Use registry for associated journal objects, not hard coded map

app/services/journals/create_service/association.rb

@@ -32,19 +32,20 @@ class Journals::CreateService
   class Association
     include Helpers
 
-    ASSOCIATION_NAMES = %i[
-      AgendaItemable
-      Attachable
-      CustomComment
-      Customizable
-      ProjectPhase
-      Storable
-    ].freeze
+    # Core associations are defined here. Module-specific associations can be defined in engines
+    # using `Journals::CreateService::Association.register`.
+    @registry = Set.new(%i[Attachable CustomComment Customizable ProjectPhase])
 
-    def self.for(journable)
-      ASSOCIATION_NAMES
-        .map { "Journals::CreateService::#{it}".constantize.new(journable) }
-        .select(&:associated?)
+    class << self
+      def register(*names)
+        @registry.merge(names.map(&:to_sym))
+      end
+
+      def for(journable)
+        @registry
+          .map { "Journals::CreateService::#{it}".constantize.new(journable) }
+          .select(&:associated?)
+      end
     end
 
     attr_reader :journable

modules/meeting/lib/open_project/meeting/engine.rb

@@ -195,6 +195,8 @@ module OpenProject::Meeting
       ::Exports::Register.register do
         single(::Meeting, Meetings::Exporter)
       end
+
+      Journals::CreateService::Association.register(:AgendaItemable)
     end
 
     add_api_path :meetings do

modules/storages/lib/open_project/storages/engine.rb

@@ -256,6 +256,8 @@ module OpenProject::Storages
 
     # This hook is executed when the module is loaded.
     config.to_prepare do
+      Journals::CreateService::Association.register(:Storable)
+
       # Load Storages::Storage descendants due to STI
       Storages::Storage::InexistentStorage
       Storages::OneDriveStorage

spec/services/journals/create_service/association_spec.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require "spec_helper"
+
+RSpec.describe Journals::CreateService::Association do
+  describe ".register" do
+    around do |example|
+      original = described_class.instance_variable_get(:@registry).dup
+      example.run
+    ensure
+      described_class.instance_variable_set(:@registry, original)
+    end
+
+    it "adds a new name to the registry" do
+      expect { described_class.register(:NewAssociation) }
+        .to change { described_class.instance_variable_get(:@registry) }
+        .to include(:NewAssociation)
+    end
+
+    it "is idempotent — duplicate registrations are ignored" do
+      described_class.register(:NewAssociation)
+      expect { described_class.register(:NewAssociation) }
+        .not_to change { described_class.instance_variable_get(:@registry).size }
+    end
+
+    it "accepts strings and coerces them to symbols" do
+      described_class.register("NewAssociation")
+      expect(described_class.instance_variable_get(:@registry)).to include(:NewAssociation)
+    end
+  end
+
+  describe ".for" do
+    it "includes core associations for any journable" do
+      journable = instance_double(WorkPackage, customizable?: true, respond_to?: false)
+      allow(journable).to receive(:respond_to?).with(:attachable?).and_return(true)
+      allow(journable).to receive(:respond_to?).with(:custom_comments).and_return(false)
+      allow(journable).to receive(:respond_to?).with(:file_links).and_return(false)
+      allow(journable).to receive(:respond_to?).with(:agenda_items).and_return(false)
+      allow(journable).to receive(:respond_to?).with(:phases).and_return(false)
+
+      associations = described_class.for(journable)
+      expect(associations.map(&:class)).to include(Journals::CreateService::Attachable)
+    end
+
+    it "excludes associations whose #associated? returns false" do
+      journable = instance_double(WorkPackage, customizable?: false, respond_to?: false)
+      allow(journable).to receive(:respond_to?).and_return(false)
+
+      associations = described_class.for(journable)
+      expect(associations).to be_empty
+    end
+  end
+end