update

app/Http/Middleware/HandleInertiaRequests.php

@@ -16,6 +16,10 @@ final class HandleInertiaRequests extends Middleware
      */
     public function rootView(Request $request): string
     {
+        if ($request->path() === 'leaderboard') {
+            return 'leaderboard';
+        }
+
         if (str_starts_with($request->path(), 'studio')) {
             return 'studio';
         }

app/Http/Middleware/RedirectLegacyProfileSubdomain.php

@@ -0,0 +1,106 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Middleware;
+
+use App\Models\User;
+use App\Support\UsernamePolicy;
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+use Symfony\Component\HttpFoundation\Response;
+
+class RedirectLegacyProfileSubdomain
+{
+    public function handle(Request $request, Closure $next): Response
+    {
+        $canonicalUsername = $this->resolveCanonicalUsername($request);
+
+        if ($canonicalUsername !== null) {
+            return redirect()->to($this->targetUrl($request, $canonicalUsername), 301);
+        }
+
+        return $next($request);
+    }
+
+    private function resolveCanonicalUsername(Request $request): ?string
+    {
+        $configuredHost = parse_url((string) config('app.url'), PHP_URL_HOST);
+
+        if (! is_string($configuredHost) || $configuredHost === '') {
+            return null;
+        }
+
+        $requestHost = strtolower($request->getHost());
+        $configuredHost = strtolower($configuredHost);
+
+        if ($requestHost === $configuredHost || ! str_ends_with($requestHost, '.' . $configuredHost)) {
+            return null;
+        }
+
+        $subdomain = substr($requestHost, 0, -strlen('.' . $configuredHost));
+
+        if ($subdomain === '' || str_contains($subdomain, '.')) {
+            return null;
+        }
+
+        $candidate = UsernamePolicy::normalize($subdomain);
+
+        if ($candidate === '' || $this->isReservedSubdomain($candidate)) {
+            return null;
+        }
+
+        $username = User::query()
+            ->whereRaw('LOWER(username) = ?', [$candidate])
+            ->value('username');
+
+        if (is_string($username) && $username !== '') {
+            return UsernamePolicy::normalize($username);
+        }
+
+        if (! Schema::hasTable('username_redirects')) {
+            return null;
+        }
+
+        $redirect = DB::table('username_redirects')
+            ->whereRaw('LOWER(old_username) = ?', [$candidate])
+            ->value('new_username');
+
+        return is_string($redirect) && $redirect !== ''
+            ? UsernamePolicy::normalize($redirect)
+            : null;
+    }
+
+    private function isReservedSubdomain(string $candidate): bool
+    {
+        $reserved = UsernamePolicy::reserved();
+
+        foreach ([config('cp.webroot'), config('cpad.webroot')] as $prefix) {
+            $value = strtolower(trim((string) $prefix, '/'));
+            if ($value !== '') {
+                $reserved[] = $value;
+            }
+        }
+
+        return in_array($candidate, array_values(array_unique($reserved)), true);
+    }
+
+    private function targetUrl(Request $request, string $username): string
+    {
+        $canonicalPath = match ($request->getPathInfo()) {
+            '/gallery', '/gallery/' => '/@' . $username . '/gallery',
+            default => '/@' . $username,
+        };
+
+        $target = rtrim((string) config('app.url'), '/') . $canonicalPath;
+        $query = $request->getQueryString();
+
+        if (is_string($query) && $query !== '') {
+            $target .= '?' . $query;
+        }
+
+        return $target;
+    }
+}