diff --git a/functionalities.php b/functionalities.php
index c1ef07c..43ae96b 100644
--- a/functionalities.php
+++ b/functionalities.php
@@ -73,6 +73,7 @@ function () {
 );
 
 \add_action( 'updated_option', array( '\Functionalities\Core\Module_Registry', 'handle_option_update' ), 10, 3 );
+\add_action( 'added_option', array( '\Functionalities\Core\Module_Registry', 'handle_option_add' ), 10, 2 );
 
 // Activation hook.
 \register_activation_hook(
diff --git a/includes/core/class-module-registry.php b/includes/core/class-module-registry.php
index 2ad4e70..5417892 100644
--- a/includes/core/class-module-registry.php
+++ b/includes/core/class-module-registry.php
@@ -152,6 +152,20 @@ public static function handle_option_update( string $option, $old_value, $value
 		}
 	}
 
+	/**
+	 * React when settings are saved for the first time.
+	 *
+	 * WordPress fires added_option instead of updated_option when an option did
+	 * not previously exist, which is the normal fresh-install PWA path.
+	 *
+	 * @param string $option Option name.
+	 * @param mixed  $value  New value.
+	 * @return void
+	 */
+	public static function handle_option_add( string $option, $value ): void {
+		self::handle_option_update( $option, null, $value );
+	}
+
 	/**
 	 * Build one normalized definition.
 	 *
diff --git a/includes/features/class-pwa.php b/includes/features/class-pwa.php
index 5e8a61c..497ac1c 100644
--- a/includes/features/class-pwa.php
+++ b/includes/features/class-pwa.php
@@ -846,7 +846,9 @@ private static function output_offline_page(): void {
 			ob_end_clean();
 		}
 
-		\status_header( 503 );
+		// This application shell is fetched during service-worker installation.
+		// cache.addAll() rejects non-2xx responses, so it must be cacheable.
+		\status_header( 200 );
 		\nocache_headers();
 
 		?>
diff --git a/readme.txt b/readme.txt
index fda8dff..128741c 100644
--- a/readme.txt
+++ b/readme.txt
@@ -135,6 +135,7 @@ Before uninstalling, go to the Functionalities dashboard and check **"Delete all
 == Changelog ==
 
 = 1.4.8 =
+* Fixed: Fresh PWA settings now register rewrite endpoints immediately, and the offline application shell returns a cacheable success response so service-worker precaching can complete.
 * Added: True lazy module registry. A frontend request with all modules disabled loads no feature class files; enabling one module loads only that feature and shared dependencies.
 * Added: Versioned settings export/import with dry-run differences, module validation, default custom-code redaction, and an explicit code opt-in.
 * Added: Privacy-conscious diagnostics download with software versions, enabled modules, writable-path status, and rewrite-rule health. Task content, redirects, users, secrets, and site URLs are excluded.
diff --git a/tests/ModuleRegistryTest.php b/tests/ModuleRegistryTest.php
index 34d5e40..8ea6c72 100644
--- a/tests/ModuleRegistryTest.php
+++ b/tests/ModuleRegistryTest.php
@@ -40,6 +40,8 @@ public function test_pwa_boots_safely_before_wordpress_init(): void {
 
 		$this->assertSame( array( 'class-pwa.php' ), $result['features'] );
 		$this->assertContains( 'init', $result['hooks'] );
+		$this->assertContains( 'added_option', $result['hooks'] );
+		$this->assertContains( 'updated_option', $result['hooks'] );
 	}
 
 	/**
diff --git a/tests/PwaOfflineStatusTest.php b/tests/PwaOfflineStatusTest.php
new file mode 100644
index 0000000..806e833
--- /dev/null
+++ b/tests/PwaOfflineStatusTest.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * PWA offline response regression test.
+ *
+ * @package FunctionalitiesTests
+ */
+
+use PHPUnit\Framework\TestCase;
+
+final class PwaOfflineStatusTest extends TestCase {
+	/**
+	 * The offline shell must be a successful response for cache.addAll().
+	 *
+	 * @return void
+	 */
+	public function test_offline_shell_is_cacheable_during_service_worker_install(): void {
+		$source = file_get_contents( dirname( __DIR__ ) . '/includes/features/class-pwa.php' );
+
+		$this->assertIsString( $source );
+		$this->assertMatchesRegularExpression(
+			'/private static function output_offline_page\(\).*?status_header\( 200 \)/s',
+			$source
+		);
+		$this->assertStringContainsString( 'c.addAll(PRECACHE_URLS)', $source );
+	}
+}