Elementor: register a Dynamic Tag

For developers shipping a companion plugin that adds Dynamic Tags — "show this product's shipping class", "this user's last order total", "this course's progress %". The dynamic-tags infrastructure (base classes, the registration manager, the hooks, the category/group system) ships in free Elementor under Elementor\Core\DynamicTags\*; this skill is the stable extension contract for registering your own tags against it. It does not cover building the tag's controls/fallback (see elementor-dynamic-tag-fields) or AJAX pickers (see elementor-dynamic-tag-ajax-select).

The Pro-feature reality (read this first)

The user's instinct that "dynamic tags are a Pro feature" is half-right, and the distinction matters:

• The API is in free Elementor — \Elementor\Core\DynamicTags\Tag, Data_Tag, Base_Tag, the Manager, the elementor/dynamic_tags/register hook, and the category constants all live in the free plugin. Your tag classes compile and register without Pro.
• Free Elementor registers zero tags of its own — Module::get_tag_classes_names() returns [] (modules/dynamic-tags/module.php:116-118) and only one group, "Base Tags" (module.php:130-136).
• Pro ships ~34 tags plus 8 groups, every one gated behind a license check — API::is_licence_has_feature( 'dynamic-tags', … ) (elementor-pro/modules/dynamic-tags/module.php:97).
• The AJAX query control (QueryControlModule::QUERY_CONTROL_ID) used to pick from large datasets is Pro-only. Without Pro you fall back to a manual field — see elementor-dynamic-tag-ajax-select.

Practical rule: build for "Elementor active, Pro likely present", feature-detect Pro-only pieces, and degrade gracefully. The reference plugin does exactly this with a has_query_control_support() check before using the Pro autocomplete control.

Misconception this skill corrects

"I'll register my tag with add_action( 'elementor/dynamic_tags/register_tags', … ) and $manager->register_tag( MyTag::class ) like the old tutorials show."