{% comment %}
Hidden server_key input shared by the sync-page action forms: carries the tab's
server scope on the POST so the handling view rebinds to it rather than the GLOBAL
selected server (with overlapping device_ids across servers, a fallback would fetch
and cache the WRONG server's device). Renders nothing when server_key is absent so
single-server deployments keep posting without it.
{% endcomment %}
{% if server_key %}<input type="hidden" name="server_key" value="{{ server_key }}">{% endif %}