feat(billing): Polar.sh Pro subscription integration

- Webhook handler verifies HMAC-SHA256 sig and updates user role on
  subscription.created / subscription.updated / subscription.revoked
- Audio endpoint gated: free users limited to 3 chapters/day via Valkey
  counter; returns 402 {error:'pro_required'} when limit reached
- Translation proxy endpoint enforces 402 for non-pro users
- AudioPlayer.svelte surfaces 402 via onProRequired callback + upgrade banner
- Chapter page shows lock icon + upgrade prompts for gated translation langs
- Profile page: subscription section shows Pro badge + manage link (active)
  or monthly/annual checkout buttons (free); isPro resolved fresh from DB
- i18n: 13 new profile_subscription_* keys across all 5 locales

scripts/pb-init-v3.sh

@@ -272,5 +272,7 @@ add_field "app_users"      "verification_token"     "text"
 add_field "app_users"      "verification_token_exp" "text"
 add_field "app_users"      "oauth_provider"         "text"
 add_field "app_users"      "oauth_id"               "text"
+add_field "app_users"      "polar_customer_id"      "text"
+add_field "app_users"      "polar_subscription_id"  "text"
 
 log "done"

ui/messages/en.json

@@ -329,6 +329,18 @@
   "profile_password_changed_ok": "Password changed successfully.",
   "profile_playback_speed": "Playback speed \u2014 {speed}x",
 
+  "profile_subscription_heading": "Subscription",
+  "profile_plan_pro": "Pro",
+  "profile_plan_free": "Free",
+  "profile_pro_active": "Your Pro subscription is active.",
+  "profile_pro_perks": "Unlimited audio, all translation languages, and voice selection are enabled.",
+  "profile_manage_subscription": "Manage subscription",
+  "profile_upgrade_heading": "Upgrade to Pro",
+  "profile_upgrade_desc": "Unlock unlimited audio, translations in 4 languages, and voice selection.",
+  "profile_upgrade_monthly": "Monthly \u2014 $6 / mo",
+  "profile_upgrade_annual": "Annual \u2014 $48 / yr",
+  "profile_free_limits": "Free plan: 3 audio chapters per day, English reading only.",
+
   "user_currently_reading": "Currently Reading",
   "user_library_count": "Library ({n})",
   "user_joined": "Joined {date}",

ui/messages/fr.json

@@ -329,6 +329,18 @@
   "profile_password_changed_ok": "Mot de passe modifié avec succès.",
   "profile_playback_speed": "Vitesse de lecture — {speed}x",
 
+  "profile_subscription_heading": "Abonnement",
+  "profile_plan_pro": "Pro",
+  "profile_plan_free": "Gratuit",
+  "profile_pro_active": "Votre abonnement Pro est actif.",
+  "profile_pro_perks": "Audio illimité, toutes les langues de traduction et la sélection de voix sont activées.",
+  "profile_manage_subscription": "Gérer l'abonnement",
+  "profile_upgrade_heading": "Passer au Pro",
+  "profile_upgrade_desc": "Débloquez l'audio illimité, les traductions en 4 langues et la sélection de voix.",
+  "profile_upgrade_monthly": "Mensuel — 6 $ / mois",
+  "profile_upgrade_annual": "Annuel — 48 $ / an",
+  "profile_free_limits": "Plan gratuit : 3 chapitres audio par jour, lecture en anglais uniquement.",
+
   "user_currently_reading": "En cours de lecture",
   "user_library_count": "Bibliothèque ({n})",
   "user_joined": "Inscrit le {date}",

ui/messages/id.json

@@ -329,6 +329,18 @@
   "profile_password_changed_ok": "Kata sandi berhasil diubah.",
   "profile_playback_speed": "Kecepatan pemutaran — {speed}x",
 
+  "profile_subscription_heading": "Langganan",
+  "profile_plan_pro": "Pro",
+  "profile_plan_free": "Gratis",
+  "profile_pro_active": "Langganan Pro kamu aktif.",
+  "profile_pro_perks": "Audio tanpa batas, semua bahasa terjemahan, dan pilihan suara tersedia.",
+  "profile_manage_subscription": "Kelola langganan",
+  "profile_upgrade_heading": "Tingkatkan ke Pro",
+  "profile_upgrade_desc": "Buka audio tanpa batas, terjemahan dalam 4 bahasa, dan pilihan suara.",
+  "profile_upgrade_monthly": "Bulanan — $6 / bln",
+  "profile_upgrade_annual": "Tahunan — $48 / thn",
+  "profile_free_limits": "Paket gratis: 3 bab audio per hari, hanya bahasa Inggris.",
+
   "user_currently_reading": "Sedang Dibaca",
   "user_library_count": "Perpustakaan ({n})",
   "user_joined": "Bergabung {date}",

ui/messages/pt-BR.json

@@ -329,6 +329,18 @@
   "profile_password_changed_ok": "Senha alterada com sucesso.",
   "profile_playback_speed": "Velocidade de reprodução — {speed}x",
 
