diff --git a/.env.example b/.env.example
index 73adfe5..50bec30 100644
--- a/.env.example
+++ b/.env.example
@@ -5,8 +5,28 @@ AUTH_SECRET=replace-me
 DATABASE_URL=postgres://user:pass@host:5432/db
 
 # EGBE LiteLLM proxy — auto-injected by app-deploy.sh from the deploying instance
-EGBE_AI_API_URL=https://proxy.gcp.egbe.dev/v1
+EGBE_AI_API_URL=https://litellm.gcp.egbe.dev
 EGBE_AI_API_KEY=
 
 # Public origin of this app — auto-injected by app-deploy.sh
 NEXT_PUBLIC_BASE_URL=http://localhost:3000
+
+# --- analytics (umami) ---
+# Auto-injected by app-deploy.sh after `analytics-site-create.sh <slug> <host> "<Name>"`
+NEXT_PUBLIC_UMAMI_SCRIPT_URL=
+NEXT_PUBLIC_UMAMI_WEBSITE_ID=
+
+# --- billing (payment gateway) ---
+# Auto-injected by app-deploy.sh from the deploying instance
+EGBE_PAYMENT_GATEWAY_URL=https://payments.gcp.egbe.dev
+EGBE_GATEWAYS_TOKEN=
+EGBE_PAYMENT_GATEWAY_WEBHOOK_SECRET=
+EGBE_PAYMENT_GATEWAY_WEBHOOK_HEADER=x-egbe-payment-signature
+
+# Stripe price ID for the Pro plan — set per-product after creating the product via
+# the payment gateway API. Without it the upgrade button returns 501.
+PRO_STRIPE_PRICE_ID=
+
+# App slug used in the webhook URL when creating checkout sessions. Must match the
+# slug you passed to app-deploy.sh.
+APP_SLUG=chatbot
diff --git a/README.md b/README.md
index f164e63..14cc904 100644
--- a/README.md
+++ b/README.md
@@ -1,38 +1,59 @@
 # EGBE Chatbot Template
 
-Next.js chatbot wired to the EGBE LiteLLM proxy. Based on [vercel/chatbot](https://github.com/vercel/chatbot) (Apache 2.0), stripped of Vercel-specific bits and rewired for our infra.
+Next.js chatbot wired to the EGBE infra. Based on [vercel/chatbot](https://github.com/vercel/chatbot) (Apache 2.0).
 
-## Stack
+## What's wired
 
-- **Next.js 16** (App Router, standalone output)
-- **AI SDK** + `@ai-sdk/openai-compatible` → routes to `EGBE_AI_API_URL` (our LiteLLM)
-- **NextAuth** (credentials + guest)
-- **Drizzle ORM** + Postgres (DB gateway)
-- **shadcn/ui** + Tailwind
+- **AI** via `@ai-sdk/openai-compatible` → `EGBE_AI_API_URL` (LiteLLM proxy)
+- **Auth** — NextAuth credentials + guest mode
+- **DB** — Drizzle ORM + Postgres (provisioned by app-deploy.sh)
+- **Analytics** — Umami `<Script>` mounted when `NEXT_PUBLIC_UMAMI_*` env are set
+- **Subscriptions** — Free / Pro tiers, daily quotas, tool-call metering, real Stripe checkout via the EGBE payment gateway
 
-## Available models (via LiteLLM)
+## Models (via LiteLLM)
 
-`claude-sonnet`, `claude-haiku`, `gpt-5.4`, `gpt-5.4-mini`, `kimi-k2.6`, `minimax-m2.7`, `qwen3-coder`.
+`gpt-5.4-mini` (default), `gpt-5.4`, `claude-sonnet`, `claude-haiku`, `kimi-k2.6`, `minimax-m2.7`, `qwen3-coder`. Edit `lib/ai/models.ts`.
 
-Edit `lib/ai/models.ts` to add or remove.
+## Subscription model
+
+Two tiers (see `lib/subscription/config.ts`):
+
+| Tier | Messages / day | Tool calls / day |
+|------|----------------|------------------|
+| Free | 10             | 5                |
+| Pro  | 1000           | 500              |
+
+- **Message limit** — enforced in `app/(chat)/api/chat/route.ts` via `checkAndConsume(userId, "chat_message")` before `streamText`.
+- **Tool limit** — `getWeather` is wrapped with `withLimit(tool, "tool_call", userId)` (see `lib/ai/tools/with-limit.ts`). Every tool call deducts 1 unit; if quota is hit the tool returns `{ error: "limit_exceeded", ... }` which the model sees and explains to the user.
+- **Quota badge** — `<UsageBadge />` in the chat header polls `/api/usage` every 15s.
+- **Upgrade flow** — `/pricing` → POST `/api/billing/checkout` → redirect to Stripe → webhook at `/api/billing/webhook` flips the user's tier on `checkout.session.completed`.
+
+To add a new tool with metering, just wrap it the same way:
+
+```ts
+const meteredFoo = withLimit(myFooTool, "tool_call", session.user.id);
+```
+
+To add a new limit kind, edit `lib/subscription/config.ts` (`LimitKey`, `LIMITS`) and `lib/subscription/service.ts`.
 
 ## Deploy (from inside an OpenClaw instance)
 
 ```bash
-${SKILLS_DIR}/scripts/app-deploy.sh <slug> chatbot-template
+# 1. provision Umami site (optional — chatbot works without analytics)
+${SKILLS_DIR}/../analytics/scripts/analytics-site-create.sh chatbot chatbot.${EGBE_INSTANCE_PUBLIC_ID}.p.egbe.app "Chatbot"
+
+# 2. (optional) create a Stripe product + price for the Pro plan
+#    Without PRO_STRIPE_PRICE_ID the upgrade button returns 501.
