nextjs-startup/app/layout.tsx

import type { Metadata } from "next";
import { Geist, Geist_Mono } from "next/font/google";

import { ThemeProvider } from "@/components/layout/theme-provider";
import "./globals.css";

const geistSans = Geist({
  variable: "--font-geist-sans",
  subsets: ["latin"],
});

const geistMono = Geist_Mono({
  variable: "--font-geist-mono",
  subsets: ["latin"],
});

const siteName = "Vertex — The Unified AI Gateway";
const siteDescription =
  "Route, optimize, and observe every AI model request through one OpenAI-compatible API.";

// Absolute origin behind `metadataBase`, so Open Graph images resolve to full
// URLs. Vercel injects VERCEL_PROJECT_PRODUCTION_URL on deployed builds.
const siteUrl =
  process.env.NEXT_PUBLIC_SITE_URL ??
  (process.env.VERCEL_PROJECT_PRODUCTION_URL
    ? `https://${process.env.VERCEL_PROJECT_PRODUCTION_URL}`
    : "http://localhost:3000");

// Routes only set their own `title`; the template appends the site name.
export const metadata: Metadata = {
  metadataBase: new URL(siteUrl),
  title: {
    default: siteName,
    template: `%s — ${siteName}`,
  },
  description: siteDescription,
  openGraph: {
    type: "website",
    siteName,
    title: siteName,
    description: siteDescription,
    url: "/",
    images: [
      {
        url: "/og.png",
        width: 1732,
        height: 908,
        alt: "Vertex — One API for every AI model",
      },
    ],
  },
  twitter: {
    card: "summary_large_image",
    title: siteName,
    description: siteDescription,
    images: ["/og.png"],
  },
};

export default function RootLayout({
  children,
}: Readonly<{
  children: React.ReactNode;
}>) {
  return (
    <html lang="en" suppressHydrationWarning className="scroll-smooth">
      <body className={`${geistSans.variable} ${geistMono.variable} min-h-screen bg-background font-sans antialiased`}>
        <ThemeProvider attribute="class" defaultTheme="dark" enableSystem disableTransitionOnChange>
          {children}
        </ThemeProvider>
      </body>
    </html>
  );
}