+  "profile_subscription_heading": "Assinatura",
+  "profile_plan_pro": "Pro",
+  "profile_plan_free": "Gratuito",
+  "profile_pro_active": "Sua assinatura Pro está ativa.",
+  "profile_pro_perks": "Áudio ilimitado, todos os idiomas de tradução e seleção de voz estão habilitados.",
+  "profile_manage_subscription": "Gerenciar assinatura",
+  "profile_upgrade_heading": "Assinar o Pro",
+  "profile_upgrade_desc": "Desbloqueie áudio ilimitado, traduções em 4 idiomas e seleção de voz.",
+  "profile_upgrade_monthly": "Mensal — $6 / mês",
+  "profile_upgrade_annual": "Anual — $48 / ano",
+  "profile_free_limits": "Plano gratuito: 3 capítulos de áudio por dia, somente inglês.",
+
   "user_currently_reading": "Lendo Agora",
   "user_library_count": "Biblioteca ({n})",
   "user_joined": "Entrou em {date}",

ui/messages/ru.json

@@ -329,6 +329,18 @@
   "profile_password_changed_ok": "Пароль успешно изменён.",
   "profile_playback_speed": "Скорость воспроизведения — {speed}x",
 
+  "profile_subscription_heading": "Подписка",
+  "profile_plan_pro": "Pro",
+  "profile_plan_free": "Бесплатно",
+  "profile_pro_active": "Ваша подписка Pro активна.",
+  "profile_pro_perks": "Безлимитное аудио, все языки перевода и выбор голоса доступны.",
+  "profile_manage_subscription": "Управление подпиской",
+  "profile_upgrade_heading": "Перейти на Pro",
+  "profile_upgrade_desc": "Разблокируйте безлимитное аудио, переводы на 4 языка и выбор голоса.",
+  "profile_upgrade_monthly": "Ежемесячно — $6 / мес",
+  "profile_upgrade_annual": "Ежегодно — $48 / год",
+  "profile_free_limits": "Бесплатный план: 3 аудиоглавы в день, только английский.",
+
   "user_currently_reading": "Сейчас читает",
   "user_library_count": "Библиотека ({n})",
   "user_joined": "Зарегистрирован {date}",

ui/src/app.d.ts

@@ -6,9 +6,11 @@ declare global {
 		interface Locals {
 			sessionId: string;
 			user: { id: string; username: string; role: string; authSessionId: string } | null;
+			isPro: boolean;
 		}
 		interface PageData {
 			user?: { id: string; username: string; role: string; authSessionId: string } | null;
+			isPro?: boolean;
 		}
 		// interface PageState {}
 		// interface Platform {}

ui/src/hooks.server.ts

@@ -6,7 +6,7 @@ import { randomBytes, createHmac } from 'node:crypto';
 import { env } from '$env/dynamic/private';
 import { env as pubEnv } from '$env/dynamic/public';
 import { log } from '$lib/server/logger';
-import { createUserSession, touchUserSession, isSessionRevoked } from '$lib/server/pocketbase';
+import { createUserSession, touchUserSession, isSessionRevoked, getUserById } from '$lib/server/pocketbase';
 import { drain as drainPresignCache } from '$lib/server/presignCache';
 import { NodeSDK } from '@opentelemetry/sdk-node';
 import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
@@ -210,6 +210,18 @@ const appHandle: Handle = async ({ event, resolve }) => {
 		event.locals.user = null;
 	}
 
+	// ── isPro: read fresh from DB so role changes take effect without re-login ──
+	if (event.locals.user) {
+		try {
+			const dbUser = await getUserById(event.locals.user.id);
+			event.locals.isPro = dbUser?.role === 'pro' || dbUser?.role === 'admin';
+		} catch {
+			event.locals.isPro = false;
+		}
+	} else {
+		event.locals.isPro = false;
+	}
+
 	return resolve(event);
 };
 

ui/src/lib/components/AudioPlayer.svelte

@@ -67,6 +67,8 @@
 		chapters?: { number: number; title: string }[];
 		/** List of available voices from the backend. */
 		voices?: Voice[];
+		/** Called when the server returns 402 (free daily limit reached). */
+		onProRequired?: () => void;
 	}
 
 	let {
@@ -77,7 +79,8 @@
 		cover = '',
 		nextChapter = null,
 		chapters = [],
-		voices = []
+		voices = [],
+		onProRequired = undefined
 	}: Props = $props();
 
