learnharness/app/layout.tsx

import { headers } from "next/headers";
import { readSettingsRecord } from "@/src/server";
import { resolveLanguage, systemLanguage, translate } from "@/src/core";
import { I18nProvider } from "@/components/i18n";
import type { Metadata } from "next";
import { JetBrains_Mono, Source_Sans_3, Noto_Sans } from "next/font/google";
import "katex/dist/katex.min.css";
import "./globals.css";
import { AppShell, SidebarProvider } from "@/components/sidebar";
import { ActivityProvider } from "@/components/activity-dock";
import { ServerEventsProvider } from "@/components/server-events";
import { AppearanceProvider } from "@/components/settings/appearance";
import UpdateBanner from "@/components/update-banner";

// Chrome = JetBrains Mono, teaching prose = Source Sans 3, titles = CMU
// Serif (the bundled lh-cmu @font-face in globals.css — no CDN).
const ui = JetBrains_Mono({ subsets: ["latin", "cyrillic"], variable: "--font-jetbrains" });
const prose = Source_Sans_3({ subsets: ["latin"], variable: "--font-sans3" });

const russianProse = Noto_Sans({ subsets: ["latin", "cyrillic"], variable: "--font-russian-prose" });

export async function generateMetadata(): Promise<Metadata> {
	const language = resolveLanguage(readSettingsRecord()?.general?.language, (await headers()).get("accept-language"));
	return {
	title: "Learning Harness",
	description: translate(language, "A teacher agent with a memory — sessions, quizzes, and a knowledge graph of what you know."),
	};
}

export default async function RootLayout({ children }: { children: React.ReactNode }) {
	const general = readSettingsRecord()?.general ?? {};
	const system = systemLanguage((await headers()).get("accept-language"));
	const language = resolveLanguage(general.language, system);
	return (
		<html lang={language} className={`dark ${ui.variable} ${prose.variable} ${russianProse.variable}`}>
			<body className="min-h-dvh antialiased">
			{/* The notification channel rides OUTSIDE everything: sidebar, dock,
				 and pages all subscribe as the polls retire (push S3, 2026-10-02). */}
			<I18nProvider initialGeneral={general} system={system}><ServerEventsProvider>
				<AppearanceProvider>
					<SidebarProvider>
						<ActivityProvider>
							<AppShell>{children}</AppShell>
						</ActivityProvider>
					</SidebarProvider>
				</AppearanceProvider>
			</ServerEventsProvider>
			{/* Auto-update banner (Wave C): fixed card, Electron-only pushes. */}
			<UpdateBanner />
		</I18nProvider>
		</body>
		</html>
	);
}