Prepare the 0.1.0-alpha.1 release

info.xml's version field is restricted by Nextcloud's own info.xsd to plain
numeric SemVer, no pre-release suffix, so the alpha/beta/rc stage from
PLAN.md's release table lives in the git tag and CHANGELOG instead; noted
that in PLAN.md so it isn't rediscovered later. Bumped the version, wrote
an honest description for an alpha (feature-complete for phase 1, not for
production), and added CHANGELOG.md.

README: new "Storage backend experiences" section, seeded with the Hetzner
Storage Box sub-account root-path quirk found while testing a real SFTP
target (root must be "home", not "/"), open for others to extend via PR.

.github/workflows/ci.yml

@@ -0,0 +1,62 @@
+# SPDX-FileCopyrightText: 2026 Dillard Blom
+# SPDX-License-Identifier: AGPL-3.0-or-later
+name: CI
+
+on:
+  push:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  unit:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php: ['8.2', '8.3', '8.4']
+    steps:
+      - uses: actions/checkout@v4
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: sodium, zip
+          coverage: none
+      - run: composer install --no-interaction --no-progress
+      - run: vendor/bin/phpunit -c tests/phpunit.xml
+
+  psalm:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.2'
+          extensions: sodium, zip
+          coverage: none
+      - run: composer install --no-interaction --no-progress
+      - run: composer psalm
+
+  integration:
+    # Full round trip (key, kit, location, backup, incremental, restore modes, database dump and
+    # restore, retention, trash) on a fresh Nextcloud per version and database.
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        nextcloud: ['32', '33', '34', '35']
+        database: ['sqlite', 'mariadb', 'pgsql']
+    steps:
+      - uses: actions/checkout@v4
+      - name: Round trip on Nextcloud ${{ matrix.nextcloud }} / ${{ matrix.database }}
+        run: tests/integration/matrix.sh "${{ matrix.nextcloud }}" "${{ matrix.database }}"
+
+  integration-targets:
+    # Same round trip, but through the real S3 (s3mock) and SFTP backends instead of a local
+    # path, so files_external's AmazonS3/SFTP backend and auth classes are actually exercised.
+    # Backend correctness does not depend on the Nextcloud version or database, so this runs once.
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Round trip against S3 and SFTP
+        run: tests/integration/targets-matrix.sh

.gitignore

@@ -1,7 +1,10 @@
 /build/
+cred-*
+*credentials*
 /css/
 /js/
 /node_modules/
 .phpunit.result.cache
+*.secret
 /spikes/out/
 /vendor/

CHANGELOG.md

@@ -0,0 +1,44 @@
+# Changelog
+
+All notable changes to NG Backup are documented here. The format follows
+[Keep a Changelog](https://keepachangelog.com/en/1.1.0/); versioning follows the stages in
+`PLAN.md` section 9. The `<version>` in `appinfo/info.xml` is plain SemVer-numeric (Nextcloud's
+own `info.xsd` doesn't allow a `-alpha`/`-beta`/`-rc` suffix there); the stability stage is instead
+carried by the git tag, the release, and this file.
+
+## [0.1.0-alpha.1] - 2026-10-05
+
+First public alpha. Feature-complete for phase 1: scheduled, encrypted, incremental backups, and
+restore of files and folders. **Not for production use** — test on a copy of production (dev,
+test, staging). Full disaster recovery (`backup:restore:full` on a fresh installation) is phase 2
+and not implemented yet.
+
+### Added
+- Encrypted (XChaCha20-Poly1305), content-addressed, deduplicated, incremental backups, streamed
+  from source to destination without a local copy of the data.
+- Backup locations via files_external's own backend/auth classes, without ever mounting the
+  location: S3 (and compatible services), SFTP, WebDAV, FTP, Swift, or a local path.
+- A recovery kit with up to three passphrase slots, mandatory download-and-confirm before the
+  first backup runs, and an optional encrypted copy by email.
+- Resumable, time-boxed background jobs (database dump, file walk, upload), so a run survives
+  short PHP time limits and a crash is resumed, never restarted, without leaving the instance in
+  maintenance mode.
+- Database dump and restore without external tools, via Nextcloud's own `IDBConnection`/DBAL,
+  streamed through the same pipeline as file data.
+- Restore of files and folders via the web interface and `occ`, into a new folder, merged, or
+  replacing the original (with the previous content going to the trash).
+- Retention policy (last/daily/weekly/monthly), prune with pack repacking, and a snapshot trash
+  with a configurable deletion delay.
+- Append-only locations and documented recommendations against ransomware and a compromised
+  server (object lock, delete-less credentials, off-site copies).
+- Admin settings page (locations, schedule, retention, key management) and a JSON API.
+- Notifications and an admin setup check for a failed or overdue backup.
+- CI: unit tests on PHP 8.2–8.4, and an end-to-end backup→restore round trip on Nextcloud 32–35 ×
+  SQLite/MariaDB/PostgreSQL, and against real S3 and SFTP backends (not just a local path).
+
+### Known limitations
+- No full/disaster-recovery restore yet (phase 2).
+- No per-user backup/restore via user_migration yet (phase 2).
+- No FTP/SMB coverage in CI yet, and no verification/checksum-audit command yet (phase 2).
+- See the "Storage backend experiences" section of the README for provider-specific quirks found
+  so far (e.g. Hetzner Storage Box sub-accounts).

PLAN.md

@@ -214,8 +214,8 @@ Daarom:
 ### 3.8 Backup en restore per gebruiker: via user_migration
 
 In plaats van zelf te bepalen welke gegevens van een gebruiker meegaan, hergebruiken we
-**user_migration** (officiële Nextcloud-app, actief onderhouden, NC29–36; staat ook op nc01).
+**user_migration** (officiële Nextcloud-app, actief onderhouden, NC29–36; draait ook op onze eigen productie-instantie).
-Die app werkt met *migrators* die andere apps zelf aanleveren. Op nc01 hebben die er al:
+Die app werkt met *migrators* die andere apps zelf aanleveren. Op onze productie-instantie zijn dat er al:
 calendar, dav (agenda's en contactpersonen), deck, files_trashbin, mail, settings (profiel,
 account, app-instellingen) en de bestanden zelf. Elke app die later een migrator toevoegt, gaat
 automatisch mee.
@@ -308,14 +308,14 @@ niet met de hunne, maar bij installatie waarschuwen als `backup` ook actief is.
 | 2 | Backup/restore per gebruiker via user_migration, volledige restore op verse installatie, FTP/SMB, verificatie | 3–4 weken |
 | 3 | In-place volledige restore (restore-modus), zelfbediening voor gebruikers, extra doelen | open |
 
-Release in de app store pas na fase 1 en een periode van eigen gebruik op nc01 (net als occweb):
+Release in de app store pas na fase 1 en een periode van eigen gebruik op onze productie-instantie (net als occweb):
 een backup-app die niet betrouwbaar is, is erger dan geen backup-app.
 
 ## 8. Besluiten (2026-10-01)
 
 1. **Doelgroep:** alle varianten: AIO, losse installaties én gehoste Nextcloud zonder SSH.
 2. **Licentie:** AGPL-3.0-or-later.
-3. **Repository:** Ensembia op Gitea + GitHub (dillardblom), zoals occweb.
+3. **Repository:** eigen Gitea + GitHub (dillardblom), zoals occweb.
 4. **Naam:** "NG Backup", app-id `ng_backup`, occ-voorvoegsel `backup:`.
 5. **Herstelkit:** verplicht downloaden + expliciete bevestiging door de beheerder (vinkje +
    "Yes, I confirm"), zie 3.2; versleuteld per e-mail als optionele extra kopie.
@@ -325,6 +325,24 @@ een backup-app die niet betrouwbaar is, is erger dan geen backup-app.
    export, verwijderen, opnieuw aanmaken), óf terugzetten als `<gebruiker>-bak`, zie 3.8.
 8. **Fase 0 afgerond (2026-10-01),** resultaten in `spikes/RESULTS.md`.
 
+## 9. Releases en versies (besluit 2026-10-02)
+
+| Versie | Betekenis |
+|---|---|
+| 0.1.0-alpha.N | publiek; meetesten gewaardeerd op een kopie van productie (dev, test, staging) |
+| 0.9.0-beta.N | mag meedraaien op productie, naast de reguliere backup; volledige restore aanwezig en getest |
+| 1.0.0-rc.N | releasekandidaten, alleen bugfixes |
+| 1.0.0 | stabiel: vervanging van de reguliere backup, noodherstel bewezen |
+| 1.2.0 e.v. | functies van fase 2 (restore per gebruiker, FTP/SMB, verificatie, ...) |
+
+Volgorde: fase 1 grondig testen, reviewen en debuggen; dan nadenken over 0.1.0-alpha.1. Een
+minimale volledige restore (`occ backup:restore:full` op een verse installatie) komt vóór de beta.
+
+**Let op (ontdekt 2026-10-05):** Nextcloud's eigen `info.xsd` staat voor `<version>` alleen
+`[0-9]+(\.[0-9]+){0,2}` toe — geen `-alpha`/`-beta`/`-rc`-achtervoegsel. De stabiliteitsaanduiding
+uit deze tabel gaat dus niet in `info.xml` (dat blijft gewoon oplopend, bijv. `0.1.0`), maar in de
+git-tag (`v0.1.0-alpha.1`), de GitHub/Gitea release (gemarkeerd als pre-release) en de CHANGELOG.
+
 ## Bijlage: lessen uit nextcloud/backup (test NC34, 2026-10-01)
 
 - Externe programma's (`pg_dump`) en extensies (`pgsql`, `mysqli`) → onbruikbaar op standaard/hosted.

README.md

@@ -1,8 +1,131 @@
 # NG Backup
 
-Encrypted, incremental backups of Nextcloud with restore from the web interface.
+Encrypted, incremental backups of Nextcloud (database, configuration and data) with restore
-Works without shell access: no external programs, no extra PHP extensions beyond sodium.
+from the web interface. Works without shell access: no external programs, no extra PHP
+extensions beyond sodium. Runs on Nextcloud All-in-One, regular installations and hosted
+Nextcloud.
 
-**Status: phase 0 (prototype). Not usable yet.** See `PLAN.md` for the design.
+**Status: in development (phase 1). Not ready for production use.** See `PLAN.md` for the design.
 
 License: AGPL-3.0-or-later.
+
+## How it works
+
+- Backups go to a **location**: S3 (and S3-compatible storage), SFTP, WebDAV, FTP, Swift or a
+  local path. NG Backup uses the connection code of Nextcloud's External storage app, but never
+  mounts the location: it is only connected while a backup or restore runs, and it never
+  appears in Files, for anyone.
+- Data is cut into blocks, deduplicated, compressed and encrypted (XChaCha20-Poly1305) before it
+  leaves the server, and streamed straight to the location: no local copy, no double disk space.
+  Unchanged files are not read again; only new data is uploaded.
+- The database is dumped through Nextcloud's own connection, inside one consistent transaction.
+- Restores go through Nextcloud, so overwritten files keep their old content as a version and
+  removed files go to the trash.
+
+## Quick start
+
+```
+occ backup:key:init --label="Safe"                 # first passphrase, deletion delay (default 7 days)
+occ backup:key:slot:add --label="CTO"              # optional second and third passphrase
+occ backup:key:slot:add --label="Head of IT"
+occ backup:key:kit --output=/root/ng_backup-kit.json
+occ backup:key:confirm
+occ backup:target:add offsite amazons3 -a amazons3::accesskey -o bucket=... -o key=... -o secret=...
+occ backup:run
+```
+
+Or use **Administration settings → NG Backup**.
+
+## The backup key, passphrases and the recovery kit
+
+All backups of an installation are encrypted with one master key.
+
+- The **server** keeps the master key, encrypted with the instance secret, so scheduled backups
+  and restores work without anyone typing a passphrase. Any administrator can restore from the
+  web interface. Consequence: whoever fully controls the server can read the backups; whoever
+  only gets hold of the backup location cannot.
+- For a **restore on a new server** (disaster recovery) you need the **recovery kit** and **one
+  passphrase**. The kit contains the master key, encrypted separately with each passphrase.
+- Up to **three passphrases** ("slots") can open the key, so one person leaving or dying does not
+  lock the company out. A suggested setup:
+
+  | Slot | Kept by |
+  |---|---|
+  | 1 | in the safe (sealed envelope) |
+  | 2 | the CTO |
+  | 3 | the head of IT |
+
+  Every holder keeps a copy of the same recovery kit and only knows their own passphrase. Using
+  a single slot is possible, but then that one passphrase is a single point of failure.
+- When a holder leaves, give their slot a new passphrase (`occ backup:key:slot:replace`), download
+  the new kit and confirm it. Note: an old kit together with the old passphrase still opens the
+  same master key; to revoke it completely, start new locations with a new key.
+- Downloading the kit, and every change to the slots, requires the administrator's password, is
+  written to the audit log and is announced to all administrators.
+
+## Protection against ransomware and a compromised server
+
+A backup is only useful if an attacker cannot destroy it. An attacker with administrator access
+to Nextcloud could try to remove old restore points so that only infected data remains.
+NG Backup makes this hard and visible, but **software alone can never guarantee it**: the
+location must refuse deletions itself.
+
+What NG Backup does:
+
+- **Deletion delay.** Removed restore points first go to a trash on the location and are only
+  deleted after the delay chosen at installation (default 7 days, cannot be changed afterwards).
+  Within that time any administrator can bring them back (`occ backup:trash:restore`, or in the
+  web interface).
+- **Notifications to all administrators** when restore points are removed, the retention is
+  changed, append-only is turned off, a location is removed or the recovery kit is downloaded,
+  and an entry in the audit log (admin_audit).
+- **Append-only locations** (`occ backup:target:append-only NAME on`): NG Backup never deletes
+  anything there; old data is cleaned up by the location's own lifecycle rules.
+- Removing a location in NG Backup only removes the connection. The backups on the location are
+  not touched and nothing keeps cleaning up in the background.
+
+What you should do on the location (strongly recommended):
+
+- **S3: enable Object Lock** on the bucket, in **compliance mode**, with a default retention of
+  for example **90 days**, plus versioning. Then nobody, not even with the server's credentials,
+  can delete or overwrite backups younger than 90 days. Combine with an append-only location in
+  NG Backup and a lifecycle rule that removes old versions after the lock expires.
+  With Object Lock, a deletion by NG Backup (or by an attacker through it) only adds a *delete
+  marker*: the locked data stays and can be brought back from the bucket's object versions until
+  the lock expires. Tested with an S3-compatible server; still to be verified on AWS itself, which
+  requires a checksum on uploads to locked buckets.
+- Use **credentials without delete rights** for the backup location where the storage supports it.
+- **SFTP / storage boxes:** enable the provider's own snapshots (e.g. daily, kept 30-90 days) and
+  give the backup user access to its own folder only, without a shell.
+- Keep at least one location **off-site**, on a different network than the Nextcloud server.
+
+## Restore
+
+- **Files and folders** of a user: in the web interface or `occ backup:restore`, into a new folder
+  ("Restored <date>"), merged into the original place, or replacing it.
+- **Raw restore** of any path (for example `config/`) to a local directory: `occ backup:restore ... --to-directory=DIR`.
+- **Whole server** (disaster recovery onto a fresh installation): planned for phase 2.
+
+## Storage backend experiences
+
+Notes from actually running a backend, beyond what's in files_external's own documentation.
+Contributions welcome via PR — add what you ran into with your own provider.
+
+- **Hetzner Storage Box, sub-account:** the SFTP backend's `root` option must be `home`, not `/`.
+  A sub-account's SFTP login lands in `/home` (confirmed via `pwd()` after login); writing to the
+  literal chroot root (`/`) fails with a generic `NET_SFTP_STATUS_FAILURE` from the SFTP server,
+  while the same write under `home` (or a path below it) succeeds. This affects any backend option
+  form that lets you set a path relative to the account's root, not just ng_backup. Not yet
+  verified whether this also applies to a Hetzner Storage Box **main** account (only tested with a
+  sub-account so far) — if you've tried a main account, please say so in a PR.
+
+## Commands
+
+| Command | Purpose |
+|---|---|
+| `backup:key:init`, `backup:key:kit`, `backup:key:confirm` | create the key, recovery kit, confirmation |
+| `backup:key:slots`, `backup:key:slot:add/replace/remove` | passphrase slots |
+| `backup:target:backends/add/list/remove/append-only` | backup locations |
+| `backup:run`, `backup:status`, `backup:list` | back up, status, restore points |
+| `backup:browse`, `backup:restore` | browse and restore |
+| `backup:retention`, `backup:prune`, `backup:trash`, `backup:trash:restore` | retention, cleanup, trash |

appinfo/info.xml

@@ -4,8 +4,12 @@
     <id>ng_backup</id>
     <name>NG Backup</name>
     <summary>Encrypted, incremental backups of your Nextcloud with restore from the web interface</summary>
-    <description><![CDATA[Work in progress, not ready for use.]]></description>
+    <description><![CDATA[Alpha: feature-complete for scheduled, encrypted, incremental backups to
-    <version>0.0.5</version>
+S3/SFTP/WebDAV/local, with restore of files and folders from the web interface and occ. Meant for
+testing on a copy of production (dev, test, staging) -- not yet for production use, and full
+disaster recovery is not implemented yet. See the recovery kit section of the README before
+relying on this for anything.]]></description>
+    <version>0.1.0</version>
     <licence>agpl</licence>
     <author>Dillard Blom</author>
     <namespace>NgBackup</namespace>
@@ -32,6 +36,17 @@
         <command>OCA\NgBackup\Command\ListSnapshots</command>
         <command>OCA\NgBackup\Command\Browse</command>
         <command>OCA\NgBackup\Command\Restore</command>
+        <command>OCA\NgBackup\Command\Prune</command>
+        <command>OCA\NgBackup\Command\Retention</command>
+        <command>OCA\NgBackup\Command\TargetAppendOnly</command>
+        <command>OCA\NgBackup\Command\TargetTrustCurrent</command>
+        <command>OCA\NgBackup\Command\TargetLimit</command>
+        <command>OCA\NgBackup\Command\Trash</command>
+        <command>OCA\NgBackup\Command\TrashRestore</command>
+        <command>OCA\NgBackup\Command\KeySlots</command>
+        <command>OCA\NgBackup\Command\KeySlotAdd</command>
+        <command>OCA\NgBackup\Command\KeySlotReplace</command>
+        <command>OCA\NgBackup\Command\KeySlotRemove</command>
     </commands>
     <settings>
         <admin>OCA\NgBackup\Settings\Admin</admin>

appinfo/routes.php

@@ -11,10 +11,16 @@ return [
 		['name' => 'AdminApi#initKey', 'url' => '/api/key', 'verb' => 'POST'],
 		['name' => 'AdminApi#downloadKit', 'url' => '/api/key/kit', 'verb' => 'GET'],
 		['name' => 'AdminApi#confirmKit', 'url' => '/api/key/confirm', 'verb' => 'POST'],
+		['name' => 'AdminApi#addSlot', 'url' => '/api/key/slots', 'verb' => 'POST'],
+		['name' => 'AdminApi#replaceSlot', 'url' => '/api/key/slots/{slot}', 'verb' => 'PUT'],
+		['name' => 'AdminApi#removeSlot', 'url' => '/api/key/slots/{slot}', 'verb' => 'DELETE'],
+		['name' => 'AdminApi#trash', 'url' => '/api/targets/{targetId}/trash', 'verb' => 'GET'],
+		['name' => 'AdminApi#untrash', 'url' => '/api/targets/{targetId}/trash/{snapshotId}', 'verb' => 'POST'],
 		['name' => 'AdminApi#backends', 'url' => '/api/backends', 'verb' => 'GET'],
 		['name' => 'AdminApi#addTarget', 'url' => '/api/targets', 'verb' => 'POST'],
 		['name' => 'AdminApi#removeTarget', 'url' => '/api/targets/{id}', 'verb' => 'DELETE'],
 		['name' => 'AdminApi#testTarget', 'url' => '/api/targets/{id}/test', 'verb' => 'POST'],
+		['name' => 'AdminApi#setTargetLimit', 'url' => '/api/targets/{id}/limit', 'verb' => 'PUT'],
 		['name' => 'AdminApi#startBackup', 'url' => '/api/backups', 'verb' => 'POST'],
 		['name' => 'AdminApi#setSchedule', 'url' => '/api/schedule', 'verb' => 'PUT'],
 		['name' => 'AdminApi#snapshots', 'url' => '/api/targets/{targetId}/snapshots', 'verb' => 'GET'],

lib/AppInfo/Application.php

@@ -12,7 +12,7 @@ use OCP\AppFramework\Bootstrap\IBootContext;
 use OCP\AppFramework\Bootstrap\IBootstrap;
 use OCP\AppFramework\Bootstrap\IRegistrationContext;
 
-class Application extends App implements IBootstrap {
+final class Application extends App implements IBootstrap {
 	public const APP_ID = 'ng_backup';
 
 	public function __construct() {
@@ -20,6 +20,8 @@ class Application extends App implements IBootstrap {
 	}
 
 	public function register(IRegistrationContext $context): void {
+		$context->registerNotifierService(\OCA\NgBackup\Notification\Notifier::class);
+		$context->registerSetupCheck(\OCA\NgBackup\SetupCheck\BackupStatusCheck::class);
 	}
 
 	public function boot(IBootContext $context): void {

lib/Backend/BackendException.php

@@ -7,5 +7,5 @@ declare(strict_types=1);
 
 namespace OCA\NgBackup\Backend;
 
-class BackendException extends \RuntimeException {
+final class BackendException extends \RuntimeException {
 }

lib/Backend/IBackend.php

@@ -27,6 +27,13 @@ interface IBackend {
 
 	public function exists(string $path): bool;
 
+	/**
+	 * Move an object within the same location (used for the trash). Backends must use a native
+	 * rename, not a read+write copy: some storages (e.g. SFTP) cannot reliably read and write on
+	 * the same connection at once, since the read side is a lazily-pulled stream.
+	 */
+	public function move(string $from, string $to): void;
+
 	/** @return list<string> object paths below $prefix (recursive) */
 	public function list(string $prefix): array;
 

lib/Backend/LocalBackend.php

@@ -106,6 +106,17 @@ final class LocalBackend implements IBackend {
 		@unlink($this->abs($path));
 	}
 
+	public function move(string $from, string $to): void {
+		$target = $this->abs($to);
+		$dir = dirname($target);
+		if (!is_dir($dir) && !mkdir($dir, 0700, true) && !is_dir($dir)) {
+			throw new BackendException('Cannot create ' . $dir);
+		}
+		if (!rename($this->abs($from), $target)) {
+			throw new BackendException("Cannot move $from to $to");
+		}
+	}
+
 	private function abs(string $path): string {
 		if (str_contains($path, '..') || str_starts_with($path, '/')) {
 			throw new BackendException('Invalid path: ' . $path);

lib/Backend/StorageBackend.php

@@ -115,6 +115,14 @@ final class StorageBackend implements IBackend {
 		$this->storage->unlink($this->abs($path));
 	}
 
+	public function move(string $from, string $to): void {
+		$target = $this->abs($to);
+		$this->mkdirs(dirname($target));
+		if (!$this->storage->rename($this->abs($from), $target)) {
+			throw new BackendException("Cannot move $from to $to");
+		}
+	}
+
 	private function listInto(string $dir, array &$result): void {
 		if (!$this->storage->is_dir($dir)) {
 			return;

lib/BackgroundJob/BackupJob.php

@@ -22,10 +22,12 @@ use Psr\Log\LoggerInterface;
  * With system cron a step may take minutes; with webcron/AJAX cron it is kept short so it fits
  * in a normal web request (hosted Nextcloud).
  */
-class BackupJob extends TimedJob {
+final class BackupJob extends TimedJob {
 	public function __construct(
 		ITimeFactory $time,
 		private BackupService $backups,
+		private \OCA\NgBackup\Service\PruneService $prune,
+		private \OCA\NgBackup\Service\AlertService $alerts,
 		private TargetService $targets,
 		private RunMapper $runs,
 		private IAppConfig $appConfig,
@@ -45,6 +47,43 @@ class BackupJob extends TimedJob {
 				$run = $this->backups->step($run, min($deadline, microtime(true) + $budget));
 			}
 		}
+		$this->failStaleRestores();
+		$this->weeklyPrune();
+		foreach ($this->targets->list() as $t) {
+			$this->alerts->checkStale($t);
+		}
+	}
+
+	/** A restore run that has not moved for 6 hours is considered dead (it would block cleanup forever). */
+	private function failStaleRestores(): void {
+		foreach ($this->runs->findRunning(null, 'restore') as $run) {
+			if (time() - $run->getUpdatedAt() > 6 * 3600) {
+				$run->setStatus(\OCA\NgBackup\Db\Run::FAILED);
+				$run->setError('No progress for 6 hours; marked as failed');
+				$run->setFinishedAt(time());
+				$this->runs->update($run);
+				$this->alerts->runFailed($run, '#' . $run->getTargetId());
+			}
+		}
+	}
+
+	/** Once a week (after Sunday's backup), apply the retention policy to non-append-only locations. */
+	private function weeklyPrune(): void {
+		$lastWeek = $this->appConfig->getValueString(Application::APP_ID, 'last_prune_week', '');
+		if (date('N') !== '7' || $lastWeek === date('o-W') || $this->runs->findRunning(null, BackupService::KIND_FULL) !== []) {
+			return;
+		}
+		foreach ($this->targets->list() as $t) {
+			if ($t->getAppendOnly()) {
+				continue;
+			}
+			try {
+				$this->prune->apply($t, false, true);
+			} catch (\Throwable $e) {
+				$this->logger->warning('NG Backup: cleanup of ' . $t->getName() . ' failed: ' . $e->getMessage());
+			}
+		}
+		$this->appConfig->setValueString(Application::APP_ID, 'last_prune_week', date('o-W'));
 	}
 
 	/** Daily schedule: appconfig ng_backup/schedule_time "HH:MM" (server time); empty = no schedule. */

lib/BackgroundJob/RestoreJob.php

@@ -16,29 +16,46 @@ use OCP\BackgroundJob\QueuedJob;
 use Psr\Log\LoggerInterface;
 
 /** Runs a restore requested from the web interface, outside the web request. */
-class RestoreJob extends QueuedJob {
+final class RestoreJob extends QueuedJob {
 	public function __construct(
 		ITimeFactory $time,
 		private RunMapper $runs,
 		private TargetService $targets,
 		private RestoreService $restore,
 		private LoggerInterface $logger,
+		private \OCA\NgBackup\Service\AlertService $alerts,
 	) {
 		parent::__construct($time);
 	}
 
 	protected function run($argument): void {
-		$run = $this->runs->find((int)$argument['run']);
+		$runId = (int)($argument['run'] ?? 0);
+		try {
+			$run = $this->runs->find($runId);
+		} catch (\Throwable $e) {
+			$this->logger->error('NG Backup restore job: run ' . $runId . ' not found', ['exception' => $e]);
+			return;
+		}
 		if ($run->getStatus() !== Run::RUNNING) {
 			return;
 		}
-		$req = json_decode($run->getState(), true, 512, JSON_THROW_ON_ERROR);
-		$run->setPhase('restoring');
-		$run->setUpdatedAt(time());
-		$this->runs->update($run);
-		@set_time_limit(0);
 		try {
-			$result = $this->restore->restoreUserFiles($this->targets->get((string)$run->getTargetId()), $req['snapshot'], $req['path'], $req['mode']);
+			$req = json_decode($run->getState(), true, 512, JSON_THROW_ON_ERROR);
+			$run->setPhase('restoring');
+			$run->setUpdatedAt(time());
+			$run = $this->runs->update($run);
+			@set_time_limit(0);
+			$lastBeat = time();
+			$result = $this->restore->restoreUserFiles($this->targets->get((string)$run->getTargetId()), $req['snapshot'], $req['path'], $req['mode'],
+				function (int $done, int $total) use (&$run, &$lastBeat): void {
+					// Heartbeat, so a long restore is not mistaken for a dead one.
+					if (time() - $lastBeat >= 60) {
+						$lastBeat = time();
+						$run->setPhase("restoring $done/$total");
+						$run->setUpdatedAt(time());
+						$run = $this->runs->update($run);
+					}
+				});
 			$run->setStatus(Run::DONE);
 			$run->setPhase('done');
 			$run->setStats(json_encode($result, JSON_THROW_ON_ERROR));
@@ -46,6 +63,10 @@ class RestoreJob extends QueuedJob {
 			$this->logger->error('NG Backup restore ' . $run->getId() . ' failed: ' . $e->getMessage(), ['exception' => $e]);
 			$run->setStatus(Run::FAILED);
 			$run->setError($e->getMessage());
+			try {
+				$this->alerts->runFailed($run, '#' . $run->getTargetId());
+			} catch (\Throwable) {
+			}
 		}
 		$run->setFinishedAt(time());
 		$run->setUpdatedAt(time());

lib/Command/Browse.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Browse extends Command {
+final class Browse extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private RestoreService $restore,

lib/Command/KeyConfirm.php

@@ -14,7 +14,7 @@ use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\Question;
 
-class KeyConfirm extends Command {
+final class KeyConfirm extends Command {
 	public const STATEMENT = 'I have downloaded the recovery kit and stored it safely, outside this server. '
 		. 'I understand that keeping these keys safe is my own responsibility and that backups cannot be restored without them.';
 	public const CONFIRMATION = 'Yes, I confirm';
@@ -28,7 +28,9 @@ class KeyConfirm extends Command {
 	protected function configure(): void {
 		$this->setName('backup:key:confirm')
 			->setDescription('Confirm that the recovery kit is stored safely (required before the first backup)')
-			->addOption('user', 'u', InputOption::VALUE_REQUIRED, 'Admin user id recorded with the confirmation', 'occ');
+			->addOption('user', 'u', InputOption::VALUE_REQUIRED, 'Admin user id recorded with the confirmation', 'occ')
+			->addOption('code', null, InputOption::VALUE_REQUIRED, 'Confirmation code from the kit file (for scripts; asked otherwise)')
+			->addOption('confirm', null, InputOption::VALUE_REQUIRED, 'The confirmation phrase "' . self::CONFIRMATION . '" (for scripts; asked otherwise)');
 	}
 
 	protected function execute(InputInterface $input, OutputInterface $output): int {
@@ -40,7 +42,12 @@ class KeyConfirm extends Command {
 		$output->writeln('');
 		$output->writeln(wordwrap(self::STATEMENT, 78));
 		$output->writeln('');
-		$answer = (string)$this->getHelper('question')->ask($input, $output, new Question('Type "' . self::CONFIRMATION . '" to proceed: '));
+		$code = $input->getOption('code') ?? (string)$this->getHelper('question')->ask($input, $output, new Question('Confirmation code from the recovery kit file ("confirmation_code"): '));
+		if (!$this->keys->checkKitCode($code)) {
+			$output->writeln('<error>That code does not match the current recovery kit (download it with occ backup:key:kit first).</error>');
+			return 1;
+		}
+		$answer = $input->getOption('confirm') ?? (string)$this->getHelper('question')->ask($input, $output, new Question('Type "' . self::CONFIRMATION . '" to proceed: '));
 		if (trim($answer) !== self::CONFIRMATION) {
 			$output->writeln('<error>Not confirmed.</error>');
 			return 1;

lib/Command/KeyInit.php

@@ -14,7 +14,7 @@ use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\Question;
 
-class KeyInit extends Command {
+final class KeyInit extends Command {
 	public function __construct(
 		private KeyService $keys,
 	) {
@@ -25,6 +25,8 @@ class KeyInit extends Command {
 		$this->setName('backup:key:init')
 			->setDescription('Create the backup key, protected by a passphrase you keep safe')
 			->addOption('passphrase-file', null, InputOption::VALUE_REQUIRED, 'Read the passphrase from this file instead of asking')
+			->addOption('label', 'l', InputOption::VALUE_REQUIRED, 'Label of the first passphrase slot (who/where), e.g. "Safe"', 'Slot 1')
+			->addOption('delete-delay-days', null, InputOption::VALUE_REQUIRED, 'Days a removed snapshot stays in the trash before its data is deleted (1-365, fixed after this)', (string)KeyService::DEFAULT_DELETE_DELAY)
 			->setHelp(<<<'HELP'
 Creates the master key that encrypts all backups of this installation.
 
