diff --git a/frontend/src/turbo/action-menu-morph-remount.ts b/frontend/src/turbo/action-menu-morph-remount.ts
new file mode 100644
index 000000000000..29266102da88
--- /dev/null
+++ b/frontend/src/turbo/action-menu-morph-remount.ts
@@ -0,0 +1,60 @@
+/*
+ * -- 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.
+ * ++
+ */
+
+/**
+ * Primer `<action-menu>` with `src` (via `Primer::Alpha::ActionMenu`) lazy loads
+ * the menu items via `<include-fragment>`.
+ * It registers `include-fragment-replaced` only in `connectedCallback`, while Turbo
+ * Idiomorph can leave the same `<action-menu>` host connected while swapping
+ * in a new `<include-fragment>`. Since the `<action-menu>` is not replaced, the fragment
+ * replaced event is never fired, the component will stay in a loading state after morph.
+ *
+ * Replacing each affected `<action-menu>` host forces `connectedCallback` and
+ * a correct listener. We hook `turbo:morph-element` so this applies to turbo-stream
+ * morph, frame morph, and full-page morph alike.
+ */
+
+interface TurboMorphElementDetail {
+  currentElement:HTMLElement;
+  newElement:HTMLElement;
+}
+
+export function registerActionMenuMorphRemount():void {
+  document.addEventListener('turbo:morph-element', (event:Event) => {
+    const { detail } = event as CustomEvent<TurboMorphElementDetail>;
+    const currentElement = detail?.currentElement;
+    if (!currentElement?.matches('action-menu:has(include-fragment[src])')) {
+      return;
+    }
+
+    const clone = currentElement.cloneNode(true);
+    currentElement.replaceWith(clone);
+  });
+}
diff --git a/frontend/src/turbo/setup.ts b/frontend/src/turbo/setup.ts
index c384b98ab41b..2b1f597f3a79 100644
--- a/frontend/src/turbo/setup.ts
+++ b/frontend/src/turbo/setup.ts
@@ -11,6 +11,7 @@ import { debugLog, whenDebugging } from 'core-app/shared/helpers/debug_output';
 import { TURBO_EVENTS } from './constants';
 import { StreamActions } from '@hotwired/turbo';
 import { addTurboAngularWrapper } from 'core-turbo/turbo-angular-wrapper';
+import { registerActionMenuMorphRemount } from './action-menu-morph-remount';
 
 Turbo.session.drive = true;
 Turbo.config.drive.progressBarDelay = 100;
@@ -37,6 +38,7 @@ whenDebugging(() => {
 // Register our own actions
 addTurboEventListeners();
 addTurboGlobalListeners();
+registerActionMenuMorphRemount();
 registerDialogStreamAction();
 registerFlashStreamAction();
 registerLiveRegionStreamAction();
diff --git a/modules/backlogs/app/components/backlogs/backlog_component.html.erb b/modules/backlogs/app/components/backlogs/backlog_component.html.erb
index dd18db687a75..5ce7f8ffec2c 100644
--- a/modules/backlogs/app/components/backlogs/backlog_component.html.erb
+++ b/modules/backlogs/app/components/backlogs/backlog_component.html.erb
@@ -56,7 +56,7 @@ See COPYRIGHT and LICENSE files for more details.
            ),
            tabindex: 0
          ) do %>
-        <%= render(Backlogs::StoryComponent.new(story:, project:, sprint:, max_position:)) %>
+        <%= render(Backlogs::StoryComponent.new(story:, project:, sprint:)) %>
       <% end %>
     <% end %>
   <% end %>
diff --git a/modules/backlogs/app/components/backlogs/backlog_component.rb b/modules/backlogs/app/components/backlogs/backlog_component.rb
index 888de7921d63..5d17e318a82f 100644
--- a/modules/backlogs/app/components/backlogs/backlog_component.rb
+++ b/modules/backlogs/app/components/backlogs/backlog_component.rb
@@ -65,10 +65,6 @@ def folded?
       current_user.backlogs_preference(:versions_default_fold_state) == "closed"
     end
 
-    def max_position
-      stories.filter_map(&:position).max
-    end
-
     def drop_target_config
       {
         generic_drag_and_drop_target: "container",
diff --git a/modules/backlogs/app/components/backlogs/inbox_component.html.erb b/modules/backlogs/app/components/backlogs/inbox_component.html.erb
index 81a3d13708a6..9165cd7de7f7 100644
--- a/modules/backlogs/app/components/backlogs/inbox_component.html.erb
+++ b/modules/backlogs/app/components/backlogs/inbox_component.html.erb
@@ -76,9 +76,7 @@ See COPYRIGHT and LICENSE files for more details.
     <%= render Backlogs::InboxItemComponent.with_collection(
           paginate? ? first_page : work_packages,
           container: border_box,
-          project:,
-          max_position:,
-          open_sprints_exist:
+          project:
         ) %>
 
     <% if paginate? %>
@@ -110,9 +108,7 @@ See COPYRIGHT and LICENSE files for more details.
       <%= render Backlogs::InboxItemComponent.with_collection(
             last_page,
             container: border_box,
-            project:,
-            max_position:,
-            open_sprints_exist:
+            project:
           ) %>
     <% end %>
   <% end %>
diff --git a/modules/backlogs/app/components/backlogs/inbox_component.rb b/modules/backlogs/app/components/backlogs/inbox_component.rb
index bce41a65225f..6749070823dd 100644
--- a/modules/backlogs/app/components/backlogs/inbox_component.rb
+++ b/modules/backlogs/app/components/backlogs/inbox_component.rb
@@ -38,16 +38,15 @@ class InboxComponent < ApplicationComponent
     FIRST_PAGE_SIZE = 50
     LAST_PAGE_SIZE = 10
 