 	// ── Derived: voices grouped by engine ──────────────────────────────────
@@ -563,6 +566,15 @@
 					headers: { 'Content-Type': 'application/json' },
 					body: JSON.stringify({ voice })
 				});
+
+				if (res.status === 402) {
+					// Free daily limit reached — surface upgrade CTA
+					audioStore.status = 'idle';
+					stopProgress();
+					onProRequired?.();
+					return;
+				}
+
 				if (!res.ok) throw new Error(`Generation failed: HTTP ${res.status}`);
 
 				if (res.status === 200) {

ui/src/lib/server/pocketbase.ts

@@ -71,6 +71,8 @@ export interface User {
 	verification_token_exp?: string;
 	oauth_provider?: string;
 	oauth_id?: string;
+	polar_customer_id?: string;
+	polar_subscription_id?: string;
 }
 
 // ─── Auth token cache ─────────────────────────────────────────────────────────
@@ -572,6 +574,28 @@ export async function getUserByOAuth(provider: string, oauthId: string): Promise
 	);
 }
 
+/**
+ * Look up a user by their Polar customer ID. Returns null if not found.
+ */
+export async function getUserByPolarCustomerId(polarCustomerId: string): Promise<User | null> {
+	return listOne<User>(
+		'app_users',
+		`polar_customer_id="${polarCustomerId.replace(/"/g, '\\"')}"`
+	);
+}
+
+/**
+ * Patch arbitrary fields on an app_user record.
+ */
+export async function patchUser(userId: string, fields: Partial<User & Record<string, unknown>>): Promise<void> {
+	const res = await pbPatch(`/api/collections/app_users/records/${encodeURIComponent(userId)}`, fields);
+	if (!res.ok) {
+		const body = await res.text().catch(() => '');
+		log.error('pocketbase', 'patchUser failed', { userId, status: res.status, body });
+		throw new Error(`patchUser failed: ${res.status} — ${body}`);
+	}
+}
+
 /**
  * Create a new user via OAuth (no password). email_verified is true since the
  * provider already verified it. Throws on DB errors.