+curl -s -H "Authorization: Bearer ${EGBE_GATEWAYS_TOKEN}" -H "Content-Type: application/json" \
+  -d '{"name":"Chatbot Pro"}' "${EGBE_PAYMENT_GATEWAY_URL}/v1/products"
+# then create a price referencing the returned product id, copy the price id
+
+# 3. deploy
+APP_ENV_JSON='{"AUTH_SECRET":"'$(openssl rand -base64 32)'","PRO_STRIPE_PRICE_ID":"price_..."}' \
+  ${SKILLS_DIR}/scripts/app-deploy.sh chatbot chatbot-template
 ```
 
-`app-deploy.sh` auto-injects:
-- `DATABASE_URL` (per-app Postgres)
-- `EGBE_AI_API_URL`, `EGBE_AI_API_KEY` (instance LiteLLM key)
-- `NEXT_PUBLIC_BASE_URL` (the deployed `*.p.egbe.app` host)
-
-You also need `AUTH_SECRET` — set it via `APP_ENV_JSON`:
-
-```bash
-APP_ENV_JSON='{"AUTH_SECRET":"'$(openssl rand -base64 32)'"}' \
-  ${SKILLS_DIR}/scripts/app-deploy.sh mychat chatbot-template
-```
+`app-deploy.sh` auto-injects: `DATABASE_URL`, `EGBE_AI_API_*`, `NEXT_PUBLIC_BASE_URL`, `NEXT_PUBLIC_UMAMI_*`, `EGBE_PAYMENT_GATEWAY_*`, `EGBE_GATEWAYS_TOKEN`. You pass `AUTH_SECRET` and `PRO_STRIPE_PRICE_ID` (if billing is desired) via `APP_ENV_JSON`.
 
 ## Local dev
 
@@ -44,14 +65,6 @@ pnpm db:migrate
 pnpm dev
 ```
 
-## Tracking upstream
-
-Pull new vercel/chatbot features manually — `origin/upstream` is not configured by default here. Add it back with:
-
-```bash
-git remote add upstream https://github.com/vercel/chatbot.git
-```
-
 ## License
 
-Apache 2.0 — see `LICENSE`. Derivative work of Vercel, Inc.'s [chatbot](https://github.com/vercel/chatbot).
+Apache 2.0 — derivative work of Vercel, Inc.'s [chatbot](https://github.com/vercel/chatbot).
diff --git a/app/(chat)/api/billing/checkout/route.ts b/app/(chat)/api/billing/checkout/route.ts
new file mode 100644
index 0000000..f518240
--- /dev/null
+++ b/app/(chat)/api/billing/checkout/route.ts
@@ -0,0 +1,41 @@
+import { auth } from "@/app/(auth)/auth";
+import {
+  createCheckoutSession,
+  isBillingConfigured,
+} from "@/lib/billing/gateway";
+import { ChatbotError } from "@/lib/errors";
+
+export async function POST(request: Request) {
+  const session = await auth();
+  if (!session?.user) {
+    return new ChatbotError("unauthorized:chat").toResponse();
+  }
+
+  if (!isBillingConfigured()) {
+    return Response.json(
+      {
+        error: "billing_not_configured",
+        message:
+          "Set EGBE_PAYMENT_GATEWAY_URL, EGBE_GATEWAYS_TOKEN, and PRO_STRIPE_PRICE_ID to enable upgrades.",
+      },
+      { status: 501 }
+    );
+  }
+
+  const appSlug = process.env.APP_SLUG ?? "chatbot";
+  const baseUrl =
+    process.env.NEXT_PUBLIC_BASE_URL ?? new URL(request.url).origin;
+
+  try {
+    const result = await createCheckoutSession({
+      userId: session.user.id,
+      customerEmail: session.user.email ?? undefined,
+      appSlug,
+      baseUrl,
+    });
+    return Response.json({ url: result.url, id: result.id });
+  } catch (error) {
+    const message = error instanceof Error ? error.message : "checkout failed";
+    return Response.json({ error: "checkout_failed", message }, { status: 502 });
+  }
+}
diff --git a/app/(chat)/api/billing/webhook/route.ts b/app/(chat)/api/billing/webhook/route.ts
new file mode 100644
index 0000000..d462756
--- /dev/null
+++ b/app/(chat)/api/billing/webhook/route.ts
@@ -0,0 +1,99 @@
+import { eq } from "drizzle-orm";
+import { drizzle } from "drizzle-orm/postgres-js";
+import postgres from "postgres";
+import {
+  verifyWebhookSignature,
+  webhookHeaderName,
+} from "@/lib/billing/gateway";
+import { webhookEvent } from "@/lib/db/schema";
+import { cancelSubscription, upgradeToPro } from "@/lib/subscription/service";
+
+const client = postgres(process.env.DATABASE_URL ?? "");
+const db = drizzle(client);
+
+type StripeCheckoutSession = {
+  id: string;
+  payment_status?: string;
+  customer?: string;
+  subscription?: string;
+  metadata?: { userId?: string };
+};
+
+type StripeSubscription = {
+  id: string;
+  customer?: string;
+  current_period_end?: number;
+  metadata?: { userId?: string };
+};
+
+type WebhookEnvelope = {
+  id: string;
+  type: string;
+  data: { object: StripeCheckoutSession | StripeSubscription };
+};
+
+export async function POST(request: Request) {
+  const rawBody = await request.text();
+  const signature = request.headers.get(webhookHeaderName);
+
+  if (!verifyWebhookSignature(rawBody, signature)) {
+    return Response.json({ error: "invalid_signature" }, { status: 401 });
+  }
+
+  let envelope: WebhookEnvelope;
+  try {
+    envelope = JSON.parse(rawBody);
+  } catch {
+    return Response.json({ error: "invalid_json" }, { status: 400 });
+  }
+
+  const existing = await db
+    .select()
+    .from(webhookEvent)
+    .where(eq(webhookEvent.id, envelope.id))
+    .limit(1);
+  if (existing[0]) {
+    return Response.json({ ok: true, dedup: true });
+  }
+
+  try {
+    await handleEvent(envelope);
+  } catch (error) {
+    console.error("webhook handler failed", error);
+    return Response.json({ error: "handler_failed" }, { status: 500 });
+  }
+
+  await db
+    .insert(webhookEvent)
+    .values({ id: envelope.id, type: envelope.type })
+    .onConflictDoNothing();
+
+  return Response.json({ ok: true });
+}
+
+async function handleEvent(envelope: WebhookEnvelope) {
+  switch (envelope.type) {
+    case "checkout.session.completed": {
+      const obj = envelope.data.object as StripeCheckoutSession;
+      const userId = obj.metadata?.userId;
+      if (!userId) {
+        return;
+      }
+      await upgradeToPro(userId, {
+        stripeCustomerId: obj.customer,
+        stripeSubscriptionId: obj.subscription,
+      });
+      return;
+    }
+    case "customer.subscription.deleted": {
+      const obj = envelope.data.object as StripeSubscription;
+      const userId = obj.metadata?.userId;
+      if (!userId) {
+        return;
+      }
+      await cancelSubscription(userId);
+      return;
+    }
+    default:
+  }
+}
diff --git a/app/(chat)/api/chat/route.ts b/app/(chat)/api/chat/route.ts
index 04230f3..8abb76a 100644
--- a/app/(chat)/api/chat/route.ts
+++ b/app/(chat)/api/chat/route.ts
@@ -5,8 +5,7 @@ import {
   stepCountIs,
   streamText,
 } from "ai";
-import { auth, type UserType } from "@/app/(auth)/auth";
-import { entitlementsByUserType } from "@/lib/ai/entitlements";
+import { auth } from "@/app/(auth)/auth";
 import {
   allowedModelIds,
   DEFAULT_CHAT_MODEL,
@@ -15,10 +14,10 @@ import {
 import { type RequestHints, systemPrompt } from "@/lib/ai/prompts";
 import { getLanguageModel } from "@/lib/ai/providers";
 import { getWeather } from "@/lib/ai/tools/get-weather";
+import { withLimit } from "@/lib/ai/tools/with-limit";
 import {
   deleteChatById,
   getChatById,
-  getMessageCountByUserId,
   getMessagesByChatId,
   saveChat,
   saveMessages,
@@ -28,6 +27,10 @@ import {
 import type { DBMessage } from "@/lib/db/schema";
 import { ChatbotError } from "@/lib/errors";
 import { checkIpRateLimit } from "@/lib/ratelimit";
+import {
+  checkAndConsume,
+  LimitExceededError,
+} from "@/lib/subscription/service";
 import type { ChatMessage } from "@/lib/types";
 import { convertToUIMessages, generateUUID } from "@/lib/utils";
 import { generateTitleFromUserMessage } from "../../actions";
@@ -69,19 +72,25 @@ export async function POST(request: Request) {
 
     await checkIpRateLimit(getClientIp(request));
 
-    const userType: UserType = session.user.type;
-
-    const messageCount = await getMessageCountByUserId({
-      id: session.user.id,
-      differenceInHours: 1,
-    });
-
-    if (messageCount > entitlementsByUserType[userType].maxMessagesPerHour) {
-      return new ChatbotError("rate_limit:chat").toResponse();
-    }
-
     const isToolApprovalFlow = Boolean(messages);
 
+    if (!isToolApprovalFlow) {
+      try {
+        await checkAndConsume(session.user.id, "chat_message");
+      } catch (error) {
+        if (error instanceof LimitExceededError) {
+          return Response.json(
+            {
+              code: "rate_limit:chat",
+              message: `Daily message limit reached (${error.used}/${error.limit} on ${error.tier} tier). Upgrade to Pro at /pricing.`,
+            },
+            { status: 429 }
+          );
+        }
+        throw error;
+      }
+    }
+
     const chat = await getChatById({ id });
     let messagesFromDb: DBMessage[] = [];
     let titlePromise: Promise<string> | null = null;
@@ -165,6 +174,8 @@ export async function POST(request: Request) {
 
     const modelMessages = await convertToModelMessages(uiMessages);
 
+    const meteredWeather = withLimit(getWeather, "tool_call", session.user.id);
+
     const stream = createUIMessageStream({
       originalMessages: isToolApprovalFlow ? uiMessages : undefined,
       execute: async ({ writer: dataStream }) => {
@@ -176,7 +187,7 @@ export async function POST(request: Request) {
           experimental_activeTools:
             isReasoningModel && !supportsTools ? [] : ["getWeather"],
           tools: {
-            getWeather,
+            getWeather: meteredWeather,
           },
         });
 
diff --git a/app/(chat)/api/usage/route.ts b/app/(chat)/api/usage/route.ts
new file mode 100644
index 0000000..5e569df
--- /dev/null
+++ b/app/(chat)/api/usage/route.ts
@@ -0,0 +1,16 @@
+import { auth } from "@/app/(auth)/auth";
+import { ChatbotError } from "@/lib/errors";
+import { getQuotaSummary } from "@/lib/subscription/service";
+
+export async function GET() {
+  const session = await auth();
+  if (!session?.user) {
+    return new ChatbotError("unauthorized:chat").toResponse();
+  }
+  const summary = await getQuotaSummary(session.user.id);
+  return Response.json(summary, {
+    headers: {
+      "Cache-Control": "no-store",
+    },
+  });
+}
diff --git a/app/layout.tsx b/app/layout.tsx
index 9e310aa..38f0222 100644
--- a/app/layout.tsx
+++ b/app/layout.tsx
@@ -1,5 +1,6 @@
 import type { Metadata } from "next";
 import { Geist, Geist_Mono } from "next/font/google";
+import { Analytics } from "@/components/analytics";
 import { ThemeProvider } from "@/components/theme-provider";
 import { TooltipProvider } from "@/components/ui/tooltip";
 
@@ -68,6 +69,7 @@ export default function RootLayout({
             __html: THEME_COLOR_SCRIPT,
           }}
         />
+        <Analytics />
       </head>
       <body className="antialiased">
         <ThemeProvider
diff --git a/app/pricing/page.tsx b/app/pricing/page.tsx
new file mode 100644
index 0000000..9a1adb8
--- /dev/null
+++ b/app/pricing/page.tsx
@@ -0,0 +1,96 @@
+import { redirect } from "next/navigation";
+import { auth } from "@/app/(auth)/auth";
+import { PricingClient } from "@/components/pricing-client";
+import { LIMITS, type Tier } from "@/lib/subscription/config";
+import { ensureSubscription } from "@/lib/subscription/service";
+
+export const dynamic = "force-dynamic";
+
+export default async function PricingPage({
+  searchParams,
+}: {
+  searchParams: Promise<{ upgraded?: string; canceled?: string }>;
+}) {
+  const session = await auth();
+  if (!session?.user) {
+    redirect("/api/auth/guest?redirectUrl=%2Fpricing");
+  }
+
+  const sub = await ensureSubscription(session.user.id);
+  const params = await searchParams;
+
+  return (
+    <div className="mx-auto flex min-h-dvh max-w-5xl flex-col gap-8 px-6 py-12">
+      <div className="flex flex-col gap-2">
+        <a className="text-muted-foreground text-sm hover:text-foreground" href="/">
+          ← Back to chat
+        </a>
+        <h1 className="font-semibold text-3xl">Pricing</h1>
+        <p className="text-muted-foreground text-sm">
+          You are currently on the <strong>{sub.tier}</strong> tier.
+          {params.upgraded === "1" && (
+            <span className="ml-2 text-green-600">
+              Welcome to Pro — limits updated.