-    attr_reader :work_packages, :project, :current_user, :show_all, :open_sprints_exist
+    attr_reader :work_packages, :project, :current_user, :show_all
 
-    def initialize(work_packages:, project:, open_sprints_exist:, show_all: false, current_user: User.current, **system_arguments)
+    def initialize(work_packages:, project:, show_all: false, current_user: User.current, **system_arguments)
       super()
 
       @work_packages = work_packages
       @project = project
       @show_all = show_all
       @current_user = current_user
-      @open_sprints_exist = open_sprints_exist
 
       @system_arguments = system_arguments
       @system_arguments[:id] = inbox_dom_id
@@ -100,9 +99,5 @@ def drop_target_config
         target_allowed_drag_type: "story"
       }
     end
-
-    def max_position
-      work_packages.maximum(:position)
-    end
   end
 end
diff --git a/modules/backlogs/app/components/backlogs/inbox_item_component.html.erb b/modules/backlogs/app/components/backlogs/inbox_item_component.html.erb
index 984d03e2ecdb..b56c2466e644 100644
--- a/modules/backlogs/app/components/backlogs/inbox_item_component.html.erb
+++ b/modules/backlogs/app/components/backlogs/inbox_item_component.html.erb
@@ -49,12 +49,21 @@ See COPYRIGHT and LICENSE files for more details.
       <% end %>
     <% end %>
     <% grid.with_area(:menu) do %>
-      <%= render Backlogs::InboxMenuComponent.new(
-            work_package:,
-            project:,
-            max_position:,
-            open_sprints_exist:
-          ) %>
+      <%= render(
+            Primer::Alpha::ActionMenu.new(
+              menu_id: dom_target(work_package, :menu),
+              src: menu_project_inbox_path(project, work_package),
+              anchor_align: :end,
+              classes: "hide-when-print"
+            )
+          ) do |menu| %>
+        <% menu.with_show_button(
+             scheme: :invisible,
+             icon: :"kebab-horizontal",
+             "aria-label": t(".label_actions"),
+             tooltip_direction: :se
+           ) %>
+      <% end %>
     <% end %>
     <% grid.with_area(:subject) do %>
       <%= render(Primer::Beta::Text.new(font_weight: :semibold)) { work_package.subject } %>
diff --git a/modules/backlogs/app/components/backlogs/inbox_item_component.rb b/modules/backlogs/app/components/backlogs/inbox_item_component.rb
index 554fbf45cd58..bad17f8b371d 100644
--- a/modules/backlogs/app/components/backlogs/inbox_item_component.rb
+++ b/modules/backlogs/app/components/backlogs/inbox_item_component.rb
@@ -32,17 +32,14 @@ module Backlogs
   class InboxItemComponent < ApplicationComponent
     include OpPrimer::ComponentHelpers
 
-    attr_reader :work_package, :project, :container, :max_position, :current_user, :open_sprints_exist
+    attr_reader :work_package, :project, :container, :current_user
 
-    def initialize(inbox_item:, project:, container:, max_position:, open_sprints_exist:,
-                   current_user: User.current)
+    def initialize(inbox_item:, project:, container:, current_user: User.current)
       super()
 
       @work_package = inbox_item
       @project = project
       @container = container
-      @max_position = max_position
-      @open_sprints_exist = open_sprints_exist
       @current_user = current_user
     end
 
diff --git a/modules/backlogs/app/components/backlogs/inbox_menu_component.html.erb b/modules/backlogs/app/components/backlogs/inbox_menu_component.html.erb
index 0d6614f107b1..94fd84e98f91 100644
--- a/modules/backlogs/app/components/backlogs/inbox_menu_component.html.erb
+++ b/modules/backlogs/app/components/backlogs/inbox_menu_component.html.erb
@@ -28,15 +28,8 @@ See COPYRIGHT and LICENSE files for more details.
 ++# %>
 
 <%=
-  render(Primer::Alpha::ActionMenu.new(**@system_arguments)) do |menu|
-    menu.with_show_button(
-      scheme: :invisible,
-      icon: :"kebab-horizontal",
-      "aria-label": t(".label_actions"),
-      tooltip_direction: :se
-    )
-
-    menu.with_item(
+  render(Primer::Alpha::ActionMenu::List.new(menu_id:)) do |list|
+    list.with_item(
       id: dom_target(work_package, :menu, :open_details),
       tag: :a,
       label: t(:"js.button_open_details"),
@@ -46,7 +39,7 @@ See COPYRIGHT and LICENSE files for more details.
       item.with_leading_visual_icon(icon: :"op-view-split")
     end
 
-    menu.with_item(
+    list.with_item(
       id: dom_target(work_package, :menu, :open_fullscreen),
       tag: :a,
       label: t(:"js.button_open_fullscreen"),
@@ -56,7 +49,7 @@ See COPYRIGHT and LICENSE files for more details.
       item.with_leading_visual_icon(icon: :"screen-full")
     end
 
-    menu.with_item(
+    list.with_item(
       id: dom_target(work_package, :menu, :copy_url_to_clipboard),
       tag: :"clipboard-copy",
       label: t(".action_menu.copy_url_to_clipboard"),
@@ -65,7 +58,7 @@ See COPYRIGHT and LICENSE files for more details.
       item.with_leading_visual_icon(icon: :copy)
     end
 
