[Feature] Add Empty component

Port the shadcn Empty component: a centered empty-state surface for when
there is no data or content. Parts: Empty, EmptyHeader, EmptyMedia
(default/icon variants), EmptyTitle, EmptyDescription, EmptyContent.

Translates shadcn's cn-empty-* CSS layer to Tailwind v4 utilities. No JS.

Docs page, route, controller, menu, site_files and MCP registry updated.

Author: djalmaaraujo

docs/app/components/shared/components_list.rb

@@ -30,6 +30,7 @@ def components
           {name: "Date Picker", path: docs_date_picker_path},
           {name: "Dialog / Modal", path: docs_dialog_path},
           {name: "Dropdown Menu", path: docs_dropdown_menu_path},
+          {name: "Empty", path: docs_empty_path},
           {name: "Form", path: docs_form_path},
           {name: "Hover Card", path: docs_hover_card_path},
           {name: "Input", path: docs_input_path},

docs/app/controllers/docs_controller.rb

@@ -146,6 +146,10 @@ def dropdown_menu
     render Views::Docs::DropdownMenu.new
   end
 
+  def empty
+    render Views::Docs::Empty.new
+  end
+
   def form
     render Views::Docs::Form.new
   end

docs/app/lib/site_files.rb

@@ -103,6 +103,7 @@ class SiteFiles
     {title: "Date Picker", path: "/docs/date_picker", description: "Date picker component with input."},
     {title: "Dialog", path: "/docs/dialog", description: "Modal window that renders background content inert."},
     {title: "Dropdown Menu", path: "/docs/dropdown_menu", description: "Button-triggered menu for actions or functions."},
+    {title: "Empty", path: "/docs/empty", description: "Empty state for when there is no data or content."},
     {title: "Form", path: "/docs/form", description: "Form fields with built-in client-side validations."},
     {title: "Hover Card", path: "/docs/hover_card", description: "Preview content exposed behind a link or trigger."},
     {title: "Input", path: "/docs/input", description: "Styled input field primitive."},

docs/app/views/docs/empty.rb

@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+class Views::Docs::Empty < Views::Base
+  def view_template
+    component = "Empty"
+
+    div(class: "max-w-2xl mx-auto w-full py-10 space-y-10") do
+      render Docs::Header.new(title: "Empty", description: "Use the empty component to display a state when there is no data or content.")
+
+      Heading(level: 2) { "Usage" }
+
+      render Docs::VisualCodeExample.new(title: "Default", context: self) do
+        <<~RUBY
+          Empty do
+            EmptyHeader do
+              EmptyMedia(variant: :icon) do
+                svg(xmlns: "http://www.w3.org/2000/svg", fill: "none", viewbox: "0 0 24 24", stroke_width: "1.5", stroke: "currentColor", class: "size-6") do |s|
+                  s.path(stroke_linecap: "round", stroke_linejoin: "round", d: "M20.25 8.511c.884.284 1.5 1.128 1.5 2.097v4.286c0 1.136-.847 2.1-1.98 2.193-.34.027-.68.052-1.02.072v3.091l-3-3c-1.354 0-2.694-.055-4.02-.163a2.115 2.115 0 0 1-.825-.242m9.345-8.334a2.126 2.126 0 0 0-.476-.095 48.64 48.64 0 0 0-8.048 0c-1.131.094-1.976 1.057-1.976 2.192v4.286c0 .837.46 1.58 1.155 1.951m9.345-8.334V6.637c0-1.621-1.152-3.026-2.76-3.235A48.455 48.455 0 0 0 11.25 3c-2.115 0-4.198.137-6.24.402-1.608.209-2.76 1.614-2.76 3.235v6.226c0 1.621 1.152 3.026 2.76 3.235.577.075 1.157.14 1.74.194V21l4.155-4.155")
+                end
+              end
+              EmptyTitle { "No messages yet" }
+              EmptyDescription { "Start a conversation to see your messages here." }
+            end
+          end
+        RUBY
+      end
+
+      render Docs::VisualCodeExample.new(title: "With action", context: self) do
+        <<~RUBY
+          Empty do
+            EmptyHeader do
+              EmptyMedia(variant: :icon) do
+                svg(xmlns: "http://www.w3.org/2000/svg", fill: "none", viewbox: "0 0 24 24", stroke_width: "1.5", stroke: "currentColor", class: "size-6") do |s|
+                  s.path(stroke_linecap: "round", stroke_linejoin: "round", d: "M2.25 12.76c0 1.6 1.123 2.994 2.707 3.227 1.129.166 2.27.293 3.423.379.35.026.67.21.865.501L12 21l2.755-4.133a1.14 1.14 0 0 1 .865-.501 48.172 48.172 0 0 0 3.423-.379c1.584-.233 2.707-1.626 2.707-3.228V6.741c0-1.602-1.123-2.995-2.707-3.228A48.394 48.394 0 0 0 12 3c-2.392 0-4.744.175-7.043.513C3.373 3.746 2.25 5.14 2.25 6.741v6.018Z")
+                end
+              end
+              EmptyTitle { "No projects" }
+              EmptyDescription { "Get started by creating your first project." }
+            end
+            EmptyContent do
+              Button { "Create project" }
+            end
+          end
+        RUBY
+      end
+
+      render Docs::VisualCodeExample.new(title: "Default media", context: self) do
+        <<~RUBY
+          Empty(class: "border-none") do
+            EmptyHeader do
+              EmptyMedia(variant: :default) do
+                Avatar(size: :lg) do
+                  AvatarFallback { "RU" }
+                end
+              end
+              EmptyTitle { "No team members" }
+              EmptyDescription { "Invite your team to start collaborating." }
+            end
+          end
+        RUBY
+      end
+
+      render Components::ComponentSetup::Tabs.new(component_name: component)
+
+      # components
+      render Docs::ComponentsTable.new(component_files(component))
+    end
+  end
+end

