Add basic CollectionItem model

app/models/collection.rb

@@ -21,6 +21,8 @@ class Collection < ApplicationRecord
   belongs_to :account
   belongs_to :tag, optional: true
 
+  has_many :collection_items, dependent: :delete_all
+
   validates :name, presence: true
   validates :description, presence: true
   validates :uri, presence: true, if: :remote?

app/models/collection_item.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: collection_items
+#
+#  id                        :bigint(8)        not null, primary key
+#  activity_uri              :string
+#  approval_last_verified_at :datetime
+#  approval_uri              :string
+#  object_uri                :string
+#  position                  :integer          default(1), not null
+#  state                     :integer          default("pending"), not null
+#  created_at                :datetime         not null
+#  updated_at                :datetime         not null
+#  account_id                :bigint(8)
+#  collection_id             :bigint(8)        not null
+#
+class CollectionItem < ApplicationRecord
+  belongs_to :collection
+  belongs_to :account, optional: true
+
+  enum :state,
+       { pending: 0, accepted: 1, rejected: 2, revoked: 3 },
+       validate: true
+
+  delegate :local?, :remote?, to: :collection
+
+  validates :position, numericality: { only_integer: true, greater_than: 0 }
+  validates :activity_uri, presence: true, if: :local_item_with_remote_account?
+  validates :account, presence: true, if: :accepted?
+  validates :object_uri, presence: true, if: -> { account.nil? }
+
+  scope :ordered, -> { order(position: :asc) }
+
+  def local_item_with_remote_account?
+    local? && account&.remote?
+  end
+end

app/models/concerns/account/associations.rb

@@ -13,6 +13,8 @@ module Account::Associations
         has_many :account_warnings
         has_many :aliases, class_name: 'AccountAlias'
         has_many :bookmarks
+        has_many :collections
+        has_many :collection_items
         has_many :conversations, class_name: 'AccountConversation'
         has_many :custom_filters
         has_many :favourites

db/migrate/20251119093332_create_collection_items.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class CreateCollectionItems < ActiveRecord::Migration[8.0]
+  def change
+    create_table :collection_items do |t|
+      t.references :collection, null: false, foreign_key: { on_delete: :cascade }
+      t.references :account, foreign_key: true
+      t.integer :position, null: false, default: 1
+      t.string :object_uri, index: { unique: true, where: 'activity_uri IS NOT NULL' }
+      t.string :approval_uri, index: { unique: true, where: 'approval_uri IS NOT NULL' }
+      t.string :activity_uri
+      t.datetime :approval_last_verified_at
+      t.integer :state, null: false, default: 0
+
+      t.timestamps
+    end
+  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_18_115657) do
+ActiveRecord::Schema[8.0].define(version: 2025_11_19_093332) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
 
@@ -351,6 +351,23 @@ ActiveRecord::Schema[8.0].define(version: 2025_11_18_115657) do
     t.index ["reference_account_id"], name: "index_canonical_email_blocks_on_reference_account_id"
   end
 
+  create_table "collection_items", force: :cascade do |t|
+    t.bigint "collection_id", null: false
+    t.bigint "account_id"
+    t.integer "position", default: 1, null: false
+    t.string "object_uri"
+    t.string "approval_uri"
+    t.string "activity_uri"
+    t.datetime "approval_last_verified_at"
+    t.integer "state", default: 0, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["account_id"], name: "index_collection_items_on_account_id"
+    t.index ["approval_uri"], name: "index_collection_items_on_approval_uri", unique: true, where: "(approval_uri IS NOT NULL)"
+    t.index ["collection_id"], name: "index_collection_items_on_collection_id"
+    t.index ["object_uri"], name: "index_collection_items_on_object_uri", unique: true, where: "(activity_uri IS NOT NULL)"
+  end
+
   create_table "collections", force: :cascade do |t|
     t.bigint "account_id", null: false
     t.string "name", null: false
@@ -1402,6 +1419,8 @@ ActiveRecord::Schema[8.0].define(version: 2025_11_18_115657) do
   add_foreign_key "bulk_import_rows", "bulk_imports", on_delete: :cascade
   add_foreign_key "bulk_imports", "accounts", on_delete: :cascade
   add_foreign_key "canonical_email_blocks", "accounts", column: "reference_account_id", on_delete: :cascade
+  add_foreign_key "collection_items", "accounts"
+  add_foreign_key "collection_items", "collections", on_delete: :cascade
   add_foreign_key "collections", "accounts"
   add_foreign_key "collections", "tags"
   add_foreign_key "conversation_mutes", "accounts", name: "fk_225b4212bb", on_delete: :cascade

spec/fabricators/account_fabricator.rb

@@ -17,3 +17,7 @@ Fabricator(:account) do
   discoverable        true
   indexable           true
 end
+
+Fabricator(:remote_account, from: :account) do
+  domain 'example.com'
+end

spec/fabricators/collection_item_fabricator.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+Fabricator(:collection_item) do
+  collection                { Fabricate.build(:collection) }
+  account                   { Fabricate.build(:account) }
+  position                  1
+  state                     :accepted
+end
+
+Fabricator(:unverified_remote_collection_item, from: :collection_item) do
+  account nil
+  object_uri { Fabricate.build(:remote_account).uri }
+  approval_uri { sequence(:uri) { |i| "https://example.com/authorizations/#{i}" } }
+end

spec/models/collection_item_spec.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe CollectionItem do
+  describe 'Validations' do
+    subject { Fabricate.build(:collection_item) }
+
+    it { is_expected.to define_enum_for(:state) }
+
+    it { is_expected.to validate_numericality_of(:position).only_integer.is_greater_than(0) }
+
+    context 'when account inclusion is accepted' do
+      subject { Fabricate.build(:collection_item, state: :accepted) }
+
+      it { is_expected.to validate_presence_of(:account) }
+    end
+
+    context 'when item is local and account is remote' do
+      subject { Fabricate.build(:collection_item, account: remote_account) }
+
+      let(:remote_account) { Fabricate.build(:remote_account) }
+
+      it { is_expected.to validate_presence_of(:activity_uri) }
+    end
+
+    context 'when account is not present' do
+      subject { Fabricate.build(:unverified_remote_collection_item) }
+
+      it { is_expected.to validate_presence_of(:object_uri) }
+    end
+  end
+end