feat(sharing): add occ sharing:fix-owncloud-group-shares command

Repairs existing USERGROUP subshares created by ownCloud-migrated group
shares that were renamed before the move() fix, leaving them with
accepted=0 (STATUS_PENDING) and non-zero permissions. Declined shares
(permissions=0) are deliberately excluded.

AI-Assisted-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Anna Larch <anna@nextcloud.com>

Author: miaulalala

apps/files_sharing/appinfo/info.xml

@@ -50,6 +50,7 @@ Turning the feature off removes shared files and folders on the server for all s
 		<command>OCA\Files_Sharing\Command\ExiprationNotification</command>
 		<command>OCA\Files_Sharing\Command\DeleteOrphanShares</command>
 		<command>OCA\Files_Sharing\Command\FixShareOwners</command>
+		<command>OCA\Files_Sharing\Command\FixOwncloudGroupShares</command>
 		<command>OCA\Files_Sharing\Command\ListShares</command>
 	</commands>
 

apps/files_sharing/lib/Command/FixOwncloudGroupShares.php

@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Files_Sharing\Command;
+
+use OC\Core\Command\Base;
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IDBConnection;
+use OCP\Share\IShare;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * Fixes USERGROUP subshares that were created without `accepted = STATUS_ACCEPTED`
+ * by the rename bug affecting ownCloud-migrated group shares.
+ *
+ * When an ownCloud-migrated group share (which has no per-user USERGROUP subshare)
+ * is renamed for the first time, a new USERGROUP row is inserted without an
+ * `accepted` value. The column defaults to 0 (STATUS_PENDING), causing
+ * MountProvider to skip the share — the file disappears for the recipient.
+ *
+ * A USERGROUP subshare with permissions = 0 was explicitly declined by the user
+ * and must not be touched.
+ */
+class FixOwncloudGroupShares extends Base {
+	public function __construct(
+		private IDBConnection $connection,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this
+			->setName('sharing:fix-owncloud-group-shares')
+			->setDescription('Fix group share subshares left with accepted = STATUS_PENDING after renaming on an ownCloud-migrated instance')
+			->addOption(
+				'dry-run',
+				null,
+				InputOption::VALUE_NONE,
+				'Show how many shares would be fixed without making any changes',
+			);
+	}
+
+	public function execute(InputInterface $input, OutputInterface $output): int {
+		$dryRun = $input->getOption('dry-run');
+
+		$qb = $this->connection->getQueryBuilder();
+		$count = (int)$qb->select($qb->func()->count('id'))
+			->from('share')
+			->where($qb->expr()->eq('share_type', $qb->createNamedParameter(IShare::TYPE_USERGROUP, IQueryBuilder::PARAM_INT)))
+			->andWhere($qb->expr()->eq('accepted', $qb->createNamedParameter(IShare::STATUS_PENDING, IQueryBuilder::PARAM_INT)))
+			->andWhere($qb->expr()->neq('permissions', $qb->createNamedParameter(0, IQueryBuilder::PARAM_INT)))
+			->executeQuery()
+			->fetchOne();
+
+		if ($count === 0) {
+			$output->writeln('No affected group share subshares found.');
+			return self::SUCCESS;
+		}
+
+		if ($dryRun) {
+			$output->writeln("Would fix <info>$count</info> group share subshare(s) (dry-run, no changes made).");
+			return self::SUCCESS;
+		}
+
+		$qb = $this->connection->getQueryBuilder();
+		$qb->update('share')
+			->set('accepted', $qb->createNamedParameter(IShare::STATUS_ACCEPTED, IQueryBuilder::PARAM_INT))
+			->where($qb->expr()->eq('share_type', $qb->createNamedParameter(IShare::TYPE_USERGROUP, IQueryBuilder::PARAM_INT)))
+			->andWhere($qb->expr()->eq('accepted', $qb->createNamedParameter(IShare::STATUS_PENDING, IQueryBuilder::PARAM_INT)))
+			->andWhere($qb->expr()->neq('permissions', $qb->createNamedParameter(0, IQueryBuilder::PARAM_INT)))
+			->executeStatement();
+
+		$output->writeln("Fixed <info>$count</info> group share subshare(s).");
+		return self::SUCCESS;
+	}
+}

tests/lib/Share20/DefaultShareProviderTest.php

@@ -2269,12 +2269,18 @@ public function testMoveGroupShare(): void {
 
 		$share = $this->provider->getShareById($id, 'user0');
 		$this->assertSame('/newTarget', $share->getTarget());
+		// The USERGROUP subshare created on first move must be STATUS_ACCEPTED so
+		// MountProvider does not skip it (default DB value is STATUS_PENDING=0).
+		$this->assertSame(IShare::STATUS_ACCEPTED, $share->getStatus());
 
 		$share->setTarget('/ultraNewTarget');
 		$this->provider->move($share, 'user0');
 
 		$share = $this->provider->getShareById($id, 'user0');
 		$this->assertSame('/ultraNewTarget', $share->getTarget());
+		// Second move hits the UPDATE branch (USERGROUP subshare already exists).
+		// STATUS_ACCEPTED must be preserved — the UPDATE only touches file_target.
+		$this->assertSame(IShare::STATUS_ACCEPTED, $share->getStatus());
 	}
 
 	public static function dataDeleteUser(): array {