@@ -57,12 +59,14 @@ HELP);
 			}
 		}
 		try {
-			$this->keys->initialize($pass);
+			$this->keys->initialize($pass, (int)$input->getOption('delete-delay-days'), (string)$input->getOption('label'));
 		} catch (\InvalidArgumentException $e) {
 			$output->writeln('<error>' . $e->getMessage() . '</error>');
 			return 1;
 		}
 		$output->writeln('Backup key created, fingerprint <info>' . $this->keys->fingerprint() . '</info>.');
+		$output->writeln('Removed snapshots stay in the trash on the location for <info>' . $this->keys->deleteDelayDays() . ' days</info> (cannot be changed later).');
+		$output->writeln('Tip: add up to two more passphrases for other people with occ backup:key:slot:add (e.g. CTO, head of IT).');
 		$output->writeln('Next: save the recovery kit with <info>occ backup:key:kit --output=FILE</info> and confirm with <info>occ backup:key:confirm</info>.');
 		return 0;
 	}

lib/Command/KeyKit.php

@@ -13,9 +13,10 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class KeyKit extends Command {
+final class KeyKit extends Command {
 	public function __construct(
 		private KeyService $keys,
+		private \OCA\NgBackup\Service\AlertService $alerts,
 	) {
 		parent::__construct();
 	}
@@ -31,6 +32,7 @@ class KeyKit extends Command {
 			$output->writeln('<error>No backup key yet: run occ backup:key:init first.</error>');
 			return 1;
 		}
+		$this->alerts->securityEvent('kit_downloaded');
 		$json = json_encode($this->keys->recoveryKit(), JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_THROW_ON_ERROR) . "\n";
 		$file = $input->getOption('output');
 		if ($file === null) {

lib/Command/KeySlotAdd.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\KeyService;
+use OCA\NgBackup\Service\KeySlotService;
+
+final class KeySlotAdd extends KeySlots {
+	public function __construct(KeyService $keys, KeySlotService $slots) {
+		parent::__construct($keys, $slots, 'add');
+	}
+}

lib/Command/KeySlotRemove.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\KeyService;
+use OCA\NgBackup\Service\KeySlotService;
+
+final class KeySlotRemove extends KeySlots {
+	public function __construct(KeyService $keys, KeySlotService $slots) {
+		parent::__construct($keys, $slots, 'remove');
+	}
+}

lib/Command/KeySlotReplace.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\KeyService;
+use OCA\NgBackup\Service\KeySlotService;
+
+final class KeySlotReplace extends KeySlots {
+	public function __construct(KeyService $keys, KeySlotService $slots) {
+		parent::__construct($keys, $slots, 'replace');
+	}
+}

lib/Command/KeySlots.php

@@ -0,0 +1,97 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\KeyService;
+use OCA\NgBackup\Service\KeySlotService;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Helper\Table;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Question\Question;
+
+/** backup:key:slots, backup:key:slot:add, backup:key:slot:replace, backup:key:slot:remove */
+class KeySlots extends Command {
+	public function __construct(
+		private KeyService $keys,
+		private KeySlotService $slots,
+		private string $action = 'list',
+	) {
+		// list is the default; subclasses pick another action
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$help = <<<'HELP'
+Up to three passphrases ("slots") can open the backup key, so that one person leaving or dying
+does not lock you out. Example: one passphrase in the safe, one with the CTO, one with the head
+of IT. Each holder keeps a copy of the same recovery kit and only knows their own passphrase.
+After every change: occ backup:key:kit and occ backup:key:confirm.
+HELP;
+		match ($this->action) {
+			'add' => $this->setName('backup:key:slot:add')->setDescription('Add a passphrase slot')
+				->addOption('label', 'l', InputOption::VALUE_REQUIRED, 'Who or where, e.g. "CTO" or "Safe"', 'Slot'),
+			'replace' => $this->setName('backup:key:slot:replace')->setDescription('Set a new passphrase for a slot (e.g. its holder left)')
+				->addArgument('slot', InputArgument::REQUIRED, 'Slot number (see backup:key:slots)')
+				->addOption('label', 'l', InputOption::VALUE_REQUIRED, 'New label'),
+			'remove' => $this->setName('backup:key:slot:remove')->setDescription('Remove a passphrase slot (not the last one)')
+				->addArgument('slot', InputArgument::REQUIRED, 'Slot number (see backup:key:slots)'),
+			default => $this->setName('backup:key:slots')->setDescription('List the passphrase slots of the backup key'),
+		};
+		if ($this->action === 'add' || $this->action === 'replace') {
+			$this->addOption('passphrase-file', null, InputOption::VALUE_REQUIRED, 'Read the passphrase from this file');
+		}
+		$this->setHelp($help);
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		if (!$this->keys->isInitialized()) {
+			$output->writeln('<error>No backup key yet: run occ backup:key:init first.</error>');
+			return 1;
+		}
+		try {
+			switch ($this->action) {
+				case 'add':
+					$n = $this->slots->add($this->passphrase($input, $output), (string)$input->getOption('label'));
+					$output->writeln("Slot $n added.");
+					break;
+				case 'replace':
+					$this->slots->replace((int)$input->getArgument('slot'), $this->passphrase($input, $output), $input->getOption('label'));
+					$output->writeln('Slot ' . (int)$input->getArgument('slot') . ' has a new passphrase.');
+					break;
+				case 'remove':
+					$this->slots->remove((int)$input->getArgument('slot'));
+					$output->writeln('Slot ' . (int)$input->getArgument('slot') . ' removed.');
+					break;
+				default:
+					(new Table($output))->setHeaders(['slot', 'label', 'set on'])
+						->setRows(array_map(fn ($s) => [$s['slot'], $s['label'], $s['created'] ? date('Y-m-d H:i', $s['created']) : ''], $this->keys->slots()))->render();
+					return 0;
+			}
+		} catch (\Throwable $e) {
+			$output->writeln('<error>' . $e->getMessage() . '</error>');
+			return 1;
+		}
+		$output->writeln('Now download and confirm the new recovery kit: occ backup:key:kit -o FILE && occ backup:key:confirm');
+		return 0;
+	}
+
+	private function passphrase(InputInterface $input, OutputInterface $output): string {
+		if ($file = $input->getOption('passphrase-file')) {
+			return rtrim((string)@file_get_contents($file), "\r\n");
+		}
+		$h = $this->getHelper('question');
+		$p = (string)$h->ask($input, $output, (new Question('Passphrase (min. 12 characters): '))->setHidden(true)->setHiddenFallback(false));
+		if ($p !== (string)$h->ask($input, $output, (new Question('Repeat: '))->setHidden(true)->setHiddenFallback(false))) {
+			throw new \InvalidArgumentException('The passphrases do not match');
+		}
+		return $p;
+	}
+}

lib/Command/ListSnapshots.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class ListSnapshots extends Command {
+final class ListSnapshots extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private SnapshotMapper $snapshots,

lib/Command/Prune.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\PruneService;
+use OCA\NgBackup\Service\TargetService;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class Prune extends Command {
+	public function __construct(
+		private TargetService $targets,
+		private PruneService $prune,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:prune')
+			->setDescription('Apply the retention policy: remove old snapshots and the data only they used')
+			->addArgument('target', InputArgument::OPTIONAL, 'Location name or id (default: all that are not append-only)')
+			->addOption('dry-run', null, InputOption::VALUE_NONE, 'Only show what would be removed');
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$name = $input->getArgument('target');
+		$targets = $name === null ? array_filter($this->targets->list(), fn ($t) => !$t->getAppendOnly()) : [$this->targets->get($name)];
+		$dry = (bool)$input->getOption('dry-run');
+		$output->writeln('Policy: ' . json_encode($this->prune->policy()->toArray()) . ($dry ? ' (dry run)' : ''));
+		$rc = 0;
+		foreach ($targets as $t) {
+			try {
+				$r = $this->prune->apply($t, $dry);
+			} catch (\Throwable $e) {
+				$output->writeln('<error>' . $t->getName() . ': ' . $e->getMessage() . '</error>');
+				$rc = 1;
+				continue;
+			}
+			$p = $r['prune'];
+			$output->writeln(sprintf('<info>%s</info>: keep %d, %s %d snapshots; packs: %d, %s %d, repack %d, frees %.1f MiB',
+				$t->getName(), count($r['kept']), $dry ? 'would forget' : 'forgot', count($r['forgotten']), $p['packs'],
+				$dry ? 'would delete' : 'deleted', $p['deleted'], $p['repacked'], $p['freedBytes'] / 1048576));
+		}
+		return $rc;
+	}
+}

lib/Command/Restore.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Restore extends Command {
+final class Restore extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private RestoreService $restore,
@@ -49,7 +49,7 @@ HELP);
 		try {
 			$target = $this->targets->get($input->getArgument('target'));
 			$snapshot = $input->getArgument('snapshot');
-			$path = $input->getArgument('path');
+			$path = trim((string)$input->getArgument('path'), '/'); // CLI convenience; the service itself only accepts canonical paths
 			if ($dir = $input->getOption('to-directory')) {
 				$n = $this->restore->restoreToDirectory($target, $snapshot, $path, $dir);
 				$output->writeln("Restored <info>$n</info> files to $dir.");

lib/Command/Retention.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\PruneService;
+use OCA\NgBackup\Service\RetentionPolicy;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class Retention extends Command {
+	public function __construct(
+		private PruneService $prune,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:retention')
+			->setDescription('Show or set how many snapshots are kept')
+			->addOption('last', null, InputOption::VALUE_REQUIRED, 'Always keep the newest N')
+			->addOption('daily', null, InputOption::VALUE_REQUIRED, 'Keep one per day for the last N days with a backup')
+			->addOption('weekly', null, InputOption::VALUE_REQUIRED, 'Keep one per week for N weeks')
+			->addOption('monthly', null, InputOption::VALUE_REQUIRED, 'Keep one per month for N months')
+			->setHelp("Example: occ backup:retention --last=3 --daily=7 --weekly=4 --monthly=12");
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$p = $this->prune->policy()->toArray();
+		$changed = false;
+		foreach (['last', 'daily', 'weekly', 'monthly'] as $k) {
+			if ($input->getOption($k) !== null) {
+				$p[$k] = max(0, (int)$input->getOption($k));
+				$changed = true;
+			}
+		}
+		if ($changed) {
+			try {
+				$this->prune->setPolicy(RetentionPolicy::fromArray($p));
+			} catch (\InvalidArgumentException $e) {
+				$output->writeln('<error>' . $e->getMessage() . '</error>');
+				return 1;
+			}
+		}
+		$output->writeln(sprintf('Keep the last %d, plus one per day for %d days, per week for %d weeks, per month for %d months.', $p['last'], $p['daily'], $p['weekly'], $p['monthly']));
+		return 0;
+	}
+}

lib/Command/RunBackup.php

@@ -16,7 +16,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class RunBackup extends Command {
+final class RunBackup extends Command {
 	public function __construct(
 		private BackupService $backups,
 		private TargetService $targets,

lib/Command/Status.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Helper\Table;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class Status extends Command {
+final class Status extends Command {
 	public function __construct(
 		private KeyService $keys,
 		private TargetService $targets,

lib/Command/TargetAdd.php

@@ -15,7 +15,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetAdd extends Command {
+final class TargetAdd extends Command {
 	public function __construct(
 		private TargetService $targets,
 		private KeyService $keys,

lib/Command/TargetAppendOnly.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\TargetService;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class TargetAppendOnly extends Command {
+	public function __construct(
+		private TargetService $targets,
+		private \OCA\NgBackup\Service\AlertService $alerts,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:target:append-only')
+			->setDescription('Make a location append-only (NG Backup never deletes there) or normal again')
+			->addArgument('target', InputArgument::REQUIRED, 'Location name or id')
+			->addArgument('state', InputArgument::REQUIRED, 'on or off')
+			->setHelp("Append-only protects backups if this server is compromised: combine it with credentials\nwithout delete rights and a lifecycle rule or object lock on the location itself.");
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$state = strtolower((string)$input->getArgument('state'));
+		if (!in_array($state, ['on', 'off'], true)) {
+			$output->writeln('<error>state must be on or off</error>');
+			return 1;
+		}
+		$t = $this->targets->setAppendOnly($this->targets->get($input->getArgument('target')), $state === 'on');
+		if ($state === 'off') {
+			$this->alerts->securityEvent('append_only_off', ['target' => $t->getName()]);
+		}
+		$output->writeln($t->getName() . ' is ' . ($t->getAppendOnly() ? 'append-only' : 'normal') . '.');
+		return 0;
+	}
+}

lib/Command/TargetBackends.php

@@ -12,7 +12,7 @@ use OCA\NgBackup\Service\TargetService;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetBackends extends Base {
+final class TargetBackends extends Base {
 	public function __construct(
 		private TargetService $targets,
 	) {

lib/Command/TargetLimit.php

@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\TargetService;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class TargetLimit extends Command {
+	public function __construct(
+		private TargetService $targets,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:target:limit')
+			->setDescription('Set a maximum size for the backups stored on a location (e.g. 100G), or "none"')
+			->addArgument('target', InputArgument::REQUIRED, 'Location name or id')
+			->addArgument('size', InputArgument::OPTIONAL, 'Size like 500M, 20G, 2T, or "none"; omit to show the current limit')
+			->setHelp("A backup that would exceed the limit stops with an error and administrators are notified.\n"
+				. "Note: with versioning or Object Lock on the location, removed data keeps using space there\n"
+				. "until it expires; keep the limit below what you are willing to pay for.");
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$t = $this->targets->get($input->getArgument('target'));
+		$size = $input->getArgument('size');
+		if ($size !== null) {
+			if (strtolower($size) === 'none') {
+				$t = $this->targets->setMaxBytes($t, null);
+			} elseif (preg_match('/^(\d+(?:\.\d+)?)\s*([KMGT]?)i?B?$/i', $size, $m)) {
+				$factor = ['' => 1, 'K' => 1024, 'M' => 1024 ** 2, 'G' => 1024 ** 3, 'T' => 1024 ** 4][strtoupper($m[2])];
+				$t = $this->targets->setMaxBytes($t, (int)round((float)$m[1] * $factor));
+			} else {
+				$output->writeln('<error>Use a size like 500M, 20G or 2T, or "none".</error>');
+				return 1;
+			}
+		}
+		$used = $this->targets->repository($t)->storedBytes();
+		$output->writeln(sprintf('%s: %.2f GiB stored, limit %s', $t->getName(), $used / 1073741824,
+			$t->getMaxBytes() === null ? 'none' : sprintf('%.2f GiB', $t->getMaxBytes() / 1073741824)));
+		return 0;
+	}
+}

lib/Command/TargetList.php

@@ -13,7 +13,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetList extends Base {
+final class TargetList extends Base {
 	public function __construct(
 		private TargetService $targets,
 	) {

lib/Command/TargetRemove.php

@@ -13,9 +13,10 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
-class TargetRemove extends Command {
+final class TargetRemove extends Command {
 	public function __construct(
 		private TargetService $targets,
+		private \OCA\NgBackup\Service\AlertService $alerts,
 	) {
 		parent::__construct();
 	}
@@ -34,6 +35,7 @@ class TargetRemove extends Command {
 			return 1;
 		}
 		$this->targets->remove($t);
+		$this->alerts->securityEvent('target_removed', ['target' => $t->getName()]);
 		$output->writeln('Removed <info>' . $t->getName() . '</info>. The backups on the location itself were not touched; add it again to use them.');
 		return 0;
 	}

lib/Command/TargetTrustCurrent.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Db\AppConfigCatalogAnchor;
+use OCA\NgBackup\Service\AlertService;
+use OCA\NgBackup\Service\TargetService;
+use OCP\IAppConfig;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Question\Question;
+
+/**
+ * Accept the state a location shows now, after NG Backup refused it as rolled back. Only for
+ * legitimate cases (e.g. the location was restored from the provider's own snapshot), only from
+ * occ, audited and announced to all administrators.
+ */
+final class TargetTrustCurrent extends Command {
+	public function __construct(
+		private TargetService $targets,
+		private IAppConfig $appConfig,
+		private AlertService $alerts,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:target:trust-current')
+			->setDescription('Accept the current state of a location that was refused as rolled back')
+			->addArgument('target', InputArgument::REQUIRED, 'Location name or id')
+			->setHelp("NG Backup refuses a location whose backup catalog is older than what this server saw\n"
+				. "before, because an attacker could have restored an old state. If you restored the location\n"
+				. "yourself (e.g. from the provider's snapshot), accept it with this command.");
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$t = $this->targets->get($input->getArgument('target'));
+		$output->writeln('<comment>Only continue if you know why the location shows an older state.</comment>');
+		$answer = (string)$this->getHelper('question')->ask($input, $output, new Question('Type the location name to accept its current state: '));
+		if ($answer !== $t->getName()) {
+			$output->writeln('<error>Not confirmed.</error>');
+			return 1;
+		}
+		$this->appConfig->deleteKey('ng_backup', 'catalog_' . preg_replace('/[^a-f0-9]/', '', (string)$t->getRepositoryId()));
+		$repo = $this->targets->repository($t); // re-anchors on the newest valid catalog
+		$this->alerts->securityEvent('catalog_trusted', ['target' => $t->getName(), 'generation' => (string)$repo->catalogGeneration()]);
+		$output->writeln(sprintf('Accepted generation %d of %s (%d snapshots).', $repo->catalogGeneration(), $t->getName(), count($repo->listSnapshots())));
+		return 0;
+	}
+}

lib/Command/Trash.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\KeyService;
+use OCA\NgBackup\Service\TargetService;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Helper\Table;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class Trash extends Command {
+	public function __construct(
+		private TargetService $targets,
+		private KeyService $keys,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:trash')
+			->setDescription('List removed snapshots that can still be restored (backup:trash:restore)')
+			->addArgument('target', InputArgument::OPTIONAL, 'Location name or id (default: all)');
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$name = $input->getArgument('target');
+		$delay = $this->keys->deleteDelayDays() * 86400;
+		$rows = [];
+		foreach ($name === null ? $this->targets->list() : [$this->targets->get($name)] as $t) {
+			foreach ($this->targets->repository($t)->trash() as $id => $info) {
+				$rows[] = [$t->getName(), $id, (string)($info['time'] ?? ''), $info['label'], date('Y-m-d H:i', $info['forgottenAt']), $info['by'],
+					date('Y-m-d H:i', $info['forgottenAt'] + $delay)];
+			}
+		}
+		if ($rows === []) {
+			$output->writeln('The trash is empty.');
+			return 0;
+		}
+		(new Table($output))->setHeaders(['location', 'snapshot', 'made', 'label', 'removed', 'by', 'deleted after'])->setRows($rows)->render();
+		return 0;
+	}
+}

lib/Command/TrashRestore.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\PruneService;
+use OCA\NgBackup\Service\TargetService;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class TrashRestore extends Command {
+	public function __construct(
+		private TargetService $targets,
+		private PruneService $prune,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:trash:restore')
+			->setDescription('Bring a removed snapshot back from the trash')
+			->addArgument('target', InputArgument::REQUIRED, 'Location name or id')
+			->addArgument('snapshot', InputArgument::REQUIRED, 'Snapshot id (see backup:trash)');
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		try {
+			$this->prune->untrash($this->targets->get($input->getArgument('target')), $input->getArgument('snapshot'));
+		} catch (\Throwable $e) {
+			$output->writeln('<error>' . $e->getMessage() . '</error>');
+			return 1;
+		}
+		$output->writeln('Snapshot restored from the trash.');
+		return 0;
+	}
+}

lib/Controller/AdminApiController.php

@@ -19,6 +19,8 @@ use OCA\NgBackup\Service\RestoreService;
 use OCA\NgBackup\Service\TargetService;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\Attribute\NoCSRFRequired;
+use OCP\AppFramework\Http\Attribute\PasswordConfirmationRequired;
 use OCP\AppFramework\Http\DataDownloadResponse;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\BackgroundJob\IJobList;
@@ -30,7 +32,7 @@ use OCP\IUserSession;
  * JSON API for the admin settings page. Every method requires an admin (the AppFramework
  * default for controllers without NoAdminRequired) and a valid CSRF token.
  */
-class AdminApiController extends Controller {
+final class AdminApiController extends Controller {
 	public function __construct(
 		IRequest $request,
 		private KeyService $keys,
@@ -42,6 +44,9 @@ class AdminApiController extends Controller {
 		private IAppConfig $appConfig,
 		private IJobList $jobs,
 		private IUserSession $session,
+		private \OCA\NgBackup\Service\AlertService $alerts,
+		private \OCA\NgBackup\Service\KeySlotService $slots,
+		private \OCA\NgBackup\Service\PruneService $prune,
 	) {
 		parent::__construct(Application::APP_ID, $request);
 	}
@@ -50,12 +55,15 @@ class AdminApiController extends Controller {
 		$targets = [];
 		foreach ($this->targets->list() as $t) {
 			$targets[] = ['id' => $t->getId(), 'name' => $t->getName(), 'backend' => $t->getBackend(), 'path' => $t->getBasePath(),
-				'repositoryId' => $t->getRepositoryId(), 'createdAt' => $t->getCreatedAt()];
+				'repositoryId' => $t->getRepositoryId(), 'createdAt' => $t->getCreatedAt(), 'appendOnly' => (bool)$t->getAppendOnly(),
+				'maxBytes' => $t->getMaxBytes(), 'storedBytes' => $this->alerts->lastStoredBytes($t)];
 		}
 		$runs = array_map(fn (Run $r) => $this->runJson($r), $this->runs->findRecent(15));
 		return new JSONResponse([
 			'key' => ['initialized' => $this->keys->isInitialized(), 'fingerprint' => $this->keys->fingerprint(),
-				'confirmation' => $this->keys->recoveryKitConfirmation()],
+				'confirmation' => $this->keys->recoveryKitConfirmation(), 'everConfirmed' => $this->keys->isInitialized() && $this->keys->everConfirmed(),
+				'slots' => $this->keys->isInitialized() ? $this->keys->slots() : [], 'maxSlots' => \OCA\NgBackup\Service\KeyService::MAX_SLOTS,
+				'deleteDelayDays' => $this->keys->isInitialized() ? $this->keys->deleteDelayDays() : \OCA\NgBackup\Service\KeyService::DEFAULT_DELETE_DELAY],
 			'statement' => KeyConfirm::STATEMENT,
 			'confirmationPhrase' => KeyConfirm::CONFIRMATION,
 			'targets' => $targets,
@@ -64,47 +72,126 @@ class AdminApiController extends Controller {
 		]);
 	}
 
-	public function initKey(string $passphrase): JSONResponse {
+	#[PasswordConfirmationRequired]
+	public function initKey(string $passphrase, int $deleteDelayDays = \OCA\NgBackup\Service\KeyService::DEFAULT_DELETE_DELAY, string $label = 'Slot 1'): JSONResponse {
 		try {
-			$this->keys->initialize($passphrase);
+			$this->keys->initialize($passphrase, $deleteDelayDays, $label);
 		} catch (\Throwable $e) {
 			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
 		}
 		return new JSONResponse(['fingerprint' => $this->keys->fingerprint()]);
 	}
 
+	/**
+	 * Plain download link (no CSRF token on a navigation), therefore guarded by a recent password
+	 * confirmation instead, logged to the audit log and announced to all administrators. The kit
+	 * only holds the passphrase-wrapped key: useless without the passphrase.
+	 */
+	#[NoCSRFRequired]
+	#[PasswordConfirmationRequired]
 	public function downloadKit(): DataDownloadResponse|JSONResponse {
 		if (!$this->keys->isInitialized()) {
 			return new JSONResponse(['error' => 'No backup key yet'], Http::STATUS_BAD_REQUEST);
 		}
+		$this->alerts->securityEvent('kit_downloaded');
 		$json = json_encode($this->keys->recoveryKit(), JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_THROW_ON_ERROR);
 		return new DataDownloadResponse($json, 'ng_backup-recovery-kit-' . $this->keys->fingerprint() . '.json', 'application/json');
 	}
 
-	/** The admin must tick the statement and send the exact confirmation phrase. */
+	/** The admin must tick the statement, send the exact phrase and the code from the kit file. */
-	public function confirmKit(bool $accepted, string $phrase): JSONResponse {
+	#[PasswordConfirmationRequired]
+	public function confirmKit(bool $accepted, string $phrase, string $code = ''): JSONResponse {
 		if (!$accepted || $phrase !== KeyConfirm::CONFIRMATION) {
 			return new JSONResponse(['error' => 'Not confirmed'], Http::STATUS_BAD_REQUEST);
 		}
+		if (!$this->keys->checkKitCode($code)) {
+			return new JSONResponse(['error' => 'The confirmation code does not match the current recovery kit'], Http::STATUS_BAD_REQUEST);
+		}
 		$this->keys->confirmRecoveryKit($this->session->getUser()?->getUID() ?? 'unknown');
 		return new JSONResponse(['confirmation' => $this->keys->recoveryKitConfirmation()]);
 	}
 
+	#[PasswordConfirmationRequired]
+	public function addSlot(string $passphrase, string $label): JSONResponse {
+		try {
+			return new JSONResponse(['slot' => $this->slots->add($passphrase, $label)]);
+		} catch (\Throwable $e) {
+			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
+		}
+	}
+
+	#[PasswordConfirmationRequired]
+	public function replaceSlot(int $slot, string $passphrase, ?string $label = null): JSONResponse {
+		try {
+			$this->slots->replace($slot, $passphrase, $label);
+			return new JSONResponse([]);
+		} catch (\Throwable $e) {
+			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
+		}
+	}
+
+	#[PasswordConfirmationRequired]
+	public function removeSlot(int $slot): JSONResponse {
+		try {
+			$this->slots->remove($slot);
+			return new JSONResponse([]);
+		} catch (\Throwable $e) {
+			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
+		}
+	}
+
+	public function trash(int $targetId): JSONResponse {
+		try {
+			$delay = $this->keys->deleteDelayDays() * 86400;
+			$out = [];
+			foreach ($this->targets->repository($this->targets->get((string)$targetId))->trash() as $id => $info) {
+				$out[] = ['id' => $id, 'label' => $info['label'], 'time' => $info['time'], 'removedAt' => $info['forgottenAt'],
+					'by' => $info['by'], 'deleteAfter' => $info['forgottenAt'] + $delay];
+			}
+			return new JSONResponse($out);
+		} catch (\Throwable $e) {
+			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
+		}
+	}
+
+	#[PasswordConfirmationRequired]
+	public function untrash(int $targetId, string $snapshotId): JSONResponse {
+		try {
+			$this->prune->untrash($this->targets->get((string)$targetId), $snapshotId);
+			return new JSONResponse([]);
+		} catch (\Throwable $e) {
+			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
+		}
+	}
+
 	public function backends(): JSONResponse {
 		return new JSONResponse($this->targets->availableBackends());
 	}
 
-	public function addTarget(string $name, string $backend, string $auth, array $options = [], string $path = 'ng_backup'): JSONResponse {
+	public function addTarget(string $name, string $backend, string $auth, array $options = [], string $path = 'ng_backup', ?float $maxGb = null): JSONResponse {
 		try {
 			$r = $this->targets->add($name, $backend, $auth, $options, $path);
+			if ($maxGb !== null && $maxGb > 0) {
+				$this->targets->setMaxBytes($r['target'], (int)round($maxGb * 1073741824));
+			}
 		} catch (\Throwable $e) {
 			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
 		}
 		return new JSONResponse(['id' => $r['target']->getId(), 'created' => $r['created']]);
 	}
 
+	/** Size limit in GiB; null or 0 = unlimited. */
+	#[PasswordConfirmationRequired]
+	public function setTargetLimit(int $id, ?float $maxGb = null): JSONResponse {
+		$t = $this->targets->setMaxBytes($this->targets->get((string)$id), ($maxGb !== null && $maxGb > 0) ? (int)round($maxGb * 1073741824) : null);
+		return new JSONResponse(['maxBytes' => $t->getMaxBytes()]);
+	}
+
+	#[PasswordConfirmationRequired]
 	public function removeTarget(int $id): JSONResponse {
-		$this->targets->remove($this->targets->get((string)$id));
+		$target = $this->targets->get((string)$id);
+		$this->targets->remove($target);
+		$this->alerts->securityEvent('target_removed', ['target' => $target->getName()]);
 		return new JSONResponse([]);
 	}
 
@@ -152,13 +239,19 @@ class AdminApiController extends Controller {
 	}
 
 	/** Queue a restore of user files; it runs as a background job and shows up in the runs. */
+	#[PasswordConfirmationRequired]
 	public function startRestore(int $targetId, string $snapshotId, string $path, string $mode = RestoreService::MODE_NEW_FOLDER): JSONResponse {
 		if (!in_array($mode, [RestoreService::MODE_NEW_FOLDER, RestoreService::MODE_MERGE, RestoreService::MODE_REPLACE], true)
-			|| !preg_match('#^data/[^/]+/files(/.*)?$#', $path)) {
+			|| !\OCA\NgBackup\Repository\Repository::isSafePath($path) || !preg_match('#^data/[^/]+/files(/.*)?$#', $path)) {
 			return new JSONResponse(['error' => 'Invalid path or mode'], Http::STATUS_BAD_REQUEST);
 		}
+		try {
+			$target = $this->targets->get((string)$targetId);
+		} catch (\Throwable) {
+			return new JSONResponse(['error' => 'No such location'], Http::STATUS_NOT_FOUND);
+		}
 		$run = new Run();
-		$run->setTargetId($targetId);
+		$run->setTargetId($target->getId());
 		$run->setKind('restore');
 		$run->setStatus(Run::RUNNING);
 		$run->setPhase('queued');
@@ -167,14 +260,27 @@ class AdminApiController extends Controller {
 		$run->setSnapshotId($snapshotId);
 		$run->setStartedAt(time());
 		$run->setUpdatedAt(time());
-		$run = $this->runs->insert($run);
+		try {
+			$run = $this->prune->underStartLock($target, fn () => $this->runs->insert($run));
+		} catch (\Throwable $e) {
+			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_CONFLICT);
+		}
 		$this->jobs->add(RestoreJob::class, ['run' => $run->getId()]);
 		return new JSONResponse($this->runJson($run));
 	}
 
 	private function runJson(Run $r): array {
+		$snapshot = null;
+		if ($r->getSnapshotId() !== null) {
+			try {
+				$s = $this->snapshots->findOne($r->getTargetId(), $r->getSnapshotId());
+				$snapshot = ['createdAt' => $s->getCreatedAt(), 'label' => $s->getLabel()];
+			} catch (\Throwable) {
+				// Snapshot already pruned or trashed: the run keeps its id, just not the date.
+			}
+		}
 		return ['id' => $r->getId(), 'targetId' => $r->getTargetId(), 'kind' => $r->getKind(), 'status' => $r->getStatus(),
-			'phase' => $r->getPhase(), 'snapshotId' => $r->getSnapshotId(), 'startedAt' => $r->getStartedAt(),
+			'phase' => $r->getPhase(), 'snapshotId' => $r->getSnapshotId(), 'snapshot' => $snapshot, 'startedAt' => $r->getStartedAt(),
 			'updatedAt' => $r->getUpdatedAt(), 'finishedAt' => $r->getFinishedAt(), 'error' => $r->getError(),
 			'stats' => json_decode($r->getStats() ?? 'null', true)];
 	}

lib/Crypto/CryptoException.php

@@ -7,5 +7,5 @@ declare(strict_types=1);
 
 namespace OCA\NgBackup\Crypto;
 
