react-dom": "^19.0.0",
diff --git a/apps/framework-editor/styles/globals.css b/apps/framework-editor/styles/globals.css
index 5cd105322f..77f5f2118a 100644
--- a/apps/framework-editor/styles/globals.css
+++ b/apps/framework-editor/styles/globals.css
@@ -1,6 +1,36 @@
 @import '@trycompai/ui/globals.css';
 @config '../tailwind.config.ts';
 
+/*
+ * Real dark-mode palette (FRAME-5). @trycompai/ui ships a `.dark` block whose
+ * values are identical to light, so without this, toggling the `dark` class
+ * changes nothing. Declared after the import (and unlayered) so it wins the
+ * cascade over the library defaults.
+ */
+.dark {
+  --background: 0 0% 7%;
+  --foreground: 0 0% 95%;
+  --card: 0 0% 9%;
+  --card-foreground: 0 0% 95%;
+  --popover: 0 0% 9%;
+  --popover-foreground: 0 0% 95%;
+  --primary: 165 70% 42%;
+  --primary-foreground: 0 0% 100%;
+  --secondary: 0 0% 15%;
+  --secondary-foreground: 0 0% 95%;
+  --muted: 0 0% 15%;
+  --muted-foreground: 0 0% 64%;
+  --accent: 0 0% 18%;
+  --accent-foreground: 0 0% 98%;
+  --destructive: 0 72% 51%;
+  --destructive-foreground: 0 0% 98%;
+  --warning: 45 93% 47%;
+  --warning-foreground: 26 83% 14%;
+  --border: 0 0% 18%;
+  --input: 0 0% 18%;
+  --ring: 165 70% 42%;
+}
+
 @layer base {
   * {
     @apply border-border;
diff --git a/bun.lock b/bun.lock
index 3d06bfdff4..f70de19c1f 100644
--- a/bun.lock
+++ b/bun.lock
@@ -417,6 +417,7 @@
         "framer-motion": "^12.23.9",
         "lucide-react": "^1.7.0",
         "next": "^16.2.0",
+        "next-themes": "^0.4.4",
         "nuqs": "^2.4.3",
         "react": "^19.0.0",
         "react-dom": "^19.0.0",