## Problem/motivation The Tagify settings page (`/admin/config/tagify/settings`) has a checkbox called "Set Tagify widget as default". When it's on, every new entity reference field gets the Tagify widget. There is no matching option for the Tagify User List widget (`tagify_user_list` submodule). Site builders who want it on their user reference fields have to change the widget by hand on each one. The existing checkbox can't be reused for this. It uses `hook_field_info_alter()`, which changes the default widget for the whole `entity_reference` field type. That hook doesn't know what the field points to, so it can't treat user reference fields differently from the others. ### Steps to reproduce 1. Install Tagify `2.0.x` and enable the `tagify_user_list` submodule. 2. Go to `/admin/config/tagify/settings`. Only one checkbox is there. 3. Add a new field to a content type and pick **Reference \> User**. 4. Check the form display for the new field. **Expected:** You can choose to get the Tagify User List widget automatically. **Actual:** The field gets the core autocomplete widget, or the plain Tagify widget if the existing checkbox is on. ## Proposed resolution Add a second setting, owned by the `tagify_user_list` submodule: "Set Tagify User List widget as default for user reference fields". - Store it in a new `tagify_user_list.settings` config object, with a schema and a default of `FALSE`. - Add the checkbox to the existing Tagify settings form with `hook_form_tagify_settings_alter()`. This way it only shows up when the submodule is enabled. - Implement `hook_field_ui_preconfigured_options_alter()`. For the `entity_reference` field type, set `entity_form_display.type` to `tagify_user_list_entity_reference_autocomplete_widget` on the `user` option. Core builds one option for each common reference target (see `EntityReferenceItem::getPreconfiguredOptions()`). Field UI applies the widget when the field is created (see `FieldStorageAddForm::getNewFieldDefaults()`). If both checkboxes are on, user reference fields get the User List widget and all other reference fields get the plain Tagify widget. Options we rejected: - **Reusing `hook_field_info_alter()`:** It works on the field type, not the target type, so it can't single out user references. - **Changing the form display when a field is saved** (for example in `hook_field_config_insert()`): This would also affect fields made by code, recipes, or config import. That could surprise people. The Field UI option only affects fields a person creates in the UI. Limits: like the existing checkbox, this only affects **new** fields created through Field UI with the "User" reference option. Existing fields and fields created in code stay as they are. ## Remaining tasks - [x] Agree on the approach. - [x] Write the merge request. - [x] Add a test: with the setting on, a new user reference field created through Field UI uses the Tagify User List widget. With it off, it doesn't. - [x] Code review. ## User interface changes There is a new checkbox on `/admin/config/tagify/settings` when `tagify_user_list` is enabled: > **Set Tagify User List widget as default for user reference fields** Enable this option to use the Tagify User List widget for new fields that reference users. ## API changes There is a new hook implementation of `hook_field_ui_preconfigured_options_alter()` in `tagify_user_list`. No public APIs change and nothing breaks backwards compatibility. ## Data model changes There is a new `tagify_user_list.settings` config object with one boolean key, `set_default_widget`, plus its schema. Sites that already have the submodule enabled get it through an update hook. The code also treats a missing value as `FALSE`, so nothing breaks before the update runs.