# Nextcloud File Locking

## Problem

When two users open the same file simultaneously via the desktop sync client, both can write to it, resulting in sync conflicts.

## Solution

Two plugins work together to prevent this:

- [**files_lock**](https://apps.nextcloud.com/apps/files_lock) — implements WebDAV locking (RFC 4918). When a user opens a file via the desktop client, a lock is acquired server-side. Other clients see the file as locked and cannot write to it.
- [**notify_push**](https://apps.nextcloud.com/apps/notify_push) — pushes lock state changes to clients in real time, so they don't have to wait for the next poll cycle to discover a lock.

## Installation

```bash
docker exec -u www-data <nextcloud-container> php occ app:install files_lock
docker exec -u www-data <nextcloud-container> php occ app:install notify_push
```

Follow the `notify_push` setup guide to expose the push daemon via Traefik.

## Limitations

- Conflicts are theoretically still possible, but the chances are minimized.
- Locks are per-session; if a client crashes without releasing the lock, the file may appear locked until the lock expires (default: 30 minutes, can be configured).