diff --git a/includes/class-shortcode-dmr.php b/includes/class-shortcode-dmr.php
new file mode 100644
index 0000000..f0474bc
--- /dev/null
+++ b/includes/class-shortcode-dmr.php
@@ -0,0 +1,32 @@
+<?php
+declare(strict_types=1);
+
+namespace WPMultiCity;
+
+final class ShortcodeDmr
+{
+    public const SHORTCODE = 'shortcode_dmr';
+
+    private static array $render_cache = [];
+
+    public static function reset_cache(): void
+    {
+        self::$render_cache = [];
+    }
+
+    public static function register(): void
+    {
+        \add_action('init', [self::class, 'do_register']);
+    }
+
+    public static function do_register(): void
+    {
+        \add_shortcode(self::SHORTCODE, [self::class, 'render']);
+    }
+
+    public static function render($atts = [], $content = null): string
+    {
+        // Implementation in Task 13.
+        return '';
+    }
+}
diff --git a/tests/ShortcodeDmrTest.php b/tests/ShortcodeDmrTest.php
new file mode 100644
index 0000000..5a819f7
--- /dev/null
+++ b/tests/ShortcodeDmrTest.php
@@ -0,0 +1,19 @@
+<?php
+declare(strict_types=1);
+
+namespace WPMultiCity\Tests;
+
+use WPMultiCity\ShortcodeDmr;
+
+final class ShortcodeDmrTest extends TestCase
+{
+    public function test_register_attaches_init_action(): void
+    {
+        ShortcodeDmr::register();
+
+        self::assertNotFalse(
+            has_action('init', [ShortcodeDmr::class, 'do_register']),
+            'ShortcodeDmr::register() must hook init'
+        );
+    }
+}
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 0240c30..55ef283 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -6,6 +6,7 @@ namespace WPMultiCity\Tests;
 use Brain\Monkey;
 use PHPUnit\Framework\TestCase as BaseTestCase;
 use WPMultiCity\Helpers;
+use WPMultiCity\ShortcodeDmr;
 
 abstract class TestCase extends BaseTestCase
 {
@@ -15,6 +16,7 @@ abstract class TestCase extends BaseTestCase
         Monkey\setUp();
         Monkey\Functions\stubTranslationFunctions();
         Helpers::reset_cache();
+        ShortcodeDmr::reset_cache();
     }
 
     protected function tearDown(): void