diff --git a/apps/files_sharing/lib/AppInfo/Application.php b/apps/files_sharing/lib/AppInfo/Application.php
index 653f3f9ec4b..1fdd042869f 100644
--- a/apps/files_sharing/lib/AppInfo/Application.php
+++ b/apps/files_sharing/lib/AppInfo/Application.php
@@ -109,13 +109,15 @@ class Application extends App implements IBootstrap {
 
 		// File request auth
 		$context->registerEventListener(BeforeTemplateRenderedEvent::class, LoadPublicFileRequestAuthListener::class);
+
+		$context->registerConfigLexicon(ConfigLexicon::class);
 	}
 
 	public function boot(IBootContext $context): void {
 		$context->injectFn([$this, 'registerMountProviders']);
 		$context->injectFn([$this, 'registerEventsScripts']);
 		$context->injectFn(function (IInitialState $initialState, IAppConfig $appConfig) {
-			$initialState->provideInitialState('showFederatedSharesAsInternal', $appConfig->getValueBool(self::APP_ID, 'show_federated_shares_as_internal', false));
+			$initialState->provideInitialState('showFederatedSharesAsInternal', $appConfig->getValueBool(self::APP_ID, ConfigLexicon::SHOW_FEDERATED_AS_INTERNAL));
 		});
 
 		Helper::registerHooks();
diff --git a/apps/files_sharing/lib/AppInfo/ConfigLexicon.php b/apps/files_sharing/lib/AppInfo/ConfigLexicon.php
new file mode 100644
index 00000000000..90739fac633
--- /dev/null
+++ b/apps/files_sharing/lib/AppInfo/ConfigLexicon.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Files_Sharing\AppInfo;
+
+use NCU\Config\Lexicon\ConfigLexiconEntry;
+use NCU\Config\Lexicon\ConfigLexiconStrictness;
+use NCU\Config\Lexicon\IConfigLexicon;
+use NCU\Config\ValueType;
+
+/**
+ * Config Lexicon for files_sharing.
+ *
+ * Please Add & Manage your Config Keys in that file and keep the Lexicon up to date!
+ *
+ * {@see IConfigLexicon}
+ */
+class ConfigLexicon implements IConfigLexicon {
+	public const SHOW_FEDERATED_AS_INTERNAL = 'show_federated_shares_as_internal';
+
+	public function getStrictness(): ConfigLexiconStrictness {
+		return ConfigLexiconStrictness::IGNORE;
+	}
+
+	public function getAppConfigs(): array {
+		return [
+			new ConfigLexiconEntry(self::SHOW_FEDERATED_AS_INTERNAL, ValueType::BOOL, false, 'shows federated shares as internal shares', true),
+		];
+	}
+
+	public function getUserConfigs(): array {
+		return [];
+	}
+}