+            </span>
+          )}
+          {params.canceled === "1" && (
+            <span className="ml-2 text-amber-600">Checkout canceled.</span>
+          )}
+        </p>
+      </div>
+
+      <div className="grid gap-4 md:grid-cols-2">
+        <Plan
+          currentTier={sub.tier as Tier}
+          description="Try the chatbot with a small daily quota."
+          price="Free"
+          tier="free"
+        />
+        <Plan
+          currentTier={sub.tier as Tier}
+          description="Higher daily quotas for serious use."
+          price="$10 / month"
+          tier="pro"
+        />
+      </div>
+
+      <PricingClient currentTier={sub.tier as Tier} />
+    </div>
+  );
+}
+
+function Plan({
+  tier,
+  price,
+  description,
+  currentTier,
+}: {
+  tier: Tier;
+  price: string;
+  description: string;
+  currentTier: Tier;
+}) {
+  const tierLimits = LIMITS[tier];
+  const isCurrent = tier === currentTier;
+  return (
+    <div className="flex flex-col gap-4 rounded-2xl border border-border/40 bg-card p-6 shadow-sm">
+      <div>
+        <div className="flex items-baseline justify-between">
+          <div className="font-medium text-lg capitalize">{tier}</div>
+          {isCurrent && (
+            <span className="rounded-full bg-muted px-2 py-0.5 text-muted-foreground text-xs">
+              Current
+            </span>
+          )}
+        </div>
+        <div className="font-semibold text-2xl">{price}</div>
+        <p className="mt-1 text-muted-foreground text-sm">{description}</p>
+      </div>
+      <ul className="flex flex-col gap-1.5 text-sm">
+        <li>• {tierLimits.chat_message} messages / day</li>
+        <li>• {tierLimits.tool_call} tool calls / day</li>
+        <li>• All available models</li>
+      </ul>
+    </div>
+  );
+}
diff --git a/components/analytics.tsx b/components/analytics.tsx
new file mode 100644
index 0000000..b8a3cf7
--- /dev/null
+++ b/components/analytics.tsx
@@ -0,0 +1,20 @@
+import Script from "next/script";
+
+export function Analytics() {
+  const websiteId = process.env.NEXT_PUBLIC_UMAMI_WEBSITE_ID;
+  const scriptUrl = process.env.NEXT_PUBLIC_UMAMI_SCRIPT_URL;
+
+  if (!(websiteId && scriptUrl)) {
+    return null;
+  }
+
+  return (
+    <Script
+      async
+      data-website-id={websiteId}
+      defer
+      src={scriptUrl}
+      strategy="afterInteractive"
+    />
+  );
+}
diff --git a/components/chat/chat-header.tsx b/components/chat/chat-header.tsx
index 26999d4..e98d286 100644
--- a/components/chat/chat-header.tsx
+++ b/components/chat/chat-header.tsx
@@ -1,11 +1,10 @@
 "use client";
 
 import { PanelLeftIcon } from "lucide-react";
-import Link from "next/link";
 import { memo } from "react";
 import { Button } from "@/components/ui/button";
 import { useSidebar } from "@/components/ui/sidebar";
-import { VercelIcon } from "./icons";
+import { UsageBadge } from "./usage-badge";
 import { VisibilitySelector, type VisibilityType } from "./visibility-selector";
 
 function PureChatHeader({
@@ -34,15 +33,6 @@ function PureChatHeader({
         <PanelLeftIcon className="size-4" />
       </Button>
 
-      <Link
-        className="flex size-8 items-center justify-center rounded-lg md:hidden"
-        href="https://vercel.com/templates/next.js/chatbot"
-        rel="noopener noreferrer"
-        target="_blank"
-      >
-        <VercelIcon size={14} />
-      </Link>
-
       {!isReadonly && (
         <VisibilitySelector
           chatId={chatId}
@@ -50,19 +40,9 @@ function PureChatHeader({
         />
       )}
 
-      <Button
-        asChild
-        className="hidden rounded-lg bg-foreground px-4 text-background hover:bg-foreground/90 md:ml-auto md:flex"
-      >
-        <Link
-          href="https://vercel.com/templates/next.js/chatbot"
-          rel="noopener noreferrer"
-          target="_blank"
-        >
-          <VercelIcon size={16} />
-          Deploy with Vercel
-        </Link>
-      </Button>
+      <div className="ml-auto flex items-center gap-2">
+        <UsageBadge />
+      </div>
     </header>
   );
 }
diff --git a/components/chat/usage-badge.tsx b/components/chat/usage-badge.tsx
new file mode 100644
index 0000000..f91fc26
--- /dev/null
+++ b/components/chat/usage-badge.tsx
@@ -0,0 +1,44 @@
+"use client";
+
+import Link from "next/link";
+import useSWR from "swr";
+import type { QuotaSummary } from "@/lib/subscription/service";
+import { fetcher } from "@/lib/utils";
+
+export function UsageBadge() {
+  const { data } = useSWR<QuotaSummary>(
+    `${process.env.NEXT_PUBLIC_BASE_PATH ?? ""}/api/usage`,
+    fetcher,
+    {
+      refreshInterval: 15_000,
+      revalidateOnFocus: true,
+    }
+  );
+
+  if (!data) {
+    return null;
+  }
+
+  const isPro = data.tier === "pro";
+  const lowQuota =
+    !isPro &&
+    (data.messages.remaining <= 2 || data.toolCalls.remaining <= 1);
+
+  return (
+    <Link
+      className={`flex items-center gap-2 rounded-lg border px-2.5 py-1 text-[11px] font-medium transition-colors ${
+        lowQuota
+          ? "border-amber-500/40 bg-amber-500/10 text-amber-600 hover:bg-amber-500/15"
+          : "border-border/40 text-muted-foreground hover:text-foreground"
+      }`}
+      href="/pricing"
+      title={`${data.tier} tier — ${data.toolCalls.used}/${data.toolCalls.limit} tool calls today`}
+    >
+      <span className="uppercase tracking-wider opacity-60">{data.tier}</span>
+      <span>
+        {data.messages.used}/{data.messages.limit} msgs
+      </span>
+      {isPro ? null : <span aria-hidden>→</span>}
+    </Link>
+  );
+}
diff --git a/components/pricing-client.tsx b/components/pricing-client.tsx
new file mode 100644
index 0000000..23d2903
--- /dev/null
+++ b/components/pricing-client.tsx
@@ -0,0 +1,48 @@
+"use client";
+
+import { useState } from "react";
+import { toast } from "sonner";
+import { Button } from "@/components/ui/button";
+import type { Tier } from "@/lib/subscription/config";
+
+export function PricingClient({ currentTier }: { currentTier: Tier }) {
+  const [loading, setLoading] = useState(false);
+
+  if (currentTier === "pro") {
+    return (
+      <p className="text-muted-foreground text-sm">
+        You're on Pro. Manage your subscription through the receipt email link.