-    menu.with_item(
+    list.with_item(
       id: dom_target(work_package, :menu, :copy_work_package_id),
       tag: :"clipboard-copy",
       label: t(".action_menu.copy_work_package_id"),
@@ -75,9 +68,14 @@ See COPYRIGHT and LICENSE files for more details.
     end
 
     if show_move_submenu?
-      menu.with_divider
-
-      menu.with_sub_menu_item(label: t(".action_menu.move_menu")) do |move_menu|
+      list.with_divider
+
+      list.with_item(
+        component_klass: Primer::Alpha::ActionMenu::SubMenuItem,
+        label: t(".action_menu.move_menu"),
+        select_variant: :none,
+        form_arguments: {}
+      ) do |move_menu|
         move_menu.with_leading_visual_icon(icon: :"op-arrow-in")
 
         with_item_group(move_menu) do
diff --git a/modules/backlogs/app/components/backlogs/inbox_menu_component.rb b/modules/backlogs/app/components/backlogs/inbox_menu_component.rb
index 28331cfe4aa6..02d6ffa4195a 100644
--- a/modules/backlogs/app/components/backlogs/inbox_menu_component.rb
+++ b/modules/backlogs/app/components/backlogs/inbox_menu_component.rb
@@ -29,27 +29,25 @@
 #++
 
 module Backlogs
+  # Renders Primer::Alpha::ActionMenu::List for the deferred menu (InboxController#menu).
+  # +menu_id+ must match the row ActionMenu in InboxItemComponent.
   class InboxMenuComponent < ApplicationComponent
     include OpPrimer::ComponentHelpers
 
     attr_reader :work_package, :project, :max_position, :current_user, :open_sprints_exist
 
-    def initialize(work_package:, project:, max_position:, open_sprints_exist:, current_user: User.current, **system_arguments)
+    def initialize(work_package:, project:, max_position:, open_sprints_exist:, current_user: User.current)
       super()
 
       @work_package = work_package
       @project = project
-      @max_position = max_position
       @current_user = current_user
+      @max_position = max_position
       @open_sprints_exist = open_sprints_exist
+    end
 
-      @system_arguments = system_arguments
-      @system_arguments[:menu_id] = dom_target(work_package, :menu)
-      @system_arguments[:anchor_align] = :end
-      @system_arguments[:classes] = class_names(
-        @system_arguments[:classes],
-        "hide-when-print"
-      )
+    def menu_id
+      dom_target(work_package, :menu)
     end
 
     private
@@ -60,7 +58,7 @@ def show_move_submenu?
 
     def show_move_items?
       allowed_to_manage_sprint_items? &&
-      !(first_item? && last_item?)
+        !(first_item? && last_item?)
     end
 
     def show_move_to_sprint?
diff --git a/modules/backlogs/app/components/backlogs/sprint_component.html.erb b/modules/backlogs/app/components/backlogs/sprint_component.html.erb
index c6c1bbd5c06c..675a2ce4ccf3 100644
--- a/modules/backlogs/app/components/backlogs/sprint_component.html.erb
+++ b/modules/backlogs/app/components/backlogs/sprint_component.html.erb
@@ -49,7 +49,7 @@ See COPYRIGHT and LICENSE files for more details.
            data: story_data_attribute(story),
            tabindex: 0
          ) do %>
-        <%= render(Backlogs::StoryComponent.new(story:, sprint:, project:, max_position:)) %>
+        <%= render(Backlogs::StoryComponent.new(story:, sprint:, project:)) %>
       <% end %>
     <% end %>
   <% end %>
diff --git a/modules/backlogs/app/components/backlogs/sprint_component.rb b/modules/backlogs/app/components/backlogs/sprint_component.rb
index 1cc7e06696b1..ad819f90219f 100644
--- a/modules/backlogs/app/components/backlogs/sprint_component.rb
+++ b/modules/backlogs/app/components/backlogs/sprint_component.rb
@@ -67,10 +67,6 @@ def folded?
       current_user.backlogs_preference(:versions_default_fold_state) == "closed"
     end
 
-    def max_position
-      stories.filter_map(&:position).max
-    end
-
     def drop_target_config
       {
         generic_drag_and_drop_target: "container",
diff --git a/modules/backlogs/app/components/backlogs/story_component.html.erb b/modules/backlogs/app/components/backlogs/story_component.html.erb
index 37dd1cc7bc00..9465c851ea9f 100644
--- a/modules/backlogs/app/components/backlogs/story_component.html.erb
+++ b/modules/backlogs/app/components/backlogs/story_component.html.erb
@@ -51,7 +51,21 @@ See COPYRIGHT and LICENSE files for more details.
   <% end %>
 
   <% grid.with_area(:menu) do %>
-    <%= render(Backlogs::StoryMenuComponent.new(story:, sprint:, project:, max_position:)) %>
+    <%= render(
+          Primer::Alpha::ActionMenu.new(
+            menu_id: dom_target(story, :menu),
+            src: menu_backlogs_project_sprint_story_path(project, sprint, story),
+            anchor_align: :end,
+            classes: "hide-when-print"
+          )
+        ) do |menu| %>
+      <% menu.with_show_button(
+           scheme: :invisible,
+           icon: :"kebab-horizontal",
+           "aria-label": t(".label_actions"),
+           tooltip_direction: :se
+         ) %>
+    <% end %>
   <% end %>
 