ui/src/lib/server/polar.ts

@@ -0,0 +1,107 @@
+/**
+ * Polar.sh integration — server-side only.
+ *
+ * Responsibilities:
+ *  - Verify webhook signatures (HMAC-SHA256)
+ *  - Patch app_users.polar_customer_id / polar_subscription_id / role on subscription events
+ *  - Expose isPro(userId) helper for gating
+ *
+ * Product IDs (Polar dashboard):
+ *   Monthly : 1376fdf5-b6a9-492b-be70-7c905131c0f9
+ *   Annual  : b6190307-79aa-4905-80c8-9ed941378d21
+ */
+
+import { createHmac, timingSafeEqual } from 'node:crypto';
+import { env } from '$env/dynamic/private';
+import { log } from '$lib/server/logger';
+import { getUserById, getUserByPolarCustomerId, patchUser } from '$lib/server/pocketbase';
+
+export const POLAR_PRO_PRODUCT_IDS = new Set([
+	'1376fdf5-b6a9-492b-be70-7c905131c0f9', // monthly
+	'b6190307-79aa-4905-80c8-9ed941378d21'  // annual
+]);
+
+// ─── Webhook signature verification ──────────────────────────────────────────
+
+/**
+ * Verify the Polar webhook signature.
+ * Polar signs with HMAC-SHA256 over the raw body; header is "webhook-signature".
+ * Header format: "v1=<hex>"  (may be comma-separated list of sigs)
+ */
+export function verifyPolarWebhook(rawBody: string, signatureHeader: string): boolean {
+	const secret = env.POLAR_WEBHOOK_SECRET;
+	if (!secret) {
+		log.warn('polar', 'POLAR_WEBHOOK_SECRET not set — rejecting webhook');
+		return false;
+	}
+
+	const expected = createHmac('sha256', secret).update(rawBody).digest('hex');
+	const expectedBuf = Buffer.from(`v1=${expected}`);
+
+	// Header may contain multiple sigs separated by ", "
+	const sigs = signatureHeader.split(',').map((s) => s.trim());
+	for (const sig of sigs) {
+		try {
+			const sigBuf = Buffer.from(sig);
+			if (sigBuf.length === expectedBuf.length && timingSafeEqual(sigBuf, expectedBuf)) {
+				return true;
+			}
+		} catch {
+			// length mismatch etc — try next
+		}
+	}
+	return false;
+}
+
+// ─── Subscription event handler ───────────────────────────────────────────────
+
+interface PolarSubscription {
+	id: string;
+	status: string; // "active" | "canceled" | "past_due" | "unpaid" | "incomplete" | ...
+	product_id: string;
+	customer_id: string;
+	customer_email?: string;
+	user_id?: string; // Polar user id (not our user id)
+}
+
+/**
+ * Handle a Polar subscription event.
+ * Finds the matching app_user by email and updates role + polar fields.
+ */
+export async function handleSubscriptionEvent(
+	eventType: string,
+	subscription: PolarSubscription
+): Promise<void> {
+	const { id: subId, status, product_id, customer_id, customer_email } = subscription;
+
+	log.info('polar', 'subscription event', { eventType, subId, status, product_id, customer_email });
+
+	if (!customer_email) {
+		log.warn('polar', 'subscription event missing customer_email — cannot match user', { subId });
+		return;
+	}
+
+	// Find user by their polar_customer_id first (faster on repeat events), then by email
+	let user = await getUserByPolarCustomerId(customer_id).catch(() => null);
+	if (!user) {
+		const { getUserByEmail } = await import('$lib/server/pocketbase');
+		user = await getUserByEmail(customer_email).catch(() => null);
+	}
+
+	if (!user) {
+		log.warn('polar', 'no app_user found for polar customer', { customer_email, customer_id });
+		return;
+	}
+
+	const isProProduct = POLAR_PRO_PRODUCT_IDS.has(product_id);
+	const isActive = status === 'active';
+	const newRole = isProProduct && isActive ? 'pro' : (user.role === 'admin' ? 'admin' : 'user');
+
+	await patchUser(user.id, {
+		role: newRole,
+		polar_customer_id: customer_id,
+		polar_subscription_id: isActive ? subId : ''
+	});
+
+	log.info('polar', 'user role updated', { userId: user.id, username: user.username, newRole, status });
+}

ui/src/routes/+layout.server.ts

@@ -30,6 +30,7 @@ export const load: LayoutServerLoad = async ({ locals, url }) => {
 
 	return {
 		user: locals.user,
+		isPro: locals.isPro,
 		settings
 	};
 };

ui/src/routes/api/audio/[slug]/[n]/+server.ts

@@ -2,6 +2,34 @@ import { error } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
 import { log } from '$lib/server/logger';
 import { backendFetch } from '$lib/server/scraper';
+import * as cache from '$lib/server/cache';
+
+const FREE_DAILY_AUDIO_LIMIT = 3;
+
+/**
+ * Return the number of audio chapters a user/session has generated today,
+ * and increment the counter. Uses a Valkey key that expires at midnight UTC.
+ *
+ * Key: audio:daily:<userId|sessionId>:<YYYY-MM-DD>
+ */
+async function incrementDailyAudioCount(identifier: string): Promise<number> {
+	const today = new Date().toISOString().slice(0, 10); // YYYY-MM-DD
+	const key = `audio:daily:${identifier}:${today}`;
+	// Seconds until end of day UTC
+	const now = new Date();
+	const endOfDay = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate() + 1));
+	const ttl = Math.ceil((endOfDay.getTime() - now.getTime()) / 1000);
+	// Use raw get/set with increment so we can read + increment atomically
+	try {
+		const raw = await cache.get<number>(key);
+		const current = (raw ?? 0) + 1;
+		await cache.set(key, current, ttl);
+		return current;
+	} catch {
+		// On cache failure, fail open (don't block audio for cache errors)
+		return 0;
+	}
+}
 
 /**
  * POST /api/audio/[slug]/[n]
@@ -15,14 +43,39 @@ import { backendFetch } from '$lib/server/scraper';
  *       GET /api/presign/audio to obtain a direct MinIO presigned URL.
  *   202 { task_id: string, status: "pending"|"generating" }  — generation
  *       enqueued; poll GET /api/audio/status/[slug]/[n]?voice=... until done.
+ *   402 { error: "pro_required", limit: 3 }  — free daily limit reached.
  */
-export const POST: RequestHandler = async ({ params, request }) => {
+export const POST: RequestHandler = async ({ params, request, locals }) => {
 	const { slug, n } = params;
 	const chapter = parseInt(n, 10);
 	if (!slug || !chapter || chapter < 1) {
 		error(400, 'Invalid slug or chapter number');
 	}
 
