Lazy load uncommon CFG_GLPI values

src/Glpi/Application/View/Extension/FrontEndAssetsExtension.php

@@ -293,14 +293,53 @@ public function configJs(): string
             $cfg_glpi += Config::getSafeConfig(true);
         }
 
+        // Common config keys used by front-end code.
+        // These will be immediately available while others will be lazy-loaded via a proxy handler.
+        $common_configs = [
+            'root_doc', 'url_base', 'planning_begin', 'planning_end', 'planning_work_days', 'toast_location',
+            'is_demo_dashboards', 'priority_1', 'priority_2', 'priority_3', 'priority_4', 'priority_5', 'priority_6',
+            'date_format', 'refresh_views',
+        ];
+        $common_config = array_filter(
+            $cfg_glpi,
+            static fn($key) => in_array($key, $common_configs, true),
+            ARRAY_FILTER_USE_KEY
+        );
+        $common_config = json_encode($common_config);
+
         $plugins_path = \array_combine(
             Plugin::getPlugins(),
-            \array_map(fn(string $plugin_key) => "/plugins/{$plugin_key}", Plugin::getPlugins())
+            \array_map(static fn(string $plugin_key) => "/plugins/{$plugin_key}", Plugin::getPlugins())
         );
-
-        $script = sprintf('window.CFG_GLPI = %s;', json_encode($cfg_glpi, JSON_PRETTY_PRINT))
-            . "\n"
-            . sprintf('window.GLPI_PLUGINS_PATH = %s;', json_encode($plugins_path, JSON_PRETTY_PRINT));
+        $plugins_path = json_encode($plugins_path);
+
+        $script = <<<JS
+            window.CFG_GLPI = new Proxy($common_config, {
+                get: (target, prop, receiver) => {
+                    if (prop in target) {
+                        return Reflect.get(target, prop, receiver);
+                    }
+                    // Note there was a request for a config not in the common set to indicate a potential optimization
+                    console.debug("Lazy loading a CFG_GLPI property that was not available by default: " + prop + '. This may be an optimization opportunity.');
+                    // Hydrate the missing config via a synchronous AJAX call
+                    $.ajax({
+                        type: 'GET',
+                        url: CFG_GLPI.root_doc + '/Session/Config/' + prop,
+                        async: false,
+                        dataType: 'json',
+                        success: (value) => {
+                            target[prop] = value;
+                        },
+                        error: () => {
+                            console.warn('Failed to load config property ' + prop);
+                            target[prop] = undefined;
+                        }
+                    });
+                    return Reflect.get(target, prop, receiver);
+                }
+            });
+            window.GLPI_PLUGINS_PATH = $plugins_path;
+JS;
 
         return Html::scriptBlock($script);
     }

src/Glpi/Controller/Session/ConfigController.php

@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * ---------------------------------------------------------------------
+ *
+ * GLPI - Gestionnaire Libre de Parc Informatique
+ *
+ * http://glpi-project.org
+ *
+ * @copyright 2015-2025 Teclib' and contributors.
+ * @licence   https://www.gnu.org/licenses/gpl-3.0.html
+ *
+ * ---------------------------------------------------------------------
+ *
+ * LICENSE
+ *
+ * This file is part of GLPI.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * ---------------------------------------------------------------------
+ */
+
+namespace Glpi\Controller\Session;
+
+use Config;
+use Glpi\Controller\AbstractController;
+use Glpi\Exception\Http\NotFoundHttpException;
+use Glpi\Http\Firewall;
+use Glpi\Security\Attribute\SecurityStrategy;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\Routing\Attribute\Route;
+
+final class ConfigController extends AbstractController
+{
+    #[Route("/Session/Config/{key}", name: "get_config_value")]
+    #[SecurityStrategy(Firewall::STRATEGY_AUTHENTICATED)]
+    public function content(Request $request): Response
+    {
+        $safe_config = Config::getSafeConfig(true);
+        $key = $request->get('key');
+        if (!array_key_exists($key, $safe_config)) {
+            throw new NotFoundHttpException();
+        }
+        return new JsonResponse($safe_config[$key]);
+    }
+}