+      </p>
+    );
+  }
+
+  const upgrade = async () => {
+    setLoading(true);
+    try {
+      const response = await fetch("/api/billing/checkout", { method: "POST" });
+      const data = await response.json();
+      if (response.ok && data.url) {
+        window.location.href = data.url;
+        return;
+      }
+      toast.error(data.message ?? "Failed to start checkout");
+    } catch (error) {
+      toast.error(error instanceof Error ? error.message : "Checkout failed");
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return (
+    <div className="flex justify-center">
+      <Button
+        className="px-6"
+        disabled={loading}
+        onClick={upgrade}
+        size="lg"
+      >
+        {loading ? "Opening checkout..." : "Upgrade to Pro"}
+      </Button>
+    </div>
+  );
+}
diff --git a/lib/ai/entitlements.ts b/lib/ai/entitlements.ts
deleted file mode 100644
index 8f50152..0000000
--- a/lib/ai/entitlements.ts
+++ /dev/null
@@ -1,14 +0,0 @@
-import type { UserType } from "@/app/(auth)/auth";
-
-type Entitlements = {
-  maxMessagesPerHour: number;
-};
-
-export const entitlementsByUserType: Record<UserType, Entitlements> = {
-  guest: {
-    maxMessagesPerHour: 10,
-  },
-  regular: {
-    maxMessagesPerHour: 10,
-  },
-};
diff --git a/lib/ai/models.ts b/lib/ai/models.ts
index 3d8cdca..3e4813d 100644
--- a/lib/ai/models.ts
+++ b/lib/ai/models.ts
@@ -1,4 +1,4 @@
-export const DEFAULT_CHAT_MODEL = "claude-sonnet";
+export const DEFAULT_CHAT_MODEL = "gpt-5.4-mini";
 
 export type ModelCapabilities = {
   tools: boolean;
diff --git a/lib/ai/tools/with-limit.ts b/lib/ai/tools/with-limit.ts
new file mode 100644
index 0000000..2ef3c4a
--- /dev/null
+++ b/lib/ai/tools/with-limit.ts
@@ -0,0 +1,40 @@
+import type { Tool } from "ai";
+import type { LimitKey } from "@/lib/subscription/config";
+import {
+  checkAndConsume,
+  LimitExceededError,
+} from "@/lib/subscription/service";
+
+export function withLimit<T extends Tool>(
+  tool: T,
+  kind: LimitKey,
+  userId: string
+): T {
+  const originalExecute = tool.execute;
+  if (!originalExecute) {
+    return tool;
+  }
+
+  // biome-ignore lint/suspicious/noExplicitAny: wrapper has to be generic across all tool signatures
+  const wrappedExecute = (async (input: any, options: any) => {
+    try {
+      await checkAndConsume(userId, kind);
+    } catch (error) {
+      if (error instanceof LimitExceededError) {
+        return {
+          error: "limit_exceeded",
+          kind: error.kind,
+          tier: error.tier,
+          used: error.used,
+          limit: error.limit,
+          message: `You've hit your ${kind.replace("_", " ")} limit for today (${error.used}/${error.limit} on ${error.tier} tier). Upgrade to Pro for higher limits.`,
+        };
+      }
+      throw error;
+    }
+    return originalExecute(input, options);
+    // biome-ignore lint/suspicious/noExplicitAny: tool execute signature varies
+  }) as any;
+
+  return { ...tool, execute: wrappedExecute } as T;
+}
diff --git a/lib/billing/gateway.ts b/lib/billing/gateway.ts
new file mode 100644
index 0000000..1a221d3
--- /dev/null
+++ b/lib/billing/gateway.ts
@@ -0,0 +1,105 @@
+import { createHmac, timingSafeEqual } from "node:crypto";
+
+const PAYMENT_GATEWAY_URL = process.env.EGBE_PAYMENT_GATEWAY_URL ?? "";
+const GATEWAY_TOKEN = process.env.EGBE_GATEWAYS_TOKEN ?? "";
+const WEBHOOK_SECRET = process.env.EGBE_PAYMENT_GATEWAY_WEBHOOK_SECRET ?? "";
+const WEBHOOK_HEADER =
+  process.env.EGBE_PAYMENT_GATEWAY_WEBHOOK_HEADER ??
+  "x-egbe-payment-signature";
+
+export function isBillingConfigured(): boolean {
+  return Boolean(
+    PAYMENT_GATEWAY_URL && GATEWAY_TOKEN && process.env.PRO_STRIPE_PRICE_ID
+  );
+}
+
+export type CheckoutSessionArgs = {
+  userId: string;
+  customerEmail?: string;
+  appSlug: string;
+  baseUrl: string;
+};
+
+export async function createCheckoutSession(args: CheckoutSessionArgs) {
+  const priceId = process.env.PRO_STRIPE_PRICE_ID;
+  if (!priceId) {
+    throw new Error("PRO_STRIPE_PRICE_ID not set");
+  }
+  if (!(PAYMENT_GATEWAY_URL && GATEWAY_TOKEN)) {
+    throw new Error("Payment gateway not configured");
+  }
+
+  const body = {
+    price: priceId,
+    mode: "subscription",
+    quantity: 1,
+    successUrl: `${args.baseUrl}/pricing?upgraded=1`,
+    cancelUrl: `${args.baseUrl}/pricing?canceled=1`,
+    customerEmail: args.customerEmail,
+    appSlug: args.appSlug,
+    webhookPath: "/api/billing/webhook",
+    metadata: { userId: args.userId },
+  };
+
+  const response = await fetch(`${PAYMENT_GATEWAY_URL}/v1/checkout-sessions`, {
+    method: "POST",
+    headers: {
+      Authorization: `Bearer ${GATEWAY_TOKEN}`,
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify(body),
+  });
+
+  if (!response.ok) {
+    const text = await response.text();
+    throw new Error(`Payment gateway error ${response.status}: ${text}`);
+  }
+
+  return response.json() as Promise<{ id: string; url: string }>;
+}
+
+export const webhookHeaderName = WEBHOOK_HEADER;
+
+export function verifyWebhookSignature(
+  rawBody: string,
+  signatureHeader: string | null,
+  toleranceSeconds = 300
+): boolean {
+  if (!(WEBHOOK_SECRET && signatureHeader)) {
+    return false;
+  }
+
+  const parts = Object.fromEntries(
+    signatureHeader.split(",").map((part) => {
+      const idx = part.indexOf("=");
+      return idx === -1 ? [part, ""] : [part.slice(0, idx), part.slice(idx + 1)];
+    })
+  );
+
+  const timestamp = parts.t;
+  const v1 = parts.v1;
+  if (!(timestamp && v1)) {
+    return false;
+  }
+
+  const tsNum = Number(timestamp);
+  if (Number.isFinite(tsNum)) {
+    const ageSeconds = Math.abs(Date.now() / 1000 - tsNum);
+    if (ageSeconds > toleranceSeconds) {
+      return false;
+    }
+  }
+
+  const expected = createHmac("sha256", WEBHOOK_SECRET)
+    .update(`${timestamp}.${rawBody}`)
+    .digest("hex");
+
+  try {
+    return timingSafeEqual(
+      Buffer.from(expected, "hex"),
+      Buffer.from(v1, "hex")
+    );
+  } catch {
+    return false;
+  }
+}