   <% grid.with_area(:subject) do %>
diff --git a/modules/backlogs/app/components/backlogs/story_component.rb b/modules/backlogs/app/components/backlogs/story_component.rb
index 50f2841b6d12..3e23fb94a323 100644
--- a/modules/backlogs/app/components/backlogs/story_component.rb
+++ b/modules/backlogs/app/components/backlogs/story_component.rb
@@ -32,15 +32,14 @@ module Backlogs
   class StoryComponent < ApplicationComponent
     include OpPrimer::ComponentHelpers
 
-    attr_reader :story, :sprint, :project, :max_position, :current_user
+    attr_reader :story, :sprint, :project, :current_user
 
-    def initialize(story:, sprint:, project:, max_position:, current_user: User.current)
+    def initialize(story:, sprint:, project:, current_user: User.current)
       super()
 
       @story = story
       @sprint = sprint
       @project = project
-      @max_position = max_position
       @current_user = current_user
     end
 
diff --git a/modules/backlogs/app/components/backlogs/story_menu_component.html.erb b/modules/backlogs/app/components/backlogs/story_menu_list_component.html.erb
similarity index 85%
rename from modules/backlogs/app/components/backlogs/story_menu_component.html.erb
rename to modules/backlogs/app/components/backlogs/story_menu_list_component.html.erb
index 3b9f1d4b560a..7d8d01fe645c 100644
--- a/modules/backlogs/app/components/backlogs/story_menu_component.html.erb
+++ b/modules/backlogs/app/components/backlogs/story_menu_list_component.html.erb
@@ -28,15 +28,8 @@ See COPYRIGHT and LICENSE files for more details.
 ++# %>
 
 <%=
-  render(Primer::Alpha::ActionMenu.new(**@system_arguments)) do |menu|
-    menu.with_show_button(
-      scheme: :invisible,
-      icon: :"kebab-horizontal",
-      "aria-label": t(".label_actions"),
-      tooltip_direction: :se
-    )
-
-    menu.with_item(
+  render(Primer::Alpha::ActionMenu::List.new(menu_id:)) do |list|
+    list.with_item(
       id: dom_target(story, :menu, :open_details),
       tag: :a,
       label: t(:"js.button_open_details"),
@@ -46,7 +39,7 @@ See COPYRIGHT and LICENSE files for more details.
       item.with_leading_visual_icon(icon: :"op-view-split")
     end
 
-    menu.with_item(
+    list.with_item(
       id: dom_target(story, :menu, :open_fullscreen),
       tag: :a,
       label: t(:"js.button_open_fullscreen"),
@@ -56,7 +49,7 @@ See COPYRIGHT and LICENSE files for more details.
       item.with_leading_visual_icon(icon: :"screen-full")
     end
 
-    menu.with_item(
+    list.with_item(
       id: dom_target(story, :menu, :copy_url_to_clipboard),
       tag: :"clipboard-copy",
       label: t(".action_menu.copy_url_to_clipboard"),
@@ -65,7 +58,7 @@ See COPYRIGHT and LICENSE files for more details.
       item.with_leading_visual_icon(icon: :copy)
     end
 
-    menu.with_item(
+    list.with_item(
       id: dom_target(story, :menu, :copy_work_package_id),
       tag: :"clipboard-copy",
       label: t(".action_menu.copy_work_package_id"),
@@ -75,9 +68,13 @@ See COPYRIGHT and LICENSE files for more details.
     end
 
     if show_move_items?
-      menu.with_divider
-
-      menu.with_sub_menu_item(label: t(".action_menu.move_menu")) do |move_menu|
+      list.with_divider
+      list.with_item(
+        component_klass: Primer::Alpha::ActionMenu::SubMenuItem,
+        label: t(".action_menu.move_menu"),
+        select_variant: :none,
+        form_arguments: {}
+      ) do |move_menu|
         move_menu.with_leading_visual_icon(icon: :"op-arrow-in")
 
         with_item_group(move_menu) do
diff --git a/modules/backlogs/app/components/backlogs/story_menu_component.rb b/modules/backlogs/app/components/backlogs/story_menu_list_component.rb
similarity index 87%
rename from modules/backlogs/app/components/backlogs/story_menu_component.rb
rename to modules/backlogs/app/components/backlogs/story_menu_list_component.rb
index 4f486f81a158..c4bf7b66cc83 100644
--- a/modules/backlogs/app/components/backlogs/story_menu_component.rb
+++ b/modules/backlogs/app/components/backlogs/story_menu_list_component.rb
@@ -29,12 +29,14 @@
 #++
 
 module Backlogs
-  class StoryMenuComponent < ApplicationComponent
+  # Renders Primer::Alpha::ActionMenu::List for the deferred menu (RbStoriesController#menu).
+  # +menu_id+ must match the row ActionMenu in StoryComponent.
+  class StoryMenuListComponent < ApplicationComponent
     include OpPrimer::ComponentHelpers
 
     attr_reader :story, :sprint, :project, :max_position, :current_user
 
-    def initialize(story:, sprint:, project:, max_position:, current_user: User.current, **system_arguments)
+    def initialize(story:, sprint:, project:, max_position:, current_user: User.current)
       super()
 
       @story = story
@@ -42,21 +44,17 @@ def initialize(story:, sprint:, project:, max_position:, current_user: User.curr
       @project = project
       @max_position = max_position
       @current_user = current_user
+    end
 
