first commit

src/Http/ClientIdResolver.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http;
+
+use Symfony\Component\HttpFoundation\Cookie;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\Uid\Uuid;
+
+/**
+ * ClientIdResolver
+ *
+ * Resolves a stable, anonymous client identifier for browser-based users.
+ * The identifier is stored as an HttpOnly cookie.
+ */
+final class ClientIdResolver
+{
+    private const COOKIE_NAME = 'ai_client_id';
+
+    public function resolve(Request $request, Response $response): string
+    {
+        $clientId = $request->cookies->get(self::COOKIE_NAME);
+
+        if (is_string($clientId) && $clientId !== '') {
+            return $clientId;
+        }
+
+        $clientId = Uuid::v4()->toRfc4122();
+
+        $response->headers->setCookie(
+            new Cookie(
+                name: self::COOKIE_NAME,
+                value: $clientId,
+                expire: strtotime('+1 year'),
+                path: '/',
+                secure: false,   // set true in production with HTTPS
+                httpOnly: true,
+                sameSite: Cookie::SAMESITE_LAX
+            )
+        );
+
+        return $clientId;
+    }
+}