-class CryptoException extends \RuntimeException {
+final class CryptoException extends \RuntimeException {
 }

lib/Crypto/KeyRing.php

@@ -76,6 +76,23 @@ final class KeyRing {
 		];
 	}
 
+	/**
+	 * Open a key field that is either one wrapped key or {"slots": [{slot, label, key}, ...]}:
+	 * every slot holds the same master key under its own passphrase.
+	 */
+	public static function unwrapAny(array $field, #[\SensitiveParameter] string $passphrase): self {
+		if (!isset($field['slots'])) {
+			return self::unwrap($field, $passphrase);
+		}
+		foreach ($field['slots'] as $slot) {
+			try {
+				return self::unwrap($slot['key'], $passphrase);
+			} catch (CryptoException) {
+			}
+		}
+		throw new CryptoException('Wrong passphrase or damaged key');
+	}
+
 	/** @param array{v:int, salt:string, ops:int, mem:int, nonce:string, key:string} $wrapped */
 	public static function unwrap(array $wrapped, #[\SensitiveParameter] string $passphrase): self {
 		$b64 = static fn (string $s): string => sodium_base642bin($s, SODIUM_BASE64_VARIANT_ORIGINAL);

lib/Db/AppConfigCatalogAnchor.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Db;
+
+use OCA\NgBackup\AppInfo\Application;
+use OCA\NgBackup\Repository\ICatalogAnchor;
+use OCP\IAppConfig;
+
+/** Keeps the newest catalog generation seen per repository in the app config (outside the location). */
+final class AppConfigCatalogAnchor implements ICatalogAnchor {
+	public function __construct(
+		private IAppConfig $appConfig,
+	) {
+	}
+
+	public function get(string $repositoryId): ?array {
+		$raw = $this->appConfig->getValueString(Application::APP_ID, $this->key($repositoryId), '', true);
+		$data = $raw === '' ? null : json_decode($raw, true);
+		return is_array($data) && isset($data['gen'], $data['hash']) ? ['gen' => (int)$data['gen'], 'hash' => (string)$data['hash']] : null;
+	}
+
+	public function set(string $repositoryId, int $gen, string $hash): void {
+		$this->appConfig->setValueString(Application::APP_ID, $this->key($repositoryId), json_encode(['gen' => $gen, 'hash' => $hash]), true);
+	}
+
+	private function key(string $repositoryId): string {
+		return 'catalog_' . preg_replace('/[^a-f0-9]/', '', $repositoryId);
+	}
+}

lib/Db/DbDumper.php

@@ -31,6 +31,8 @@ use OCA\NgBackup\Repository\Repository;
  */
 final class DbDumper {
 	private const BATCH = 2000;
+	/** Rows per INSERT on restore; keeps the number of bound parameters well below database limits. */
+	private const INSERT_ROWS = 100;
 	/** Tables without a primary key are read in one query; refuse that above this size. */
 	private const MAX_ROWS_WITHOUT_PK = 50000;
 
@@ -41,39 +43,87 @@ final class DbDumper {
 	}
 
 	/**
-	 * @return array{tables: array<string, array{blobs: list<string>, rows: int, bytes: int, sha256: string}>, provider: string}
+	 * Dump everything in one go (one transaction, fully consistent).
+	 *
+	 * @return array{tables: array<string, array{blobs: list<string>, rows: int, bytes: int, sha256: string}>, sequences: array, provider: string, consistent: bool}
 	 */
 	public function dump(Repository $repo, array &$stats): array {
-		$sm = $this->db->createSchemaManager();
+		$state = $this->startDump();
-		$tables = array_values(array_filter($sm->listTableNames(), fn (string $t) => str_starts_with($t, $this->prefix)));
+		while (!$state['done']) {
-		sort($tables);
+			$state = $this->dumpStep($repo, $state, PHP_FLOAT_MAX, $stats);
+		}
+		return $this->manifest($state);
+	}
 
+	/** State for a resumable dump (see dumpStep()). */
+	public function startDump(): array {
+		$tables = array_values(array_filter($this->db->createSchemaManager()->listTableNames(), fn (string $t) => str_starts_with($t, $this->prefix)));
+		sort($tables);
+		return ['tables' => $tables, 'i' => 0, 'after' => null, 'segments' => [], 'rows' => 0, 'bytes' => 0, 'hash' => null,
+			'result' => [], 'sequences' => [], 'steps' => 0, 'done' => false];
+	}
+
+	/**
+	 * Dump tables until $deadline, inside one REPEATABLE READ transaction for this step. A table
+	 * that does not fit is resumed in the next step at the last primary key written. If the whole
+	 * dump fits in one step it is fully consistent; otherwise each step is consistent on its own
+	 * ('consistent' => false in the manifest).
+	 */
+	public function dumpStep(Repository $repo, array $state, float $deadline, array &$stats): array {
+		$state['steps']++;
+		$sm = $this->db->createSchemaManager();
 		$this->db->setTransactionIsolation(TransactionIsolationLevel::REPEATABLE_READ);
 		$this->db->beginTransaction();
 		try {
 			if ($this->db->getDatabasePlatform() instanceof \Doctrine\DBAL\Platforms\PostgreSQLPlatform) {
 				$this->db->executeStatement('SET TRANSACTION READ ONLY');
 			}
-			$result = [];
+			while ($state['i'] < count($state['tables'])) {
-			foreach ($tables as $table) {
+				$table = $state['tables'][$state['i']];
+				$schema = $sm->introspectTable($table);
 				$writer = $repo->blobWriter($stats);
-				$hash = hash_init('sha256');
+				$hash = $state['hash'] !== null ? unserialize(base64_decode($state['hash']), ['allowed_classes' => [\HashContext::class]]) : hash_init('sha256');
-				$rows = 0;
+				if ($state['after'] === null && $state['segments'] === []) {
-				foreach ($this->tableLines($sm->introspectTable($table)) as $kind => $line) {
+					$writer->write($this->header($schema) . "\n");
+				}
+				$complete = true;
+				foreach ($this->rowLines($schema, $state['after']) as [$key, $line]) {
 					$writer->write($line . "\n");
-					if ($kind === 'row') {
+					hash_update($hash, $line . "\n");
-						hash_update($hash, $line . "\n");
+					$state['rows']++;
-						$rows++;
+					$state['after'] = $key;
+					if (microtime(true) >= $deadline) {
+						$complete = false;
+						break;
 					}
 				}
-				$result[$table] = ['blobs' => $writer->finish(), 'rows' => $rows, 'bytes' => $writer->bytes(), 'sha256' => hash_final($hash)];
+				$state['segments'][] = $writer->finish();
+				$state['bytes'] += $writer->bytes();
+				if (!$complete) {
+					$state['hash'] = base64_encode(serialize($hash));
+					break;
+				}
+				$state['result'][$table] = ['blobs' => array_merge(...$state['segments']), 'rows' => $state['rows'],
+					'bytes' => $state['bytes'], 'sha256' => hash_final($hash)];
+				$state = array_merge($state, ['i' => $state['i'] + 1, 'after' => null, 'segments' => [], 'rows' => 0, 'bytes' => 0, 'hash' => null]);
+				if (microtime(true) >= $deadline && $state['i'] < count($state['tables'])) {
+					break;
+				}
+			}
+			if ($state['i'] >= count($state['tables'])) {
+				$state['sequences'] = $this->sequenceStates($state['tables']);
+				$state['done'] = true;
 			}
-			$sequences = $this->sequenceStates($tables);
 		} finally {
 			$this->db->rollBack();
 		}
 		$repo->flushPacks();
-		return ['tables' => $result, 'sequences' => $sequences, 'provider' => get_class($this->db->getDatabasePlatform())];
+		return $state;
+	}
+
+	public function manifest(array $state): array {
+		return ['tables' => $state['result'], 'sequences' => $state['sequences'],
+			'provider' => get_class($this->db->getDatabasePlatform()), 'consistent' => $state['steps'] === 1];
 	}
 
 	/**
@@ -82,16 +132,23 @@ final class DbDumper {
 	 *
 	 * @param array{tables: array<string, array{blobs: list<string>, rows: int}>} $manifest
 	 */
-	public function restore(Repository $repo, array $manifest): int {
+	public function restore(Repository $repo, array $manifest, ?array &$report = null): int {
 		$sm = $this->db->createSchemaManager();
 		$existing = array_flip($sm->listTableNames());
 		$total = 0;
+		$report = ['skipped' => [], 'restored' => []];
 		$this->db->beginTransaction();
 		try {
 			foreach ($manifest['tables'] as $table => $info) {
 				if (!isset($existing[$table])) {
 					throw new \RuntimeException("Table $table from the backup does not exist here (different app versions?)");
 				}
+				// Unchanged since the backup: leave it alone (much faster than delete + insert).
+				$live = $this->checksum($table);
+				if ($live['rows'] === $info['rows'] && hash_equals($info['sha256'], $live['sha256'])) {
+					$report['skipped'][] = $table;
+					continue;
+				}
 				$this->db->executeStatement('DELETE FROM ' . $this->db->quoteIdentifier($table));
 				$columns = null;
 				$binary = [];
@@ -112,17 +169,18 @@ final class DbDumper {
 						if (is_array($value) && isset($value['$b'])) {
 							$value = base64_decode($value['$b'], true); // text that was not valid UTF-8
 						}
-						$row[$col] = ($value !== null && isset($binary[$col])) ? base64_decode($value, true) : $value;
+						$row[] = ($value !== null && isset($binary[$col])) ? base64_decode($value, true) : $value;
 					}
 					$batch[] = $row;
-					if (count($batch) >= 500) {
+					if (count($batch) >= self::INSERT_ROWS) {
-						$total += $this->insertBatch($table, $batch, $binary);
+						$total += $this->insertBatch($table, $columns, $batch, $binary);
 						$batch = [];
 					}
 				}
 				if ($batch !== []) {
-					$total += $this->insertBatch($table, $batch, $binary);
+					$total += $this->insertBatch($table, $columns, $batch, $binary);
 				}
+				$report['restored'][] = $table;
 			}
 			$this->restoreSequences($manifest['sequences'] ?? []);
 			$this->db->commit();
@@ -135,20 +193,22 @@ final class DbDumper {
 
 	/** Same checksum as dump(): sha256 over the row lines in primary-key order. */
 	public function checksum(string $table): array {
-		$sm = $this->db->createSchemaManager();
 		$hash = hash_init('sha256');
 		$rows = 0;
-		foreach ($this->tableLines($sm->introspectTable($table)) as $kind => $line) {
+		foreach ($this->rowLines($this->db->createSchemaManager()->introspectTable($table)) as [, $line]) {
-			if ($kind === 'row') {
+			hash_update($hash, $line . "\n");
-				hash_update($hash, $line . "\n");
+			$rows++;
-				$rows++;
-			}
 		}
 		return ['rows' => $rows, 'sha256' => hash_final($hash)];
 	}
 
-	/** @return \Generator<string, string> 'header' => line, then 'row' => line ... */
+	private function header(\Doctrine\DBAL\Schema\Table $table): string {
-	private function tableLines(\Doctrine\DBAL\Schema\Table $table): \Generator {
+		[$columns, $binary, $pk] = $this->describe($table);
+		return json_encode(['table' => $table->getName(), 'columns' => $columns, 'binary' => $binary, 'pk' => $pk], JSON_THROW_ON_ERROR);
+	}
+
+	/** @return array{0: list<string>, 1: list<string>, 2: list<string>} columns, binary columns, primary key */
+	private function describe(\Doctrine\DBAL\Schema\Table $table): array {
 		$columns = array_values(array_map(fn ($c) => $c->getName(), $table->getColumns()));
 		$binary = [];
 		foreach ($table->getColumns() as $c) {
@@ -156,25 +216,34 @@ final class DbDumper {
 				$binary[] = $c->getName();
 			}
 		}
-		$pk = $table->getPrimaryKey()?->getColumns() ?? [];
+		return [$columns, $binary, $table->getPrimaryKey()?->getColumns() ?? []];
-		yield 'header' => json_encode(['table' => $table->getName(), 'columns' => array_values($columns), 'binary' => $binary, 'pk' => $pk], JSON_THROW_ON_ERROR);
+	}
 
+	/**
+	 * Rows in primary-key order, after the key $after (resume), as [key, JSON line].
+	 *
+	 * @return \Generator<array{0: list<mixed>|null, 1: string}>
+	 */
+	private function rowLines(\Doctrine\DBAL\Schema\Table $table, ?array $after = null): \Generator {
+		[$columns, $binary, $pk] = $this->describe($table);
 		$binaryFlip = array_flip($binary);
 		$q = fn (string $c) => $this->db->quoteIdentifier($c);
 		$select = 'SELECT ' . implode(', ', array_map($q, $columns)) . ' FROM ' . $q($table->getName());
-
 		if ($pk === []) {
-			// Nextcloud requires primary keys; small odd tables are read in one query.
+			// Nextcloud requires primary keys; small odd tables are read in one query (not resumable).
 			$count = (int)$this->db->fetchOne('SELECT COUNT(*) FROM ' . $q($table->getName()));
 			if ($count > self::MAX_ROWS_WITHOUT_PK) {
 				throw new \RuntimeException("Table {$table->getName()} has no primary key and $count rows; cannot dump it with bounded memory");
 			}
 			$batches = [$this->db->fetchAllNumeric($select)];
+			$pkIdx = [];
 		} else {
-			$batches = $this->keysetBatches($select, $pk, $columns);
+			$batches = $this->keysetBatches($select, $pk, $columns, $after);
+			$pkIdx = array_map(fn ($c) => array_search($c, $columns, true), $pk);
 		}
 		foreach ($batches as $rows) {
 			foreach ($rows as $row) {
+				$key = $pkIdx === [] ? null : array_map(fn ($i) => $row[$i], $pkIdx);
 				foreach ($columns as $i => $col) {
 					if (is_resource($row[$i])) {
 						$row[$i] = stream_get_contents($row[$i]);
@@ -189,23 +258,23 @@ final class DbDumper {
 						$row[$i] = (string)(is_bool($row[$i]) ? (int)$row[$i] : $row[$i]);
 					}
 				}
-				yield 'row' => json_encode($row, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_THROW_ON_ERROR);
+				yield [$key, json_encode($row, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_THROW_ON_ERROR)];
 			}
 		}
 	}
 
 	/** @return \Generator<list<list<mixed>>> */
-	private function keysetBatches(string $select, array $pk, array $columns): \Generator {
+	private function keysetBatches(string $select, array $pk, array $columns, ?array $after): \Generator {
 		$q = fn (string $c) => $this->db->quoteIdentifier($c);
 		$order = ' ORDER BY ' . implode(', ', array_map($q, $pk));
-		$pkIdx = array_map(fn ($c) => array_search($c, $columns, true), $pk);
+		$cols = array_map(fn ($c) => $q($c), $pk);
-		$last = null;
+		$last = $after;
 		while (true) {
 			$sql = $select;
 			$params = [];
 			if ($last !== null) {
 				// Row-value comparison (a, b) > (?, ?), supported by PostgreSQL, MySQL/MariaDB and SQLite.
-				$sql .= ' WHERE (' . implode(', ', array_map($q, $pk)) . ') > (' . implode(', ', array_fill(0, count($pk), '?')) . ')';
+				$sql .= ' WHERE (' . implode(', ', $cols) . ') > (' . implode(', ', array_fill(0, count($pk), '?')) . ')';
 				$params = $last;
 			}
 			$rows = $this->db->fetchAllNumeric($sql . $order . ' LIMIT ' . self::BATCH, $params);
@@ -213,22 +282,29 @@ final class DbDumper {
 				return;
 			}
 			yield $rows;
-			$end = end($rows);
-			$last = array_map(fn ($i) => $end[$i], $pkIdx);
 			if (count($rows) < self::BATCH) {
 				return;
 			}
+			$end = end($rows);
+			$last = array_map(fn ($c) => $end[array_search($c, $columns, true)], $pk);
 		}
 	}
 
-	private function insertBatch(string $table, array $rows, array $binary): int {
+	/** One INSERT with several rows (portable multi-row VALUES). */
+	private function insertBatch(string $table, array $columns, array $rows, array $binary): int {
+		$q = fn (string $c) => $this->db->quoteIdentifier($c);
+		$placeholders = '(' . implode(', ', array_fill(0, count($columns), '?')) . ')';
+		$sql = 'INSERT INTO ' . $q($table) . ' (' . implode(', ', array_map($q, $columns)) . ') VALUES '
+			. implode(', ', array_fill(0, count($rows), $placeholders));
+		$params = [];
+		$types = [];
 		foreach ($rows as $row) {
-			$types = [];
+			foreach ($columns as $i => $col) {
-			foreach ($row as $col => $_) {
+				$params[] = $row[$i];
-				$types[$col] = isset($binary[$col]) ? \Doctrine\DBAL\ParameterType::LARGE_OBJECT : \Doctrine\DBAL\ParameterType::STRING;
+				$types[] = isset($binary[$col]) ? \Doctrine\DBAL\ParameterType::LARGE_OBJECT : ($row[$i] === null ? \Doctrine\DBAL\ParameterType::NULL : \Doctrine\DBAL\ParameterType::STRING);
 			}
-			$this->db->insert($this->db->quoteIdentifier($table), array_combine(array_map(fn ($c) => $this->db->quoteIdentifier($c), array_keys($row)), $row), array_values($types));
 		}
+		$this->db->executeStatement($sql, $params, $types);
 		return count($rows);
 	}
 

lib/Db/DbIndexCache.php

@@ -11,7 +11,7 @@ use OCA\NgBackup\Repository\IIndexCache;
 use OCP\DB\Exception;
 use OCP\IDBConnection;
 
-class DbIndexCache implements IIndexCache {
+final class DbIndexCache implements IIndexCache {
 	public function __construct(
 		private IDBConnection $db,
 	) {

lib/Db/Run.php

@@ -33,7 +33,7 @@ use OCP\AppFramework\Db\Entity;
  * @method int|null getFinishedAt()
  * @method void setFinishedAt(?int $v)
  */
-class Run extends Entity {
+final class Run extends Entity {
 	public const RUNNING = 'running';
 	public const DONE = 'done';
 	public const FAILED = 'failed';

lib/Db/RunMapper.php

@@ -12,7 +12,7 @@ use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
 
 /** @template-extends QBMapper<Run> */
-class RunMapper extends QBMapper {
+final class RunMapper extends QBMapper {
 	public function __construct(IDBConnection $db) {
 		parent::__construct($db, 'ngb_runs', Run::class);
 	}

lib/Db/Snapshot.php

@@ -25,7 +25,7 @@ use OCP\AppFramework\Db\Entity;
  * @method int|null getBytes()
  * @method void setBytes(?int $v)
  */
-class Snapshot extends Entity {
+final class Snapshot extends Entity {
 	protected int $targetId = 0;
 	protected string $snapshotId = '';
 	protected string $kind = '';

lib/Db/SnapshotMapper.php

@@ -12,7 +12,7 @@ use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
 
 /** @template-extends QBMapper<Snapshot> */
-class SnapshotMapper extends QBMapper {
+final class SnapshotMapper extends QBMapper {
 	public function __construct(IDBConnection $db) {
 		parent::__construct($db, 'ngb_snapshots', Snapshot::class);
 	}

lib/Db/Target.php

@@ -22,10 +22,14 @@ use OCP\AppFramework\Db\Entity;
  * @method void setBasePath(string $v)
  * @method string|null getRepositoryId()
  * @method void setRepositoryId(?string $v)
+ * @method bool|null getAppendOnly()
+ * @method void setAppendOnly(bool $v)
+ * @method int|null getMaxBytes()
+ * @method void setMaxBytes(?int $v)
  * @method int getCreatedAt()
  * @method void setCreatedAt(int $v)
  */
-class Target extends Entity {
+final class Target extends Entity {
 	protected string $name = '';
 	protected string $backend = '';
 	protected string $auth = '';
@@ -33,8 +37,12 @@ class Target extends Entity {
 	protected string $basePath = '';
 	protected ?string $repositoryId = null;
 	protected int $createdAt = 0;
+	protected ?bool $appendOnly = null;
+	protected ?int $maxBytes = null;
 
 	public function __construct() {
 		$this->addType('createdAt', 'integer');
+		$this->addType('appendOnly', 'boolean');
+		$this->addType('maxBytes', 'integer');
 	}
 }

lib/Db/TargetMapper.php

@@ -11,7 +11,7 @@ use OCP\AppFramework\Db\QBMapper;
 use OCP\IDBConnection;
 
 /** @template-extends QBMapper<Target> */
-class TargetMapper extends QBMapper {
+final class TargetMapper extends QBMapper {
 	public function __construct(IDBConnection $db) {
 		parent::__construct($db, 'ngb_targets', Target::class);
 	}

lib/Migration/Version000001Date20261002000000.php

@@ -13,7 +13,7 @@ use OCP\DB\Types;
 use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
-class Version000001Date20261002000000 extends SimpleMigrationStep {
+final class Version000001Date20261002000000 extends SimpleMigrationStep {
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();

lib/Migration/Version000002Date20261002010000.php

@@ -14,7 +14,7 @@ use OCP\Migration\IOutput;
 use OCP\Migration\SimpleMigrationStep;
 
 /** Local cache of the per-pack index files, so opening a repository does not download them all. */
-class Version000002Date20261002010000 extends SimpleMigrationStep {
+final class Version000002Date20261002010000 extends SimpleMigrationStep {
 	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
 		/** @var ISchemaWrapper $schema */
 		$schema = $schemaClosure();

lib/Migration/Version000003Date20261002020000.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+/** Append-only locations: NG Backup never deletes anything there (cleanup by the location's own lifecycle rules). */
+final class Version000003Date20261002020000 extends SimpleMigrationStep {
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+		$t = $schema->getTable('ngb_targets');
+		if (!$t->hasColumn('append_only')) {
+			$t->addColumn('append_only', Types::BOOLEAN, ['notnull' => false, 'default' => false]);
+			return $schema;
+		}
+		return null;
+	}
+}

lib/Migration/Version000004Date20261002030000.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+/** Optional size limit per location (cost control; S3 has no bucket quota). */
+final class Version000004Date20261002030000 extends SimpleMigrationStep {
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+		$t = $schema->getTable('ngb_targets');
+		if (!$t->hasColumn('max_bytes')) {
+			$t->addColumn('max_bytes', Types::BIGINT, ['notnull' => false, 'unsigned' => true]);
+			return $schema;
+		}
+		return null;
+	}
+}

lib/Migration/Version000005Date20261002040000.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+/** Leases with an expiry: a killed process cannot block a location for longer than its lease. */
+final class Version000005Date20261002040000 extends SimpleMigrationStep {
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+		if ($schema->hasTable('ngb_leases')) {
+			return null;
+		}
+		$t = $schema->createTable('ngb_leases');
+		$t->addColumn('id', Types::STRING, ['notnull' => true, 'length' => 32]);
+		$t->addColumn('name', Types::STRING, ['notnull' => true, 'length' => 128]);
+		$t->addColumn('mode', Types::STRING, ['notnull' => true, 'length' => 1]);
+		$t->addColumn('expires_at', Types::BIGINT, ['notnull' => true, 'unsigned' => true]);
+		$t->setPrimaryKey(['id']);
+		$t->addIndex(['name'], 'ngb_leases_name');
+		return $schema;
+	}
+}

lib/Notification/Notifier.php

@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Notification;
+
+use OCA\NgBackup\AppInfo\Application;
+use OCP\IURLGenerator;
+use OCP\L10N\IFactory;
+use OCP\Notification\INotification;
+use OCP\Notification\INotifier;
+use OCP\Notification\UnknownNotificationException;
+
+final class Notifier implements INotifier {
+	public function __construct(
+		private IFactory $l10n,
+		private IURLGenerator $url,
+	) {
+	}
+
+	public function getID(): string {
+		return Application::APP_ID;
+	}
+
+	public function getName(): string {
+		return $this->l10n->get(Application::APP_ID)->t('NG Backup');
+	}
+
+	public function prepare(INotification $notification, string $languageCode): INotification {
+		if ($notification->getApp() !== Application::APP_ID) {
+			throw new UnknownNotificationException();
+		}
+		$l = $this->l10n->get(Application::APP_ID, $languageCode);
+		$p = $notification->getSubjectParameters();
+		switch ($notification->getSubject()) {
+			case 'run_failed':
+				$notification->setParsedSubject($p['kind'] === 'restore'
+					? $l->t('Restore from %s failed', [$p['target']])
+					: $l->t('Backup to %s failed', [$p['target']]));
+				$notification->setParsedMessage((string)($p['error'] ?? ''));
+				break;
+			case 'quota_warning':
+				$notification->setParsedSubject($l->t('Backup location %1$s is at %2$s%% of its limit (%3$s of %4$s)', [$p['target'], $p['percent'], $p['used'], $p['limit']]));
+				$notification->setParsedMessage($l->t('Backups stop when the limit is reached. Raise the limit, or let the retention policy remove older backups.'));
+				break;
+			case 'backup_stale':
+				$notification->setParsedSubject($l->t('No successful backup to %1$s since %2$s', [$p['target'], $p['since']]));
+				$notification->setParsedMessage($l->t('Check the backup settings and the server log.'));
+				break;
+			case 'security_event':
+				$who = (string)($p['actor'] ?? '');
+				$notification->setParsedSubject(match ($p['event'] ?? '') {
+					'kit_downloaded' => $l->t('%s downloaded the backup recovery kit', [$who]),
+					'target_removed' => $l->t('%1$s removed backup location %2$s', [$who, $p['target'] ?? '']),
+					'append_only_off' => $l->t('%1$s turned off append-only for backup location %2$s', [$who, $p['target'] ?? '']),
+					'retention_changed' => $l->t('%1$s changed the backup retention to %2$s', [$who, $p['policy'] ?? '']),
+					'snapshots_forgotten' => $l->t('%1$s moved %2$s snapshots of %3$s to the trash; they are deleted permanently after %4$s unless restored', [$who, $p['count'] ?? '', $p['target'] ?? '', $p['until'] ?? '']),
+					'snapshot_untrashed' => $l->t('%1$s restored snapshot %2$s of %3$s from the trash', [$who, $p['snapshot'] ?? '', $p['target'] ?? '']),
+					'catalog_trusted' => $l->t('%1$s accepted an older state of backup location %2$s (catalog generation %3$s)', [$who, $p['target'] ?? '', $p['generation'] ?? '']),
+					'slot_added' => $l->t('%1$s added backup passphrase slot %2$s (%3$s); download and confirm the new recovery kit', [$who, $p['slot'] ?? '', $p['label'] ?? '']),
+					'slot_replaced' => $l->t('%1$s set a new passphrase for backup key slot %2$s (%3$s); download and confirm the new recovery kit', [$who, $p['slot'] ?? '', $p['label'] ?? '']),
+					'slot_removed' => $l->t('%1$s removed backup passphrase slot %2$s; download and confirm the new recovery kit', [$who, $p['slot'] ?? '']),
+					default => $l->t('NG Backup security event'),
+				});
+				$notification->setParsedMessage($l->t('If this was not you or another administrator, check who has admin access.'));
+				break;
+			default:
+				throw new UnknownNotificationException();
+		}
+		$notification->setLink($this->url->linkToRouteAbsolute('settings.AdminSettings.index', ['section' => 'ng_backup']));
+		$notification->setIcon($this->url->getAbsoluteURL($this->url->imagePath(Application::APP_ID, 'app-dark.svg')));
+		return $notification;
+	}
+}

lib/Repository/BlobIndex.php

@@ -45,8 +45,9 @@ final class BlobIndex {
 	 * and only the index files that are not cached yet are downloaded. Cached packs that no
 	 * longer exist on the backend are dropped from the cache.
 	 */
-	public function load(): void {
+	public function load(bool $verify = false): void {
-		$cached = $this->cache?->all($this->repositoryId) ?? [];
+		$this->blobs = [];
+		$cached = $verify ? [] : ($this->cache?->all($this->repositoryId) ?? []);
 		$present = [];
 		$this->downloaded = 0;
 		foreach ($this->backend->list('index') as $path) {
@@ -65,6 +66,20 @@ final class BlobIndex {
 				$this->blobs[$e['id']] = [$packId, $e['offset'], $e['length'], $e['raw'], $e['flags']];
 			}
 		}
+		if ($verify && $this->cache !== null) {
+			// Refresh the cache from what was just verified.
+			$this->cache->remove($this->repositoryId, array_keys($this->cache->all($this->repositoryId)));
+			foreach ($this->packs() as $packId => $_) {
+				$entries = [];
+				foreach ($this->blobs as $id => [$pack, $offset, $length, $raw, $flags]) {
+					if ($pack === $packId) {
+						$entries[] = ['id' => $id, 'offset' => $offset, 'length' => $length, 'raw' => $raw, 'flags' => $flags];
+					}
+				}
+				$this->cache->put($this->repositoryId, $packId, $entries);
+			}
+			return;
+		}
 		$stale = array_keys(array_diff_key($cached, $present));
 		if ($stale !== []) {
 			$this->cache?->remove($this->repositoryId, $stale);
@@ -104,6 +119,35 @@ final class BlobIndex {
 		}
 	}
 