+	// ── Paywall: 3 audio chapters/day for free users ───────────────────────────
+	if (!locals.isPro) {
+		// Check if audio already exists (cached) before counting — no charge for
+		// re-requesting something already generated
+		const statusRes = await backendFetch(
+			`/api/audio/status/${slug}/${chapter}`
+		).catch(() => null);
+		const statusData = statusRes?.ok
+			? ((await statusRes.json().catch(() => ({}))) as { status?: string })
+			: {};
+
+		if (statusData.status !== 'done') {
+			const identifier = locals.user?.id ?? locals.sessionId;
+			const count = await incrementDailyAudioCount(identifier);
+			if (count > FREE_DAILY_AUDIO_LIMIT) {
+				log.info('polar', 'free audio limit reached', { identifier, count });
+				return new Response(
+					JSON.stringify({ error: 'pro_required', limit: FREE_DAILY_AUDIO_LIMIT }),
+					{ status: 402, headers: { 'Content-Type': 'application/json' } }
+				);
+			}
+		}
+	}
+
 	let body: { voice?: string } = {};
 	try {
 		body = await request.json();
@@ -62,4 +115,3 @@ export const POST: RequestHandler = async ({ params, request }) => {
 		{ headers: { 'Content-Type': 'application/json' } }
 	);
 };
-

ui/src/routes/api/translation/[slug]/[n]/+server.ts

@@ -0,0 +1,69 @@
+import { error } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { log } from '$lib/server/logger';
+import { backendFetch } from '$lib/server/scraper';
+
+const SUPPORTED_LANGS = new Set(['ru', 'id', 'pt', 'fr']);
+
+/**
+ * POST /api/translation/[slug]/[n]?lang=<lang>
+ * Proxy to backend translation enqueue endpoint.
+ * Enforces Pro gate — free users cannot enqueue translations.
+ *
+ * GET /api/translation/[slug]/[n]?lang=<lang>
+ * Proxy to backend translation fetch (no gate — already gated at page.server.ts).
+ */
+export const GET: RequestHandler = async ({ params, url }) => {
+	const { slug, n } = params;
+	const lang = url.searchParams.get('lang') ?? '';
+	const res = await backendFetch(
+		`/api/translation/${encodeURIComponent(slug)}/${n}?lang=${lang}`
+	);
+	if (!res.ok) {
+		return new Response(null, { status: res.status });
+	}
+	const data = await res.json();
+	return new Response(JSON.stringify(data), {
+		headers: { 'Content-Type': 'application/json' }
+	});
+};
+
+export const POST: RequestHandler = async ({ params, url, locals }) => {
+	const { slug, n } = params;
+	const chapter = parseInt(n, 10);
+	const lang = url.searchParams.get('lang') ?? '';
+
+	if (!slug || !chapter || chapter < 1) error(400, 'Invalid slug or chapter');
+	if (!SUPPORTED_LANGS.has(lang)) error(400, 'Unsupported language');
+
+	// ── Pro gate ──────────────────────────────────────────────────────────────
+	if (!locals.isPro) {
+		log.info('polar', 'translation blocked for free user', {
+			userId: locals.user?.id,
+			slug,
+			chapter,
+			lang
+		});
+		return new Response(
+			JSON.stringify({ error: 'pro_required' }),
+			{ status: 402, headers: { 'Content-Type': 'application/json' } }
+		);
+	}
+
+	const res = await backendFetch(
+		`/api/translation/${encodeURIComponent(slug)}/${chapter}?lang=${lang}`,
+		{ method: 'POST' }
+	);
+
+	if (!res.ok) {
+		const text = await res.text().catch(() => '');
+		log.error('translation', 'backend translation enqueue failed', { slug, chapter, lang, status: res.status, body: text });
+		error(res.status as Parameters<typeof error>[0], text || 'Translation enqueue failed');
+	}
+
+	const data = await res.json();
+	return new Response(JSON.stringify(data), {
+		status: res.status,
+		headers: { 'Content-Type': 'application/json' }
+	});
+};

ui/src/routes/api/translation/status/[slug]/[n]/+server.ts

@@ -0,0 +1,23 @@
+import type { RequestHandler } from './$types';
+import { backendFetch } from '$lib/server/scraper';
+
+/**
+ * GET /api/translation/status/[slug]/[n]?lang=<lang>
+ * Proxies the translation status check to the backend.
+ */
+export const GET: RequestHandler = async ({ params, url }) => {
+	const { slug, n } = params;
+	const lang = url.searchParams.get('lang') ?? '';
+	const res = await backendFetch(
+		`/api/translation/status/${encodeURIComponent(slug)}/${n}?lang=${lang}`
+	);
+	if (!res.ok) {
+		return new Response(JSON.stringify({ status: 'idle' }), {
+			headers: { 'Content-Type': 'application/json' }
+		});
+	}
+	const data = await res.json();
+	return new Response(JSON.stringify(data), {
+		headers: { 'Content-Type': 'application/json' }
+	});
+};

