Preview tokens: Use homepage for site token

Site does not have a preview by itself, so Kirby will render the homepage and check its token instead.

src/Content/Version.php

@@ -398,15 +398,24 @@ protected function prepareFieldsForContent(
 	 */
 	public function previewToken(): string
 	{
-		$id = match (true) {
-			$this->model instanceof Site => '',
-			$this->model instanceof Page => $this->model->id() . $this->model->template(),
-			default                      => throw new LogicException('Invalid model type')
-		};
+		if ($this->model instanceof Site) {
+			// the site itself does not render; its preview is the home page
+			$homePage = $this->model->homePage();
+
+			if ($homePage === null) {
+				throw new NotFoundException('The home page does not exist');
+			}
+
+			return $homePage->version($this->id)->previewToken();
+		}
+
+		if (($this->model instanceof Page) === false) {
+			throw new LogicException('Invalid model type');
+		}
 
 		return $this->model->kirby()->contentToken(
 			$this->model,
-			$id
+			$this->model->id() . $this->model->template()
 		);
 	}
 

tests/Content/TestCase.php

@@ -85,6 +85,10 @@ public function setUpMultiLanguage(
 		parent::setUpMultiLanguage(
 			site: $site ?? [
 				'children' => [
+					[
+						'slug'     => 'home',
+						'template' => 'default'
+					],
 					[
 						'slug'     => 'a-page',
 						'template' => 'article',
@@ -109,6 +113,10 @@ public function setUpSingleLanguage(
 		parent::setUpSingleLanguage(
 			site: $site ?? [
 				'children' => [
+					[
+						'slug'     => 'home',
+						'template' => 'default'
+					],
 					[
 						'slug'     => 'a-page',
 						'template' => 'article',

tests/Content/VersionTest.php

@@ -2,6 +2,7 @@
 
 namespace Kirby\Content;
 
+use Kirby\Cms\App;
 use Kirby\Cms\File;
 use Kirby\Cms\Page;
 use Kirby\Cms\Site;
@@ -785,7 +786,7 @@ public function testPreviewToken()
 			model: $this->app->site(),
 			id: VersionId::latest()
 		);
-		$this->assertSame(hash_hmac('sha1', '', static::TMP . '/content/'), $version->previewToken());
+		$this->assertSame(hash_hmac('sha1', 'home' . 'default', static::TMP . '/content/home'), $version->previewToken());
 
 		// page
 		$version = new Version(
@@ -813,6 +814,28 @@ public function testPreviewTokenInvalidModel()
 		$version->previewToken();
 	}
 
+	/**
+	 * @covers ::previewToken
+	 */
+	public function testPreviewTokenMissingHomePage()
+	{
+		$this->expectException(NotFoundException::class);
+		$this->expectExceptionMessage('The home page does not exist');
+
+		$app = new App([
+			'roots' => [
+				'index' => static::TMP
+			]
+		]);
+
+		$version = new Version(
+			model: $app->site(),
+			id: VersionId::latest()
+		);
+
+		$version->previewToken();
+	}
+
 	/**
 	 * @covers ::publish
 	 */