+	/** @return array<string, list<array{id:string, offset:int, length:int}>> packId => blobs currently located in that pack */
+	public function packs(): array {
+		$packs = [];
+		foreach ($this->blobs as $id => [$pack, $offset, $length]) {
+			$packs[$pack][] = ['id' => $id, 'offset' => $offset, 'length' => $length];
+		}
+		return $packs;
+	}
+
+	/** Forget a pack: delete its index file and cache row. Blobs that now live elsewhere are kept. */
+	public function removePack(string $packId): void {
+		$this->backend->delete('index/' . $packId);
+		$this->cache?->remove($this->repositoryId, [$packId]);
+		foreach ($this->blobs as $id => $loc) {
+			if ($loc[0] === $packId) {
+				unset($this->blobs[$id]);
+			}
+		}
+	}
+
+	/** Bytes of all blobs in the index (encrypted size, i.e. what is stored in packs). */
+	public function storedBytes(): int {
+		$total = 0;
+		foreach ($this->blobs as [, , $length]) {
+			$total += $length;
+		}
+		return $total;
+	}
+
 	public function count(): int {
 		return count($this->blobs);
 	}

lib/Repository/Catalog.php

@@ -0,0 +1,129 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Repository;
+
+use OCA\NgBackup\Backend\IBackend;
+use OCA\NgBackup\Crypto\StreamCipher;
+
+/**
+ * Chained catalog of a repository's state, against rollback and hidden snapshots.
+ *
+ * Every change to the set of snapshots or trash entries writes catalog/<generation>: the
+ * encrypted list of snapshot and trash ids plus the hash of the previous generation. The server
+ * keeps the newest generation it has seen (ICatalogAnchor). On open, the newest catalog on the
+ * location must be at least the anchored generation and lead back to it through the chain;
+ * snapshots listed in the catalog must exist. Otherwise the location was rolled back or
+ * tampered with, and the repository is refused.
+ */
+final class Catalog {
+	private const KEEP = 200; // generations kept on the location (enough to verify long gaps)
+
+	public int $gen = 0;
+	/** @var array<string, true> */
+	public array $snapshots = [];
+	/** @var array<string, true> */
+	public array $trash = [];
+	public string $hash = '';
+
+	public function __construct(
+		private IBackend $backend,
+		private StreamCipher $cipher,
+		private string $repositoryId,
+		private ?ICatalogAnchor $anchor,
+	) {
+	}
+
+	/** Load and verify the newest catalog; create the first one for repositories that have none. */
+	public function load(callable $listSnapshots, callable $listTrash): void {
+		$gens = $this->generations();
+		if ($gens === []) {
+			// First use (new or pre-catalog repository): adopt the current state as generation 1.
+			$anchored = $this->anchor?->get($this->repositoryId);
+			if ($anchored !== null) {
+				throw new RepositoryException('The catalog of this repository has disappeared from the location (possible tampering)');
+			}
+			$this->snapshots = array_fill_keys($listSnapshots(), true);
+			$this->trash = array_fill_keys($listTrash(), true);
+			$this->write();
+			return;
+		}
+		$head = max($gens);
+		[$data, $hash] = $this->read($head);
+		$anchored = $this->anchor?->get($this->repositoryId);
+		if ($anchored !== null) {
+			if ($head < $anchored['gen']) {
+				throw new RepositoryException(sprintf('The location shows catalog generation %d, but this server has seen %d: the backups were rolled back', $head, $anchored['gen']));
+			}
+			// Walk back to the anchored generation, checking every link.
+			[$cur, $curHash] = [$data, $hash];
+			for ($g = $head; $g > $anchored['gen']; $g--) {
+				[$prev, $prevHash] = $this->read($g - 1);
+				if (!hash_equals($prevHash, (string)$cur['prev'])) {
+					throw new RepositoryException("Catalog chain broken at generation $g (possible tampering)");
+				}
+				[$cur, $curHash] = [$prev, $prevHash];
+			}
+			if (!hash_equals($anchored['hash'], $curHash)) {
+				throw new RepositoryException('The catalog does not match what this server saw before (possible tampering)');
+			}
+		}
+		$this->gen = $head;
+		$this->hash = $hash;
+		$this->snapshots = array_fill_keys($data['snapshots'], true);
+		$this->trash = array_fill_keys($data['trash'], true);
+		$this->anchor?->set($this->repositoryId, $this->gen, $this->hash);
+	}
+
+	/** Write the next generation after the in-memory state was changed. */
+	public function write(): void {
+		$next = $this->gen + 1;
+		$plain = json_encode(['repository' => $this->repositoryId, 'gen' => $next, 'time' => gmdate('c'), 'prev' => $this->hash,
+			'snapshots' => array_keys($this->snapshots), 'trash' => array_keys($this->trash)], JSON_THROW_ON_ERROR);
+		$encrypted = $this->cipher->encryptString($plain, $this->ad($next));
+		$stream = fopen('php://memory', 'w+b');
+		fwrite($stream, $encrypted);
+		rewind($stream);
+		$this->backend->put($this->path($next), $stream);
+		$this->gen = $next;
+		$this->hash = hash('sha256', $encrypted);
+		$this->anchor?->set($this->repositoryId, $this->gen, $this->hash);
+		$old = $next - self::KEEP;
+		if ($old > 0) {
+			$this->backend->delete($this->path($old));
+		}
+	}
+
+	/** @return array{0: array, 1: string} decoded catalog and the hash of its encrypted bytes */
+	private function read(int $gen): array {
+		try {
+			$fh = $this->backend->get($this->path($gen));
+		} catch (\Throwable) {
+			throw new RepositoryException("Catalog generation $gen is missing (possible tampering)");
+		}
+		$encrypted = (string)stream_get_contents($fh);
+		fclose($fh);
+		$data = json_decode($this->cipher->decryptString($encrypted, $this->ad($gen)), true, 512, JSON_THROW_ON_ERROR);
+		if (($data['repository'] ?? '') !== $this->repositoryId || ($data['gen'] ?? 0) !== $gen) {
+			throw new RepositoryException("Catalog generation $gen belongs to another repository or position");
+		}
+		return [$data, hash('sha256', $encrypted)];
+	}
+
+	/** @return list<int> */
+	private function generations(): array {
+		return array_map(fn ($p) => (int)basename($p), $this->backend->list('catalog'));
+	}
+
+	private function path(int $gen): string {
+		return sprintf('catalog/%010d', $gen);
+	}
+
+	private function ad(int $gen): string {
+		return 'catalog:' . $this->repositoryId . ':' . $gen;
+	}
+}

lib/Repository/ICatalogAnchor.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Repository;
+
+/**
+ * Where the server remembers the newest catalog generation it has seen for a repository, outside
+ * the (untrusted) location. A location that presents an older generation, or a chain that does
+ * not lead back to this anchor, is rolled back or tampered with.
+ */
+interface ICatalogAnchor {
+	/** @return array{gen:int, hash:string}|null */
+	public function get(string $repositoryId): ?array;
+
+	public function set(string $repositoryId, int $gen, string $hash): void;
+}

lib/Repository/PackWriter.php

@@ -32,6 +32,7 @@ final class PackWriter {
 		private StreamCipher $cipher,
 		private BlobIndex $index,
 		private int $targetSize = 32 * 1048576,
+		private ?int $maxBytes = null,
 	) {
 		$this->reset();
 	}
@@ -49,11 +50,27 @@ final class PackWriter {
 		return strlen($encrypted);
 	}
 
+	/** Add an already encrypted blob as-is (repacking: no decryption needed, the blob is bound to its id, not to a pack). */
+	public function addRaw(string $id, string $encrypted, int $rawLength, int $flags): void {
+		fwrite($this->buffer, $encrypted);
+		$this->entries[] = ['id' => $id, 'offset' => $this->size, 'length' => strlen($encrypted), 'raw' => $rawLength, 'flags' => $flags];
+		$this->size += strlen($encrypted);
+		if ($this->size >= $this->targetSize) {
+			$this->flush();
+		}
+	}
+
 	/** Upload the current pack (if any) and record it in the index. */
 	public function flush(): void {
 		if ($this->entries === []) {
 			return;
 		}
+		if ($this->maxBytes !== null && $this->index->storedBytes() + $this->size > $this->maxBytes) {
+			$this->index->dropPending(array_column($this->entries, 'id'));
+			$this->reset();
+			throw new QuotaExceededException(sprintf('Storage limit of this location reached (%.1f GiB): backup stopped',
+				$this->maxBytes / 1073741824));
+		}
 		$packId = bin2hex(random_bytes(16));
 		$header = $this->cipher->encryptString(json_encode($this->entries, JSON_THROW_ON_ERROR), 'pack-header:' . $packId);
 		fwrite($this->buffer, $header . pack('N', strlen($header)));

lib/Repository/QuotaExceededException.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Repository;
+
+final class QuotaExceededException extends RepositoryException {
+}

lib/Repository/Repository.php

@@ -32,6 +32,8 @@ final class Repository {
 	private StreamCipher $cipher;
 	private BlobIndex $index;
 	private ?PackWriter $runPacks = null;
+	private ?int $maxBytes = null;
+	private Catalog $catalog;
 
 	private function __construct(
 		private IBackend $backend,
@@ -52,7 +54,7 @@ final class Repository {
 	 * copy (KeyRing::wrap) stored in the repository config, so the repository can be opened
 	 * with the passphrase from the recovery kit even when the server is gone.
 	 */
-	public static function initWithKey(IBackend $backend, KeyRing $keys, array $wrappedKey): self {
+	public static function initWithKey(IBackend $backend, KeyRing $keys, array $wrappedKey, ?ICatalogAnchor $anchor = null): self {
 		if ($backend->exists('config')) {
 			throw new RepositoryException('A repository already exists at this location');
 		}
@@ -60,11 +62,13 @@ final class Repository {
 		$config = ['format' => self::FORMAT, 'id' => $id, 'created' => gmdate('c'), 'key' => $wrappedKey,
 			'check' => base64_encode((new StreamCipher($keys))->encryptString($id, 'config-check'))];
 		self::putString($backend, 'config', json_encode($config, JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR));
-		return new self($backend, $keys, $id);
+		$repo = new self($backend, $keys, $id);
+		$repo->loadCatalog($anchor);
+		return $repo;
 	}
 
 	/** Open with the master key the server holds (scheduled backups, no passphrase needed). */
-	public static function openWithKey(IBackend $backend, KeyRing $keys, ?IIndexCache $cache = null): self {
+	public static function openWithKey(IBackend $backend, KeyRing $keys, ?IIndexCache $cache = null, ?ICatalogAnchor $anchor = null): self {
 		$config = self::readConfig($backend);
 		try {
 			$ok = isset($config['check']) && (new StreamCipher($keys))->decryptString((string)base64_decode($config['check'], true), 'config-check') === $config['id'];
@@ -79,9 +83,31 @@ final class Repository {
 			$repo->index->setCache($cache, $config['id']);
 		}
 		$repo->index->load();
+		$repo->loadCatalog($anchor);
 		return $repo;
 	}
 
+	private function loadCatalog(?ICatalogAnchor $anchor): void {
+		$this->catalog = new Catalog($this->backend, $this->cipher, $this->repositoryId, $anchor);
+		$this->catalog->load(
+			fn () => array_map('basename', $this->backend->list('snapshots')),
+			fn () => array_map('basename', $this->backend->list('trash/info')));
+	}
+
+	/** Refuse uploads that would make the stored data larger than this (null = no limit). */
+	public function setMaxBytes(?int $maxBytes): void {
+		$this->maxBytes = $maxBytes;
+	}
+
+	public function storedBytes(): int {
+		return $this->index->storedBytes();
+	}
+
+	/** Current catalog generation (for status and tests). */
+	public function catalogGeneration(): int {
+		return $this->catalog->gen;
+	}
+
 	/** Index files downloaded when this repository was opened (0 when the local cache was complete). */
 	public function indexDownloads(): int {
 		return $this->index->downloaded;
@@ -101,14 +127,22 @@ final class Repository {
 		return $config;
 	}
 
+	/** Replace the passphrase-wrapped key slots in this repository's config (after a slot change). */
+	public function updateWrappedKey(array $wrappedKey): void {
+		$config = self::readConfig($this->backend);
+		$config['key'] = $wrappedKey;
+		self::putString($this->backend, 'config', json_encode($config, JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR));
+	}
+
 	public function id(): string {
 		return $this->repositoryId;
 	}
 
 	public static function open(IBackend $backend, #[\SensitiveParameter] string $passphrase): self {
 		$config = self::readConfig($backend);
-		$repo = new self($backend, KeyRing::unwrap($config['key'], $passphrase), $config['id']);
+		$repo = new self($backend, KeyRing::unwrapAny($config['key'], $passphrase), $config['id']);
 		$repo->index->load();
+		$repo->loadCatalog(null); // disaster recovery on a new server: no anchor yet, trust the newest valid chain
 		return $repo;
 	}
 
@@ -121,7 +155,7 @@ final class Repository {
 	public function backupDirectory(string $source, ?string $parent = null, string $label = ''): array {
 		$source = rtrim($source, '/');
 		$previous = $parent !== null ? $this->loadEntries($parent) : [];
-		$packs = new PackWriter($this->backend, $this->cipher, $this->index);
+		$packs = new PackWriter($this->backend, $this->cipher, $this->index, 32 * 1048576, $this->maxBytes);
 		$stats = ['files' => 0, 'reused' => 0, 'read' => 0, 'newBlobs' => 0, 'dupBlobs' => 0, 'uploaded' => 0];
 
 		$tree = fopen('php://temp/maxmemory:' . (4 * 1048576), 'w+b');
@@ -149,12 +183,17 @@ final class Repository {
 		rewind($encrypted);
 		$this->backend->put('snapshots/' . $snapshotId, $encrypted);
 		fclose($tree);
+		$this->catalog->snapshots[$snapshotId] = true;
+		$this->catalog->write();
 
 		return ['snapshot' => $snapshotId] + $stats;
 	}
 
 	/** Restore a snapshot (or only paths starting with $prefix) into a local directory. */
 	public function restore(string $snapshotId, string $target, string $prefix = ''): int {
+		if ($prefix !== '' && !self::isSafePath(rtrim($prefix, '/'))) {
+			throw new RepositoryException('Invalid path prefix');
+		}
 		$count = 0;
 		foreach ($this->streamEntries($snapshotId) as $entry) {
 			if ($prefix !== '' && !str_starts_with($entry['p'], $prefix)) {
@@ -164,10 +203,19 @@ final class Repository {
 			if (!is_dir(dirname($dest))) {
 				mkdir(dirname($dest), 0700, true);
 			}
+			// Defence in depth: the resolved directory must stay below the target (no symlink escapes).
+			$base = realpath($target);
+			$dir = realpath(dirname($dest));
+			if ($base === false || $dir === false || ($dir !== $base && !str_starts_with($dir, $base . '/')) || is_link($dest)) {
+				throw new RepositoryException('Refusing to write outside the restore directory: ' . $entry['p']);
+			}
 			// Write next to the destination and rename after all blobs verified: at most one file
 			// is ever present twice.
-			$tmp = $dest . '.ngb-restore';
+			$tmp = $dest . '.ngb-restore-' . bin2hex(random_bytes(6));
-			$out = fopen($tmp, 'wb');
+			$out = @fopen($tmp, 'xb'); // fails if anything (including a symlink) already exists there
+			if ($out === false) {
+				throw new RepositoryException('Cannot create a temporary file for ' . $entry['p']);
+			}
 			foreach ($entry['b'] as $id) {
 				fwrite($out, $this->loadBlob($id));
 			}
@@ -188,7 +236,7 @@ final class Repository {
 	 * run is done, so the last pack is uploaded before anything references it.
 	 */
 	public function blobWriter(array &$stats): BlobWriter {
-		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index);
+		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index, 32 * 1048576, $this->maxBytes);
 		$packs = $this->runPacks;
 		return new BlobWriter(function (string $data) use ($packs, &$stats): string {
 			return $this->storeBlob($data, $packs, $stats);
@@ -220,7 +268,7 @@ final class Repository {
 
 	/** Store one blob of file data in the current run (deduplicated); returns its id. */
 	public function storeData(string $data, array &$stats): string {
-		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index);
+		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index, 32 * 1048576, $this->maxBytes);
 		return $this->storeBlob($data, $this->runPacks, $stats);
 	}
 
@@ -244,6 +292,8 @@ final class Repository {
 		fclose($tree);
 		rewind($encrypted);
 		$this->backend->put('snapshots/' . $snapshotId, $encrypted);
+		$this->catalog->snapshots[$snapshotId] = true;
+		$this->catalog->write();
 	}
 
 	/** @return array<string, array{s:int, m:int, b:list<string>}> */
@@ -261,6 +311,19 @@ final class Repository {
 		}
 	}
 
+	/** Relative path of non-empty segments, without ".", "..", NUL, backslash or control characters. */
+	public static function isSafePath(string $path): bool {
+		if ($path === '' || str_starts_with($path, '/') || preg_match('/[\x00-\x1f\\\\]/', $path)) {
+			return false;
+		}
+		foreach (explode('/', $path) as $segment) {
+			if ($segment === '' || $segment === '.' || $segment === '..') {
+				return false;
+			}
+		}
+		return true;
+	}
+
 	/** Small encrypted objects (manifests). */
 	public function putObject(string $path, string $data): void {
 		self::putString($this->backend, $path, $this->cipher->encryptString($data, 'object:' . $path));
@@ -273,9 +336,200 @@ final class Repository {
 		return $data;
 	}
 
-	/** @return list<string> */
+	/**
+	 * Move a snapshot (and its database dump) to the trash on the location. Its data stays in
+	 * use until purgeTrash() removes it after the deletion delay, so a malicious or mistaken
+	 * cleanup can be undone with untrash() within that time.
+	 */
+	public function forget(string $snapshotId, string $by = ''): void {
+		$meta = $this->snapshotMeta($snapshotId);
+		$dbInTrash = null;
+		if (isset($meta['db']) && is_string($meta['db']) && $this->backend->exists($meta['db'])) {
+			// Its encryption is bound to its path (object:db/...), which changes on a move, so it
+			// must be decrypted and re-encrypted under the new path, not moved as raw bytes.
+			$dbInTrash = 'trash/' . $meta['db'];
+			$this->putObject($dbInTrash, $this->getObject($meta['db']));
+			$this->backend->delete($meta['db']);
+		}
+		// The snapshot object is bound to its id (not its path), so it can be moved as raw bytes.
+		$this->backend->move('snapshots/' . $snapshotId, 'trash/snapshots/' . $snapshotId);
+		$this->putObject('trash/info/' . $snapshotId, json_encode(['forgottenAt' => time(), 'by' => $by, 'db' => $meta['db'] ?? null,
+			'dbInTrash' => $dbInTrash, 'time' => $meta['time'] ?? null, 'label' => $meta['label'] ?? ''], JSON_THROW_ON_ERROR));
+		unset($this->catalog->snapshots[$snapshotId]);
+		$this->catalog->trash[$snapshotId] = true;
+		$this->catalog->write();
+	}
+
+	/** Undo forget(): move a snapshot back from the trash. */
+	public function untrash(string $snapshotId): void {
+		$info = $this->trashInfo($snapshotId);
+		if ($info['dbInTrash'] !== null && $this->backend->exists($info['dbInTrash'])) {
+			$this->putObject($info['db'], $this->getObject($info['dbInTrash']));
+			$this->backend->delete($info['dbInTrash']);
+		}
+		$this->backend->move('trash/snapshots/' . $snapshotId, 'snapshots/' . $snapshotId);
+		$this->catalog->snapshots[$snapshotId] = true;
+		unset($this->catalog->trash[$snapshotId]);
+		$this->catalog->write();
+		$this->backend->delete('trash/info/' . $snapshotId);
+	}
+
+	/** @return array<string, array{forgottenAt:int, by:string, db:?string, dbInTrash:?string, time:?string, label:string}> */
+	public function trash(): array {
+		$out = [];
+		foreach (array_keys($this->catalog->trash) as $id) {
+			try {
+				$out[$id] = $this->trashInfo($id);
+			} catch (\Throwable) {
+				throw new RepositoryException("Trash entry $id listed in the catalog is missing on the location (possible tampering)");
+			}
+		}
+		return $out;
+	}
+
+	/** Permanently delete trash entries older than $delaySeconds. @return list<string> purged snapshot ids */
+	public function purgeTrash(int $delaySeconds): array {
+		$purged = [];
+		foreach ($this->trash() as $id => $info) {
+			if (time() - $info['forgottenAt'] < $delaySeconds) {
+				continue;
+			}
+			if ($info['dbInTrash'] !== null) {
+				$this->backend->delete($info['dbInTrash']);
+			}
+			$this->backend->delete('trash/snapshots/' . $id);
+			$this->backend->delete('trash/info/' . $id);
+			unset($this->catalog->trash[$id]);
+			$purged[] = $id;
+		}
+		if ($purged !== []) {
+			$this->catalog->write();
+		}
+		return $purged;
+	}
+
+	private function trashInfo(string $snapshotId): array {
+		return json_decode($this->getObject('trash/info/' . $snapshotId), true, 512, JSON_THROW_ON_ERROR);
+	}
+
+	/**
+	 * Delete packs no snapshot or user export uses any more, and repack packs where more than
+	 * $repackThreshold of the bytes are unused. Must not run while a backup to this repository
+	 * is in progress (its blobs are not referenced by a snapshot yet); callers hold the lock.
+	 *
+	 * @return array{packs:int, deleted:int, repacked:int, freedBytes:int, keptBlobs:int, unusedBlobs:int}
+	 */
+	public function prune(bool $dryRun = false, float $repackThreshold = 0.5, array $ignoreSnapshots = []): array {
+		// Deleting is decided on the authenticated index files on the location, never on the local cache.
+		$this->index->load(true);
+		$used = [];
+		$ignore = array_flip($ignoreSnapshots); // e.g. snapshots a dry run would forget first
+		foreach ($this->listSnapshots() as $sid) {
+			if (isset($ignore[$sid])) {
+				continue;
+			}
+			foreach ($this->streamEntries($sid) as $e) {
+				foreach ($e['b'] as $b) {
+					$used[$b] = true;
+				}
+			}
+			$meta = $this->snapshotMeta($sid);
+			if (isset($meta['db']) && $this->backend->exists($meta['db'])) {
+				foreach (json_decode($this->getObject($meta['db']), true, 512, JSON_THROW_ON_ERROR)['tables'] as $t) {
+					foreach ($t['blobs'] as $b) {
+						$used[$b] = true;
+					}
+				}
+			}
+		}
+		// Snapshots in the trash keep their data until purgeTrash() removed them.
+		foreach ($this->trash() as $sid => $info) {
+			foreach ($this->streamEntries($sid, 'trash/snapshots/') as $e) {
+				foreach ($e['b'] as $b) {
+					$used[$b] = true;
+				}
+			}
+			if ($info['dbInTrash'] !== null && $this->backend->exists($info['dbInTrash'])) {
+				foreach (json_decode($this->getObject($info['dbInTrash']), true, 512, JSON_THROW_ON_ERROR)['tables'] as $t) {
+					foreach ($t['blobs'] as $b) {
+						$used[$b] = true;
+					}
+				}
+			}
+		}
+		foreach ($this->backend->list('users') as $path) {
+			foreach (json_decode($this->getObject($path), true, 512, JSON_THROW_ON_ERROR)['entries'] as $e) {
+				foreach ($e['b'] ?? [] as $b) {
+					$used[$b] = true;
+				}
+			}
+		}
+
+		$stats = ['packs' => 0, 'deleted' => 0, 'repacked' => 0, 'freedBytes' => 0, 'keptBlobs' => count($used), 'unusedBlobs' => 0];
+		$packs = $this->index->packs();
+		$stats['packs'] = count($packs);
+		$writer = null;
+		$toRemove = [];
+		foreach ($packs as $packId => $blobs) {
+			$total = 0;
+			$unused = 0;
+			foreach ($blobs as $b) {
+				$total += $b['length'];
+				if (!isset($used[$b['id']])) {
+					$unused += $b['length'];
+					$stats['unusedBlobs']++;
+				}
+			}
+			if ($unused === 0 || ($unused < $total && $unused / $total <= $repackThreshold)) {
+				continue;
+			}
+			$stats['freedBytes'] += $unused;
+			if ($unused === $total) {
+				$stats['deleted']++;
+			} else {
+				$stats['repacked']++;
+				if (!$dryRun) {
+					// No size limit here: repacking is how space is freed.
+					$writer ??= new PackWriter($this->backend, $this->cipher, $this->index);
+					$path = 'packs/' . substr($packId, 0, 2) . '/' . $packId;
+					foreach ($blobs as $b) {
+						if (isset($used[$b['id']])) {
+							[, , , $raw, $flags] = $this->index->get($b['id']);
+							$writer->addRaw($b['id'], $this->backend->getRange($path, $b['offset'], $b['length']), $raw, $flags);
+						}
+					}
+				}
+			}
+			$toRemove[] = $packId;
+		}
+		if ($dryRun) {
+			return $stats;
+		}
+		// New packs and their index entries are durable before any old pack is removed.
+		$writer?->flush();
+		foreach ($toRemove as $packId) {
+			$this->index->removePack($packId);
+			$this->backend->delete('packs/' . substr($packId, 0, 2) . '/' . $packId);
+		}
+		return $stats;
+	}
+
+	/**
+	 * Snapshots according to the verified catalog. A snapshot the catalog lists but the location
+	 * no longer has means it was deleted or hidden behind NG Backup's back.
+	 *
+	 * @return list<string>
+	 */
 	public function listSnapshots(): array {
-		return array_map('basename', $this->backend->list('snapshots'));
+		$present = array_flip(array_map('basename', $this->backend->list('snapshots')));
+		$listed = array_keys($this->catalog->snapshots);
+		foreach ($listed as $id) {
+			if (!isset($present[$id])) {
+				throw new RepositoryException("Snapshot $id is missing on the location (deleted or hidden outside NG Backup)");
+			}
+		}
+		sort($listed);
+		return $listed;
 	}
 
 	public function blobCount(): int {
@@ -368,15 +622,20 @@ final class Repository {
 	}
 
 	/** @return \Generator<array{p:string, s:int, m:int, b:list<string>}> */
-	private function streamEntries(string $snapshotId): \Generator {
+	private function streamEntries(string $snapshotId, string $dir = 'snapshots/'): \Generator {
 		$plain = fopen('php://temp/maxmemory:' . (4 * 1048576), 'w+b');
-		$fh = $this->backend->get('snapshots/' . $snapshotId);
+		$fh = $this->backend->get($dir . $snapshotId);
 		$this->cipher->decrypt($fh, $plain, 'snapshot:' . $snapshotId);
 		fclose($fh);
 		rewind($plain);
 		fgets($plain); // meta line
 		while (($line = fgets($plain)) !== false) {
-			yield json_decode($line, true, 512, JSON_THROW_ON_ERROR);
+			$entry = json_decode($line, true, 512, JSON_THROW_ON_ERROR);
+			if (!is_array($entry) || !is_string($entry['p'] ?? null) || !self::isSafePath($entry['p'])
+				|| !is_int($entry['s'] ?? null) || !is_array($entry['b'] ?? null)) {
+				throw new RepositoryException('Invalid entry in snapshot ' . $snapshotId);
+			}
+			yield $entry;
 		}
 		fclose($plain);
 	}

lib/Service/AlertService.php

@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Service;
+
+use OCA\NgBackup\AppInfo\Application;
+use OCA\NgBackup\Db\Run;
+use OCA\NgBackup\Db\RunMapper;
+use OCA\NgBackup\Db\Target;
+use OCP\IGroupManager;
+use OCP\Notification\IManager;
+
+/** Notifies administrators about failed runs and locations without a recent successful backup. */
+final class AlertService {
+	public const STALE_AFTER = 2 * 86400;
+
+	public function __construct(
+		private IManager $notifications,
+		private IGroupManager $groups,
+		private RunMapper $runs,
+		private \OCP\IAppConfig $appConfig,
+		private \OCP\EventDispatcher\IEventDispatcher $events,
+		private \OCP\IUserSession $session,
+	) {
+	}
+
+	/**
+	 * Security-relevant change (recovery kit downloaded, location removed, append-only off,
+	 * retention changed, snapshots forgotten): written to the audit log (admin_audit) and sent
+	 * to every administrator, so a single compromised admin account cannot do it unnoticed.
+	 *
+	 * @param array<string, string> $params
+	 */
+	public function actor(): string {
+		return $this->session->getUser()?->getUID() ?? (PHP_SAPI === 'cli' ? 'occ' : 'unknown');
+	}
+
+	public function securityEvent(string $event, array $params = [], bool $notify = true): void {
+		$actor = $this->actor();
+		$params = ['actor' => $actor] + $params;
+		$this->events->dispatchTyped(new \OCP\Log\Audit\CriticalActionPerformedEvent(
+			'NG Backup: %s by %s ' . json_encode(array_diff_key($params, ['actor' => 1]), JSON_UNESCAPED_SLASHES), ['event' => $event, 'actor' => $actor]));
+		if ($notify) {
+			$this->notifyAdmins('security_event', $event . '-' . time(), ['event' => $event] + $params);
+		}
+	}
+
+	public function runFailed(Run $run, string $targetName): void {
+		$this->notifyAdmins('run_failed', 'run-' . $run->getId(),
+			['kind' => $run->getKind(), 'target' => $targetName, 'error' => mb_strimwidth((string)$run->getError(), 0, 300, '…')]);
+	}
+
+	/**
+	 * Remember how much is stored on a location (for the settings page) and warn administrators
+	 * once a day when it is at 80% of its limit or more.
+	 */
+	public function storedBytes(Target $target, int $bytes): void {
+		$this->appConfig->setValueString(Application::APP_ID, 'stored_' . $target->getId(), (string)$bytes);
+		$limit = $target->getMaxBytes();
+		if ($limit === null || $limit <= 0 || $bytes < 0.8 * $limit) {
+			return;
+		}
+		$key = 'quota_notified_' . $target->getId();
+		if ($this->appConfig->getValueString(Application::APP_ID, $key, '') === date('Y-m-d')) {
+			return;
+		}
+		$this->appConfig->setValueString(Application::APP_ID, $key, date('Y-m-d'));
+		$this->notifyAdmins('quota_warning', 'quota-' . $target->getId() . '-' . date('Y-m-d'), [
+			'target' => $target->getName(), 'percent' => (string)round($bytes / $limit * 100),
+			'used' => self::gib($bytes), 'limit' => self::gib($limit)]);
+	}
+
+	private static function gib(int $bytes): string {
+		$g = $bytes / 1073741824;
+		return sprintf($g < 10 ? '%.2f GiB' : '%.1f GiB', $g);
+	}
+
+	public function lastStoredBytes(Target $target): ?int {
+		$v = $this->appConfig->getValueString(Application::APP_ID, 'stored_' . $target->getId(), '');
+		return $v === '' ? null : (int)$v;
+	}
+
+	/** At most one notification per location per day. */
+	public function checkStale(Target $target): void {
+		$last = $this->runs->lastFinished($target->getId(), BackupService::KIND_FULL);
+		$lastTime = $last?->getFinishedAt() ?? $target->getCreatedAt();
+		if (time() - $lastTime < self::STALE_AFTER || $this->runs->findRunning($target->getId(), BackupService::KIND_FULL) !== []) {
+			return;
+		}
+		$key = 'stale_notified_' . $target->getId();
+		if ($this->appConfig->getValueString(Application::APP_ID, $key, '') === date('Y-m-d')) {
+			return;
+		}
+		$this->appConfig->setValueString(Application::APP_ID, $key, date('Y-m-d'));
+		$this->notifyAdmins('backup_stale', 'stale-' . $target->getId() . '-' . date('Y-m-d'),
+			['target' => $target->getName(), 'since' => $last ? date('Y-m-d H:i', $lastTime) : 'never']);
+	}
+
+	private function notifyAdmins(string $subject, string $objectId, array $params): void {
+		foreach ($this->groups->get('admin')?->getUsers() ?? [] as $admin) {
+			$n = $this->notifications->createNotification();
+			$n->setApp(Application::APP_ID)
+				->setUser($admin->getUID())
+				->setDateTime(new \DateTime())
+				->setObject($subject, $objectId)
+				->setSubject($subject, $params);
+			$this->notifications->notify($n);
+		}
+	}
+}

lib/Service/BackupService.php

@@ -28,7 +28,7 @@ use Psr\Log\LoggerInterface;
  * Excluded by default: previews, log files, the updater's backups and each user's cache and
  * temporary uploads (all regenerable or temporary).
  */
-class BackupService {
+final class BackupService {
 	public const KIND_FULL = 'full';
 
 	public function __construct(
@@ -41,16 +41,33 @@ class BackupService {
 		private IAppManager $appManager,
 		private ILockingProvider $locking,
 		private LoggerInterface $logger,
+		private AlertService $alerts,
+		private LeaseService $leases,
 	) {
 	}
 
 	public function start(Target $target, string $label = ''): Run {
-		if ($this->keys->recoveryKitConfirmation() === null) {
+		if (!$this->keys->everConfirmed()) {
 			throw new \RuntimeException('Confirm the recovery kit first (occ backup:key:confirm)');
 		}
 		if ($this->config->getSystemValue('objectstore', null) !== null) {
 			throw new \RuntimeException('Object storage as primary storage is not supported yet');
 		}
+		// Check and create the run under the location's exclusive lock, so a cleanup cannot start
+		// in between (it takes the same lock and refuses while a run exists).
+		// A run that is already in progress is simply continued; no lease needed for that.
+		$running = $this->runs->findRunning($target->getId(), self::KIND_FULL);
+		if ($running !== []) {
+			return $running[0];
+		}
+		try {
+			return $this->leases->with(PruneService::lockKey($target), LeaseService::EXCLUSIVE, 60, fn () => $this->createRun($target, $label));
+		} catch (LockedException) {
+			throw new \RuntimeException('A cleanup or another start for ' . $target->getName() . ' is running; try again later');
+		}
+	}
+
+	private function createRun(Target $target, string $label): Run {
 		$running = $this->runs->findRunning($target->getId(), self::KIND_FULL);
 		if ($running !== []) {
 			return $running[0];
@@ -86,10 +103,18 @@ class BackupService {
 	 * run locked and returns immediately.
 	 */
 	public function step(Run $run, float $deadline): Run {
-		$lockKey = 'ng_backup/run/' . $run->getId();
+		// Leases expire on their own: a step killed by a time limit or OOM blocks nothing for long.
+		$ttl = (int)min(3600, max(120, $deadline - microtime(true) + 120));
 		try {
-			$this->locking->acquireLock($lockKey, ILockingProvider::LOCK_EXCLUSIVE);
+			$runLease = $this->leases->acquire('run/' . $run->getId(), LeaseService::EXCLUSIVE, $ttl);
 		} catch (LockedException) {
+			return $run; // another process is doing this step
+		}
+		// Shared lease on the location while this step writes: a cleanup (exclusive) cannot run now.
+		try {
+			$targetLease = $this->leases->acquire('ng_backup/target/' . $run->getTargetId(), LeaseService::SHARED, $ttl);
+		} catch (LockedException) {
+			$this->leases->release($runLease);
 			return $run;
 		}
 		try {
@@ -102,18 +127,29 @@ class BackupService {
 			$state = json_decode($run->getState(), true, 512, JSON_THROW_ON_ERROR);
 
 			if ($run->getPhase() === 'db') {
-				@set_time_limit(0); // the dump is one transaction; it cannot be split across requests yet
+				$dumper = new DbDumper($this->db->getInner(), $this->config->getSystemValueString('dbtableprefix', 'oc_'));
-				$dbStats = [];
+				$dbStats = $state['dbStats'] ?? [];
-				$manifest = (new DbDumper($this->db->getInner(), $this->config->getSystemValueString('dbtableprefix', 'oc_')))->dump($repo, $dbStats);
+				// With system cron the whole dump usually fits in one step (one transaction, fully
-				$repo->putObject('db/' . $state['files']['snapshot'], json_encode($manifest, JSON_THROW_ON_ERROR));
+				// consistent). Under web cron it continues per step; the snapshot then says so.
-				$state['files']['meta']['db'] = 'db/' . $state['files']['snapshot'];
+				$dump = $dumper->dumpStep($repo, $state['dump'] ?? $dumper->startDump(), $deadline, $dbStats);
-				$state['dbStats'] = $dbStats + ['tables' => count($manifest['tables']),
+				$state['dbStats'] = $dbStats;
-					'rows' => array_sum(array_column($manifest['tables'], 'rows'))];
+				if ($dump['done']) {
-				$run->setPhase('files');
+					$manifest = $dumper->manifest($dump);
+					$repo->putObject('db/' . $state['files']['snapshot'], json_encode($manifest, JSON_THROW_ON_ERROR));
+					$state['files']['meta']['db'] = 'db/' . $state['files']['snapshot'];
+					$state['files']['meta']['dbConsistent'] = $manifest['consistent'];
+					$state['dbStats'] += ['tables' => count($manifest['tables']), 'rows' => array_sum(array_column($manifest['tables'], 'rows')),
+						'steps' => $dump['steps'], 'consistent' => $manifest['consistent']];
+					unset($state['dump']);
+					$run->setPhase('files');
+				} else {
+					$state['dump'] = $dump;
+				}
 			} else {
 				$state['files'] = BackupRun::step($repo, $state['files'], $deadline);
 				if ($state['files']['phase'] === 'done') {
 					$this->recordSnapshot($run, $state['files']);
+					$this->alerts->storedBytes($target, $repo->storedBytes());
 					$run->setStatus(Run::DONE);
 					$run->setPhase('done');
 					$run->setFinishedAt(time());
@@ -129,16 +165,29 @@ class BackupService {
 			$run->setError($e->getMessage());
 			$run->setFinishedAt(time());
 			$run->setUpdatedAt(time());
-			return $this->runs->update($run);
+			$run = $this->runs->update($run);
+			try {
+				$this->alerts->runFailed($run, isset($target) ? $target->getName() : '#' . $run->getTargetId());
+			} catch (\Throwable) {
+			}
+			return $run;
 		} finally {
-			$this->locking->releaseLock($lockKey, ILockingProvider::LOCK_EXCLUSIVE);
+			$this->leases->release($targetLease);
+			$this->leases->release($runLease);
 		}
 	}
 
