Emoji: Update emoji categories with featured emoji (#37084)

app/javascript/mastodon/api_types/custom_emoji.ts

@@ -1,8 +1,9 @@
-// See app/serializers/rest/account_serializer.rb
+// See app/serializers/rest/custom_emoji_serializer.rb
 export interface ApiCustomEmojiJSON {
   shortcode: string;
   static_url: string;
   url: string;
   category?: string;
+  featured?: boolean;
   visible_in_picker: boolean;
 }

app/javascript/mastodon/models/custom_emoji.ts

@@ -11,6 +11,7 @@ export const CustomEmojiFactory = ImmutableRecord<CustomEmojiShape>({
   static_url: '',
   url: '',
   category: '',
+  featured: false,
   visible_in_picker: false,
 });
 

app/models/custom_emoji.rb

@@ -66,6 +66,10 @@ class CustomEmoji < ApplicationRecord
     :emoji
   end
 
+  def featured?
+    category&.featured_emoji_id == id
+  end
+
   def copy!
     copy = self.class.find_or_initialize_by(domain: nil, shortcode: shortcode)
     copy.image = image

app/models/custom_emoji_category.rb

@@ -8,10 +8,12 @@
 #  name              :string
 #  created_at        :datetime         not null
 #  updated_at        :datetime         not null
+#  featured_emoji_id :bigint(8)
 #
 
 class CustomEmojiCategory < ApplicationRecord
   has_many :emojis, class_name: 'CustomEmoji', foreign_key: 'category_id', inverse_of: :category, dependent: nil
+  belongs_to :featured_emoji, class_name: 'CustomEmoji', optional: true, inverse_of: :category
 
   validates :name, presence: true, uniqueness: true
 

app/serializers/rest/custom_emoji_serializer.rb

@@ -8,6 +8,7 @@ class REST::CustomEmojiSerializer < ActiveModel::Serializer
   attributes :shortcode, :url, :static_url, :visible_in_picker
 
   attribute :category, if: :category_loaded?
+  attribute :featured, if: :category_loaded?
 
   def url
     full_asset_url(object.image.url)
@@ -21,6 +22,10 @@ class REST::CustomEmojiSerializer < ActiveModel::Serializer
     object.category.name
   end
 
+  def featured
+    object.featured?
+  end
+
   def category_loaded?
     object.association(:category).loaded? && object.category.present?
   end

db/migrate/20251201154910_add_featured_emoji_to_custom_emoji_categories.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class AddFeaturedEmojiToCustomEmojiCategories < ActiveRecord::Migration[8.0]
+  def change
+    add_column :custom_emoji_categories, :featured_emoji_id, :bigint, null: true
+    add_foreign_key :custom_emoji_categories, :custom_emojis, column: :featured_emoji_id, on_delete: :nullify, validate: false
+  end
+end

db/migrate/20251201155054_validate_add_featured_emoji_to_custom_emoji_categories.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class ValidateAddFeaturedEmojiToCustomEmojiCategories < ActiveRecord::Migration[8.0]
+  def change
+    validate_foreign_key :custom_emoji_categories, :custom_emojis
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_11_19_093332) do
+ActiveRecord::Schema[8.0].define(version: 2025_12_01_155054) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
 
@@ -404,6 +404,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_11_19_093332) do
     t.string "name"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
+    t.bigint "featured_emoji_id"
     t.index ["name"], name: "index_custom_emoji_categories_on_name", unique: true
   end
 
@@ -1426,6 +1427,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_11_19_093332) do
   add_foreign_key "collections", "tags"
   add_foreign_key "conversation_mutes", "accounts", name: "fk_225b4212bb", on_delete: :cascade
   add_foreign_key "conversation_mutes", "conversations", on_delete: :cascade
+  add_foreign_key "custom_emoji_categories", "custom_emojis", column: "featured_emoji_id", on_delete: :nullify
   add_foreign_key "custom_filter_keywords", "custom_filters", on_delete: :cascade
   add_foreign_key "custom_filter_statuses", "custom_filters", on_delete: :cascade
   add_foreign_key "custom_filter_statuses", "statuses", on_delete: :cascade