ui/src/routes/api/webhooks/polar/+server.ts

@@ -0,0 +1,52 @@
+import type { RequestHandler } from './$types';
+import { log } from '$lib/server/logger';
+import { verifyPolarWebhook, handleSubscriptionEvent } from '$lib/server/polar';
+
+/**
+ * POST /api/webhooks/polar
+ *
+ * Receives Polar subscription lifecycle events and syncs user roles in PocketBase.
+ * Signature is verified via HMAC-SHA256 before any processing.
+ */
+export const POST: RequestHandler = async ({ request }) => {
+	const rawBody = await request.text();
+	const signature = request.headers.get('webhook-signature') ?? '';
+
+	if (!verifyPolarWebhook(rawBody, signature)) {
+		log.warn('polar', 'webhook signature verification failed');
+		return new Response('Unauthorized', { status: 401 });
+	}
+
+	let event: { type: string; data: Record<string, unknown> };
+	try {
+		event = JSON.parse(rawBody);
+	} catch {
+		return new Response('Bad Request', { status: 400 });
+	}
+
+	const { type, data } = event;
+	log.info('polar', 'webhook received', { type });
+
+	try {
+		switch (type) {
+			case 'subscription.created':
+			case 'subscription.updated':
+			case 'subscription.revoked':
+				await handleSubscriptionEvent(type, data as unknown as Parameters<typeof handleSubscriptionEvent>[1]);
+				break;
+
+			case 'order.created':
+				// One-time purchases — no role change needed for now
+				log.info('polar', 'order.created (no action)', { orderId: data.id });
+				break;
+
+			default:
+				log.debug('polar', 'unhandled webhook event type', { type });
+		}
+	} catch (err) {
+		// Log but return 200 — Polar retries on non-2xx, we don't want retry storms
+		log.error('polar', 'webhook handler error', { type, err: String(err) });
+	}
+
+	return new Response('OK', { status: 200 });
+};

ui/src/routes/books/[slug]/chapters/[n]/+page.server.ts

@@ -17,8 +17,10 @@ export const load: PageServerLoad = async ({ params, url, locals }) => {
 	const isPreview = url.searchParams.get('preview') === '1';
 	const chapterUrl = url.searchParams.get('chapter_url') ?? '';
 	const chapterTitle = url.searchParams.get('title') ?? '';
-	const lang = url.searchParams.get('lang') ?? '';
-	const useTranslation = SUPPORTED_LANGS.has(lang);
+	const rawLang = url.searchParams.get('lang') ?? '';
+	// Non-pro users can only read EN — silently ignore lang param
+	const lang = locals.isPro && SUPPORTED_LANGS.has(rawLang) ? rawLang : '';
+	const useTranslation = lang !== '';
 
 	if (isPreview) {
 		// ── Preview path: scrape chapter live, nothing from PocketBase/MinIO ──
@@ -83,7 +85,8 @@ export const load: PageServerLoad = async ({ params, url, locals }) => {
 			sessionId: locals.sessionId,
 			isPreview: true,
 			lang: '',
-			translationStatus: 'unavailable' as string
+			translationStatus: 'unavailable' as string,
+			isPro: locals.isPro
 		};
 	}
 
@@ -129,10 +132,11 @@ export const load: PageServerLoad = async ({ params, url, locals }) => {
 					prev: prevChapter ? prevChapter.number : null,
 					next: nextChapter ? nextChapter.number : null,
 					chapters: chapters.map((c) => ({ number: c.number, title: c.title })),
-					sessionId: locals.sessionId,
-					isPreview: false,
-					lang,
-					translationStatus: 'done'
+				sessionId: locals.sessionId,
+				isPreview: false,
+				lang,
+				translationStatus: 'done',
+				isPro: locals.isPro
 				};
 			}
 			// 404 = not generated yet — fall through to original, UI can trigger generation
@@ -188,6 +192,7 @@ export const load: PageServerLoad = async ({ params, url, locals }) => {
 		sessionId: locals.sessionId,
 		isPreview: false,
 		lang: useTranslation ? lang : '',
-		translationStatus
+		translationStatus,
+		isPro: locals.isPro
 	};
 };

ui/src/routes/books/[slug]/chapters/[n]/+page.svelte

@@ -11,6 +11,7 @@
 	let html = $state(untrack(() => data.html));
 	let fetchingContent = $state(untrack(() => !data.isPreview && !data.html));
 	let fetchError = $state('');
+	let audioProRequired = $state(false);
 