 	/** Run to completion in this process (occ, system cron), reporting progress. */
 	public function runToCompletion(Run $run, ?callable $progress = null, float $stepSeconds = 30): Run {
 		while ($run->getStatus() === Run::RUNNING) {
+			$before = $run->getUpdatedAt();
 			$run = $this->step($run, microtime(true) + $stepSeconds);
+			if ($run->getStatus() === Run::RUNNING && $run->getUpdatedAt() === $before) {
+				// Step was not possible (another process holds the run, or a crashed step's lease has
+				// not expired yet): wait instead of spinning.
+				sleep(5);
+				$run = $this->runs->find($run->getId());
+			}
 			if ($progress !== null) {
 				$progress($run);
 			}
@@ -177,6 +226,15 @@ class BackupService {
 			'data/*/cache',
 			'data/*/uploads',
 		];
+		// SQLite: the database file is in the data directory; it is backed up by the logical dump,
+		// and copying the live file would give an inconsistent copy.
+		if ($this->config->getSystemValueString('dbtype') === 'sqlite3') {
+			$dbName = $this->config->getSystemValueString('dbname', 'owncloud');
+			$exclude[] = "data/$dbName.db";
+			$exclude[] = "data/$dbName.db-journal";
+			$exclude[] = "data/$dbName.db-wal";
+			$exclude[] = "data/$dbName.db-shm";
+		}
 		$logFile = $this->config->getSystemValueString('logfile', '');
 		if ($logFile !== '' && str_starts_with($logFile, $dataDir . '/')) {
 			$exclude[] = 'data/' . substr($logFile, strlen($dataDir) + 1);

lib/Service/KeyService.php

@@ -22,11 +22,15 @@ use OCP\Security\ICrypto;
  *   into the recovery kit, so backups can be restored on a fresh server with the passphrase.
  * - The admin must confirm having stored the recovery kit before the first backup runs.
  */
-class KeyService {
+final class KeyService {
 	private const KEY_MASTER = 'master_key';
 	private const KEY_WRAPPED = 'master_key_wrapped';
 	private const KEY_CONFIRMED = 'recovery_kit_confirmed';
 	private const KEY_FINGERPRINT = 'master_key_fingerprint';
+	private const KEY_DELETE_DELAY = 'delete_delay_days';
+	private const KEY_KIT_VERSION = 'recovery_kit_version';
+	private const KEY_KIT_CODE = 'recovery_kit_code';
+	public const DEFAULT_DELETE_DELAY = 7;
 
 	private ?KeyRing $cached = null;
 
@@ -40,7 +44,15 @@ class KeyService {
 		return $this->appConfig->getValueString(Application::APP_ID, self::KEY_MASTER, '', true) !== '';
 	}
 
-	public function initialize(#[\SensitiveParameter] string $passphrase): void {
+	/**
+	 * @param int $deleteDelayDays how long forgotten snapshots stay in the trash on the location
+	 *                             before their data is really deleted. Fixed here, at installation:
+	 *                             there is deliberately no way to change it later from NG Backup.
+	 */
+	public function initialize(#[\SensitiveParameter] string $passphrase, int $deleteDelayDays = self::DEFAULT_DELETE_DELAY, string $label = 'Slot 1'): void {
+		if ($deleteDelayDays < 1 || $deleteDelayDays > 365) {
+			throw new \InvalidArgumentException('The deletion delay must be between 1 and 365 days');
+		}
 		if ($this->isInitialized()) {
 			throw new \RuntimeException('A backup key already exists');
 		}
@@ -50,9 +62,11 @@ class KeyService {
 		$keys = KeyRing::generate();
 		$this->appConfig->setValueString(Application::APP_ID, self::KEY_MASTER,
 			$this->crypto->encrypt(base64_encode($keys->exportMasterKey())), true, true);
-		$this->appConfig->setValueString(Application::APP_ID, self::KEY_WRAPPED,
+		$this->cached = $keys;
-			json_encode($keys->wrap($passphrase), JSON_THROW_ON_ERROR), true, true);
+		$this->saveSlots([['slot' => 1, 'label' => self::cleanLabel($label), 'created' => time(), 'key' => $keys->wrap($passphrase)]]);
 		$this->appConfig->setValueString(Application::APP_ID, self::KEY_FINGERPRINT, $this->fingerprintOf($keys), true);
+		$this->appConfig->setValueInt(Application::APP_ID, self::KEY_DELETE_DELAY, $deleteDelayDays, true);
+		$this->appConfig->setValueInt(Application::APP_ID, self::KEY_KIT_VERSION, 1, true);
 		$this->appConfig->deleteKey(Application::APP_ID, self::KEY_CONFIRMED);
 		$this->cached = $keys;
 	}
@@ -68,9 +82,99 @@ class KeyService {
 		return $this->cached;
 	}
 
+	/** Deletion delay in days, fixed at installation (installations from before this setting get the default once). */
+	public function deleteDelayDays(): int {
+		$days = $this->appConfig->getValueInt(Application::APP_ID, self::KEY_DELETE_DELAY, 0, true);
+		if ($days === 0 && $this->isInitialized()) {
+			$days = self::DEFAULT_DELETE_DELAY;
+			$this->appConfig->setValueInt(Application::APP_ID, self::KEY_DELETE_DELAY, $days, true);
+		}
+		return $days;
+	}
+
+	public const MAX_SLOTS = 3;
+
+	/** @return list<array{slot:int, label:string, created:int}> passphrase slots, without key material */
+	public function slots(): array {
+		return array_map(fn ($s) => ['slot' => $s['slot'], 'label' => $s['label'], 'created' => $s['created']], $this->wrappedKey()['slots']);
+	}
+
+	/** Add a passphrase slot (e.g. one per person who must be able to restore). Returns the slot number. */
+	public function addSlot(#[\SensitiveParameter] string $passphrase, string $label): int {
+		self::checkPassphrase($passphrase);
+		$slots = $this->wrappedKey()['slots'];
+		if (count($slots) >= self::MAX_SLOTS) {
+			throw new \InvalidArgumentException('At most ' . self::MAX_SLOTS . ' passphrase slots');
+		}
+		$used = array_column($slots, 'slot');
+		$n = min(array_diff(range(1, self::MAX_SLOTS), $used));
+		$slots[] = ['slot' => $n, 'label' => self::cleanLabel($label), 'created' => time(), 'key' => $this->keyRing()->wrap($passphrase)];
+		usort($slots, fn ($a, $b) => $a['slot'] <=> $b['slot']);
+		$this->saveSlots($slots);
+		return $n;
+	}
+
+	/** New passphrase for a slot (e.g. its holder left). The master key and all backups stay the same. */
+	public function replaceSlot(int $slot, #[\SensitiveParameter] string $passphrase, ?string $label = null): void {
+		self::checkPassphrase($passphrase);
+		$slots = $this->wrappedKey()['slots'];
+		$found = false;
+		foreach ($slots as &$s) {
+			if ($s['slot'] === $slot) {
+				$s['key'] = $this->keyRing()->wrap($passphrase);
+				$s['created'] = time();
+				if ($label !== null) {
+					$s['label'] = self::cleanLabel($label);
+				}
+				$found = true;
+			}
+		}
+		unset($s);
+		if (!$found) {
+			throw new \InvalidArgumentException("There is no slot $slot");
+		}
+		$this->saveSlots($slots);
+	}
+
+	public function removeSlot(int $slot): void {
+		$slots = array_values(array_filter($this->wrappedKey()['slots'], fn ($s) => $s['slot'] !== $slot));
+		if (count($slots) === count($this->wrappedKey()['slots'])) {
+			throw new \InvalidArgumentException("There is no slot $slot");
+		}
+		if ($slots === []) {
+			throw new \InvalidArgumentException('The last passphrase slot cannot be removed');
+		}
+		$this->saveSlots($slots);
+	}
+
+	/** Every change to the slots asks for a new recovery kit (and its confirmation). */
+	private function saveSlots(array $slots): void {
+		$this->appConfig->setValueString(Application::APP_ID, self::KEY_WRAPPED, json_encode(['slots' => $slots], JSON_THROW_ON_ERROR), true, true);
+		$this->appConfig->setValueInt(Application::APP_ID, self::KEY_KIT_VERSION, $this->kitVersion() + 1, true);
+	}
+
+	private static function checkPassphrase(string $passphrase): void {
+		if (strlen($passphrase) < 12) {
+			throw new \InvalidArgumentException('The passphrase must be at least 12 characters');
+		}
+	}
+
+	private static function cleanLabel(string $label): string {
+		$label = trim(preg_replace('/[\x00-\x1f]/', '', $label) ?? '');
+		return mb_substr($label === '' ? 'Slot' : $label, 0, 64);
+	}
+
+	public function kitVersion(): int {
+		return $this->appConfig->getValueInt(Application::APP_ID, self::KEY_KIT_VERSION, 1, true);
+	}
+
 	/** Passphrase-wrapped copy of the master key (for repository configs and the recovery kit). */
 	public function wrappedKey(): array {
-		return json_decode($this->appConfig->getValueString(Application::APP_ID, self::KEY_WRAPPED, '{}', true), true, 512, JSON_THROW_ON_ERROR);
+		$data = json_decode($this->appConfig->getValueString(Application::APP_ID, self::KEY_WRAPPED, '{}', true), true, 512, JSON_THROW_ON_ERROR);
+		if (!isset($data['slots'])) {
+			$data = ['slots' => $data === [] ? [] : [['slot' => 1, 'label' => 'Slot 1', 'created' => 0, 'key' => $data]]];
+		}
+		return $data;
 	}
 
 	/** Short identifier of the key, shown in the UI and the kit (not secret). */
@@ -84,23 +188,68 @@ class KeyService {
 			'version' => 1,
 			'app' => 'NG Backup',
 			'fingerprint' => $this->fingerprint(),
+			'kit_version' => $this->kitVersion(),
+			'confirmation_code' => $this->kitCode(),
 			'created' => gmdate('c'),
 			'wrapped_key' => $this->wrappedKey(),
-			'instructions' => 'Keep this file and your passphrase safe, outside this server. To restore on a new server: install NG Backup, '
+			'slots' => $this->slots(),
-				. 'add the backup location, and enter this kit with your passphrase. Without both, the backups cannot be decrypted.',
+			'instructions' => 'Keep this file safe, outside this server. Any one of the passphrases of the slots listed here opens it. '
+				. 'To restore on a new server: install NG Backup, add the backup location and enter this kit with one passphrase. '
+				. 'Without the kit (or the location) and a passphrase, the backups cannot be decrypted.',
 		];
 	}
 
+	/**
+	 * Short code printed in the current kit file. Typing it back when confirming proves the
+	 * admin actually has the downloaded kit. A new code per kit version; the server only keeps
+	 * its own copy encrypted with the instance secret.
+	 */
+	private function kitCode(): string {
+		$stored = json_decode($this->appConfig->getValueString(Application::APP_ID, self::KEY_KIT_CODE, '{}', true), true) ?: [];
+		if (($stored['version'] ?? 0) === $this->kitVersion() && isset($stored['code'])) {
+			return $this->crypto->decrypt($stored['code']);
+		}
+		$alphabet = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789'; // no 0/O, 1/I
+		$code = '';
+		for ($i = 0; $i < 8; $i++) {
+			$code .= $alphabet[random_int(0, strlen($alphabet) - 1)];
+		}
+		$code = substr($code, 0, 4) . '-' . substr($code, 4);
+		$this->appConfig->setValueString(Application::APP_ID, self::KEY_KIT_CODE,
+			json_encode(['version' => $this->kitVersion(), 'code' => $this->crypto->encrypt($code)], JSON_THROW_ON_ERROR), true, true);
+		return $code;
+	}
+
+	public function checkKitCode(string $code): bool {
+		$stored = json_decode($this->appConfig->getValueString(Application::APP_ID, self::KEY_KIT_CODE, '{}', true), true) ?: [];
+		if (($stored['version'] ?? 0) !== $this->kitVersion() || !isset($stored['code'])) {
+			return false; // no kit downloaded for this version yet
+		}
+		$normalise = static fn (string $c) => strtoupper(preg_replace('/[^A-Za-z0-9]/', '', $c) ?? '');
+		return hash_equals($normalise($this->crypto->decrypt($stored['code'])), $normalise($code));
+	}
+
 	public function confirmRecoveryKit(string $uid): void {
 		$this->appConfig->setValueString(Application::APP_ID, self::KEY_CONFIRMED,
-			json_encode(['uid' => $uid, 'time' => time(), 'fingerprint' => $this->fingerprint()], JSON_THROW_ON_ERROR), true);
+			json_encode(['uid' => $uid, 'time' => time(), 'fingerprint' => $this->fingerprint(), 'kit_version' => $this->kitVersion()], JSON_THROW_ON_ERROR), true);
 	}
 
-	/** Confirmation for the current key, or null. */
+	/**
+	 * Whether a recovery kit for this key was ever confirmed (any passphrase version). Backups
+	 * keep running after a passphrase change, so changing it cannot be used to stop backups; the
+	 * missing re-confirmation is reported as an error in the admin overview instead.
+	 */
+	public function everConfirmed(): bool {
+		$raw = $this->appConfig->getValueString(Application::APP_ID, self::KEY_CONFIRMED, '', true);
+		$data = $raw === '' ? null : json_decode($raw, true);
+		return $data !== null && ($data['fingerprint'] ?? '') === $this->fingerprint();
+	}
+
+	/** Confirmation for the current key and kit version, or null. */
 	public function recoveryKitConfirmation(): ?array {
 		$raw = $this->appConfig->getValueString(Application::APP_ID, self::KEY_CONFIRMED, '', true);
 		$data = $raw === '' ? null : json_decode($raw, true);
-		return ($data !== null && ($data['fingerprint'] ?? '') === $this->fingerprint()) ? $data : null;
+		return ($data !== null && ($data['fingerprint'] ?? '') === $this->fingerprint() && ($data['kit_version'] ?? 1) === $this->kitVersion()) ? $data : null;
 	}
 
 	private function fingerprintOf(KeyRing $keys): string {

lib/Service/KeySlotService.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Service;
+
+/**
+ * Passphrase slots (like LUKS): up to three passphrases, each opening the same master key, so
+ * that one person leaving or dying does not lock the company out of its backups. Every change
+ * is written to all locations and announced to all administrators; a new recovery kit must be
+ * downloaded and confirmed afterwards (backups keep running meanwhile).
+ */
+final class KeySlotService {
+	public function __construct(
+		private KeyService $keys,
+		private TargetService $targets,
+		private AlertService $alerts,
+	) {
+	}
+
+	public function add(#[\SensitiveParameter] string $passphrase, string $label): int {
+		$slot = $this->keys->addSlot($passphrase, $label);
+		$this->apply('slot_added', $slot);
+		return $slot;
+	}
+
+	public function replace(int $slot, #[\SensitiveParameter] string $passphrase, ?string $label = null): void {
+		$this->keys->replaceSlot($slot, $passphrase, $label);
+		$this->apply('slot_replaced', $slot);
+	}
+
+	public function remove(int $slot): void {
+		$this->keys->removeSlot($slot);
+		$this->apply('slot_removed', $slot);
+	}
+
+	private function apply(string $event, int $slot): void {
+		$wrapped = $this->keys->wrappedKey();
+		$failed = [];
+		foreach ($this->targets->list() as $t) {
+			try {
+				$this->targets->repository($t)->updateWrappedKey($wrapped);
+			} catch (\Throwable $e) {
+				$failed[] = $t->getName();
+			}
+		}
+		$label = '';
+		foreach ($this->keys->slots() as $s) {
+			if ($s['slot'] === $slot) {
+				$label = $s['label'];
+			}
+		}
+		$this->alerts->securityEvent($event, ['slot' => (string)$slot, 'label' => $label]);
+		if ($failed !== []) {
+			throw new \RuntimeException('Saved, but these locations could not be updated (they still accept the previous passphrases): ' . implode(', ', $failed));
+		}
+	}
+}

lib/Service/LeaseService.php

@@ -0,0 +1,88 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Service;
+
+use OCP\IDBConnection;
+use OCP\Lock\ILockingProvider;
+use OCP\Lock\LockedException;
+
+/**
+ * Shared/exclusive leases with an expiry, stored in ngb_leases.
+ *
+ * Nextcloud's locks live up to an hour; a PHP process killed while holding one (web cron time
+ * limit, OOM, kill -9) would block a location that long. A lease expires on its own unless its
+ * holder keeps refreshing it. Nextcloud's lock is only held for the few milliseconds in which a
+ * lease is checked and written.
+ */
+final class LeaseService {
+	public const SHARED = 's';
+	public const EXCLUSIVE = 'x';
+
+	public function __construct(
+		private IDBConnection $db,
+		private ILockingProvider $locking,
+	) {
+	}
+
+	/** @return string lease id; throws LockedException when it conflicts with a live lease */
+	public function acquire(string $name, string $mode, int $ttl): string {
+		$guard = 'ng_backup/lease/' . $name;
+		$this->locking->acquireLock($guard, ILockingProvider::LOCK_EXCLUSIVE);
+		try {
+			$now = time();
+			$qb = $this->db->getQueryBuilder();
+			$qb->delete('ngb_leases')
+				->where($qb->expr()->eq('name', $qb->createNamedParameter($name)))
+				->andWhere($qb->expr()->lt('expires_at', $qb->createNamedParameter($now)));
+			$qb->executeStatement();
+
+			$qb = $this->db->getQueryBuilder();
+			$qb->select('mode')->from('ngb_leases')->where($qb->expr()->eq('name', $qb->createNamedParameter($name)));
+			$modes = $qb->executeQuery()->fetchAll(\PDO::FETCH_COLUMN);
+			if ($modes !== [] && ($mode === self::EXCLUSIVE || in_array(self::EXCLUSIVE, $modes, true))) {
+				throw new LockedException($name);
+			}
+			$id = bin2hex(random_bytes(16));
+			$qb = $this->db->getQueryBuilder();
+			$qb->insert('ngb_leases')->values([
+				'id' => $qb->createNamedParameter($id),
+				'name' => $qb->createNamedParameter($name),
+				'mode' => $qb->createNamedParameter($mode),
+				'expires_at' => $qb->createNamedParameter($now + $ttl),
+			]);
+			$qb->executeStatement();
+			return $id;
+		} finally {
+			$this->locking->releaseLock($guard, ILockingProvider::LOCK_EXCLUSIVE);
+		}
+	}
+
+	/** Extend a lease while its holder is still working. */
+	public function refresh(string $id, int $ttl): void {
+		$qb = $this->db->getQueryBuilder();
+		$qb->update('ngb_leases')->set('expires_at', $qb->createNamedParameter(time() + $ttl))
+			->where($qb->expr()->eq('id', $qb->createNamedParameter($id)));
+		$qb->executeStatement();
+	}
+
+	public function release(string $id): void {
+		$qb = $this->db->getQueryBuilder();
+		$qb->delete('ngb_leases')->where($qb->expr()->eq('id', $qb->createNamedParameter($id)));
+		$qb->executeStatement();
+	}
+
+	/** Run $fn under a lease; $refresh() can be called during long work. */
+	public function with(string $name, string $mode, int $ttl, callable $fn): mixed {
+		$id = $this->acquire($name, $mode, $ttl);
+		try {
+			return $fn(fn () => $this->refresh($id, $ttl));
+		} finally {
+			$this->release($id);
+		}
+	}
+}

lib/Service/PruneService.php

@@ -0,0 +1,163 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Service;
+
+use OCA\NgBackup\AppInfo\Application;
+use OCA\NgBackup\Db\RunMapper;
+use OCA\NgBackup\Db\SnapshotMapper;
+use OCA\NgBackup\Db\Target;
+use OCP\IAppConfig;
+use OCP\Lock\ILockingProvider;
+use OCP\Lock\LockedException;
+
+/**
+ * Applies the retention policy to a location: forgets snapshots the policy does not keep and
+ * prunes data no remaining snapshot uses. Never runs on append-only locations, never while a
+ * backup to the same location is running (the location lock is shared with BackupService).
+ */
+final class PruneService {
+	public function __construct(
+		private TargetService $targets,
+		private RunMapper $runs,
+		private SnapshotMapper $snapshots,
+		private IAppConfig $appConfig,
+		private ILockingProvider $locking,
+		private AlertService $alerts,
+		private KeyService $keys,
+		private LeaseService $leases,
+	) {
+	}
+
+	public function untrash(Target $target, string $snapshotId): void {
+		$lease = $this->lockExclusive($target, 300);
+		try {
+			$this->doUntrash($target, $snapshotId);
+		} finally {
+			$this->leases->release($lease);
+		}
+	}
+
+	/**
+	 * Run $fn under the location's exclusive lock (to create a run atomically with respect to a
+	 * cleanup, which takes the same lock and then refuses while a run exists).
+	 */
+	public function underStartLock(Target $target, callable $fn): mixed {
+		try {
+			return $this->leases->with(self::lockKey($target), LeaseService::EXCLUSIVE, 60, fn () => $fn());
+		} catch (LockedException) {
+			throw new \RuntimeException('A cleanup of ' . $target->getName() . ' is in progress; try again later');
+		}
+	}
+
+	/**
+	 * Exclusive lock on the location, then make sure no run of any kind (backup, restore, export)
+	 * is in progress: their data may not be referenced by a snapshot yet, or is being read.
+	 */
+	private function lockExclusive(Target $target, int $ttl): string {
+		try {
+			$lease = $this->leases->acquire(self::lockKey($target), LeaseService::EXCLUSIVE, $ttl);
+		} catch (LockedException) {
+			throw new \RuntimeException('A backup, restore or cleanup of ' . $target->getName() . ' is in progress; try again later');
+		}
+		if ($this->runs->findRunning($target->getId()) !== []) {
+			$this->leases->release($lease);
+			throw new \RuntimeException('A backup or restore of ' . $target->getName() . ' is running; try again later');
+		}
+		return $lease;
+	}
+
+	private function doUntrash(Target $target, string $snapshotId): void {
+		$repo = $this->targets->repository($target);
+		if (!array_key_exists($snapshotId, $repo->trash())) {
+			throw new \InvalidArgumentException('That snapshot is not in the trash (or was already deleted)');
+		}
+		$repo->untrash($snapshotId);
+		// Put it back in the local snapshot list as well.
+		$meta = $repo->snapshotMeta($snapshotId);
+		$s = new \OCA\NgBackup\Db\Snapshot();
+		$s->setTargetId($target->getId());
+		$s->setSnapshotId($snapshotId);
+		$s->setKind((string)($meta['kind'] ?? 'full'));
+		$s->setLabel(($meta['label'] ?? '') !== '' ? $meta['label'] : null);
+		$s->setCreatedAt((int)strtotime((string)($meta['time'] ?? 'now')));
+		$s->setFiles((int)($meta['stats']['files'] ?? 0));
+		$s->setBytes((int)($meta['stats']['bytes'] ?? 0));
+		try {
+			$this->snapshots->insert($s);
+		} catch (\Throwable) {
+		}
+		$this->alerts->securityEvent('snapshot_untrashed', ['target' => $target->getName(), 'snapshot' => $snapshotId]);
+	}
+
+	public static function lockKey(Target $target): string {
+		return 'ng_backup/target/' . $target->getId();
+	}
+
+	public function policy(): RetentionPolicy {
+		return RetentionPolicy::fromArray(json_decode($this->appConfig->getValueString(Application::APP_ID, 'retention', '{}'), true) ?: []);
+	}
+
+	public function setPolicy(RetentionPolicy $policy): void {
+		if ($policy->last < 1) {
+			throw new \InvalidArgumentException('Keep at least the last snapshot');
+		}
+		$old = $this->policy()->toArray();
+		$this->appConfig->setValueString(Application::APP_ID, 'retention', json_encode($policy->toArray(), JSON_THROW_ON_ERROR));
+		if ($old !== $policy->toArray()) {
+			$this->alerts->securityEvent('retention_changed', ['policy' => json_encode($policy->toArray())]);
+		}
+	}
+
+	/**
+	 * Snapshots the policy drops go to the trash on the location; trash entries older than the
+	 * deletion delay are purged, and only then is their data freed.
+	 *
+	 * @return array{kept: array<string, list<string>>, forgotten: list<string>, purged: list<string>, prune: array}
+	 */
+	public function apply(Target $target, bool $dryRun = false, bool $scheduled = false): array {
+		if ($target->getAppendOnly()) {
+			throw new \RuntimeException('Location ' . $target->getName() . ' is append-only: NG Backup does not delete anything there');
+		}
+		$lease = $this->lockExclusive($target, 1800);
+		try {
+			$repo = $this->targets->repository($target);
+			$times = [];
+			foreach ($repo->listSnapshots() as $id) {
+				$meta = $repo->snapshotMeta($id);
+				$times[$id] = (int)strtotime((string)($meta['time'] ?? '@0'));
+			}
+			$keep = $this->policy()->keep($times);
+			$forget = array_values(array_diff(array_keys($times), array_keys($keep)));
+			$actor = $scheduled ? 'retention policy' : $this->alerts->actor();
+			$purged = [];
+			if (!$dryRun) {
+				foreach ($forget as $id) {
+					$repo->forget($id, $actor);
+					try {
+						$this->snapshots->delete($this->snapshots->findOne($target->getId(), $id));
+					} catch (\Throwable) {
+					}
+				}
+			}
+			// Also removes leftovers of interrupted runs. A dry run counts the snapshots it would forget as gone.
+			$delay = $this->keys->deleteDelayDays();
+			if (!$dryRun && $forget !== []) {
+				// Scheduled cleanup follows the policy: audit log only, no notification every week.
+				$this->alerts->securityEvent('snapshots_forgotten', ['target' => $target->getName(), 'count' => (string)count($forget),
+					'until' => date('Y-m-d', time() + $delay * 86400)], !$scheduled);
+			}
+			if (!$dryRun) {
+				$purged = $repo->purgeTrash($delay * 86400);
+			}
+			$prune = $repo->prune($dryRun);
+			return ['kept' => $keep, 'forgotten' => $forget, 'purged' => $purged, 'prune' => $prune];
+		} finally {
+			$this->leases->release($lease);
+		}
+	}
+}

lib/Service/RestoreService.php

@@ -28,7 +28,7 @@ use OCP\Files\NotFoundException;
  *  - merge:   into the original place, existing files are overwritten (old content kept as a version)
  *  - replace: like merge, and files that are not in the snapshot are moved to the trash
  */
-class RestoreService {
+final class RestoreService {
 	public const MODE_NEW_FOLDER = 'new-folder';
 	public const MODE_MERGE = 'merge';
 	public const MODE_REPLACE = 'replace';
@@ -36,9 +36,19 @@ class RestoreService {
 	public function __construct(
 		private TargetService $targets,
 		private IRootFolder $root,
+		private LeaseService $leases,
 	) {
 	}
 
+	/** Shared lock on the location while restoring: a cleanup (exclusive) must not delete what is being read. */
+	private function withSharedLock(Target $target, callable $fn, int $ttl = 600): mixed {
+		try {
+			return $this->leases->with(PruneService::lockKey($target), LeaseService::SHARED, $ttl, $fn);
+		} catch (\OCP\Lock\LockedException) {
+			throw new \RuntimeException('A cleanup of ' . $target->getName() . ' is running; try again later');
+		}
+	}
+
 	/**
 	 * Direct children (files and folders) of a path in a snapshot.
 	 *
@@ -72,7 +82,24 @@ class RestoreService {
 	 * @return array{restored:int, trashed:int, target:string}
 	 */
 	public function restoreUserFiles(Target $target, string $snapshotId, string $logicalPath, string $mode = self::MODE_NEW_FOLDER, ?callable $progress = null): array {
-		if (!preg_match('#^data/([^/]+)/files(?:/(.*))?$#', trim($logicalPath, '/'), $m)) {
+		return $this->withSharedLock($target, function (callable $refresh) use ($target, $snapshotId, $logicalPath, $mode, $progress) {
+			$last = time();
+			// Keep the lease alive while files are being written.
+			$beat = function (int $done, int $total, string $name) use ($refresh, $progress, &$last): void {
+				if (time() - $last >= 60) {
+					$refresh();
+					$last = time();
+				}
+				if ($progress !== null) {
+					$progress($done, $total, $name);
+				}
+			};
+			return $this->doRestoreUserFiles($target, $snapshotId, $logicalPath, $mode, $beat);
+		});
+	}
+
+	private function doRestoreUserFiles(Target $target, string $snapshotId, string $logicalPath, string $mode, ?callable $progress): array {
+		if (!Repository::isSafePath($logicalPath) || !preg_match('#^data/([^/]+)/files(?:/(.*))?$#', $logicalPath, $m)) {
 			throw new \InvalidArgumentException('Expected a path like data/<user>/files/<folder or file>');
 		}
 		[$uid, $rel] = [$m[1], trim($m[2] ?? '', '/')];
@@ -124,10 +151,13 @@ class RestoreService {
 