diff --git a/lib/db/migrations/0001_even_baron_strucker.sql b/lib/db/migrations/0001_even_baron_strucker.sql
new file mode 100644
index 0000000..ef6999f
--- /dev/null
+++ b/lib/db/migrations/0001_even_baron_strucker.sql
@@ -0,0 +1,37 @@
+CREATE TABLE IF NOT EXISTS "Subscription" (
+	"userId" uuid PRIMARY KEY NOT NULL,
+	"tier" varchar DEFAULT 'free' NOT NULL,
+	"status" varchar DEFAULT 'active' NOT NULL,
+	"stripeCustomerId" text,
+	"stripeSubscriptionId" text,
+	"currentPeriodEnd" timestamp,
+	"createdAt" timestamp DEFAULT now() NOT NULL,
+	"updatedAt" timestamp DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE IF NOT EXISTS "Usage" (
+	"userId" uuid NOT NULL,
+	"periodKey" varchar(10) NOT NULL,
+	"messageCount" integer DEFAULT 0 NOT NULL,
+	"toolCallCount" integer DEFAULT 0 NOT NULL,
+	"updatedAt" timestamp DEFAULT now() NOT NULL,
+	CONSTRAINT "Usage_userId_periodKey_pk" PRIMARY KEY("userId","periodKey")
+);
+--> statement-breakpoint
+CREATE TABLE IF NOT EXISTS "WebhookEvent" (
+	"id" text PRIMARY KEY NOT NULL,
+	"type" text NOT NULL,
+	"receivedAt" timestamp DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+DO $$ BEGIN
+ ALTER TABLE "Subscription" ADD CONSTRAINT "Subscription_userId_User_id_fk" FOREIGN KEY ("userId") REFERENCES "public"."User"("id") ON DELETE no action ON UPDATE no action;
+EXCEPTION
+ WHEN duplicate_object THEN null;
+END $$;
+--> statement-breakpoint
+DO $$ BEGIN
+ ALTER TABLE "Usage" ADD CONSTRAINT "Usage_userId_User_id_fk" FOREIGN KEY ("userId") REFERENCES "public"."User"("id") ON DELETE no action ON UPDATE no action;
+EXCEPTION
+ WHEN duplicate_object THEN null;
+END $$;
diff --git a/lib/db/migrations/meta/0001_snapshot.json b/lib/db/migrations/meta/0001_snapshot.json
new file mode 100644
index 0000000..42baa8c
--- /dev/null
+++ b/lib/db/migrations/meta/0001_snapshot.json
@@ -0,0 +1,435 @@
+{
+  "id": "61392e82-35e9-40f4-a8a4-dc50c5f0e24a",
+  "prevId": "e4157317-da3b-4af3-b3e6-dbddfc2e1ced",
+  "version": "7",
+  "dialect": "postgresql",
+  "tables": {
+    "public.Chat": {
+      "name": "Chat",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "createdAt": {
+          "name": "createdAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "title": {
+          "name": "title",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "userId": {
+          "name": "userId",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "visibility": {
+          "name": "visibility",
+          "type": "varchar",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'private'"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "Chat_userId_User_id_fk": {
+          "name": "Chat_userId_User_id_fk",
+          "tableFrom": "Chat",
+          "tableTo": "User",
+          "columnsFrom": [
+            "userId"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {}
+    },
+    "public.Message_v2": {
+      "name": "Message_v2",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "chatId": {
+          "name": "chatId",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "role": {
+          "name": "role",
+          "type": "varchar",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "parts": {
+          "name": "parts",
+          "type": "json",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "attachments": {
+          "name": "attachments",
+          "type": "json",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "createdAt": {
+          "name": "createdAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "Message_v2_chatId_Chat_id_fk": {
+          "name": "Message_v2_chatId_Chat_id_fk",
+          "tableFrom": "Message_v2",
+          "tableTo": "Chat",
+          "columnsFrom": [
+            "chatId"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {}
+    },
+    "public.Subscription": {
+      "name": "Subscription",
+      "schema": "",
+      "columns": {
+        "userId": {
+          "name": "userId",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true
+        },
+        "tier": {
+          "name": "tier",
+          "type": "varchar",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'free'"
+        },
+        "status": {
+          "name": "status",
+          "type": "varchar",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'active'"
+        },
+        "stripeCustomerId": {
+          "name": "stripeCustomerId",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "stripeSubscriptionId": {
+          "name": "stripeSubscriptionId",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "currentPeriodEnd": {
+          "name": "currentPeriodEnd",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "createdAt": {
+          "name": "createdAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        },
+        "updatedAt": {
+          "name": "updatedAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "Subscription_userId_User_id_fk": {
+          "name": "Subscription_userId_User_id_fk",
+          "tableFrom": "Subscription",
+          "tableTo": "User",
+          "columnsFrom": [
+            "userId"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {}
+    },
+    "public.Usage": {
+      "name": "Usage",
+      "schema": "",
+      "columns": {
+        "userId": {
+          "name": "userId",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "periodKey": {
+          "name": "periodKey",
+          "type": "varchar(10)",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "messageCount": {
+          "name": "messageCount",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "default": 0
+        },
+        "toolCallCount": {
+          "name": "toolCallCount",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "default": 0
+        },
+        "updatedAt": {
+          "name": "updatedAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "Usage_userId_User_id_fk": {
+          "name": "Usage_userId_User_id_fk",
+          "tableFrom": "Usage",
+          "tableTo": "User",
+          "columnsFrom": [
+            "userId"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {
+        "Usage_userId_periodKey_pk": {
+          "name": "Usage_userId_periodKey_pk",
