Add auto-close registration and admin settings page

First user to register automatically becomes admin and registration
closes. Admins can re-open registration from a new settings page.
Uses Better Auth admin plugin for role management and a new appSettings
table for the registration flag. Mobile tab bar now links to settings
instead of inline logout.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/auth/client.ts

@@ -1,7 +1,10 @@
 "use client";
 
+import { adminClient } from "better-auth/client/plugins";
 import { createAuthClient } from "better-auth/react";
 
-export const authClient = createAuthClient();
+export const authClient = createAuthClient({
+  plugins: [adminClient()],
+});
 
 export const { signIn, signUp, signOut, useSession } = authClient;

lib/auth/server.ts

@@ -1,7 +1,14 @@
 import { betterAuth } from "better-auth";
 import { drizzleAdapter } from "better-auth/adapters/drizzle";
+import { APIError } from "better-auth/api";
+import { admin } from "better-auth/plugins";
 import { v4 as uuid } from "uuid";
 import { db } from "@/lib/db/client";
+import {
+  getUserCount,
+  isRegistrationOpen,
+  setSetting,
+} from "@/lib/services/settings";
 
 export const auth = betterAuth({
   database: drizzleAdapter(db, {
@@ -10,9 +17,40 @@ export const auth = betterAuth({
   emailAndPassword: {
     enabled: true,
   },
+  plugins: [admin()],
   advanced: {
     database: {
       generateId: () => uuid(),
     },
   },
+  databaseHooks: {
+    user: {
+      create: {
+        before: async (userData) => {
+          const userCount = await getUserCount();
+          if (userCount === 0) {
+            return {
+              data: {
+                ...userData,
+                role: "admin",
+              },
+            };
+          }
+          const open = await isRegistrationOpen();
+          if (!open) {
+            throw new APIError("FORBIDDEN", {
+              message: "Registration is currently closed",
+            });
+          }
+          return { data: userData };
+        },
+        after: async () => {
+          const userCount = await getUserCount();
+          if (userCount === 1) {
+            await setSetting("registrationOpen", "false");
+          }
+        },
+      },
+    },
+  },
 });

lib/db/schema.ts

@@ -24,6 +24,10 @@ export const user = sqliteTable("user", {
     .notNull()
     .default(false),
   image: text("image"),
+  role: text("role").default("user"),
+  banned: int("banned", { mode: "boolean" }).default(false),
+  banReason: text("banReason"),
+  banExpires: int("banExpires", { mode: "timestamp" }),
   createdAt: int("createdAt", { mode: "timestamp" }).notNull(),
   updatedAt: int("updatedAt", { mode: "timestamp" }).notNull(),
 });
@@ -37,6 +41,7 @@ export const session = sqliteTable("session", {
   expiresAt: int("expiresAt", { mode: "timestamp" }).notNull(),
   ipAddress: text("ipAddress"),
   userAgent: text("userAgent"),
+  impersonatedBy: text("impersonatedBy"),
   createdAt: int("createdAt", { mode: "timestamp" }).notNull(),
   updatedAt: int("updatedAt", { mode: "timestamp" }).notNull(),
 });
@@ -277,3 +282,10 @@ export const titleRecommendations = sqliteTable(
     ),
   ],
 );
+
+// ─── App Settings ───────────────────────────────────────────────────
+
+export const appSettings = sqliteTable("appSettings", {
+  key: text("key").primaryKey(),
+  value: text("value"),
+});

lib/services/settings.ts

@@ -0,0 +1,32 @@
+import { count, eq } from "drizzle-orm";
+import { db } from "@/lib/db/client";
+import { appSettings, user } from "@/lib/db/schema";
+
+export async function getSetting(key: string): Promise<string | null> {
+  const row = await db
+    .select()
+    .from(appSettings)
+    .where(eq(appSettings.key, key))
+    .get();
+  return row?.value ?? null;
+}
+
+export async function setSetting(key: string, value: string): Promise<void> {
+  await db
+    .insert(appSettings)
+    .values({ key, value })
+    .onConflictDoUpdate({ target: appSettings.key, set: { value } });
+}
+
+export async function getUserCount(): Promise<number> {
+  const result = await db.select({ count: count() }).from(user).get();
+  return result?.count ?? 0;
+}
+
+export async function isRegistrationOpen(): Promise<boolean> {
+  const userCount = await getUserCount();
+  if (userCount === 0) return true;
+
+  const setting = await getSetting("registrationOpen");
+  return setting === "true";
+}