 	/** Raw restore of any snapshot path to a local directory (administrators, disaster recovery). */
 	public function restoreToDirectory(Target $target, string $snapshotId, string $prefix, string $directory): int {
+		if ($prefix !== '' && !Repository::isSafePath($prefix)) {
+			throw new \InvalidArgumentException('Invalid path: ' . $prefix);
+		}
 		if (!is_dir($directory) && !mkdir($directory, 0750, true) && !is_dir($directory)) {
 			throw new \RuntimeException("Cannot create $directory");
 		}
-		return $this->targets->repository($target)->restore($snapshotId, $directory, trim($prefix, '/') === '' ? '' : trim($prefix, '/') . '/');
+		return $this->withSharedLock($target, fn () => $this->targets->repository($target)->restore($snapshotId, $directory, trim($prefix, '/') === '' ? '' : trim($prefix, '/') . '/'), 3600);
 	}
 
 	private function writeFile(Repository $repo, Folder $dest, string $relPath, array $entry): void {

lib/Service/RetentionPolicy.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Service;
+
+/**
+ * Which snapshots to keep: the newest $last, plus the newest snapshot of each of the most recent
+ * $daily days, $weekly ISO weeks and $monthly months that have a snapshot (like restic/borg).
+ */
+final class RetentionPolicy {
+	public function __construct(
+		public readonly int $last = 3,
+		public readonly int $daily = 7,
+		public readonly int $weekly = 4,
+		public readonly int $monthly = 6,
+	) {
+	}
+
+	public static function fromArray(array $a): self {
+		return new self((int)($a['last'] ?? 3), (int)($a['daily'] ?? 7), (int)($a['weekly'] ?? 4), (int)($a['monthly'] ?? 6));
+	}
+
+	public function toArray(): array {
+		return ['last' => $this->last, 'daily' => $this->daily, 'weekly' => $this->weekly, 'monthly' => $this->monthly];
+	}
+
+	/**
+	 * @param array<string, int> $snapshots id => unix time
+	 * @return array<string, list<string>> id => reasons it is kept (ids not in the result are removed)
+	 */
+	public function keep(array $snapshots): array {
+		arsort($snapshots);
+		$keep = [];
+		$i = 0;
+		foreach ($snapshots as $id => $time) {
+			if ($i++ < $this->last) {
+				$keep[$id][] = 'last';
+			}
+		}
+		foreach (['daily' => 'Y-m-d', 'weekly' => 'o-W', 'monthly' => 'Y-m'] as $kind => $format) {
+			$seen = [];
+			foreach ($snapshots as $id => $time) {
+				$bucket = date($format, $time);
+				if (isset($seen[$bucket])) {
+					continue;
+				}
+				if (count($seen) >= $this->$kind) {
+					break;
+				}
+				$seen[$bucket] = true;
+				$keep[$id][] = $kind;
+			}
+		}
+		return $keep;
+	}
+}

lib/Service/TargetService.php

@@ -22,13 +22,14 @@ use OCP\Server;
  * object is built only while it is used; nothing is mounted. files_external is loaded for its
  * classes but its enabled/disabled state is left as the admin set it.
  */
-class TargetService {
+final class TargetService {
 	public function __construct(
 		private TargetMapper $mapper,
 		private KeyService $keys,
 		private ICrypto $crypto,
 		private IAppManager $appManager,
 		private \OCA\NgBackup\Db\DbIndexCache $indexCache,
+		private \OCA\NgBackup\Db\AppConfigCatalogAnchor $anchor,
 	) {
 	}
 
@@ -56,10 +57,10 @@ class TargetService {
 		$keys = $this->keys->keyRing();
 		$storageBackend = $this->buildBackend($backend, $auth, $options, $basePath);
 		if ($storageBackend->exists('config')) {
-			$repo = Repository::openWithKey($storageBackend, $keys);
+			$repo = Repository::openWithKey($storageBackend, $keys, $this->indexCache, $this->anchor);
 			$created = false;
 		} else {
-			$repo = Repository::initWithKey($storageBackend, $keys, $this->keys->wrappedKey());
+			$repo = Repository::initWithKey($storageBackend, $keys, $this->keys->wrappedKey(), $this->anchor);
 			$created = true;
 		}
 
@@ -89,6 +90,17 @@ class TargetService {
 		return ctype_digit($nameOrId) ? $this->mapper->find((int)$nameOrId) : $this->mapper->findByName($nameOrId);
 	}
 
+	/** Size limit for the data stored on this location (null = none). */
+	public function setMaxBytes(Target $target, ?int $maxBytes): Target {
+		$target->setMaxBytes($maxBytes);
+		return $this->mapper->update($target);
+	}
+
+	public function setAppendOnly(Target $target, bool $appendOnly): Target {
+		$target->setAppendOnly($appendOnly);
+		return $this->mapper->update($target);
+	}
+
 	/** Remove the target from NG Backup. The backups on the target itself are not touched. */
 	public function remove(Target $target): void {
 		$this->mapper->delete($target);
@@ -99,10 +111,11 @@ class TargetService {
 	}
 
 	public function repository(Target $target): Repository {
-		$repo = Repository::openWithKey($this->backend($target), $this->keys->keyRing(), $this->indexCache);
+		$repo = Repository::openWithKey($this->backend($target), $this->keys->keyRing(), $this->indexCache, $this->anchor);
 		if ($target->getRepositoryId() !== null && $repo->id() !== $target->getRepositoryId()) {
 			throw new \RuntimeException('The target now contains a different repository than when it was added');
 		}
+		$repo->setMaxBytes($target->getMaxBytes());
 		return $repo;
 	}
 
@@ -115,11 +128,33 @@ class TargetService {
 		return new StorageBackend($this->factory()->create($backend, $auth, $options), $basePath);
 	}
 
+	private ?ExternalStorageFactory $factory = null;
+
+	/**
+	 * files_external's connection code, without changing the app's state:
+	 * - enabled: it is booted by Nextcloud; use its own BackendService;
+	 * - disabled: do NOT boot it (booting registers its mount provider and listeners, which use
+	 *   its database tables; on installations where it was never enabled those do not exist).
+	 *   Only its classes are loaded, and a private BackendService gets its backends and auth
+	 *   mechanisms from its Application class.
+	 */
 	private function factory(): ExternalStorageFactory {
-		// Load files_external's classes without enabling the app (its state stays as the admin set it).
+		if ($this->factory !== null) {
-		if (!class_exists(\OCA\Files_External\Service\BackendService::class)) {
+			return $this->factory;
-			$this->appManager->loadApp('files_external');
 		}
-		return new ExternalStorageFactory(Server::get(\OCA\Files_External\Service\BackendService::class));
+		if ($this->appManager->isEnabledForAnyone('files_external')) {
+			$this->appManager->loadApp('files_external');
+			return $this->factory = new ExternalStorageFactory(Server::get(\OCA\Files_External\Service\BackendService::class));
+		}
+		if (!class_exists(\OCA\Files_External\AppInfo\Application::class)) {
+			$path = $this->appManager->getAppPath('files_external');
+			require_once $path . '/composer/autoload.php';
+		}
+		$service = new \OCA\Files_External\Service\BackendService(
+			Server::get(\OCP\IAppConfig::class), Server::get(\Psr\Log\LoggerInterface::class));
+		$app = new \OCA\Files_External\AppInfo\Application();
+		$service->registerBackendProvider($app);
+		$service->registerAuthMechanismProvider($app);
+		return $this->factory = new ExternalStorageFactory($service);
 	}
 }

lib/Settings/Admin.php

@@ -11,7 +11,7 @@ use OCP\AppFramework\Http\TemplateResponse;
 use OCP\Settings\ISettings;
 use OCP\Util;
 
-class Admin implements ISettings {
+final class Admin implements ISettings {
 	public function getForm(): TemplateResponse {
 		Util::addScript('ng_backup', 'ng_backup-admin');
 		Util::addStyle('ng_backup', 'ng_backup-admin');

lib/Settings/AdminSection.php

@@ -11,7 +11,7 @@ use OCP\IL10N;
 use OCP\IURLGenerator;
 use OCP\Settings\IIconSection;
 
-class AdminSection implements IIconSection {
+final class AdminSection implements IIconSection {
 	public function __construct(
 		private IL10N $l,
 		private IURLGenerator $url,

lib/SetupCheck/BackupStatusCheck.php

@@ -0,0 +1,71 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\SetupCheck;
+
+use OCA\NgBackup\Db\Run;
+use OCA\NgBackup\Db\RunMapper;
+use OCA\NgBackup\Service\AlertService;
+use OCA\NgBackup\Service\BackupService;
+use OCA\NgBackup\Service\KeyService;
+use OCA\NgBackup\Service\TargetService;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use OCP\SetupCheck\ISetupCheck;
+use OCP\SetupCheck\SetupResult;
+
+/** Shows the backup state in the admin overview (Security & setup warnings). */
+final class BackupStatusCheck implements ISetupCheck {
+	public function __construct(
+		private IL10N $l,
+		private IURLGenerator $url,
+		private KeyService $keys,
+		private TargetService $targets,
+		private RunMapper $runs,
+	) {
+	}
+
+	public function getCategory(): string {
+		return 'system';
+	}
+
+	public function getName(): string {
+		return $this->l->t('NG Backup');
+	}
+
+	public function run(): SetupResult {
+		$link = $this->url->linkToRouteAbsolute('settings.AdminSettings.index', ['section' => 'ng_backup']);
+		if (!$this->keys->isInitialized() || !$this->keys->everConfirmed()) {
+			return SetupResult::error($this->l->t('Backups are not set up: create the backup key and confirm the recovery kit.'), $link);
+		}
+		if ($this->keys->recoveryKitConfirmation() === null) {
+			return SetupResult::error($this->l->t('The backup passphrase was changed: download and confirm the new recovery kit.'), $link);
+		}
+		$targets = $this->targets->list();
+		if ($targets === []) {
+			return SetupResult::warning($this->l->t('No backup location is configured.'), $link);
+		}
+		$problems = [];
+		foreach ($targets as $t) {
+			$last = $this->runs->lastFinished($t->getId(), BackupService::KIND_FULL);
+			if ($last === null) {
+				$problems[] = $this->l->t('%s: no successful backup yet', [$t->getName()]);
+			} elseif (time() - (int)$last->getFinishedAt() > AlertService::STALE_AFTER) {
+				$problems[] = $this->l->t('%1$s: last successful backup %2$s', [$t->getName(), date('Y-m-d H:i', (int)$last->getFinishedAt())]);
+			}
+		}
+		foreach ($this->runs->findRecent(10) as $r) {
+			if ($r->getStatus() === Run::FAILED && $r->getStartedAt() > time() - AlertService::STALE_AFTER) {
+				$problems[] = $this->l->t('A %1$s run failed: %2$s', [$r->getKind(), mb_strimwidth((string)$r->getError(), 0, 120, '…')]);
+				break;
+			}
+		}
+		return $problems === []
+			? SetupResult::success($this->l->t('Recent backups to all locations succeeded.'))
+			: SetupResult::warning(implode("\n", $problems), $link);
+	}
+}

lib/UserMigration/RepositoryImportSource.php

@@ -8,6 +8,7 @@ declare(strict_types=1);
 namespace OCA\NgBackup\UserMigration;
 
 use OCA\NgBackup\Repository\Repository;
+use OCP\Files\File;
 use OCP\Files\Folder;
 use OCP\UserMigration\IImportSource;
 use OCP\UserMigration\UserMigrationException;
@@ -30,10 +31,14 @@ final class RepositoryImportSource implements IImportSource {
 		return $data;
 	}
 
+	/** @return resource */
 	public function getFileAsStream(string $path) {
 		$entry = $this->entry($path, 'f');
 		// Phase 0: buffer in php://temp (memory up to 8 MiB, then a temp file for this one file).
 		$stream = fopen('php://temp/maxmemory:' . (8 * 1048576), 'w+b');
+		if ($stream === false) {
+			throw new UserMigrationException('Cannot buffer ' . $path);
+		}
 		foreach ($this->repo->readBlobs($entry['b']) as $data) {
 			for ($done = 0, $len = strlen($data); $done < $len; $done += $n) {
 				$n = fwrite($stream, $done === 0 ? $data : substr($data, $done));
@@ -51,6 +56,7 @@ final class RepositoryImportSource implements IImportSource {
 		$prefix = trim($path, '/');
 		$prefix = $prefix === '' ? '' : $prefix . '/';
 		$names = [];
+		/** @var string $p */
 		foreach (array_keys($this->manifest['entries']) as $p) {
 			if ($prefix === '' || str_starts_with($p, $prefix)) {
 				$rest = substr($p, strlen($prefix));
@@ -70,6 +76,7 @@ final class RepositoryImportSource implements IImportSource {
 		if (isset($this->manifest['entries'][$p])) {
 			return true;
 		}
+		/** @var string $k */
 		foreach (array_keys($this->manifest['entries']) as $k) {
 			if (str_starts_with($k, $p . '/')) {
 				return true;
@@ -91,12 +98,17 @@ final class RepositoryImportSource implements IImportSource {
 				$this->copyToFolder($sub, $path);
 			} else {
 				$stream = $this->getFileAsStream($path);
-				if ($destination->nodeExists($name)) {
+				try {
-					$destination->get($name)->putContent($stream);
+					if ($destination->nodeExists($name)) {
-				} else {
+						$existing = $destination->get($name);
-					$destination->newFile($name, $stream);
+						if (!$existing instanceof File) {
-				}
+							throw new UserMigrationException("$path exists and is not a file");
-				if (is_resource($stream)) {
+						}
+						$existing->putContent($stream);
+					} else {
+						$destination->newFile($name, $stream);
+					}
+				} finally {
 					fclose($stream);
 				}
 			}

package-lock.json

@@ -12,6 +12,7 @@
 				"@nextcloud/axios": "^2.5.1",
 				"@nextcloud/dialogs": "^7.4.0",
 				"@nextcloud/l10n": "^3.4.0",
+				"@nextcloud/password-confirmation": "^6.1.0",
 				"@nextcloud/router": "^3.0.1",
 				"@nextcloud/vue": "^9.0.0",
 				"vue": "^3.5.0"
@@ -885,6 +886,24 @@
 				"node": "^20.0.0 || ^22.0.0 || ^24.0.0"
 			}
 		},
+		"node_modules/@nextcloud/password-confirmation": {
+			"version": "6.1.0",
+			"resolved": "https://registry.npmjs.org/@nextcloud/password-confirmation/-/password-confirmation-6.1.0.tgz",
+			"integrity": "sha512-N2ChXDbPcUcQCoAjj1yc65zfc61yiKpdM3qm/y3Y/y//NG7XWNNINwBg85lqJ2SISgmVStpsQ1d0blpFCoQXkQ==",
+			"license": "MIT",
+			"dependencies": {
+				"@nextcloud/auth": "^2.5.3",
+				"@nextcloud/axios": "^2.5.2",
+				"@nextcloud/l10n": "^3.4.1",
+				"@nextcloud/logger": "^3.0.3",
+				"@nextcloud/router": "^3.1.0",
+				"@nextcloud/vue": "^9.6.0",
+				"vue": "^3.5.30"
+			},
+			"engines": {
+				"node": "^20.0.0 || ^22.0.0 || ^24.0.0"
+			}
+		},
 		"node_modules/@nextcloud/paths": {
 			"version": "3.1.0",
 			"resolved": "https://registry.npmjs.org/@nextcloud/paths/-/paths-3.1.0.tgz",

package.json

@@ -12,6 +12,7 @@
 		"@nextcloud/axios": "^2.5.1",
 		"@nextcloud/dialogs": "^7.4.0",
 		"@nextcloud/l10n": "^3.4.0",
+		"@nextcloud/password-confirmation": "^6.1.0",
 		"@nextcloud/router": "^3.0.1",
 		"@nextcloud/vue": "^9.0.0",
 		"vue": "^3.5.0"

psalm-baseline.xml

@@ -0,0 +1,497 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<files psalm-version="6.19.1@e2ca44251c1f1aa2e35452d426895746b47de64e">
+  <file src="lib/Backend/ExternalStorageFactory.php">
+    <MissingClosureParamType>
+      <code><![CDATA[$p]]></code>
+      <code><![CDATA[$p]]></code>
+    </MissingClosureParamType>
+    <MissingClosureReturnType>
+      <code><![CDATA[fn ($p) => $p->jsonSerialize()]]></code>
+      <code><![CDATA[fn ($p) => $p->jsonSerialize()]]></code>
+    </MissingClosureReturnType>
+  </file>
+  <file src="lib/Backend/IBackend.php">
+    <MissingParamType>
+      <code><![CDATA[$stream]]></code>
+    </MissingParamType>
+  </file>
+  <file src="lib/Backend/LocalBackend.php">
+    <MissingParamType>
+      <code><![CDATA[$stream]]></code>
+    </MissingParamType>
+    <TypeDoesNotContainType>
+      <code><![CDATA[$out !== false]]></code>
+    </TypeDoesNotContainType>
+  </file>
+  <file src="lib/Backend/StorageBackend.php">
+    <MissingParamType>
+      <code><![CDATA[$stream]]></code>
+    </MissingParamType>
+  </file>
+  <file src="lib/BackgroundJob/BackupJob.php">
+    <MissingParamType>
+      <code><![CDATA[$argument]]></code>
+    </MissingParamType>
+  </file>
+  <file src="lib/BackgroundJob/RestoreJob.php">
+    <MissingParamType>
+      <code><![CDATA[$argument]]></code>
+    </MissingParamType>
+  </file>
+  <file src="lib/Command/Browse.php">
+    <InvalidOperand>
+      <code><![CDATA[$b /= 1024]]></code>
+    </InvalidOperand>
+  </file>
+  <file src="lib/Command/KeyConfirm.php">
+    <UndefinedInterfaceMethod>
+      <code><![CDATA[ask]]></code>
+      <code><![CDATA[ask]]></code>
+    </UndefinedInterfaceMethod>
+  </file>
+  <file src="lib/Command/KeyInit.php">
+    <UndefinedInterfaceMethod>
+      <code><![CDATA[ask]]></code>
+      <code><![CDATA[ask]]></code>
+    </UndefinedInterfaceMethod>
+  </file>
+  <file src="lib/Command/KeySlots.php">
+    <UndefinedInterfaceMethod>
+      <code><![CDATA[ask]]></code>
+      <code><![CDATA[ask]]></code>
+    </UndefinedInterfaceMethod>
+  </file>
+  <file src="lib/Command/Prune.php">
+    <PossiblyFalseOperand>
+      <code><![CDATA[json_encode($this->prune->policy()->toArray())]]></code>
+    </PossiblyFalseOperand>
+  </file>
+  <file src="lib/Command/RunBackup.php">
+    <PossiblyNullArgument>
+      <code><![CDATA[$run->getSnapshotId()]]></code>
+    </PossiblyNullArgument>
+  </file>
+  <file src="lib/Command/Status.php">
+    <RiskyTruthyFalsyComparison>
+      <code><![CDATA[$c]]></code>
+      <code><![CDATA[$r->getFinishedAt()]]></code>
+    </RiskyTruthyFalsyComparison>
+  </file>
+  <file src="lib/Command/TargetAdd.php">
+    <PossiblyNullArgument>
+      <code><![CDATA[$r['target']->getRepositoryId()]]></code>
+    </PossiblyNullArgument>
+    <PossiblyUndefinedArrayOffset>
+      <code><![CDATA[$v]]></code>
+    </PossiblyUndefinedArrayOffset>
+  </file>
+  <file src="lib/Command/TargetBackends.php">
+    <UndefinedClass>
+      <code><![CDATA[Base]]></code>
+    </UndefinedClass>
+  </file>
+  <file src="lib/Command/TargetLimit.php">
+    <InvalidOperand>
+      <code><![CDATA[(float)$m[1] * $factor]]></code>
+    </InvalidOperand>
+  </file>
+  <file src="lib/Command/TargetList.php">
+    <UndefinedClass>
+      <code><![CDATA[Base]]></code>
+    </UndefinedClass>
+  </file>
+  <file src="lib/Command/TargetTrustCurrent.php">
+    <UndefinedInterfaceMethod>
+      <code><![CDATA[ask]]></code>
+    </UndefinedInterfaceMethod>
+  </file>
+  <file src="lib/Command/Trash.php">
+    <RedundantCastGivenDocblockType>
+      <code><![CDATA[(string)($info['time'] ?? '')]]></code>
+    </RedundantCastGivenDocblockType>
+  </file>
+  <file src="lib/Controller/AdminApiController.php">
+    <InvalidOperand>
+      <code><![CDATA[$maxGb * 1073741824]]></code>
+      <code><![CDATA[$maxGb * 1073741824]]></code>
+    </InvalidOperand>
+    <PossiblyNullArgument>
+      <code><![CDATA[$r->getSnapshotId()]]></code>
+    </PossiblyNullArgument>
+  </file>
+  <file src="lib/Crypto/StreamCipher.php">
+    <MissingParamType>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$out]]></code>
+    </MissingParamType>
+    <PossiblyFalseArgument>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$out]]></code>
+      <code><![CDATA[$out]]></code>
+      <code><![CDATA[$out]]></code>
+      <code><![CDATA[$out]]></code>
+      <code><![CDATA[$out]]></code>
+      <code><![CDATA[$out]]></code>
+    </PossiblyFalseArgument>
+    <PossiblyInvalidArrayAccess>
+      <code><![CDATA[unpack('N', $len)[1]]]></code>
+    </PossiblyInvalidArrayAccess>
+  </file>
+  <file src="lib/Db/AppConfigCatalogAnchor.php">
+    <PossiblyFalseArgument>
+      <code><![CDATA[json_encode(['gen' => $gen, 'hash' => $hash])]]></code>
+    </PossiblyFalseArgument>
+  </file>
+  <file src="lib/Db/DbDumper.php">
+    <InvalidArrayOffset>
+      <code><![CDATA[$info['sha256']]]></code>
+      <code><![CDATA[$manifest['sequences']]]></code>
+    </InvalidArrayOffset>
+    <MissingClosureReturnType>
+      <code><![CDATA[fn ($c) => $end[array_search($c, $columns, true)]]]></code>
+      <code><![CDATA[fn ($c) => $q($c)]]></code>
+      <code><![CDATA[fn (string $c) => $this->db->quoteIdentifier($c)]]></code>
+      <code><![CDATA[fn (string $c) => $this->db->quoteIdentifier($c)]]></code>
+    </MissingClosureReturnType>
+    <PossiblyFalseArgument>
+      <code><![CDATA[$value]]></code>
+    </PossiblyFalseArgument>
+    <PossiblyNullArgument>
+      <code><![CDATA[$columns]]></code>
+    </PossiblyNullArgument>
+    <UndefinedClass>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[$this->db]]></code>
+      <code><![CDATA[TransactionIsolationLevel]]></code>
+      <code><![CDATA[\Doctrine\DBAL\ParameterType]]></code>
+      <code><![CDATA[\Doctrine\DBAL\ParameterType]]></code>
+      <code><![CDATA[\Doctrine\DBAL\ParameterType]]></code>
+      <code><![CDATA[\Doctrine\DBAL\Platforms\PostgreSQLPlatform]]></code>
+      <code><![CDATA[\Doctrine\DBAL\Platforms\PostgreSQLPlatform]]></code>
+      <code><![CDATA[\Doctrine\DBAL\Platforms\PostgreSQLPlatform]]></code>
+      <code><![CDATA[\Doctrine\DBAL\Schema\Table]]></code>
+      <code><![CDATA[\Doctrine\DBAL\Schema\Table]]></code>
+      <code><![CDATA[\Doctrine\DBAL\Schema\Table]]></code>
+      <code><![CDATA[private]]></code>
+    </UndefinedClass>
+  </file>
+  <file src="lib/Db/Run.php">
+    <PropertyNotSetInConstructor>
+      <code><![CDATA[Run]]></code>
+    </PropertyNotSetInConstructor>
+  </file>
+  <file src="lib/Db/Snapshot.php">
+    <PropertyNotSetInConstructor>
+      <code><![CDATA[Snapshot]]></code>
+    </PropertyNotSetInConstructor>
+  </file>
+  <file src="lib/Db/Target.php">
+    <PropertyNotSetInConstructor>
+      <code><![CDATA[Target]]></code>
+    </PropertyNotSetInConstructor>
+  </file>
+  <file src="lib/Job/BackupRun.php">
+    <ArgumentTypeCoercion>
+      <code><![CDATA[$blobs]]></code>
+    </ArgumentTypeCoercion>
+    <MissingParamType>
+      <code><![CDATA[$fh]]></code>
+    </MissingParamType>
+    <PossiblyNullIterator>
+      <code><![CDATA[$segments]]></code>
+    </PossiblyNullIterator>
+    <PossiblyUndefinedArrayOffset>
+      <code><![CDATA[$mtime]]></code>
+      <code><![CDATA[$state['cur']]]></code>
+      <code><![CDATA[$state['phase']]]></code>
+      <code><![CDATA[$state['segments']]]></code>
+      <code><![CDATA[$state['stats']]]></code>
+    </PossiblyUndefinedArrayOffset>
+  </file>
+  <file src="lib/Job/ParentCursor.php">
+    <PossiblyNullReference>
+      <code><![CDATA[next]]></code>
+    </PossiblyNullReference>
+  </file>
+  <file src="lib/Job/TreeWalker.php">
+    <RedundantCastGivenDocblockType>
+      <code><![CDATA[(string)$name]]></code>
+    </RedundantCastGivenDocblockType>
+  </file>
+  <file src="lib/Migration/Version000001Date20261002000000.php">
+    <UndefinedDocblockClass>
+      <code><![CDATA[$schema->createTable('ngb_targets')]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+    </UndefinedDocblockClass>
+  </file>
+  <file src="lib/Migration/Version000002Date20261002010000.php">
+    <UndefinedDocblockClass>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+    </UndefinedDocblockClass>
+  </file>
+  <file src="lib/Migration/Version000003Date20261002020000.php">
+    <UndefinedDocblockClass>
+      <code><![CDATA[$schema->getTable('ngb_targets')]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+    </UndefinedDocblockClass>
+  </file>
+  <file src="lib/Migration/Version000004Date20261002030000.php">
+    <UndefinedDocblockClass>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+    </UndefinedDocblockClass>
+  </file>
+  <file src="lib/Migration/Version000005Date20261002040000.php">
+    <UndefinedDocblockClass>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+      <code><![CDATA[$t]]></code>
+    </UndefinedDocblockClass>
+  </file>
+  <file src="lib/Repository/BlobIndex.php">
+    <PossiblyFalseArgument>
+      <code><![CDATA[$stream]]></code>
+      <code><![CDATA[$stream]]></code>
+    </PossiblyFalseArgument>
+  </file>
+  <file src="lib/Repository/Catalog.php">
+    <PossiblyFalseArgument>
+      <code><![CDATA[$stream]]></code>
+      <code><![CDATA[$stream]]></code>
+    </PossiblyFalseArgument>
+  </file>
+  <file src="lib/Repository/PackWriter.php">
+    <InvalidPropertyAssignmentValue>
+      <code><![CDATA[$this->buffer]]></code>
+    </InvalidPropertyAssignmentValue>
+    <PossiblyFalsePropertyAssignmentValue>
+      <code><![CDATA[fopen('php://temp/maxmemory:' . ($this->targetSize + 8 * 1048576), 'w+b')]]></code>
+    </PossiblyFalsePropertyAssignmentValue>
+    <RedundantPropertyInitializationCheck>
+      <code><![CDATA[isset($this->buffer)]]></code>
+    </RedundantPropertyInitializationCheck>
+  </file>
+  <file src="lib/Repository/Repository.php">
+    <InvalidOperand>
+      <code><![CDATA[strlen($data) * 0.95]]></code>
+    </InvalidOperand>
+    <InvalidReturnStatement>
+      <code><![CDATA[['snapshot' => $snapshotId] + $stats]]></code>
+    </InvalidReturnStatement>
+    <InvalidReturnType>
+      <code><![CDATA[array{snapshot:string, files:int, reused:int, read:int, newBlobs:int, dupBlobs:int, uploaded:int}]]></code>
+    </InvalidReturnType>
+    <MissingParamType>
+      <code><![CDATA[$fh]]></code>
+    </MissingParamType>
+    <PossiblyFalseArgument>
+      <code><![CDATA[$encrypted]]></code>
+      <code><![CDATA[$encrypted]]></code>
+      <code><![CDATA[$encrypted]]></code>
+      <code><![CDATA[$encrypted]]></code>
+      <code><![CDATA[$fh]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$plain]]></code>
+      <code><![CDATA[$s]]></code>
+      <code><![CDATA[$s]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+      <code><![CDATA[$tree]]></code>
+    </PossiblyFalseArgument>
+    <PossiblyUndefinedArrayOffset>
+      <code><![CDATA[$stats['files']]]></code>
+      <code><![CDATA[$stats['reused']]]></code>
+    </PossiblyUndefinedArrayOffset>
+    <PropertyNotSetInConstructor>
+      <code><![CDATA[$catalog]]></code>
+    </PropertyNotSetInConstructor>
+  </file>
+  <file src="lib/Service/AlertService.php">
+    <InvalidOperand>
+      <code><![CDATA[$bytes / $limit * 100]]></code>
+      <code><![CDATA[0.8 * $limit]]></code>
+    </InvalidOperand>
+    <PossiblyFalseOperand>
+      <code><![CDATA[json_encode(array_diff_key($params, ['actor' => 1]), JSON_UNESCAPED_SLASHES)]]></code>
+    </PossiblyFalseOperand>
+  </file>
+  <file src="lib/Service/BackupService.php">
+    <InvalidOperand>
+      <code><![CDATA[$deadline - microtime(true) + 120]]></code>
+    </InvalidOperand>
+    <UndefinedClass>
+      <code><![CDATA[\OC]]></code>
+      <code><![CDATA[\OC]]></code>
+    </UndefinedClass>
+    <UndefinedInterfaceMethod>
+      <code><![CDATA[getInner]]></code>
+    </UndefinedInterfaceMethod>
+  </file>
+  <file src="lib/Service/KeyService.php">
+    <ArgumentTypeCoercion>
+      <code><![CDATA[array_diff(range(1, self::MAX_SLOTS), $used)]]></code>
+    </ArgumentTypeCoercion>
+    <InvalidReturnStatement>
+      <code><![CDATA[[
+			'version' => 1,
+			'app' => 'NG Backup',
+			'fingerprint' => $this->fingerprint(),
+			'kit_version' => $this->kitVersion(),
+			'confirmation_code' => $this->kitCode(),
+			'created' => gmdate('c'),
+			'wrapped_key' => $this->wrappedKey(),
+			'slots' => $this->slots(),
+			'instructions' => 'Keep this file safe, outside this server. Any one of the passphrases of the slots listed here opens it. '
+				. 'To restore on a new server: install NG Backup, add the backup location and enter this kit with one passphrase. '
+				. 'Without the kit (or the location) and a passphrase, the backups cannot be decrypted.',
+		]]]></code>
+    </InvalidReturnStatement>
+    <InvalidReturnType>
+      <code><![CDATA[array{version:int, app:string, fingerprint:string, created:string, wrapped_key:array, instructions:string}]]></code>
+    </InvalidReturnType>
+    <LessSpecificReturnStatement>
+      <code><![CDATA[array_map(fn ($s) => ['slot' => $s['slot'], 'label' => $s['label'], 'created' => $s['created']], $this->wrappedKey()['slots'])]]></code>
+    </LessSpecificReturnStatement>
+    <MissingClosureParamType>
+      <code><![CDATA[$s]]></code>
+      <code><![CDATA[$s]]></code>
+    </MissingClosureParamType>
+    <MissingClosureReturnType>
+      <code><![CDATA[static fn (string $c) => strtoupper(preg_replace('/[^A-Za-z0-9]/', '', $c) ?? '')]]></code>
+    </MissingClosureReturnType>
+    <MoreSpecificReturnType>
+      <code><![CDATA[list<array{slot:int, label:string, created:int}>]]></code>
+    </MoreSpecificReturnType>
+    <PossiblyFalseArgument>
+      <code><![CDATA[base64_decode($this->crypto->decrypt($enc), true)]]></code>
+    </PossiblyFalseArgument>
+  </file>
+  <file src="lib/Service/PruneService.php">
+    <LessSpecificReturnStatement>
+      <code><![CDATA[['kept' => $keep, 'forgotten' => $forget, 'purged' => $purged, 'prune' => $prune]]]></code>
+    </LessSpecificReturnStatement>
+    <MissingClosureReturnType>
+      <code><![CDATA[fn () => $fn()]]></code>
+    </MissingClosureReturnType>
+    <MoreSpecificReturnType>
+      <code><![CDATA[array{kept: array<string, list<string>>, forgotten: list<string>, purged: list<string>, prune: array}]]></code>
+    </MoreSpecificReturnType>
+  </file>
+  <file src="lib/Service/RestoreService.php">
+    <LessSpecificReturnStatement>
+      <code><![CDATA[array_values($children)]]></code>
+    </LessSpecificReturnStatement>
+    <MissingDependency>
+      <code><![CDATA[$this->root]]></code>
+      <code><![CDATA[private]]></code>
+    </MissingDependency>
+    <MoreSpecificReturnType>
+      <code><![CDATA[list<array{name:string, type:string, size:int, mtime:int|null, files:int}>]]></code>
+    </MoreSpecificReturnType>
+    <PossiblyFalseArgument>
+      <code><![CDATA[$in]]></code>
+      <code><![CDATA[$out]]></code>
+      <code><![CDATA[$out]]></code>
+    </PossiblyFalseArgument>
+    <PossiblyNullArrayOffset>
+      <code><![CDATA[$children]]></code>
+      <code><![CDATA[$children]]></code>
+    </PossiblyNullArrayOffset>
+    <RedundantCastGivenDocblockType>
+      <code><![CDATA[(string)$relPath]]></code>
+      <code><![CDATA[(string)$relPath]]></code>
+    </RedundantCastGivenDocblockType>
+  </file>
+  <file src="lib/Service/TargetService.php">
+    <InvalidReturnStatement>
+      <code><![CDATA[$this->factory()->describeBackends()]]></code>
+    </InvalidReturnStatement>
+    <InvalidReturnType>
+      <code><![CDATA[list<array{id:string, name:string, auth:list<string>, parameters:array}>]]></code>
+    </InvalidReturnType>
+    <UndefinedDocblockClass>
+      <code><![CDATA[Server::get(\OCA\Files_External\Service\BackendService::class)]]></code>
+    </UndefinedDocblockClass>
+    <UnresolvableInclude>
+      <code><![CDATA[require_once $path . '/composer/autoload.php']]></code>
+    </UnresolvableInclude>
+  </file>
+</files>