-      @system_arguments = system_arguments
-      @system_arguments[:menu_id] = dom_target(story, :menu)
-      @system_arguments[:anchor_align] = :end
-      @system_arguments[:classes] = class_names(
-        @system_arguments[:classes],
-        "hide-when-print"
-      )
+    def menu_id
+      dom_target(story, :menu)
     end
 
     private
 
     def show_move_items?
       allowed_to_manage_sprint_items? &&
-      !(first_item? && last_item?)
+        !(first_item? && last_item?)
     end
 
     def allowed_to_manage_sprint_items?
diff --git a/modules/backlogs/app/controllers/inbox_controller.rb b/modules/backlogs/app/controllers/inbox_controller.rb
index 653009c6a728..8b44cfe30f40 100644
--- a/modules/backlogs/app/controllers/inbox_controller.rb
+++ b/modules/backlogs/app/controllers/inbox_controller.rb
@@ -34,6 +34,21 @@ class InboxController < RbApplicationController
   before_action :not_authorized_on_feature_flag_inactive
   before_action :load_work_package
 
+  # Deferred ActionMenu items (Primer include-fragment).
+  def menu
+    max_position = Backlog.inbox_for(project: @project).maximum(:position) || 0
+    open_sprints_exist = Agile::Sprint.for_project(@project).visible.not_completed.exists?
+
+    render(Backlogs::InboxMenuComponent.new(
+             work_package: @work_package,
+             project: @project,
+             max_position:,
+             open_sprints_exist:,
+             current_user:
+           ),
+           layout: false)
+  end
+
   def move_to_sprint_dialog
     respond_with_dialog Backlogs::MoveToSprintDialogComponent.new(
       work_package: @work_package,
@@ -71,7 +86,7 @@ def move
   private
 
   def load_work_package
-    @work_package = WorkPackage.visible.find(params[:id])
+    @work_package = WorkPackage.visible.where(project: @project).find(params[:id])
   end
 
   def replace_inbox_component_via_turbo_stream
@@ -79,8 +94,7 @@ def replace_inbox_component_via_turbo_stream
     replace_via_turbo_stream(
       component: Backlogs::InboxComponent.new(
         work_packages:,
-        project: @project,
-        open_sprints_exist: true
+        project: @project
       ),
       method: :morph
     )
diff --git a/modules/backlogs/app/controllers/rb_stories_controller.rb b/modules/backlogs/app/controllers/rb_stories_controller.rb
index 488d598c5f29..4696e7035153 100644
--- a/modules/backlogs/app/controllers/rb_stories_controller.rb
+++ b/modules/backlogs/app/controllers/rb_stories_controller.rb
@@ -33,6 +33,20 @@ class RbStoriesController < RbApplicationController
 
   before_action :load_story
 
+  # Deferred ActionMenu items (Primer include-fragment).
+  def menu
+    max_position = @allowed_stories.maximum(:position) || 0
+
+    render(Backlogs::StoryMenuListComponent.new(
+             story: @story,
+             sprint: @sprint,
+             project: @project,
+             max_position:,
+             current_user:
+           ),
+           layout: false)
+  end
+
   # Move a story from a Sprint to another Sprint or an Agile::Sprint.
   def move_legacy
     # The update service reloads the story internally (via #move_after),
@@ -128,9 +142,8 @@ def moved_to_inbox
       message: I18n.t(:notice_successful_move, from: @sprint.name, to: I18n.t(:label_inbox))
     )
     work_packages = Backlog.inbox_for(project: @project)
-    open_sprints_exist = Agile::Sprint.for_project(@project).not_completed.exists?
     replace_via_turbo_stream(
-      component: Backlogs::InboxComponent.new(work_packages:, project: @project, open_sprints_exist:),
+      component: Backlogs::InboxComponent.new(work_packages:, project: @project),
       method: :morph
     )
   end
@@ -202,11 +215,13 @@ def replace_sprint_component_via_turbo_stream(sprint:)
   end
 
   def load_story
-    @story = if OpenProject::FeatureDecisions.scrum_projects_active?
-               WorkPackage.visible.find(params[:id])
-             else
-               Story.visible.find(params[:id])
-             end
+    @allowed_stories =
+      if OpenProject::FeatureDecisions.scrum_projects_active?
+        WorkPackage.visible.where(sprint: @sprint, project: @project)
+      else
+        Story.visible.where(Story.condition(@project, @sprint))
+      end
+    @story = @allowed_stories.find(params[:id])
   end
 
   def move_params
diff --git a/modules/backlogs/app/views/rb_master_backlogs/_backlog_list.html.erb b/modules/backlogs/app/views/rb_master_backlogs/_backlog_list.html.erb
index a31c53d9ff00..598080216ae0 100644
--- a/modules/backlogs/app/views/rb_master_backlogs/_backlog_list.html.erb
+++ b/modules/backlogs/app/views/rb_master_backlogs/_backlog_list.html.erb
@@ -35,8 +35,7 @@ See COPYRIGHT and LICENSE files for more details.
       <%= render Backlogs::InboxComponent.new(
             work_packages: @inbox_work_packages,
             project: @project,
-            show_all: show_all_backlog,
-            open_sprints_exist: @sprints.any?
+            show_all: show_all_backlog
           ) %>
     </div>
     <div id="sprint_backlogs_container" class="op-sprint-planning-lists"
diff --git a/modules/backlogs/config/locales/en.yml b/modules/backlogs/config/locales/en.yml
index 7e8b6c12575c..73bea2cf93bc 100644
--- a/modules/backlogs/config/locales/en.yml
+++ b/modules/backlogs/config/locales/en.yml
@@ -162,9 +162,9 @@ en:
 
     inbox_item_component:
       label_drag_work_package: "Move %{name}"
+      label_actions: "Work package actions"
 