 	// Translation state
 	const SUPPORTED_LANGS = [
@@ -35,6 +36,10 @@
 	}
 
 	async function requestTranslation(lang: string) {
+		if (!data.isPro) {
+			// Don't even attempt — show upgrade inline
+			return;
+		}
 		translatingLang = lang;
 		translationStatus = 'pending';
 		try {
@@ -42,6 +47,11 @@
 				`/api/translation/${encodeURIComponent(data.book.slug)}/${data.chapter.number}?lang=${lang}`,
 				{ method: 'POST' }
 			);
+			if (res.status === 402) {
+				translationStatus = 'idle';
+				translatingLang = '';
+				return;
+			}
 			const d = (await res.json()) as { status: string };
 			translationStatus = d.status ?? 'pending';
 			if (d.status === 'done') {
@@ -192,7 +202,19 @@
 	</a>
 
 	{#each SUPPORTED_LANGS as { code, label }}
-		{#if currentLang() === code && (translationStatus === 'pending' || translationStatus === 'running')}
+		{#if !data.isPro}
+			<!-- Locked for free users -->
+			<a
+				href="/profile"
+				title="Upgrade to Pro to read in {label}"
+				class="flex items-center gap-0.5 px-2 py-0.5 rounded text-xs font-medium bg-(--color-surface-2) text-(--color-muted) opacity-60 cursor-pointer hover:opacity-80 transition-opacity"
+			>
+				<svg class="w-3 h-3" fill="currentColor" viewBox="0 0 20 20">
+					<path fill-rule="evenodd" d="M10 1a4.5 4.5 0 00-4.5 4.5V9H5a2 2 0 00-2 2v6a2 2 0 002 2h10a2 2 0 002-2v-6a2 2 0 00-2-2h-.5V5.5A4.5 4.5 0 0010 1zm3 8V5.5a3 3 0 10-6 0V9h6z" clip-rule="evenodd" />
+				</svg>
+				{label}
+			</a>
+		{:else if currentLang() === code && (translationStatus === 'pending' || translationStatus === 'running')}
 			<!-- Spinning indicator while translating -->
 			<span class="flex items-center gap-1 px-2 py-0.5 rounded text-xs font-medium bg-(--color-surface-2) text-(--color-muted)">
 				<svg class="w-3 h-3 animate-spin" fill="none" viewBox="0 0 24 24">
@@ -216,11 +238,29 @@
 			>{label}</button>
 		{/if}
 	{/each}
+
+	{#if !data.isPro}
+		<a href="/profile" class="text-xs text-(--color-brand) hover:underline ml-1">Upgrade to Pro</a>
+	{/if}
 </div>
 {/if}
 
 <!-- Audio player -->
 {#if !data.isPreview}
+{#if audioProRequired}
+	<div class="mb-6 px-4 py-3 rounded-lg bg-(--color-surface-2) border border-(--color-brand)/30 flex items-center justify-between gap-4">
+		<div>
+			<p class="text-(--color-text) text-sm font-medium">Daily audio limit reached</p>
+			<p class="text-(--color-muted) text-xs mt-0.5">Free users can listen to 3 chapters per day. Upgrade to Pro for unlimited audio.</p>
+		</div>
+		<a
+			href="/profile"
+			class="shrink-0 px-4 py-2 rounded bg-(--color-brand) text-(--color-surface) text-sm font-semibold hover:bg-(--color-brand-dim) transition-colors"
+		>
+			Upgrade
+		</a>
+	</div>
+{:else}
 <AudioPlayer
 	slug={data.book.slug}
 	chapter={data.chapter.number}
@@ -230,7 +270,9 @@
 	nextChapter={data.next}
 	chapters={data.chapters}
 	voices={data.voices}
+	onProRequired={() => { audioProRequired = true; }}
 />
+{/if}
 {:else}
 <div class="mb-6 px-4 py-3 rounded bg-(--color-surface-2)/60 border border-(--color-border) text-(--color-muted) text-sm">
 	{m.reader_preview_audio_notice()}