psalm.xml

@@ -0,0 +1,45 @@
+<?xml version="1.0"?>
+<!-- SPDX-FileCopyrightText: 2026 Dillard Blom -->
+<!-- SPDX-License-Identifier: AGPL-3.0-or-later -->
+<psalm
+    errorLevel="2"
+    resolveFromConfigFile="true"
+    findUnusedBaselineEntry="true"
+    findUnusedCode="false"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+    errorBaseline="psalm-baseline.xml"
+>
+    <projectFiles>
+        <directory name="lib" />
+        <ignoreFiles>
+            <directory name="vendor" />
+        </ignoreFiles>
+    </projectFiles>
+
+    <!-- Interface-only stubs for Nextcloud's public API, not autoloaded at runtime: scanned for
+         type resolution only, never reported on. lib/ must only use OCP\, never internal OC\
+         classes, since those differ between the supported Nextcloud versions (PLAN.md section 6). -->
+    <extraFiles>
+        <directory name="vendor/nextcloud/ocp/OCP" />
+        <directory name="vendor/nextcloud/ocp/NCU" />
+    </extraFiles>
+
+    <issueHandlers>
+        <UndefinedClass>
+            <errorLevel type="suppress">
+                <!-- Provided by files_external at runtime; not a composer dependency (PLAN.md 3.5). -->
+                <referencedClass name="OCA\Files_External\**" />
+            </errorLevel>
+        </UndefinedClass>
+        <!-- The #[\Override] attribute convention (PHP 8.3+) adds no behaviour; this app supports
+             PHP 8.1+, and applying it to every interface-implementing method project-wide is pure
+             ceremony with no bug-catching value, so it's suppressed rather than papered over. -->
+        <MissingOverrideAttribute>
+            <errorLevel type="suppress">
+                <directory name="lib" />
+            </errorLevel>
+        </MissingOverrideAttribute>
+    </issueHandlers>
+</psalm>

spikes/03-db-dump.php

@@ -48,9 +48,11 @@ $seqStates = static function () use ($db, $prefix): array {
 	return $out;
 };
 // Let one sequence run ahead of the data (deleted rows, rollbacks): MAX+1 would be wrong.
-$fcSeq = $db->fetchOne("SELECT pg_get_serial_sequence(?, 'fileid')", [$prefix . 'filecache']);
+if ($db->getDatabasePlatform() instanceof \Doctrine\DBAL\Platforms\PostgreSQLPlatform) {
-for ($i = 0; $i < 50; $i++) {
+	$fcSeq = $db->fetchOne("SELECT pg_get_serial_sequence(?, 'fileid')", [$prefix . 'filecache']);
-	$db->fetchOne('SELECT nextval(CAST(? AS regclass))', [$fcSeq]);
+	for ($i = 0; $i < 50; $i++) {
+		$db->fetchOne('SELECT nextval(CAST(? AS regclass))', [$fcSeq]);
+	}
 }
 $seqBefore = $seqStates();
 $before = [];
@@ -71,6 +73,17 @@ $dumpBytes = array_sum(array_column($manifest['tables'], 'bytes'));
 printf("dump size (plain JSON lines): %.1f MiB\n", $dumpBytes / 1048576);
 $check('checksums in dump match live tables', array_map(fn ($x) => $x['sha256'], $manifest['tables']) === array_map(fn ($x) => $x['sha256'], $before));
 
+// The same dump in many tiny steps (as under web cron) must give identical table checksums.
+$stepped = $dumper->startDump();
+$stepStats = [];
+while (!$stepped['done']) {
+	$stepped = $dumper->dumpStep($repo, $stepped, microtime(true) + 0.05, $stepStats);
+}
+$sm = $dumper->manifest($stepped);
+printf("stepped dump: %d steps, consistent=%s\n", $stepped['steps'], json_encode($sm['consistent']));
+$check('stepped dump: same checksums as the one-shot dump', array_map(fn ($x) => $x['sha256'], $sm['tables']) === array_map(fn ($x) => $x['sha256'], $manifest['tables']));
+$check('stepped dump is marked as not fully consistent', $stepped['steps'] === 1 || $sm['consistent'] === false);
+
 // Second dump without changes: blobs are reused.
 $stats2 = ['newBlobs' => 0, 'dupBlobs' => 0, 'uploaded' => 0];
 $dumper->dump($repo, $stats2);
@@ -90,8 +103,10 @@ memory_reset_peak_usage();
 $t = microtime(true);
 $repo2 = Repository::open(new LocalBackend($repoDir), 'spike passphrase');
 $m = json_decode($repo2->getObject('db/1'), true, 512, JSON_THROW_ON_ERROR);
-$rows = $dumper->restore($repo2, $m);
+$report = [];
-printf("restore: %d rows in %.1fs, peak %.1f MiB\n", $rows, microtime(true) - $t, memory_get_peak_usage() / 1048576);
+$rows = $dumper->restore($repo2, $m, $report);
+printf("restore: %d rows in %.1fs, peak %.1f MiB, %d tables restored, %d unchanged skipped\n", $rows, microtime(true) - $t, memory_get_peak_usage() / 1048576, count($report['restored']), count($report['skipped']));
+$check('restore only rewrote the damaged tables', count($report['restored']) === count($changed));
 
 $mismatch = [];
 foreach ($tables as $tb) {
@@ -109,7 +124,8 @@ if ($mismatch) {
 // Sequences must be restored exactly (PostgreSQL), including one that ran ahead of the data.
 $seqAfter = $seqStates();
 $diff = array_filter(array_keys($seqBefore), fn ($k) => ($seqAfter[$k] ?? null) !== $seqBefore[$k]);
-$check(sprintf('all %d sequences restored exactly (filecache seq 50 ahead of data)', count($seqBefore)), $diff === [] && count($seqBefore) > 0);
+$isPg = $db->getDatabasePlatform() instanceof \Doctrine\DBAL\Platforms\PostgreSQLPlatform;
+$check(sprintf('all %d sequences restored exactly%s', count($seqBefore), $isPg ? ' (filecache seq 50 ahead of data)' : ' (n/a on this database)'), $diff === [] && (!$isPg || count($seqBefore) > 0));
 if ($diff) {
 	foreach (array_slice($diff, 0, 5) as $k) {
 		echo "$k before=" . json_encode($seqBefore[$k]) . ' after=' . json_encode($seqAfter[$k] ?? null) . "\n";

src/AdminSettings.vue

@@ -11,12 +11,23 @@
 		</NcSettingsSection>
 
 		<template v-if="status">
-			<KeySetup :status="status" @changed="refresh" />
+			<div class="ngb-tabs">
-			<template v-if="status.key.confirmation">
+				<NcButton :variant="tab === 'backup' ? 'primary' : 'secondary'" @click="tab = 'backup'">{{ t('ng_backup', 'Backup and restore') }}</NcButton>
-				<Locations :status="status" @changed="refresh" />
+				<NcButton :variant="tab === 'settings' ? 'primary' : 'secondary'" @click="tab = 'settings'">{{ t('ng_backup', 'Settings') }}</NcButton>
-				<Backups v-if="status.targets.length" :status="status" @changed="refresh" />
+			</div>
-				<RestoreBrowser v-if="status.targets.length" :status="status" @changed="refresh" />
+
+			<template v-if="tab === 'settings'">
+				<KeySetup :status="status" @changed="refresh" />
+				<Locations v-if="status.key.everConfirmed" :status="status" @changed="refresh" />
 			</template>
+			<template v-else-if="status.key.everConfirmed">
+				<template v-if="status.targets.length">
+					<Backups :status="status" @changed="refresh" />
+					<RestoreBrowser :status="status" @changed="refresh" />
+				</template>
+				<NcNoteCard v-else type="info">{{ t('ng_backup', 'Add a backup location under "Settings" first.') }}</NcNoteCard>
+			</template>
+			<NcNoteCard v-else type="warning">{{ t('ng_backup', 'Set up the backup key under "Settings" first.') }}</NcNoteCard>
 		</template>
 	</div>
 </template>
@@ -24,6 +35,7 @@
 <script setup>
 import { onBeforeUnmount, onMounted, ref } from 'vue'
 import { t } from '@nextcloud/l10n'
+import NcButton from '@nextcloud/vue/components/NcButton'
 import NcLoadingIcon from '@nextcloud/vue/components/NcLoadingIcon'
 import NcNoteCard from '@nextcloud/vue/components/NcNoteCard'
 import NcSettingsSection from '@nextcloud/vue/components/NcSettingsSection'
@@ -35,12 +47,20 @@ import RestoreBrowser from './components/RestoreBrowser.vue'
 
 const status = ref(null)
 const error = ref('')
+const tab = ref('settings')
+let tabInitialized = false
 let timer = null
 
 async function refresh() {
 	try {
 		status.value = await api.status()
 		error.value = ''
+		// Default to the daily-use tab once the key is set up; stay on Settings otherwise.
+		// Only decided on first load, so switching tabs ourselves isn't undone by polling.
+		if (!tabInitialized) {
+			tab.value = status.value.key.everConfirmed ? 'backup' : 'settings'
+			tabInitialized = true
+		}
 	} catch (e) {
 		error.value = e.message
 	}
@@ -59,4 +79,9 @@ onBeforeUnmount(() => clearTimeout(timer))
 .ng-backup :deep(.settings-section) {
 	max-width: 900px;
 }
+.ngb-tabs {
+	display: flex;
+	gap: 8px;
+	margin: 0 0 12px;
+}
 </style>

src/api.js

@@ -17,13 +17,19 @@ async function call(method, path, data) {
 
 export default {
 	status: () => call('get', '/status'),
-	initKey: (passphrase) => call('post', '/key', { passphrase }),
+	initKey: (passphrase, deleteDelayDays, label) => call('post', '/key', { passphrase, deleteDelayDays, label }),
+	addSlot: (passphrase, label) => call('post', '/key/slots', { passphrase, label }),
+	replaceSlot: (slot, passphrase, label) => call('put', `/key/slots/${slot}`, { passphrase, label }),
+	removeSlot: (slot) => call('delete', `/key/slots/${slot}`),
+	trash: (targetId) => call('get', `/targets/${targetId}/trash`),
+	untrash: (targetId, snapshotId) => call('post', `/targets/${targetId}/trash/${snapshotId}`),
 	kitUrl: () => url('/key/kit'),
-	confirmKit: (accepted, phrase) => call('post', '/key/confirm', { accepted, phrase }),
+	confirmKit: (accepted, phrase, code) => call('post', '/key/confirm', { accepted, phrase, code }),
 	backends: () => call('get', '/backends'),
 	addTarget: (target) => call('post', '/targets', target),
 	removeTarget: (id) => call('delete', `/targets/${id}`),
 	testTarget: (id) => call('post', `/targets/${id}/test`),
+	setTargetLimit: (id, maxGb) => call('put', `/targets/${id}/limit`, { maxGb }),
 	startBackup: (targetId, label) => call('post', '/backups', { targetId, label }),
 	setSchedule: (time) => call('put', '/schedule', { time }),
 	snapshots: (targetId) => call('get', `/targets/${targetId}/snapshots`),

src/components/Backups.vue

@@ -16,12 +16,27 @@
 		</div>
 		<NcNoteCard v-if="error" type="error">{{ error }}</NcNoteCard>
 
+		<template v-for="target in status.targets" :key="'trash' + target.id">
+			<div v-if="trash[target.id]?.length" class="ngb-trash">
+				<h3>{{ t('ng_backup', 'Trash of {name}', { name: target.name }) }}</h3>
+				<p class="ngb-muted">{{ t('ng_backup', 'Removed restore points can be brought back until they are deleted permanently.') }}</p>
+				<ul>
+					<li v-for="item in trash[target.id]" :key="item.id">
+						{{ item.time ? new Date(item.time).toLocaleString() : item.id }}{{ item.label ? ' – ' + item.label : '' }}
+						<span class="ngb-muted">{{ t('ng_backup', 'removed by {by}, deleted after {date}', { by: item.by, date: new Date(item.deleteAfter * 1000).toLocaleDateString() }) }}</span>
+						<NcButton variant="tertiary" @click="untrash(target, item)">{{ t('ng_backup', 'Restore') }}</NcButton>
+					</li>
+				</ul>
+			</div>
+		</template>
+
 		<table v-if="status.runs.length" class="ngb-table">
 			<thead>
 				<tr>
 					<th>{{ t('ng_backup', 'Started') }}</th>
 					<th>{{ t('ng_backup', 'Location') }}</th>
 					<th>{{ t('ng_backup', 'Kind') }}</th>
+					<th>{{ t('ng_backup', 'Restore point') }}</th>
 					<th>{{ t('ng_backup', 'Status') }}</th>
 					<th>{{ t('ng_backup', 'Files') }}</th>
 					<th>{{ t('ng_backup', 'Uploaded') }}</th>
@@ -32,6 +47,7 @@
 					<td>{{ new Date(run.startedAt * 1000).toLocaleString() }}</td>
 					<td>{{ targetName(run.targetId) }}</td>
 					<td>{{ run.kind }}</td>
+					<td>{{ run.snapshot ? new Date(run.snapshot.createdAt * 1000).toLocaleString() + (run.snapshot.label ? ' – ' + run.snapshot.label : '') : '' }}</td>
 					<td :class="'ngb-' + run.status">{{ run.status }}{{ run.status === 'running' ? ' (' + run.phase + ')' : '' }}{{ run.error ? ': ' + run.error : '' }}</td>
 					<td>{{ run.stats?.files?.files ?? run.stats?.restored ?? '' }}</td>
 					<td>{{ run.stats?.files ? formatSize(run.stats.files.uploaded) : '' }}</td>
@@ -50,6 +66,8 @@ import NcSettingsSection from '@nextcloud/vue/components/NcSettingsSection'
 import NcTextField from '@nextcloud/vue/components/NcTextField'
 import api from '../api.js'
 import { formatSize } from '../format.js'
+import { confirmPassword } from '@nextcloud/password-confirmation'
+import { reactive } from 'vue'
 
 const props = defineProps({ status: { type: Object, required: true } })
 const emit = defineEmits(['changed'])
@@ -57,6 +75,30 @@ const schedule = ref(props.status.schedule)
 const error = ref('')
 watch(() => props.status.schedule, (s) => { schedule.value = s })
 
+const trash = reactive({})
+async function loadTrash() {
+	for (const target of props.status.targets) {
+		try {
+			trash[target.id] = await api.trash(target.id)
+		} catch (e) {
+			trash[target.id] = []
+		}
+	}
+}
+watch(() => props.status.targets.map(tg => tg.id).join(','), loadTrash, { immediate: true })
+
+async function untrash(target, item) {
+	error.value = ''
+	try {
+		await confirmPassword()
+		await api.untrash(target.id, item.id)
+		await loadTrash()
+		emit('changed')
+	} catch (e) {
+		error.value = e?.message || ''
+	}
+}
+
 const isRunning = (targetId) => props.status.runs.some(r => r.targetId === targetId && r.kind === 'full' && r.status === 'running')
 const targetName = (id) => props.status.targets.find(tg => tg.id === id)?.name ?? '#' + id
 
@@ -87,5 +129,8 @@ async function saveSchedule() {
 .ngb-table { width: 100%; border-collapse: collapse; }
 .ngb-table th, .ngb-table td { text-align: start; padding: 4px 8px; border-bottom: 1px solid var(--color-border); }
 .ngb-failed { color: var(--color-error-text); }
+.ngb-muted { color: var(--color-text-maxcontrast); }
+.ngb-trash { margin: 12px 0; }
+.ngb-trash h3 { font-weight: bold; }
 .ngb-done { color: var(--color-success-text); }
 </style>

src/components/KeySetup.vue

@@ -4,38 +4,74 @@
 -->
 <template>
 	<NcSettingsSection :name="t('ng_backup', 'Backup key and recovery kit')"
-		:description="t('ng_backup', 'All backups are encrypted with one key. The server keeps it for scheduled backups; the recovery kit, protected by your passphrase, is what you need to restore on a new server.')">
+		:description="t('ng_backup', 'All backups are encrypted with one key. The server keeps it for scheduled backups. To restore on a new server you need the recovery kit and one of the passphrases.')">
 		<!-- 1. Create the key -->
 		<form v-if="!status.key.initialized" class="ngb-form" @submit.prevent="createKey">
+			<NcTextField v-model="label" :label="t('ng_backup', 'Who keeps this passphrase (e.g. Safe, CTO)')" />
 			<NcPasswordField v-model="pass1" :label="t('ng_backup', 'Passphrase (at least 12 characters)')" autocomplete="new-password" />
 			<NcPasswordField v-model="pass2" :label="t('ng_backup', 'Repeat passphrase')" autocomplete="new-password"
 				:error="pass2 !== '' && pass1 !== pass2" :helper-text="pass2 !== '' && pass1 !== pass2 ? t('ng_backup', 'The passphrases do not match') : ''" />
-			<NcButton type="submit" variant="primary" :disabled="busy || pass1.length < 12 || pass1 !== pass2">
+			<NcTextField v-model="delay" type="number" min="1" max="365"
+				:label="t('ng_backup', 'Days a removed backup stays in the trash before it is really deleted')"
+				:helper-text="t('ng_backup', 'Protects against a malicious or mistaken cleanup. Cannot be changed later.')" />
+			<NcButton type="submit" variant="primary" :disabled="busy || pass1.length < 12 || pass1 !== pass2 || !(delay >= 1 && delay <= 365)">
 				{{ t('ng_backup', 'Create backup key') }}
 			</NcButton>
 		</form>
 
 		<template v-else>
-			<p>{{ t('ng_backup', 'Key fingerprint: {fingerprint}', { fingerprint: status.key.fingerprint }) }}</p>
+			<p>
+				{{ t('ng_backup', 'Key fingerprint: {fingerprint}', { fingerprint: status.key.fingerprint }) }} ·
+				{{ t('ng_backup', 'Removed backups are kept in the trash for {days} days', { days: status.key.deleteDelayDays }) }}
+			</p>
 
-			<!-- 2. Download the kit and confirm -->
+			<!-- Passphrase slots -->
+			<h3>{{ t('ng_backup', 'Passphrases') }}</h3>
+			<p class="ngb-muted">
+				{{ t('ng_backup', 'Up to {max} passphrases can open the key, so one person leaving does not lock you out. For example: one in the safe, one with the CTO, one with the head of IT. Everyone keeps the same recovery kit and only knows their own passphrase.', { max: status.key.maxSlots }) }}
+			</p>
+			<table class="ngb-table">
+				<tbody>
+					<tr v-for="slot in status.key.slots" :key="slot.slot">
+						<td>{{ t('ng_backup', 'Slot {n}', { n: slot.slot }) }}</td>
+						<td><strong>{{ slot.label }}</strong></td>
+						<td class="ngb-muted">{{ slot.created ? new Date(slot.created * 1000).toLocaleDateString() : '' }}</td>
+						<td>
+							<NcButton variant="tertiary" @click="openSlotForm(slot)">{{ t('ng_backup', 'New passphrase') }}</NcButton>
+							<NcButton v-if="status.key.slots.length > 1" variant="tertiary" @click="removeSlot(slot)">{{ t('ng_backup', 'Remove') }}</NcButton>
+						</td>
+					</tr>
+				</tbody>
+			</table>
+			<NcButton v-if="!slotForm && status.key.slots.length < status.key.maxSlots" @click="openSlotForm(null)">{{ t('ng_backup', 'Add passphrase') }}</NcButton>
+			<form v-if="slotForm" class="ngb-form" @submit.prevent="saveSlot">
+				<NcTextField v-model="slotForm.label" :label="t('ng_backup', 'Who keeps this passphrase')" />
+				<NcPasswordField v-model="slotForm.pass1" :label="t('ng_backup', 'Passphrase (at least 12 characters)')" autocomplete="new-password" />
+				<NcPasswordField v-model="slotForm.pass2" :label="t('ng_backup', 'Repeat passphrase')" autocomplete="new-password" :error="slotForm.pass2 !== '' && slotForm.pass1 !== slotForm.pass2" />
+				<div class="ngb-row">
+					<NcButton type="submit" variant="primary" :disabled="busy || slotForm.pass1.length < 12 || slotForm.pass1 !== slotForm.pass2">{{ t('ng_backup', 'Save') }}</NcButton>
+					<NcButton @click="slotForm = null">{{ t('ng_backup', 'Cancel') }}</NcButton>
+				</div>
+			</form>
+
+			<!-- Recovery kit -->
+			<h3>{{ t('ng_backup', 'Recovery kit') }}</h3>
 			<div v-if="!status.key.confirmation" class="ngb-confirm">
-				<NcNoteCard type="warning">
+				<NcNoteCard :type="status.key.everConfirmed ? 'error' : 'warning'">
-					{{ t('ng_backup', 'Before the first backup: download the recovery kit and store it, together with your passphrase, somewhere safe outside this server.') }}
+					{{ status.key.everConfirmed
+						? t('ng_backup', 'The passphrases changed: download the new recovery kit, give a copy to every passphrase holder and confirm. Backups keep running meanwhile.')
+						: t('ng_backup', 'Before the first backup: download the recovery kit and store it, together with the passphrase, somewhere safe outside this server.') }}
 				</NcNoteCard>
-				<NcButton :href="kitUrl" download @click="downloaded = true">
+				<NcButton @click="downloadKit">{{ t('ng_backup', 'Download recovery kit') }}</NcButton>
-					{{ t('ng_backup', 'Download recovery kit') }}
+				<NcTextField v-model="code" :disabled="!downloaded" :label="t('ng_backup', 'Confirmation code from the kit file')"
-				</NcButton>
+					:helper-text="t('ng_backup', 'Open the downloaded file and type the value of confirmation_code, e.g. ABCD-2345.')" />
-				<NcCheckboxRadioSwitch v-model="accepted" :disabled="!downloaded">
+				<NcCheckboxRadioSwitch v-model="accepted" :disabled="!downloaded">{{ status.statement }}</NcCheckboxRadioSwitch>
-					{{ status.statement }}
+				<NcButton variant="primary" :disabled="!downloaded || !accepted || code.length < 8 || busy" @click="confirm">{{ status.confirmationPhrase }}</NcButton>
-				</NcCheckboxRadioSwitch>
-				<NcButton variant="primary" :disabled="!downloaded || !accepted || busy" @click="confirm">
-					{{ status.confirmationPhrase }}
-				</NcButton>
 			</div>
 			<p v-else>
 				{{ t('ng_backup', 'Recovery kit confirmed by {user} on {date}.', { user: status.key.confirmation.uid, date: new Date(status.key.confirmation.time * 1000).toLocaleString() }) }}
-				<a :href="kitUrl" download>{{ t('ng_backup', 'Download the kit again') }}</a>
+				<NcButton variant="tertiary" @click="downloadKit">{{ t('ng_backup', 'Download the kit again') }}</NcButton>
+				<span class="ngb-muted">{{ t('ng_backup', 'Requires your password; all administrators are notified.') }}</span>
 			</p>
 		</template>
 		<NcNoteCard v-if="error" type="error">{{ error }}</NcNoteCard>
@@ -45,57 +81,86 @@
 <script setup>
 import { ref } from 'vue'
 import { t } from '@nextcloud/l10n'
+import { confirmPassword } from '@nextcloud/password-confirmation'
+import '@nextcloud/password-confirmation/style.css'
 import NcButton from '@nextcloud/vue/components/NcButton'
 import NcCheckboxRadioSwitch from '@nextcloud/vue/components/NcCheckboxRadioSwitch'
 import NcNoteCard from '@nextcloud/vue/components/NcNoteCard'
 import NcPasswordField from '@nextcloud/vue/components/NcPasswordField'
 import NcSettingsSection from '@nextcloud/vue/components/NcSettingsSection'
+import NcTextField from '@nextcloud/vue/components/NcTextField'
 import api from '../api.js'
 
 const props = defineProps({ status: { type: Object, required: true } })
 const emit = defineEmits(['changed'])
 
+const label = ref('')
 const pass1 = ref('')
 const pass2 = ref('')
+const delay = ref(props.status.key.deleteDelayDays)
+const slotForm = ref(null)
 const downloaded = ref(false)
 const accepted = ref(false)
+const code = ref('')
 const busy = ref(false)
 const error = ref('')
 const kitUrl = api.kitUrl()
 
-async function createKey() {
+/** Run fn after a password confirmation; report errors in the card. */
+async function guarded(fn) {
 	busy.value = true
 	error.value = ''
 	try {
-		await api.initKey(pass1.value)
+		await confirmPassword()
-		pass1.value = pass2.value = ''
+		await fn()
 		emit('changed')
 	} catch (e) {
-		error.value = e.message
+		error.value = e?.message || ''
 	} finally {
 		busy.value = false
 	}
 }
 
-async function confirm() {
+const createKey = () => guarded(async () => {
-	busy.value = true
+	await api.initKey(pass1.value, Number(delay.value), label.value || 'Slot 1')
-	error.value = ''
+	pass1.value = pass2.value = ''
-	try {
+})
-		await api.confirmKit(accepted.value, props.status.confirmationPhrase)
+
-		emit('changed')
+const downloadKit = () => guarded(async () => {
-	} catch (e) {
+	window.location.href = kitUrl
-		error.value = e.message
+	downloaded.value = true
-	} finally {
+})
-		busy.value = false
+
-	}
+function openSlotForm(slot) {
+	slotForm.value = { slot: slot?.slot ?? null, label: slot?.label ?? '', pass1: '', pass2: '' }
 }
+
+const saveSlot = () => guarded(async () => {
+	const f = slotForm.value
+	if (f.slot === null) {
+		await api.addSlot(f.pass1, f.label || 'Slot')
+	} else {
+		await api.replaceSlot(f.slot, f.pass1, f.label || null)
+	}
+	slotForm.value = null
+	downloaded.value = accepted.value = false
+})
+
+const removeSlot = (slot) => guarded(async () => {
+	await api.removeSlot(slot.slot)
+	downloaded.value = accepted.value = false
+})
+
+const confirm = () => guarded(async () => {
+	await api.confirmKit(accepted.value, props.status.confirmationPhrase, code.value)
+	code.value = ''
+})
 </script>
 
 <style scoped>
-.ngb-form, .ngb-confirm {
+.ngb-muted { color: var(--color-text-maxcontrast); }
-	display: flex;
+.ngb-form, .ngb-confirm { display: flex; flex-direction: column; gap: 12px; max-width: 600px; margin: 8px 0; }
-	flex-direction: column;
+.ngb-row { display: flex; gap: 8px; }
-	gap: 12px;
+.ngb-table td { padding: 2px 12px 2px 0; }
-	max-width: 600px;
+h3 { margin-top: 16px; font-weight: bold; }
-}
 </style>

src/components/Locations.vue

@@ -8,7 +8,8 @@
 		<ul v-if="status.targets.length" class="ngb-list">
 			<li v-for="target in status.targets" :key="target.id">
 				<strong>{{ target.name }}</strong>
-				<span class="ngb-muted">{{ target.backend }} · {{ target.path }}</span>
+				<span class="ngb-muted">{{ target.backend }} · {{ target.path }}{{ target.appendOnly ? ' · ' + t('ng_backup', 'append-only') : '' }}</span>
+				<span :class="usageClass(target)">{{ usageText(target) }}</span>
 				<span v-if="tests[target.id]" :class="tests[target.id].ok ? 'ngb-ok' : 'ngb-err'">
 					{{ tests[target.id].ok ? t('ng_backup', 'OK, {n} snapshots', { n: tests[target.id].snapshots }) : tests[target.id].error }}
 				</span>
@@ -28,6 +29,8 @@
 				<NcTextField v-else v-model="form.options[field.key]" :label="field.label + (field.optional ? '' : ' *')" />
 			</template>
 			<NcTextField v-model="form.path" :label="t('ng_backup', 'Folder on the location for the backups')" />
+			<NcTextField v-model="form.maxGb" type="number" min="0" :label="t('ng_backup', 'Maximum size in GiB')"
+				:helper-text="form.maxGb ? t('ng_backup', 'Backups stop at this size; administrators are warned at 80%.') : t('ng_backup', 'Empty = unlimited: everything stored is billed by your provider, and nothing stops a backup that keeps growing.')" />
 			<div class="ngb-row">
 				<NcButton type="submit" variant="primary" :disabled="busy || !form.name || !backend || !auth">{{ t('ng_backup', 'Connect and add') }}</NcButton>
 				<NcButton @click="adding = false">{{ t('ng_backup', 'Cancel') }}</NcButton>
@@ -47,6 +50,8 @@ import NcPasswordField from '@nextcloud/vue/components/NcPasswordField'
 import NcSelect from '@nextcloud/vue/components/NcSelect'
 import NcSettingsSection from '@nextcloud/vue/components/NcSettingsSection'
 import NcTextField from '@nextcloud/vue/components/NcTextField'
+import { confirmPassword } from '@nextcloud/password-confirmation'
+import '@nextcloud/password-confirmation/style.css'
 import api from '../api.js'
 
 defineProps({ status: { type: Object, required: true } })
@@ -59,7 +64,18 @@ const backends = ref([])
 const backend = ref(null)
 const auth = ref(null)
 const tests = reactive({})
-const form = reactive({ name: '', path: 'ng_backup', options: {} })
+const form = reactive({ name: '', path: 'ng_backup', options: {}, maxGb: '' })
+
+const gib = (b) => (b / 1073741824).toFixed(1) + ' GiB'
+function usageText(target) {
+	if (target.storedBytes === null || target.storedBytes === undefined) {
+		return target.maxBytes ? t('ng_backup', 'limit {limit}', { limit: gib(target.maxBytes) }) : t('ng_backup', 'no limit')
+	}
+	return target.maxBytes
+		? t('ng_backup', '{used} of {limit}', { used: gib(target.storedBytes), limit: gib(target.maxBytes) })
+		: t('ng_backup', '{used} stored, no limit', { used: gib(target.storedBytes) })
+}
+const usageClass = (target) => (target.maxBytes && target.storedBytes >= 0.8 * target.maxBytes) ? 'ngb-err' : 'ngb-muted'
 
