Add Umami analytics, subscription tiers, tool-call metering

- Analytics: <Analytics /> in root layout loads umami when NEXT_PUBLIC_UMAMI_* env are set
- Subscription: free/pro tiers in Postgres, daily quotas (10msg/5tool free, 1000/500 pro)
- Chat route: checkAndConsume(chat_message) gate before streamText, 429 when exhausted
- Tool metering: getWeather wrapped with withLimit decorator that deducts tool_call quota
- Pricing page at /pricing with upgrade button
- /api/billing/checkout posts to EGBE payment gateway, /api/billing/webhook verifies HMAC and upgrades user on checkout.session.completed
- UsageBadge in chat header polls /api/usage every 15s
- Dropped now-unused entitlements.ts

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>>;