feat(files): Add capability for clients to check WCF state

This adds a non-initial-state capability for the
windows-compatibile-filemnames feature.
It is not required by the webui and it might have performance impacts
(always compares system config against windows presets), so it is not
included in every page load, but instead for querying from the clients.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: susnux

apps/files/lib/AdvancedCapabilities.php

@@ -0,0 +1,36 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Files;
+
+use OCA\Files\Service\SettingsService;
+use OCP\Capabilities\ICapability;
+use OCP\Capabilities\IInitialStateExcludedCapability;
+
+/**
+ * Capabilities not needed for every request.
+ * This capabilities might be hard to compute or no used by the webui.
+ */
+class AdvancedCapabilities implements ICapability, IInitialStateExcludedCapability {
+
+	public function __construct(
+		protected SettingsService $service,
+	) {
+	}
+
+	/**
+	 * Return this classes capabilities
+	 *
+	 * @return array{files: array{'windows_compatible_filenames': bool}}
+	 */
+	public function getCapabilities(): array {
+		return [
+			'files' => [
+				'windows_compatible_filenames' => $this->service->hasFilesWindowsSupport(),
+			],
+		];
+	}
+}

apps/files/lib/AppInfo/Application.php

@@ -9,6 +9,7 @@
 namespace OCA\Files\AppInfo;
 
 use Closure;
+use OCA\Files\AdvancedCapabilities;
 use OCA\Files\Capabilities;
 use OCA\Files\Collaboration\Resources\Listener;
 use OCA\Files\Collaboration\Resources\ResourceProvider;
@@ -107,6 +108,7 @@ public function register(IRegistrationContext $context): void {
 		 * Register capabilities
 		 */
 		$context->registerCapability(Capabilities::class);
+		$context->registerCapability(AdvancedCapabilities::class);
 		$context->registerCapability(DirectEditingCapabilities::class);
 
 		$context->registerDeclarativeSettings(DeclarativeAdminSettings::class);