Read a page category in a template

The page controller supplies id. Resolve its category directly:

{% with id.category_id as category_id %}
    <p>{{ category_id.title }}</p>
{% endwith %}

Use id.is_a.article for an inherited category test, replacing article with your category's name. To select category-specific rendering, prefer tag#catinclude over a long chain of category conditions.

A page URL is not a reliable category identifier: custom paths, language prefixes and dispatch rules can change its shape. For a value from a request, resolve it through m.rsc[value].id and handle a missing resource before reading properties.