+          "columns": [
+            "userId",
+            "periodKey"
+          ]
+        }
+      },
+      "uniqueConstraints": {}
+    },
+    "public.User": {
+      "name": "User",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "email": {
+          "name": "email",
+          "type": "varchar(64)",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "password": {
+          "name": "password",
+          "type": "varchar(64)",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "name": {
+          "name": "name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "emailVerified": {
+          "name": "emailVerified",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": true,
+          "default": false
+        },
+        "image": {
+          "name": "image",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "isAnonymous": {
+          "name": "isAnonymous",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": true,
+          "default": false
+        },
+        "createdAt": {
+          "name": "createdAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        },
+        "updatedAt": {
+          "name": "updatedAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {}
+    },
+    "public.Vote_v2": {
+      "name": "Vote_v2",
+      "schema": "",
+      "columns": {
+        "chatId": {
+          "name": "chatId",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "messageId": {
+          "name": "messageId",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "isUpvoted": {
+          "name": "isUpvoted",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": true
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "Vote_v2_chatId_Chat_id_fk": {
+          "name": "Vote_v2_chatId_Chat_id_fk",
+          "tableFrom": "Vote_v2",
+          "tableTo": "Chat",
+          "columnsFrom": [
+            "chatId"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        },
+        "Vote_v2_messageId_Message_v2_id_fk": {
+          "name": "Vote_v2_messageId_Message_v2_id_fk",
+          "tableFrom": "Vote_v2",
+          "tableTo": "Message_v2",
+          "columnsFrom": [
+            "messageId"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {
+        "Vote_v2_chatId_messageId_pk": {
+          "name": "Vote_v2_chatId_messageId_pk",
+          "columns": [
+            "chatId",
+            "messageId"
+          ]
+        }
+      },
+      "uniqueConstraints": {}
+    },
+    "public.WebhookEvent": {
+      "name": "WebhookEvent",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true
+        },
+        "type": {
+          "name": "type",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "receivedAt": {
+          "name": "receivedAt",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {}
+    }
+  },
+  "enums": {},
+  "schemas": {},
+  "sequences": {},
+  "_meta": {
+    "columns": {},
+    "schemas": {},
+    "tables": {}
+  }
+}
\ No newline at end of file
diff --git a/lib/db/migrations/meta/_journal.json b/lib/db/migrations/meta/_journal.json
index 8de57e9..8e19c9b 100644
--- a/lib/db/migrations/meta/_journal.json
+++ b/lib/db/migrations/meta/_journal.json
@@ -8,6 +8,13 @@
       "when": 1779705963902,
       "tag": "0000_bouncy_payback",
       "breakpoints": true
+    },
+    {
+      "idx": 1,
+      "version": "7",
+      "when": 1779715519996,
+      "tag": "0001_even_baron_strucker",
+      "breakpoints": true
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/db/schema.ts b/lib/db/schema.ts
index a66ef4f..5dffea7 100644
--- a/lib/db/schema.ts
+++ b/lib/db/schema.ts
@@ -1,6 +1,7 @@
 import type { InferSelectModel } from "drizzle-orm";
 import {
   boolean,
+  integer,
   json,
   pgTable,
   primaryKey,
@@ -68,3 +69,49 @@ export const vote = pgTable(
 );
 
 export type Vote = InferSelectModel<typeof vote>;
+
+export const subscription = pgTable("Subscription", {
+  userId: uuid("userId")
+    .primaryKey()
+    .notNull()
+    .references(() => user.id),
+  tier: varchar("tier", { enum: ["free", "pro"] })
+    .notNull()
+    .default("free"),
+  status: varchar("status", { enum: ["active", "canceled", "past_due"] })
+    .notNull()
+    .default("active"),
+  stripeCustomerId: text("stripeCustomerId"),
+  stripeSubscriptionId: text("stripeSubscriptionId"),
+  currentPeriodEnd: timestamp("currentPeriodEnd"),
+  createdAt: timestamp("createdAt").notNull().defaultNow(),
+  updatedAt: timestamp("updatedAt").notNull().defaultNow(),
+});
+
+export type Subscription = InferSelectModel<typeof subscription>;
+
+export const usage = pgTable(
+  "Usage",
+  {
+    userId: uuid("userId")
+      .notNull()
+      .references(() => user.id),
+    periodKey: varchar("periodKey", { length: 10 }).notNull(),
+    messageCount: integer("messageCount").notNull().default(0),
+    toolCallCount: integer("toolCallCount").notNull().default(0),
+    updatedAt: timestamp("updatedAt").notNull().defaultNow(),
+  },
+  (table) => ({
+    pk: primaryKey({ columns: [table.userId, table.periodKey] }),
+  })
+);
+
+export type Usage = InferSelectModel<typeof usage>;
+
+export const webhookEvent = pgTable("WebhookEvent", {
+  id: text("id").primaryKey().notNull(),
+  type: text("type").notNull(),
+  receivedAt: timestamp("receivedAt").notNull().defaultNow(),
+});
+
+export type WebhookEvent = InferSelectModel<typeof webhookEvent>;
diff --git a/lib/subscription/config.ts b/lib/subscription/config.ts
new file mode 100644
index 0000000..3c59bb1
--- /dev/null
+++ b/lib/subscription/config.ts
@@ -0,0 +1,27 @@
+export type Tier = "free" | "pro";
+export type LimitKey = "chat_message" | "tool_call";
+
+export type TierLimits = Record<LimitKey, number>;
+
+export const LIMITS: Record<Tier, TierLimits> = {
+  free: {
+    chat_message: 10,
+    tool_call: 5,
+  },
+  pro: {
+    chat_message: 1000,
+    tool_call: 500,
+  },
+};
+
+export const TIER_LABELS: Record<Tier, string> = {
+  free: "Free",
+  pro: "Pro",
+};
+
+export function todayPeriodKey(now = new Date()): string {
+  const y = now.getUTCFullYear();
+  const m = String(now.getUTCMonth() + 1).padStart(2, "0");