     inbox_menu_component:
-      label_actions: "Work package actions"
       action_menu:
         copy_url_to_clipboard: "Copy URL to clipboard"
         copy_work_package_id: "Copy work package ID"
@@ -226,9 +226,9 @@ en:
 
     story_component:
       label_drag_story: "Move %{name}"
-
-    story_menu_component:
       label_actions: "Story actions"
+
+    story_menu_list_component:
       action_menu:
         copy_url_to_clipboard: "Copy URL to clipboard"
         copy_work_package_id: "Copy work package ID"
diff --git a/modules/backlogs/config/routes.rb b/modules/backlogs/config/routes.rb
index 7e89f4140668..f11657e72911 100644
--- a/modules/backlogs/config/routes.rb
+++ b/modules/backlogs/config/routes.rb
@@ -48,6 +48,7 @@
 
         resources :stories, controller: :rb_stories, only: [] do
           member do
+            get :menu
             put :move
           end
         end
@@ -55,6 +56,7 @@
 
       resources :inbox, only: [] do
         member do
+          get :menu
           put :move
           post :reorder
           get :move_to_sprint_dialog
@@ -99,6 +101,7 @@
 
         resources :stories, controller: :rb_stories, only: [] do
           member do
+            get :menu
             put :move_legacy
             post :reorder
           end
diff --git a/modules/backlogs/lib/open_project/backlogs/engine.rb b/modules/backlogs/lib/open_project/backlogs/engine.rb
index efb7dd705e8d..004587ec6c89 100644
--- a/modules/backlogs/lib/open_project/backlogs/engine.rb
+++ b/modules/backlogs/lib/open_project/backlogs/engine.rb
@@ -71,7 +71,8 @@ def self.settings
                    { rb_master_backlogs: %i[index backlog details],
                      rb_sprints: %i[index show show_name],
                      rb_wikis: :show,
-                     rb_stories: %i[index show],
+                     rb_stories: %i[index show menu],
+                     inbox: :menu,
                      rb_queries: :show,
                      rb_burndown_charts: :show,
                      rb_taskboards: :show,
diff --git a/modules/backlogs/spec/components/backlogs/inbox_component_spec.rb b/modules/backlogs/spec/components/backlogs/inbox_component_spec.rb
index 3700317f9a1a..6454b8aa8e1e 100644
--- a/modules/backlogs/spec/components/backlogs/inbox_component_spec.rb
+++ b/modules/backlogs/spec/components/backlogs/inbox_component_spec.rb
@@ -40,14 +40,12 @@
 
   let(:work_packages) { WorkPackage.none }
   let(:show_all) { false }
-  let(:open_sprints_exist) { true }
 
   def render_component(**extra)
     render_inline(
       described_class.new(
         work_packages:,
         project:,
-        open_sprints_exist:,
         current_user: user,
         **extra
       )
diff --git a/modules/backlogs/spec/components/backlogs/inbox_item_component_spec.rb b/modules/backlogs/spec/components/backlogs/inbox_item_component_spec.rb
index ddd7cba68dbe..d6f038344c2c 100644
--- a/modules/backlogs/spec/components/backlogs/inbox_item_component_spec.rb
+++ b/modules/backlogs/spec/components/backlogs/inbox_item_component_spec.rb
@@ -56,7 +56,6 @@
       Backlogs::InboxComponent.new(
         work_packages:,
         project:,
-        open_sprints_exist: true,
         current_user: user
       )
     )
@@ -69,8 +68,10 @@
     expect(page).to have_octicon(:grabber)
     # renders WorkPackages::InfoLineComponent with type and ID
     expect(page).to have_text("##{work_package.id}")
-    # renders an InboxMenuComponent action menu
+    # deferred action menu (kebab + include-fragment src)
     expect(page).to have_css("action-menu")
+    expect(page).to have_css(%(include-fragment[src*="menu"]))
+    expect(page).to have_element(:button, id: /\Awork_package_#{work_package.id}_menu-button\z/)
   end
 
   describe "row data attributes" do
diff --git a/modules/backlogs/spec/components/backlogs/inbox_menu_component_spec.rb b/modules/backlogs/spec/components/backlogs/inbox_menu_component_spec.rb
index d0cec83a7d23..4a50d13c1bf4 100644
--- a/modules/backlogs/spec/components/backlogs/inbox_menu_component_spec.rb
+++ b/modules/backlogs/spec/components/backlogs/inbox_menu_component_spec.rb
@@ -70,10 +70,9 @@ def render_component(position: 2, max_position: 3, open_sprints_exist: true)
   end
 
   describe "standard items" do
-    it "renders stable ids for the action menu and primary actions" do
+    it "renders stable ids for the list and primary actions" do
       render_component
 
-      expect(page).to have_element(:button, id: /\Awork_package_#{work_package.id}_menu-button\z/)
       expect(page).to have_element(:ul, id: /\Awork_package_#{work_package.id}_menu-list\z/)
       expect(page).to have_element(:a, id: /\Awork_package_#{work_package.id}_menu_open_details\z/)
       expect(page).to have_element(:a, id: /\Awork_package_#{work_package.id}_menu_open_fullscreen\z/)
diff --git a/modules/backlogs/spec/components/backlogs/story_component_spec.rb b/modules/backlogs/spec/components/backlogs/story_component_spec.rb
index 15ebdefa6993..8871a242cc42 100644
--- a/modules/backlogs/spec/components/backlogs/story_component_spec.rb
+++ b/modules/backlogs/spec/components/backlogs/story_component_spec.rb
@@ -52,7 +52,6 @@
            position: 1,
            version: sprint)
   end
-  let(:max_position) { 3 }
   let(:permissions) { %i[manage_sprint_items] }
 
   before do
@@ -66,7 +65,7 @@
   end
 
   def render_component
-    render_inline(described_class.new(story:, sprint:, project:, max_position:, current_user: user))
+    render_inline(described_class.new(story:, sprint:, project:, current_user: user))
   end
 
   it "renders WorkPackages::InfoLineComponent" do
@@ -89,10 +88,12 @@ def render_component
     expect(page).to have_text("5 points", normalize_ws: true)
   end
 
