Added auth support and a helper script, targeting frankenphp

auth.php

@@ -0,0 +1,50 @@
+<?php
+// auth.php
+declare(strict_types=1);
+
+function auth_session_start(): void
+{
+    //$secure = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off');
+
+    session_set_cookie_params([
+        'lifetime' => 0,
+        'path'     => '/',
+        'domain'   => '',
+        'secure'   => true,
+        'httponly' => true,
+        'samesite' => 'Lax',
+    ]);
+
+    if (session_status() !== PHP_SESSION_ACTIVE) {
+        session_start();
+    }
+}
+
+/**
+ * Require a valid login.
+ * IMPORTANT: releases the session lock immediately to avoid deadlocks/timeouts.
+ */
+function require_auth(bool $json = true): void
+{
+    auth_session_start();
+
+    $ok = (isset($_SESSION['authed']) && $_SESSION['authed'] === true);
+
+    // Release the session file lock ASAP.
+    // This prevents other requests from blocking on session_start().
+    session_write_close();
+
+    if (!$ok) {
+        http_response_code(401);
+
+        if ($json) {
+            header('Content-Type: application/json; charset=utf-8');
+            echo json_encode(['error' => 'Unauthorized']);
+        } else {
+            header('Content-Type: text/plain; charset=utf-8');
+            echo "Unauthorized";
+        }
+        exit;
+    }
+}
+