Add a filter or rendering component

Use a scomp when rendering needs arguments, context, or more substantial server work. Follow an existing scomp's callback contract and declare caching behavior deliberately.

Place the implementation in the application's src/filters or src/scomps directory and follow Zotonic naming conventions. Compile and confirm discovery before changing templates to depend on it.

A complete filter example in src/filters/filter_garden_label.erl:

-module(filter_garden_label).
-export([garden_label/2]).

-spec garden_label(Value, Context) -> binary()
    when Value :: term(), Context :: z:context().
garden_label(<<"open">>, _Context) -> <<"Open to visitors">>;
garden_label(_Value, _Context) -> <<"Check visiting times">>.

Compile it and render {{ "open"|garden_label|escape }}. Expect “Open to visitors”; a missing value should produce the fallback. These fixed English labels illustrate the callback only: use translation support for real interface labels.

For a scomp, use the current zotonic_scomp behaviour and its render/3 callback, not the old gen_scomp behaviour. Start with the source of scomp#button for a maintained example that queues browser actions.