-  it "renders StoryMenuComponent" do
+  it "renders deferred action menu with include-fragment src" do
     render_component
 
     expect(page).to have_css("action-menu")
+    expect(page).to have_css(%(include-fragment[src*="menu"]))
+    expect(page).to have_element(:button, id: /\Astory_#{story.id}_menu-button\z/)
   end
 
   describe "drag handle behaviour" do
diff --git a/modules/backlogs/spec/components/backlogs/story_menu_component_spec.rb b/modules/backlogs/spec/components/backlogs/story_menu_list_component_spec.rb
similarity index 92%
rename from modules/backlogs/spec/components/backlogs/story_menu_component_spec.rb
rename to modules/backlogs/spec/components/backlogs/story_menu_list_component_spec.rb
index 72430ef9b398..7d0d9e6d826f 100644
--- a/modules/backlogs/spec/components/backlogs/story_menu_component_spec.rb
+++ b/modules/backlogs/spec/components/backlogs/story_menu_list_component_spec.rb
@@ -30,7 +30,7 @@
 
 require "rails_helper"
 
-RSpec.describe Backlogs::StoryMenuComponent, type: :component do
+RSpec.describe Backlogs::StoryMenuListComponent, type: :component do
   shared_let(:type_feature) { create(:type_feature) }
   shared_let(:type_task) { create(:type_task) }
   shared_let(:default_status) { create(:default_status) }
@@ -66,10 +66,9 @@ def render_component(position: 2, max_position: 3)
   end
 
   describe "standard items" do
-    it "renders stable ids for the action menu and primary actions" do
+    it "renders stable ids for the list and primary actions" do
       render_component
 
-      expect(page).to have_element(:button, id: /\Astory_#{story.id}_menu-button\z/)
       expect(page).to have_element(:ul, id: /\Astory_#{story.id}_menu-list\z/)
       expect(page).to have_element(:a, id: /\Astory_#{story.id}_menu_open_details\z/)
       expect(page).to have_element(:a, id: /\Astory_#{story.id}_menu_open_fullscreen\z/)
@@ -107,7 +106,7 @@ def render_component(position: 2, max_position: 3)
         :"clipboard-copy",
         id: "story_#{story.id}_menu_copy_url_to_clipboard",
         value: /\/work_packages\/#{story.id}\z/,
-        text: I18n.t("backlogs.story_menu_component.action_menu.copy_url_to_clipboard")
+        text: "Copy URL to clipboard"
       )
     end
 
@@ -119,7 +118,7 @@ def render_component(position: 2, max_position: 3)
         :"clipboard-copy",
         id: "story_#{story.id}_menu_copy_work_package_id",
         value: story.id.to_s,
-        text: I18n.t("backlogs.story_menu_component.action_menu.copy_work_package_id")
+        text: "Copy work package ID"
       )
     end
 
@@ -132,7 +131,7 @@ def render_component(position: 2, max_position: 3)
     it "shows the Move submenu with incoming-arrow icon" do
       render_component
 
-      expect(page).to have_selector(:menuitem, text: I18n.t("backlogs.story_menu_component.action_menu.move_menu"))
+      expect(page).to have_selector(:menuitem, text: "Move")
       expect(page).to have_octicon(:"op-arrow-in")
     end
   end
@@ -226,7 +225,7 @@ def render_component(position: 2, max_position: 3)
 
         expect(page).to have_no_selector(
           :menuitem,
-          text: I18n.t("backlogs.story_menu_component.action_menu.move_menu")
+          text: "Move"
         )
       end
     end
diff --git a/modules/backlogs/spec/controllers/inbox_controller_spec.rb b/modules/backlogs/spec/controllers/inbox_controller_spec.rb
index 45c5e1b75238..29c7f8cec2ed 100644
--- a/modules/backlogs/spec/controllers/inbox_controller_spec.rb
+++ b/modules/backlogs/spec/controllers/inbox_controller_spec.rb
@@ -205,6 +205,38 @@
     it_behaves_like "checks permissions for private projects"
   end
 
+  describe "GET #menu" do
+    subject do
+      get :menu, params: { project_id: project.id, id: work_package.id }, format: :html
+    end
+
+    it "returns deferred action menu list HTML", :aggregate_failures do
+      subject
+      expect(response).to have_http_status :ok
+      expect(response.body).to include(I18n.t(:"js.button_open_details"))
+    end
+
+    context "when the work package belongs to another project" do
+      let(:other_project) { create(:project) }
+      let(:work_package) { create(:work_package, project: other_project) }
+
+      it "responds with 404" do
+        expect(response).to have_http_status :not_found
+      end
+    end
+
+    context "with a user lacking project permission" do
+      let(:user) { create(:user) }
+
+      it "responds with 404" do
+        subject
+        expect(response).to have_http_status :not_found
+      end
+    end
+
+    it_behaves_like "checks permissions for private projects"
+  end
+
   describe "GET #move_to_sprint_dialog" do
     let!(:sprint) { create(:agile_sprint, name: "Sprint 1", project:) }
 
diff --git a/modules/backlogs/spec/controllers/rb_stories_controller_spec.rb b/modules/backlogs/spec/controllers/rb_stories_controller_spec.rb
index be2f00c5b75a..215608223ed1 100644
--- a/modules/backlogs/spec/controllers/rb_stories_controller_spec.rb
+++ b/modules/backlogs/spec/controllers/rb_stories_controller_spec.rb
@@ -51,6 +51,57 @@
             .and_return({ "story_types" => [type_feature.id], "task_type" => type_task.id })
   end
 