docs/config/routes.rb

@@ -47,6 +47,7 @@
     get "date_picker", to: "docs#date_picker", as: :docs_date_picker
     get "dialog", to: "docs#dialog", as: :docs_dialog
     get "dropdown_menu", to: "docs#dropdown_menu", as: :docs_dropdown_menu
+    get "empty", to: "docs#empty", as: :docs_empty
     get "form", to: "docs#form", as: :docs_form
     get "hover_card", to: "docs#hover_card", as: :docs_hover_card
     get "input", to: "docs#input", as: :docs_input

docs/public/llms-full.txt

@@ -203,6 +203,11 @@ This file expands the curated /llms.txt map into a compact reference that can be
 - URL: https://rubyui.com/docs/dropdown_menu
 - Summary: Button-triggered menu for actions or functions.
 
+### Empty
+
+- URL: https://rubyui.com/docs/empty
+- Summary: Empty state for when there is no data or content.
+
 ### Form
 
 - URL: https://rubyui.com/docs/form

docs/public/llms.txt

@@ -45,6 +45,7 @@ Use the core docs first for installation, theming, dark mode, and customization
 - [Date Picker](https://rubyui.com/docs/date_picker): Date picker component with input.
 - [Dialog](https://rubyui.com/docs/dialog): Modal window that renders background content inert.
 - [Dropdown Menu](https://rubyui.com/docs/dropdown_menu): Button-triggered menu for actions or functions.
+- [Empty](https://rubyui.com/docs/empty): Empty state for when there is no data or content.
 - [Form](https://rubyui.com/docs/form): Form fields with built-in client-side validations.
 - [Hover Card](https://rubyui.com/docs/hover_card): Preview content exposed behind a link or trigger.
 - [Input](https://rubyui.com/docs/input): Styled input field primitive.

docs/public/sitemap.xml

@@ -180,6 +180,11 @@
     <changefreq>monthly</changefreq>
     <priority>0.7</priority>
   </url>
+  <url>
+    <loc>https://rubyui.com/docs/empty</loc>
+    <changefreq>monthly</changefreq>
+    <priority>0.7</priority>
+  </url>
   <url>
     <loc>https://rubyui.com/docs/form</loc>
     <changefreq>monthly</changefreq>

gem/lib/ruby_ui/empty/empty.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module RubyUI
+  class Empty < Base
+    def view_template(&)
+      div(**attrs, &)
+    end
+
+    private
+
+    def default_attrs
+      {
+        data: {slot: "empty"},
+        class: "flex w-full min-w-0 flex-1 flex-col items-center justify-center gap-4 rounded-3xl border border-dashed p-12 text-center text-balance"
+      }
+    end
+  end
+end

gem/lib/ruby_ui/empty/empty_content.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module RubyUI
+  class EmptyContent < Base
+    def view_template(&)
+      div(**attrs, &)
+    end
+
+    private
+
+    def default_attrs
+      {
+        data: {slot: "empty-content"},
+        class: "flex w-full max-w-sm min-w-0 flex-col items-center gap-4 text-sm text-balance"
+      }
+    end
+  end
+end