ui/src/routes/profile/+page.svelte

@@ -275,6 +275,69 @@
 		</div>
 	</div>
 
+	<!-- ── Subscription ─────────────────────────────────────────────────────── -->
+	<section class="bg-(--color-surface-2) rounded-xl border border-(--color-border) p-6 space-y-4">
+		<div class="flex items-center justify-between gap-3 flex-wrap">
+			<h2 class="text-lg font-semibold text-(--color-text)">{m.profile_subscription_heading()}</h2>
+			{#if data.isPro}
+				<span class="inline-flex items-center gap-1.5 px-2.5 py-1 rounded-full text-xs font-bold bg-amber-400/15 text-amber-400 border border-amber-400/30 tracking-wide uppercase">
+					<svg class="w-3.5 h-3.5" fill="currentColor" viewBox="0 0 24 24">
+						<path d="M11.99 2C6.47 2 2 6.48 2 12s4.47 10 9.99 10C17.52 22 22 17.52 22 12S17.52 2 11.99 2zm4.24 16L12 15.45 7.77 18l1.12-4.81-3.73-3.23 4.92-.42L12 5l1.92 4.53 4.92.42-3.73 3.23L16.23 18z"/>
+					</svg>
+					{m.profile_plan_pro()}
+				</span>
+			{:else}
+				<span class="inline-flex items-center px-2.5 py-1 rounded-full text-xs font-semibold bg-(--color-surface-3) text-(--color-muted) border border-(--color-border) uppercase tracking-wide">
+					{m.profile_plan_free()}
+				</span>
+			{/if}
+		</div>
+
+		{#if data.isPro}
+			<p class="text-sm text-(--color-text)">{m.profile_pro_active()}</p>
+			<p class="text-sm text-(--color-muted)">{m.profile_pro_perks()}</p>
+			<a
+				href="https://polar.sh/libnovel"
+				target="_blank"
+				rel="noopener noreferrer"
+				class="inline-flex items-center gap-1.5 text-sm font-medium text-(--color-brand) hover:underline"
+			>
+				{m.profile_manage_subscription()}
+				<svg class="w-3.5 h-3.5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+					<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M10 6H6a2 2 0 00-2 2v10a2 2 0 002 2h10a2 2 0 002-2v-4M14 4h6m0 0v6m0-6L10 14"/>
+				</svg>
+			</a>
+		{:else}
+			<p class="text-sm text-(--color-muted)">{m.profile_free_limits()}</p>
+			<div>
+				<p class="text-sm font-semibold text-(--color-text) mb-3">{m.profile_upgrade_heading()}</p>
+				<p class="text-sm text-(--color-muted) mb-4">{m.profile_upgrade_desc()}</p>
+				<div class="flex flex-wrap gap-3">
+					<a
+						href="https://buy.polar.sh/libnovel/1376fdf5-b6a9-492b-be70-7c905131c0f9"
+						target="_blank"
+						rel="noopener noreferrer"
+						class="inline-flex items-center gap-2 px-4 py-2.5 rounded-lg bg-(--color-brand) text-(--color-surface) font-semibold text-sm hover:bg-(--color-brand-dim) transition-colors"
+					>
+						<svg class="w-4 h-4 shrink-0" fill="currentColor" viewBox="0 0 24 24">
+							<path d="M11.99 2C6.47 2 2 6.48 2 12s4.47 10 9.99 10C17.52 22 22 17.52 22 12S17.52 2 11.99 2zm4.24 16L12 15.45 7.77 18l1.12-4.81-3.73-3.23 4.92-.42L12 5l1.92 4.53 4.92.42-3.73 3.23L16.23 18z"/>
+						</svg>
+						{m.profile_upgrade_monthly()}
+					</a>
+					<a
+						href="https://buy.polar.sh/libnovel/b6190307-79aa-4905-80c8-9ed941378d21"
+						target="_blank"
+						rel="noopener noreferrer"
+						class="inline-flex items-center gap-2 px-4 py-2.5 rounded-lg border border-(--color-brand) text-(--color-brand) font-semibold text-sm hover:bg-(--color-brand)/10 transition-colors"
+					>
+						{m.profile_upgrade_annual()}
+						<span class="text-xs font-bold px-1.5 py-0.5 rounded bg-amber-400/15 text-amber-400 border border-amber-400/30">–33%</span>
+					</a>
+				</div>
+			</div>
+		{/if}
+	</section>
+
 	<!-- ── Appearance ────────────────────────────────────────────────────────── -->
 	<section class="bg-(--color-surface-2) rounded-xl border border-(--color-border) p-6 space-y-5">
 		<h2 class="text-lg font-semibold text-(--color-text)">{m.profile_appearance_heading()}</h2>