Many thx. As a workaround, i have now created 2 systemd units:

Service Unit: nc_scanfolder.service

[Unit]
Description=Starts scanning the folder
After=network.target

[Service]
Type=oneshot
User=www-data
ExecStartPre=/usr/bin/sleep 10
ExecStart=/usr/bin/php /var/www/nextcloud/occ files:scan --path="/username/files/folder"

and Path Unit: nc_scanfolder.path

[Unit]
Description=Checks for changes

[Path]
PathChanged=/mnt/external/storage/folder
Unit=nc_scanfolder.service
TriggerLimitIntervalSec=30
TriggerLimitBurst=1

[Install]
WantedBy=multi-user.target

This works fine so far. If a file changes in this folder, the scan will be initialized. To prevent running the scan to often for to much changes, i have added a delay of 10 seconds in the service unit and a burst limit in the path unit. With this, multiple changes are bundled in 1 scan. At least, its a workaround. I dont know if there are better ways to do this.

For me, WebDAV is just a workaround, since it’s the only way I can sync files even without Wi-Fi and while on the go. But here’s an idea: Is there a way to send some kind of webhook to Nextcloud that would trigger the scan? Then, after editing in Roundcube or running an rsync, I could send a REST request that would initiate the scan. Since I developed the Roundcube plugin myself, I can integrate that whenever I want and, if necessary, delay it to capture multiple changes. Of course, this only works if there’s a corresponding feature in Nextcloud.

On the Desktop I’m using Obsidian and sync via rsync. On Android also Obsidian, but sync via WebDAV. On the web im using my own plug-in for roundcube and edit it directly on the external storage

Maybe, but the Markdown editor in “Text” is horrible.

DMS = Document Management System. Something like Paperless-ngx, but easier…