+  describe "load_story" do
+    subject do
+      get :menu,
+          params: { project_id: project.id, sprint_id: requested_sprint.id, id: load_story_id },
+          format: :html
+    end
+
+    context "when scrum_projects flag is inactive", with_flag: { scrum_projects: false } do
+      let(:load_story_id) { story.id }
+      let(:requested_sprint) { version_sprint }
+
+      context "when the story is in the requested sprint" do
+        it "assigns the visible story", :aggregate_failures do
+          subject
+          expect(response).to be_successful
+          expect(response).to have_http_status :ok
+          expect(assigns(:story)).to eq(story)
+        end
+      end
+
+      context "when the story is not in the requested sprint" do
+        let(:requested_sprint) { create(:sprint, name: "Sprint load_story other", project:) }
+
+        it { is_expected.to have_http_status :not_found }
+      end
+    end
+
+    context "when scrum_projects flag is active", with_flag: { scrum_projects: true } do
+      let(:agile_sprint) { create(:agile_sprint, name: "Agile Sprint load_story", project:) }
+      let(:work_package_in_sprint) { create(:work_package, status:, sprint: agile_sprint, project:) }
+      let(:load_story_id) { work_package_in_sprint.id }
+
+      context "when the work package is in the requested sprint" do
+        let(:requested_sprint) { agile_sprint }
+
+        it "assigns the visible work package", :aggregate_failures do
+          subject
+          expect(response).to be_successful
+          expect(response).to have_http_status :ok
+          expect(assigns(:story)).to eq(work_package_in_sprint)
+        end
+      end
+
+      context "when the work package is not in the requested sprint" do
+        let(:requested_sprint) { create(:agile_sprint, name: "Other Sprint load_story", project:) }
+
+        it { is_expected.to have_http_status :not_found }
+      end
+    end
+  end
+
   describe "PUT #move_legacy" do
     context "with a user lacking project permission" do
       let(:user) { create(:user) }
@@ -334,4 +385,25 @@
       end
     end
   end
+
+  describe "GET #menu" do
+    subject do
+      get :menu, params: { project_id: project.id, sprint_id: version_sprint.id, id: story.id }, format: :html
+    end
+
+    it "returns deferred action menu list HTML", :aggregate_failures do
+      subject
+      expect(response).to have_http_status :ok
+      expect(response.body).to include(I18n.t(:"js.button_open_details"))
+    end
+
+    context "with a user lacking project permission" do
+      let(:user) { create(:user) }
+
+      it "responds with 404" do
+        subject
+        expect(response).to have_http_status :not_found
+      end
+    end
+  end
 end
diff --git a/modules/backlogs/spec/lib/open_project/backlogs/permissions_spec.rb b/modules/backlogs/spec/lib/open_project/backlogs/permissions_spec.rb
index 4e4a5724a2db..7aaa9c0605f0 100644
--- a/modules/backlogs/spec/lib/open_project/backlogs/permissions_spec.rb
+++ b/modules/backlogs/spec/lib/open_project/backlogs/permissions_spec.rb
@@ -37,6 +37,10 @@
     it "depends on view_work_packages and show_board_views" do
       expect(subject.dependencies).to contain_exactly(:view_work_packages, :show_board_views)
     end
+
+    it "includes deferred backlog story and inbox menu fragments" do
+      expect(subject.controller_actions).to include("rb_stories/menu", "inbox/menu")
+    end
   end
 
   describe "create_sprints" do
diff --git a/modules/backlogs/spec/routing/inbox_routing_spec.rb b/modules/backlogs/spec/routing/inbox_routing_spec.rb
index 21a81f2ddb38..cfa1e7288daf 100644
--- a/modules/backlogs/spec/routing/inbox_routing_spec.rb
+++ b/modules/backlogs/spec/routing/inbox_routing_spec.rb
@@ -49,5 +49,14 @@
         id: "85"
       )
     }
+
+    it {
+      expect(get("/projects/project_42/inbox/85/menu")).to route_to(
+        controller: "inbox",
+        action: "menu",
+        project_id: "project_42",
+        id: "85"
+      )
+    }
   end
 end
diff --git a/modules/backlogs/spec/routing/rb_stories_routing_spec.rb b/modules/backlogs/spec/routing/rb_stories_routing_spec.rb
index 910795cf440b..4bf6b239918d 100644
--- a/modules/backlogs/spec/routing/rb_stories_routing_spec.rb
+++ b/modules/backlogs/spec/routing/rb_stories_routing_spec.rb
@@ -67,5 +67,15 @@
         id: "85"
       )
     }
+
+    it {
+      expect(get("/projects/project_42/sprints/21/stories/85/menu")).to route_to(
+        controller: "rb_stories",
+        action: "menu",
+        project_id: "project_42",
+        sprint_id: "21",
+        id: "85"
+      )
+    }
   end
 end