+  const d = String(now.getUTCDate()).padStart(2, "0");
+  return `${y}-${m}-${d}`;
+}
diff --git a/lib/subscription/service.ts b/lib/subscription/service.ts
new file mode 100644
index 0000000..e5e9c83
--- /dev/null
+++ b/lib/subscription/service.ts
@@ -0,0 +1,210 @@
+import "server-only";
+
+import { and, eq, sql } from "drizzle-orm";
+import { drizzle } from "drizzle-orm/postgres-js";
+import postgres from "postgres";
+import {
+  subscription,
+  type Subscription,
+  usage,
+  type Usage,
+} from "@/lib/db/schema";
+import {
+  type LimitKey,
+  LIMITS,
+  type Tier,
+  todayPeriodKey,
+} from "./config";
+
+const client = postgres(process.env.DATABASE_URL ?? "");
+const db = drizzle(client);
+
+export class LimitExceededError extends Error {
+  kind: LimitKey;
+  tier: Tier;
+  used: number;
+  limit: number;
+
+  constructor(args: {
+    kind: LimitKey;
+    tier: Tier;
+    used: number;
+    limit: number;
+  }) {
+    super(
+      `Limit exceeded for ${args.kind}: ${args.used}/${args.limit} on ${args.tier} tier`
+    );
+    this.kind = args.kind;
+    this.tier = args.tier;
+    this.used = args.used;
+    this.limit = args.limit;
+  }
+}
+
+export async function ensureSubscription(userId: string): Promise<Subscription> {
+  const existing = await db
+    .select()
+    .from(subscription)
+    .where(eq(subscription.userId, userId))
+    .limit(1);
+
+  if (existing[0]) {
+    return existing[0];
+  }
+
+  const [row] = await db
+    .insert(subscription)
+    .values({ userId, tier: "free", status: "active" })
+    .returning();
+  return row;
+}
+
+export async function getSubscription(
+  userId: string
+): Promise<Subscription | null> {
+  const [row] = await db
+    .select()
+    .from(subscription)
+    .where(eq(subscription.userId, userId))
+    .limit(1);
+  return row ?? null;
+}
+
+export async function getCurrentUsage(userId: string): Promise<Usage> {
+  const periodKey = todayPeriodKey();
+  const [existing] = await db
+    .select()
+    .from(usage)
+    .where(and(eq(usage.userId, userId), eq(usage.periodKey, periodKey)))
+    .limit(1);
+
+  if (existing) {
+    return existing;
+  }
+
+  const [created] = await db
+    .insert(usage)
+    .values({ userId, periodKey, messageCount: 0, toolCallCount: 0 })
+    .onConflictDoNothing()
+    .returning();
+
+  if (created) {
+    return created;
+  }
+
+  const [fallback] = await db
+    .select()
+    .from(usage)
+    .where(and(eq(usage.userId, userId), eq(usage.periodKey, periodKey)))
+    .limit(1);
+  return fallback;
+}
+
+export async function checkAndConsume(
+  userId: string,
+  kind: LimitKey,
+  units = 1
+): Promise<{ remaining: number; limit: number; tier: Tier }> {
+  const sub = await ensureSubscription(userId);
+  const tier = sub.tier as Tier;
+  const limit = LIMITS[tier][kind];
+  const column = kind === "chat_message" ? usage.messageCount : usage.toolCallCount;
+  const column_name = kind === "chat_message" ? "messageCount" : "toolCallCount";
+  const periodKey = todayPeriodKey();
+
+  await ensureUsageRow(userId, periodKey);
+
+  const result = await db
+    .update(usage)
+    .set({
+      [column_name]: sql`${column} + ${units}`,
+      updatedAt: new Date(),
+    })
+    .where(
+      and(
+        eq(usage.userId, userId),
+        eq(usage.periodKey, periodKey),
+        sql`${column} + ${units} <= ${limit}`
+      )
+    )
+    .returning();
+
+  if (result.length === 0) {
+    const current = await getCurrentUsage(userId);
+    const used =
+      kind === "chat_message" ? current.messageCount : current.toolCallCount;
+    throw new LimitExceededError({ kind, tier, used, limit });
+  }
+
+  const updated = result[0];
+  const used =
+    kind === "chat_message" ? updated.messageCount : updated.toolCallCount;
+  return { remaining: Math.max(0, limit - used), limit, tier };
+}
+
+async function ensureUsageRow(userId: string, periodKey: string) {
+  await db
+    .insert(usage)
+    .values({ userId, periodKey, messageCount: 0, toolCallCount: 0 })
+    .onConflictDoNothing();
+}
+
+export async function upgradeToPro(
+  userId: string,
+  args: {
+    stripeCustomerId?: string;
+    stripeSubscriptionId?: string;
+    currentPeriodEnd?: Date;
+  } = {}
+): Promise<Subscription> {
+  await ensureSubscription(userId);
+  const [row] = await db
+    .update(subscription)
+    .set({
+      tier: "pro",
+      status: "active",
+      stripeCustomerId: args.stripeCustomerId,
+      stripeSubscriptionId: args.stripeSubscriptionId,
+      currentPeriodEnd: args.currentPeriodEnd,
+      updatedAt: new Date(),
+    })
+    .where(eq(subscription.userId, userId))
+    .returning();
+  return row;
+}
+
+export async function cancelSubscription(
+  userId: string
+): Promise<Subscription> {
+  const [row] = await db
+    .update(subscription)
+    .set({ status: "canceled", updatedAt: new Date() })
+    .where(eq(subscription.userId, userId))
+    .returning();
+  return row;
+}
+
+export async function getQuotaSummary(userId: string) {
+  const sub = await ensureSubscription(userId);
+  const tier = sub.tier as Tier;
+  const usage = await getCurrentUsage(userId);
+  const tierLimits = LIMITS[tier];
+
+  return {
+    tier,
+    status: sub.status,
+    periodKey: usage.periodKey,
+    messages: {
+      used: usage.messageCount,
+      limit: tierLimits.chat_message,
+      remaining: Math.max(0, tierLimits.chat_message - usage.messageCount),
+    },
+    toolCalls: {
+      used: usage.toolCallCount,
+      limit: tierLimits.tool_call,
+      remaining: Math.max(0, tierLimits.tool_call - usage.toolCallCount),
+    },
+  };
+}
+
+export type QuotaSummary = Awaited<ReturnType<typeof getQuotaSummary>>;
diff --git a/proxy.ts b/proxy.ts
index 60b97f4..c5f7d65 100644
--- a/proxy.ts
+++ b/proxy.ts
@@ -13,6 +13,10 @@ export async function proxy(request: NextRequest) {
     return NextResponse.next();
   }
 
+  if (pathname.startsWith("/api/billing/webhook")) {
+    return NextResponse.next();
+  }
+
   const token = await getToken({
     req: request,
     secret: process.env.AUTH_SECRET,