 // files_external DefinitionParameter: type 0 text, 1 boolean, 2 password; flag 1 = optional, 4 = hidden
 const toFields = (params) => Object.entries(params || {})
@@ -88,9 +104,10 @@ async function add() {
 	busy.value = true
 	error.value = ''
 	try {
-		await api.addTarget({ name: form.name, backend: backend.value.id, auth: auth.value.id, options: form.options, path: form.path })
+		await api.addTarget({ name: form.name, backend: backend.value.id, auth: auth.value.id, options: form.options, path: form.path,
+			maxGb: form.maxGb === '' ? null : Number(form.maxGb) })
 		adding.value = false
-		Object.assign(form, { name: '', path: 'ng_backup', options: {} })
+		Object.assign(form, { name: '', path: 'ng_backup', options: {}, maxGb: '' })
 		emit('changed')
 	} catch (e) {
 		error.value = e.message
@@ -107,7 +124,13 @@ async function remove(target) {
 	if (!window.confirm(t('ng_backup', 'Remove "{name}" from NG Backup? The backups on the location itself are kept.', { name: target.name }))) {
 		return
 	}
-	await api.removeTarget(target.id)
+	try {
+		await confirmPassword()
+		await api.removeTarget(target.id)
+	} catch (e) {
+		error.value = e?.message || ''
+		return
+	}
 	emit('changed')
 }
 </script>

src/components/RestoreBrowser.vue

@@ -7,7 +7,7 @@
 		:description="t('ng_backup', 'Pick a restore point and a user folder or file. Restores run in the background and go through Nextcloud, so overwritten files keep their old content as a version and removed files go to the trash.')">
 		<div class="ngb-row">
 			<NcSelect v-model="target" :options="status.targets" label="name" :input-label="t('ng_backup', 'Location')" :clearable="false" />
-			<NcSelect v-if="target" v-model="snapshot" :options="snapshots" :get-option-label="snapshotLabel" :input-label="t('ng_backup', 'Restore point')" :clearable="false" />
+			<NcSelect v-if="target" v-model="snapshot" :options="snapshots" label="displayLabel" :input-label="t('ng_backup', 'Restore point')" :clearable="false" />
 		</div>
 
 		<template v-if="snapshot">
@@ -30,7 +30,7 @@
 			<NcButton v-if="restorable(path) && path !== selected" variant="tertiary" @click="selected = path">{{ t('ng_backup', 'Select this folder') }}</NcButton>
 
 			<div v-if="selected" class="ngb-restore">
-				<p>{{ t('ng_backup', 'Selected: {path}', { path: selected }) }}</p>
+				<p>{{ t('ng_backup', 'Selected: {path}, from the restore point of {date}', { path: selected, date: snapshotLabel(snapshot) }) }}</p>
 				<NcCheckboxRadioSwitch v-for="m in modes" :key="m.id" v-model="mode" :value="m.id" type="radio" name="ngb-mode">{{ m.label }}</NcCheckboxRadioSwitch>
 				<NcButton variant="primary" :disabled="busy" @click="restore">{{ t('ng_backup', 'Restore') }}</NcButton>
 			</div>
@@ -49,6 +49,8 @@ import NcLoadingIcon from '@nextcloud/vue/components/NcLoadingIcon'
 import NcNoteCard from '@nextcloud/vue/components/NcNoteCard'
 import NcSelect from '@nextcloud/vue/components/NcSelect'
 import NcSettingsSection from '@nextcloud/vue/components/NcSettingsSection'
+import { confirmPassword } from '@nextcloud/password-confirmation'
+import '@nextcloud/password-confirmation/style.css'
 import api from '../api.js'
 import { formatSize } from '../format.js'
 
@@ -82,7 +84,8 @@ const crumbs = computed(() => {
 
 watch(target, async (tg) => {
 	snapshot.value = null
-	snapshots.value = tg ? await api.snapshots(tg.id) : []
+	const list = tg ? await api.snapshots(tg.id) : []
+	snapshots.value = list.map(s => ({ ...s, displayLabel: snapshotLabel(s) }))
 	snapshot.value = snapshots.value[0] ?? null
 }, { immediate: true })
 watch(snapshot, () => { selected.value = ''; open('data') })
@@ -107,6 +110,7 @@ async function restore() {
 	busy.value = true
 	error.value = message.value = ''
 	try {
+		await confirmPassword()
 		await api.startRestore(target.value.id, snapshot.value.id, selected.value, mode.value)
 		message.value = t('ng_backup', 'Restore queued. It runs with the next cron job; progress is shown under Backups.')
 		emit('changed')

tests/Unit/Crypto/KeyRingTest.php

@@ -33,4 +33,19 @@ class KeyRingTest extends TestCase {
 		$this->expectException(\InvalidArgumentException::class);
 		new KeyRing('short');
 	}
+
+	public function testAnySlotOpensTheSameKey(): void {
+		$keys = KeyRing::generate();
+		$field = ['slots' => [
+			['slot' => 1, 'label' => 'Safe', 'key' => $keys->wrap('passphrase in the safe')],
+			['slot' => 2, 'label' => 'CTO', 'key' => $keys->wrap('passphrase of the cto')],
+			['slot' => 3, 'label' => 'Head of IT', 'key' => $keys->wrap('passphrase head of it')],
+		]];
+		foreach (['passphrase in the safe', 'passphrase of the cto', 'passphrase head of it'] as $p) {
+			$this->assertSame($keys->blobId('x'), KeyRing::unwrapAny($field, $p)->blobId('x'));
+		}
+		$this->assertSame($keys->blobId('x'), KeyRing::unwrapAny($keys->wrap('legacy single'), 'legacy single')->blobId('x'));
+		$this->expectException(CryptoException::class);
+		KeyRing::unwrapAny($field, 'nobody knows this');
+	}
 }

tests/Unit/Repository/CatalogTest.php

@@ -0,0 +1,90 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\NgBackup\Tests\Unit\Repository;
+
+use OCA\NgBackup\Backend\LocalBackend;
+use OCA\NgBackup\Crypto\KeyRing;
+use OCA\NgBackup\Repository\ICatalogAnchor;
+use OCA\NgBackup\Repository\Repository;
+use OCA\NgBackup\Repository\RepositoryException;
+use OCA\NgBackup\Tests\Unit\TempDirTrait;
+use PHPUnit\Framework\TestCase;
+
+class CatalogTest extends TestCase {
+	use TempDirTrait;
+
+	private LocalBackend $backend;
+	private KeyRing $keys;
+	private ICatalogAnchor $anchor;
+	private string $root;
+	private string $src;
+
+	protected function setUp(): void {
+		$this->root = $this->tempDir();
+		$this->backend = new LocalBackend($this->root);
+		$this->keys = KeyRing::generate();
+		$this->anchor = new class implements ICatalogAnchor {
+			public array $data = [];
+			public function get(string $r): ?array { return $this->data[$r] ?? null; }
+			public function set(string $r, int $g, string $h): void { $this->data[$r] = ['gen' => $g, 'hash' => $h]; }
+		};
+		$this->src = $this->tempDir();
+		file_put_contents("$this->src/a", random_bytes(100000));
+	}
+
+	private function open(): Repository {
+		return Repository::openWithKey($this->backend, $this->keys, null, $this->anchor);
+	}
+
+	public function testNormalUseAdvancesTheChain(): void {
+		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'), $this->anchor);
+		$s1 = $repo->backupDirectory($this->src);
+		file_put_contents("$this->src/b", 'x');
+		$s2 = $repo->backupDirectory($this->src, $s1['snapshot']);
+		$repo->forget($s1['snapshot']);
+		$again = $this->open();
+		$this->assertSame([$s2['snapshot']], $again->listSnapshots());
+		$this->assertArrayHasKey($s1['snapshot'], $again->trash());
+		$this->assertSame(4, $again->catalogGeneration());
+	}
+
+	public function testRollbackIsDetected(): void {
+		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'), $this->anchor);
+		$repo->backupDirectory($this->src);
+		$repo->backupDirectory($this->src);
+		// The location "loses" the newest generation and presents an older, validly encrypted state.
+		$catalogs = $this->backend->list('catalog');
+		unlink($this->root . '/' . end($catalogs));
+		$this->expectException(RepositoryException::class);
+		$this->expectExceptionMessage('rolled back');
+		$this->open();
+	}
+
+	public function testHiddenSnapshotIsDetected(): void {
+		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'), $this->anchor);
+		$s = $repo->backupDirectory($this->src);
+		unlink($this->root . '/snapshots/' . $s['snapshot']);
+		$this->expectException(RepositoryException::class);
+		$this->open()->listSnapshots();
+	}
+
+	public function testSwappedGenerationIsRejected(): void {
+		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'), $this->anchor);
+		$repo->backupDirectory($this->src);
+		$repo->backupDirectory($this->src);
+		$c = $this->backend->list('catalog');
+		// Put generation 2's bytes where generation 3 should be.
+		copy($this->root . '/' . $c[1], $this->root . '/' . $c[2]);
+		$this->expectException(\RuntimeException::class);
+		$this->open();
+	}
+
+	public function testWithoutAnchorTheNewestChainIsAccepted(): void {
+		$repo = Repository::initWithKey($this->backend, $this->keys, $this->keys->wrap('pw'));
+		$s = $repo->backupDirectory($this->src);
+		// Disaster recovery on a new server: opened with the passphrase, no anchor.
+		$this->assertSame([$s['snapshot']], Repository::open($this->backend, 'pw')->listSnapshots());
+	}
+}

tests/Unit/Repository/PruneTest.php

@@ -0,0 +1,115 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\NgBackup\Tests\Unit\Repository;
+
+use OCA\NgBackup\Backend\LocalBackend;
+use OCA\NgBackup\Crypto\KeyRing;
+use OCA\NgBackup\Repository\Repository;
+use OCA\NgBackup\Tests\Unit\TempDirTrait;
+use PHPUnit\Framework\TestCase;
+
+class PruneTest extends TestCase {
+	use TempDirTrait;
+
+	private function du(LocalBackend $b): int {
+		$root = (new \ReflectionProperty(LocalBackend::class, 'root'))->getValue($b);
+		$total = 0;
+		foreach ($b->list('packs') as $p) {
+			$total += filesize("$root/$p");
+		}
+		return $total;
+	}
+
+	public function testForgetAndPruneFreesSpaceAndKeepsTheRest(): void {
+		$src = $this->tempDir();
+		$backend = new LocalBackend($this->tempDir());
+		$keys = KeyRing::generate();
+		$repo = Repository::initWithKey($backend, $keys, $keys->wrap('pw'));
+
+		file_put_contents("$src/keep.bin", random_bytes(6 * 1048576));
+		file_put_contents("$src/old.bin", random_bytes(40 * 1048576));
+		$old = $repo->backupDirectory($src);
+		unlink("$src/old.bin");
+		file_put_contents("$src/new.bin", random_bytes(3 * 1048576));
+		$new = $repo->backupDirectory($src, $old['snapshot']);
+		$expected = self::hashTree($src);
+		$before = $this->du($backend);
+
+		$dry = $repo->prune(true);
+		$this->assertSame(0, $dry['freedBytes'], 'nothing is unused while both snapshots exist');
+		$preview = $repo->prune(true, 0.5, [$old['snapshot']]);
+		$this->assertGreaterThan(35 * 1048576, $preview['freedBytes'], 'dry run can preview forgetting a snapshot');
+
+		$repo->forget($old['snapshot'], 'tester');
+		$this->assertSame(0, $repo->prune(true)['freedBytes'], 'a snapshot in the trash keeps its data');
+		$this->assertArrayHasKey($old['snapshot'], $repo->trash());
+		$this->assertSame([], $repo->purgeTrash(3600), 'not purged before the delay');
+		$this->assertSame([$old['snapshot']], $repo->purgeTrash(0));
+		$plan = $repo->prune(true);
+		$this->assertSame($plan, $repo->prune(true, 0.5, []));
+		$this->assertGreaterThan(35 * 1048576, $plan['freedBytes']);
+		$this->assertSame($before, $this->du($backend), 'dry run changes nothing');
+
+		$result = $repo->prune();
+		$this->assertGreaterThan(0, $result['deleted'] + $result['repacked']);
+		$this->assertLessThan($before - 35 * 1048576, $this->du($backend));
+
+		$reopened = Repository::openWithKey($backend, $keys);
+		$target = $this->tempDir();
+		$reopened->restore($new['snapshot'], $target);
+		$this->assertSame($expected, self::hashTree($target));
+		$this->assertSame([$new['snapshot']], $reopened->listSnapshots());
+	}
+
+	public function testRepackKeepsUsedBlobsOfMixedPacks(): void {
+		$src = $this->tempDir();
+		$backend = new LocalBackend($this->tempDir());
+		$keys = KeyRing::generate();
+		$repo = Repository::initWithKey($backend, $keys, $keys->wrap('pw'));
+		// Small files share packs: deleting most of them leaves mixed packs to repack.
+		for ($i = 0; $i < 40; $i++) {
+			file_put_contents("$src/f$i", random_bytes(500000));
+		}
+		$a = $repo->backupDirectory($src);
+		for ($i = 0; $i < 40; $i++) {
+			if ($i % 5 !== 0) {
+				unlink("$src/f$i");
+			}
+		}
+		$b = $repo->backupDirectory($src, $a['snapshot']);
+		$repo->forget($a['snapshot']);
+		$repo->purgeTrash(0);
+		$r = $repo->prune(false, 0.5);
+		$this->assertGreaterThan(0, $r['repacked']);
+		$target = $this->tempDir();
+		Repository::openWithKey($backend, $keys)->restore($b['snapshot'], $target);
+		$this->assertSame(self::hashTree($src), self::hashTree($target));
+	}
+
+	public function testUntrashRestoresAWorkingSnapshot(): void {
+		$src = $this->tempDir();
+		$backend = new LocalBackend($this->tempDir());
+		$keys = KeyRing::generate();
+		$repo = Repository::initWithKey($backend, $keys, $keys->wrap('pw'));
+		file_put_contents("$src/a", random_bytes(2 * 1048576));
+		$repo->putObject('db/x', '{"tables":{}}');
+		$s = $repo->backupDirectory($src);
+		$expected = self::hashTree($src);
+		unlink("$src/a");
+		file_put_contents("$src/b", 'other');
+		$s2 = $repo->backupDirectory($src, $s['snapshot']);
+
+		$repo->forget($s['snapshot'], 'attacker');
+		$this->assertNotContains($s['snapshot'], $repo->listSnapshots());
+		$repo->prune(); // must not free the trashed snapshot's data
+		$repo->untrash($s['snapshot']);
+		$this->assertContains($s['snapshot'], $repo->listSnapshots());
+		$this->assertSame([], $repo->trash());
+
+		$target = $this->tempDir();
+		Repository::openWithKey($backend, $keys)->restore($s['snapshot'], $target);
+		$this->assertSame($expected, self::hashTree($target));
+	}
+}

tests/Unit/Repository/RepositoryTest.php

@@ -120,4 +120,42 @@ class RepositoryTest extends TestCase {
 		$this->expectException(CryptoException::class);
 		$repo->getObject('db/2');
 	}
+
+	public function testSafePaths(): void {
+		foreach (['data/alice/files/a.txt', 'config/config.php', 'a b/c-d_e.f'] as $ok) {
+			$this->assertTrue(Repository::isSafePath($ok), $ok);
+		}
+		foreach (['', '/etc/passwd', '../x', 'a/../b', 'a/./b', 'a//b', 'a/', "a\0b", 'a\\b', "a\nb"] as $bad) {
+			$this->assertFalse(Repository::isSafePath($bad), json_encode($bad));
+		}
+	}
+
+	public function testMaliciousSnapshotPathIsRejectedOnRestore(): void {
+		$repo = Repository::init($this->backend, 'pw');
+		$stats = [];
+		$blob = $repo->storeData('evil', $stats);
+		$repo->flushPacks();
+		$repo->writeSnapshot('bad', ['time' => gmdate('c')], [json_encode(['p' => '../../escaped.txt', 's' => 4, 'm' => 0, 'b' => [$blob]])]);
+		$target = $this->tempDir() . '/inner';
+		mkdir($target);
+		try {
+			$repo->restore('bad', $target);
+			$this->fail('restore of a ../ path must fail');
+		} catch (RepositoryException) {
+		}
+		$this->assertFileDoesNotExist(dirname($target, 2) . '/escaped.txt');
+		$this->assertFileDoesNotExist(dirname($target) . '/escaped.txt');
+	}
+
+	public function testStorageLimitStopsTheBackup(): void {
+		$repo = Repository::init($this->backend, 'pw');
+		$repo->setMaxBytes(6 * 1048576); // less than the test tree
+		try {
+			$repo->backupDirectory($this->src);
+			$this->fail('backup should hit the limit');
+		} catch (\OCA\NgBackup\Repository\QuotaExceededException) {
+		}
+		$this->assertLessThanOrEqual(6 * 1048576, $repo->storedBytes());
+		$this->assertSame([], $repo->listSnapshots(), 'no snapshot from an incomplete backup');
+	}
 }

tests/Unit/Service/RetentionPolicyTest.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\NgBackup\Tests\Unit\Service;
+
+use OCA\NgBackup\Service\RetentionPolicy;
+use PHPUnit\Framework\TestCase;
+
+class RetentionPolicyTest extends TestCase {
+	public function testDailyWeeklyMonthly(): void {
+		$snaps = [];
+		$start = strtotime('2026-01-01 03:00:00');
+		for ($d = 0; $d < 120; $d++) {
+			$snaps["d$d"] = $start + $d * 86400;          // one per day for 120 days
+			$snaps["d$d-b"] = $start + $d * 86400 + 3600; // and a second one an hour later
+		}
+		$keep = (new RetentionPolicy(2, 7, 4, 3))->keep($snaps);
+		$this->assertArrayHasKey('d119-b', $keep, 'newest is always kept');
+		$this->assertArrayHasKey('d119', $keep, 'last=2');
+		$this->assertContains('daily', $keep['d113-b']);
+		$this->assertArrayNotHasKey('d113', $keep, 'only the newest of a day');
+		$this->assertLessThanOrEqual(2 + 7 + 4 + 3, count($keep));
+		$months = array_unique(array_map(fn ($id) => date('Y-m', $snaps[$id]), array_keys(array_filter($keep, fn ($r) => in_array('monthly', $r, true)))));
+		$this->assertCount(3, $months);
+	}
+
+	public function testKeepsEverythingWhenFewSnapshots(): void {
+		$keep = (new RetentionPolicy())->keep(['a' => 100, 'b' => 200]);
+		$this->assertSame(['a', 'b'], array_values(array_intersect(['a', 'b'], array_keys($keep))));
+	}
+}

tests/integration/matrix.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+# Local test matrix for NG Backup: fresh Nextcloud per (version, database), run the round trip, tear down.
+# Usage: tests/integration/matrix.sh "32 35" "sqlite mariadb pgsql"
+VERSIONS=${1:-"32 35"}; DBS=${2:-"sqlite mariadb pgsql"}
+APP=$(cd "$(dirname "$0")/../.." && pwd)
+RESULTS=()
+for v in $VERSIONS; do for db in $DBS; do
+  n=ngbm-$v-$db; net=$n-net
+  docker network create $net >/dev/null
+  env=(-e NEXTCLOUD_ADMIN_USER=admin -e NEXTCLOUD_ADMIN_PASSWORD=admin-matrix-pw -e NEXTCLOUD_TRUSTED_DOMAINS=localhost)
+  case $db in
+    sqlite) env+=(-e SQLITE_DATABASE=nextcloud) ;;
+    mariadb) docker run -d --name $n-db --network $net -e MARIADB_ROOT_PASSWORD=r -e MARIADB_DATABASE=nextcloud -e MARIADB_USER=nc -e MARIADB_PASSWORD=nc mariadb:11 --transaction-isolation=READ-COMMITTED --binlog-format=ROW >/dev/null
+             env+=(-e MYSQL_HOST=$n-db -e MYSQL_DATABASE=nextcloud -e MYSQL_USER=nc -e MYSQL_PASSWORD=nc) ;;
+    pgsql) docker run -d --name $n-db --network $net -e POSTGRES_DB=nextcloud -e POSTGRES_USER=nc -e POSTGRES_PASSWORD=nc postgres:16-alpine >/dev/null
+           env+=(-e POSTGRES_HOST=$n-db -e POSTGRES_DB=nextcloud -e POSTGRES_USER=nc -e POSTGRES_PASSWORD=nc) ;;
+  esac
+  [ "$db" != sqlite ] && sleep 8
+  docker run -d --name $n --network $net "${env[@]}" -v "$APP:/var/www/html/custom_apps/ng_backup:ro" nextcloud:$v-apache >/dev/null
+  for i in $(seq 1 90); do docker exec -u www-data $n php occ status 2>/dev/null | grep -q "installed: true" && break; sleep 4; done
+  docker exec $n chown www-data:www-data /var/www/html/custom_apps
+  echo "=== NC $v / $db: $(docker exec -u www-data $n php occ -V 2>/dev/null)"
+  if bash ${NGB_TRACE:+-x} "$APP/tests/integration/roundtrip.sh" "docker exec -u www-data $n" /var/www/html/data /var/www/html/custom_apps; then
+    RESULTS+=("NC $v / $db: PASS")
+  else
+    RESULTS+=("NC $v / $db: FAIL"); docker exec $n tail -c 2000 /var/www/html/data/nextcloud.log | tr ',' '\n' | grep -E '"message"' | tail -3
+  fi
+  # -v removes only these containers' own anonymous volumes (never a global prune)
+  docker rm -fv $n $n-db >/dev/null 2>&1; docker network rm $net >/dev/null
+done; done
+printf '%s\n' "${RESULTS[@]}"
+# Non-zero exit when any combination failed (CI).
+printf '%s\n' "${RESULTS[@]}" | grep -q FAIL && exit 1
+exit 0

tests/integration/roundtrip.sh

@@ -0,0 +1,71 @@
+#!/bin/bash
+# End-to-end round trip of NG Backup inside a Nextcloud installation (CI and local matrix).
+# Usage: roundtrip.sh "<command prefix to run occ/php as the web user in the instance>" <datadir> <apps-path> [target-args]
+#   e.g. roundtrip.sh "docker exec -u www-data ngb-nc35-pgsql" /var/www/html/data /var/www/html/custom_apps
+#   target-args defaults to a local files_external location; pass backend/auth/options to exercise
+#   a different backend (e.g. amazons3 or sftp), see tests/integration/targets-matrix.sh.
+set -euo pipefail
+X="$1"; DATA="$2"; APPS="$3"
+TARGET_ARGS="${4:-local -a null::null -o datadir=/tmp/ngb-rt-target}"
+occ() { $X php occ "$@"; }
+fail() { echo "FAIL: $*"; exit 1; }
+ok() { echo "ok   $*"; }
+U=ngbtest-$RANDOM
+
+occ app:enable ng_backup >/dev/null
+sleep 8 # APCu app config cache
+$X sh -c "printf 'roundtrip passphrase 2026\n' > /tmp/ngb-rt-pass && mkdir -p /tmp/ngb-rt-target"
+occ backup:key:init --passphrase-file=/tmp/ngb-rt-pass --label=CI --delete-delay-days=7 >/dev/null || fail "key init"
+CODE=$(occ backup:key:kit | php -r 'echo json_decode(stream_get_contents(STDIN), true)["confirmation_code"];')
+occ backup:key:confirm -u admin --code="$CODE" --confirm="Yes, I confirm" >/dev/null || fail "confirm"
+ok "key, kit code and confirmation"
+
+occ backup:target:add ci $TARGET_ARGS --path=repo >/dev/null || fail "target add"
+ok "location added"
+
+# Test data: a user with files.
+$X sh -c "OC_PASS='Roundtrip-pw-2026' php occ user:add --password-from-env $U >/dev/null"
+$X sh -c "mkdir -p $DATA/$U/files/Docs/Sub && for i in 1 2 3 4 5; do head -c 300000 /dev/urandom > $DATA/$U/files/Docs/f\$i.bin; done; echo hello > $DATA/$U/files/Docs/Sub/note.txt; head -c 6000000 /dev/urandom > $DATA/$U/files/big.bin"
+occ files:scan "$U" >/dev/null
+SUM_BEFORE=$($X sh -c "cd $DATA/$U/files && find . -type f -print0 | sort -z | xargs -0 md5sum | md5sum")
+
+occ backup:run ci -l first >/dev/null || fail "first backup"
+SECOND=$(occ backup:run ci -l second)
+echo "$SECOND" | tail -2 | head -1
+echo "$SECOND" | grep -qE "uploaded 0\.[0-9] MiB" || fail "unchanged second backup uploaded more than 1 MiB"
+ok "full backup and unchanged incremental backup"
+SNAP=$(occ backup:list ci | awk -F'|' '!f && / second /{gsub(/ /,"",$3); print $3; f=1}')
+[ -n "$SNAP" ] || fail "snapshot not listed"
+
+# Damage, then restore in each mode.
+$X sh -c "cd $DATA/$U/files && rm Docs/Sub/note.txt && echo broken > Docs/f1.bin && echo extra > Docs/extra.txt"
+occ files:scan "$U" >/dev/null
+occ backup:restore ci "$SNAP" "data/$U/files/Docs" -m new-folder >/dev/null || fail "restore new-folder"
+$X sh -c "ls $DATA/$U/files | grep -q '^Restored '" || fail "no Restored folder"
+occ backup:restore ci "$SNAP" "data/$U/files/Docs" -m replace >/dev/null || fail "restore replace"
+$X sh -c "rm -rf '$DATA/$U/files/Restored '*" ; occ files:scan "$U" >/dev/null
+SUM_AFTER=$($X sh -c "cd $DATA/$U/files && find . -type f -print0 | sort -z | xargs -0 md5sum | md5sum")
+[ "$SUM_BEFORE" = "$SUM_AFTER" ] || fail "files differ after restore"
+$X sh -c "ls $DATA/$U/files_trashbin/files/ | grep -q '^extra.txt'" || fail "extra file not in trash"
+ok "restore new-folder and replace: files identical, extra file in the trash"
+
+# Database dump/restore round trip (all tables, checksums, sequences on PostgreSQL).
+$X php -d memory_limit=512M "$APPS/ng_backup/spikes/03-db-dump.php" /tmp/ngb-rt-db | grep "ALL PASS" >/dev/null || fail "database round trip"
+ok "database dump and restore"
+
+# Retention, trash and catalog.
+occ backup:retention --last=1 --daily=0 --weekly=0 --monthly=0 >/dev/null
+occ backup:prune ci | grep "forgot 1" >/dev/null || fail "prune"
+occ backup:trash ci | grep " first " >/dev/null || fail "trash"
+TID=$(occ backup:trash ci | awk -F'|' '!f && / first /{gsub(/ /,"",$3); print $3; f=1}')
+occ backup:trash:restore ci "$TID" >/dev/null || fail "trash restore"
+[ "$(occ backup:list ci | grep -c ' ci ')" = "2" ] || fail "snapshot not back from the trash"
+ok "retention, trash and restore from trash"
+
+# No errors caused by loading files_external while it is disabled (its tables may not exist).
+if $X sh -c "grep -q 'external_mounts' $DATA/nextcloud.log 2>/dev/null"; then fail "files_external table errors in the log"; fi
+ok "no files_external errors in the log"
+
+occ user:delete "$U" >/dev/null
+$X sh -c "rm -rf /tmp/ngb-rt-target /tmp/ngb-rt-pass /tmp/ngb-rt-db"
+echo "ROUNDTRIP PASS"

tests/integration/targets-matrix.sh

@@ -0,0 +1,65 @@
+#!/bin/bash
+# Round trip of NG Backup against real S3 (s3mock) and SFTP backends, through files_external's own
+# backend/auth classes, same as a production location would use. Backend correctness does not
+# depend on the Nextcloud version or database, so this runs once (not matrixed across NC/DB),
+# on a recent Nextcloud with sqlite. Each backend gets its own fresh Nextcloud container, since
+# NG Backup's key can only be initialised once per instance.
+# Usage: tests/integration/targets-matrix.sh [nextcloud-version]
+set -euo pipefail
+V=${1:-35}
+APP=$(cd "$(dirname "$0")/../.." && pwd)
+NET=ngb-targets-net
+RESULTS=()
+
+cleanup() { docker rm -fv ngb-targets-nc-s3 ngb-targets-nc-sftp ngb-targets-s3 ngb-targets-sftp >/dev/null 2>&1; docker network rm "$NET" >/dev/null 2>&1; }
+trap cleanup EXIT
+
+wait_tcp() { # host port
+  docker run --rm --network "$NET" alpine:3 sh -c "for i in \$(seq 1 30); do nc -z $1 $2 2>/dev/null && exit 0; sleep 1; done; exit 1" \
+    || { echo "FAIL: $1:$2 never came up"; exit 1; }
+}
+
+start_nc() { # container-name
+  docker run -d --name "$1" --network "$NET" \
+    -e NEXTCLOUD_ADMIN_USER=admin -e NEXTCLOUD_ADMIN_PASSWORD=admin-targets-pw -e NEXTCLOUD_TRUSTED_DOMAINS=localhost \
+    -e SQLITE_DATABASE=nextcloud \
+    -v "$APP:/var/www/html/custom_apps/ng_backup:ro" nextcloud:$V-apache >/dev/null
+  for i in $(seq 1 90); do docker exec -u www-data "$1" php occ status 2>/dev/null | grep -q "installed: true" && break; sleep 4; done
+  docker exec "$1" chown www-data:www-data /var/www/html/custom_apps
+  echo "=== NC $V / sqlite ($1): $(docker exec -u www-data "$1" php occ -V 2>/dev/null)"
+}
+
+run() { # label, nc-container, target-args
+  echo "=== $1"
+  if bash ${NGB_TRACE:+-x} "$APP/tests/integration/roundtrip.sh" "docker exec -u www-data $2" /var/www/html/data /var/www/html/custom_apps "$3"; then
+    RESULTS+=("$1: PASS")
+  else
+    RESULTS+=("$1: FAIL")
+    docker exec "$2" tail -c 2000 /var/www/html/data/nextcloud.log | tr ',' '\n' | grep -E '"message"' | tail -3
+  fi
+}
+
+docker network create "$NET" >/dev/null
+
+# adobe/s3mock: an S3-compatible test server (MinIO's Docker Hub image now needs a paid login;
+# this one is freely pullable and pre-creates a bucket via INITIAL_BUCKETS, no auth to configure).
+docker run -d --name ngb-targets-s3 --network "$NET" \
+  -e INITIAL_BUCKETS=ngbackups \
+  adobe/s3mock >/dev/null
+
+# atmoz/sftp: "user:pass:::dir" creates /home/user/dir as the upload root.
+docker run -d --name ngb-targets-sftp --network "$NET" \
+  atmoz/sftp ngbackup:ngbackuppw:::upload >/dev/null
+
+wait_tcp ngb-targets-s3 9090
+wait_tcp ngb-targets-sftp 22
+
+start_nc ngb-targets-nc-s3
+run "S3 (s3mock)" ngb-targets-nc-s3 "amazons3 -a amazons3::accesskey -o bucket=ngbackups -o hostname=ngb-targets-s3 -o port=9090 -o region=us-east-1 -o use_ssl=false -o use_path_style=true -o key=test -o secret=test"
+
+start_nc ngb-targets-nc-sftp
+run "SFTP" ngb-targets-nc-sftp "sftp -a password::password -o host=ngb-targets-sftp -o root=/upload -o user=ngbackup -o password=ngbackuppw"
+
+printf '%s\n' "${RESULTS[@]}"
+printf '%s\n' "${RESULTS[@]}" | grep -q FAIL && exit 1
+exit 0