Omit the class description when the group block shows one class

The Group Classes block can be pinned to a single class via its Class
option so it can be embedded on a page dedicated to that class. On such a
page the surrounding copy already describes the class, so the card
repeated it. In single-class mode the description is now left out and the
card shows only the schedule, instructor, schedule note, price, enrolment
deadline and the enrol/withdraw controls.

The editor preview follows the same rule: BlockPreview::groupClasses()
takes the mode from the block's offeringId attribute, drops the sample
description when a class is pinned, and notes what the published page
shows. Its sample card also gained the .us-class-when and
.us-enrol-deadline elements the live markup has always rendered.

Closes #114

Co-Authored-By: Claude Opus 5 <[email protected]>

src/BlockPreview.php

@@ -58,13 +58,29 @@ class BlockPreview {
 		);
 	}
 
-	public static function groupClasses(): string {
+	/**
+	 * Sample group-class card.
+	 *
+	 * @param bool $singleClass Whether the block is pinned to one class, in
+	 *                          which case the live page omits the class
+	 *                          description and the preview does too.
+	 */
+	public static function groupClasses( bool $singleClass = false ): string {
+		$note = $singleClass
+			? __( 'Editor preview — the published page shows the chosen class with its live schedule and enrolment status.', 'unsupervised-schedular' )
+			: __( 'Editor preview — students see live group classes on the published page.', 'unsupervised-schedular' );
+
+		$description = $singleClass
+			? ''
+			: '<p>' . esc_html__( 'A sample class shown so the page can be styled.', 'unsupervised-schedular' ) . '</p>';
+
 		return sprintf(
-			'<div id="us-group-app">%s<div id="us-group-list"><div class="us-class"><h3>%s</h3><p>%s</p><p>%s</p><p>25.00 CAD</p><button type="button" class="us-enrol-btn" disabled>%s</button></div></div></div>',
-			self::note( __( 'Editor preview — students see live group classes on the published page.', 'unsupervised-schedular' ) ),
+			'<div id="us-group-app">%s<div id="us-group-list"><div class="us-class"><h3>%s</h3><p class="us-class-when">%s</p>%s<p>25.00 CAD</p><p class="us-enrol-deadline">%s</p><button type="button" class="us-enrol-btn" disabled>%s</button></div></div></div>',
+			self::note( $note ),
 			esc_html__( 'Beginner Group Class', 'unsupervised-schedular' ),
 			esc_html__( 'Saturdays 10:00 AM–11:00 AM', 'unsupervised-schedular' ),
-			esc_html__( 'A sample class shown so the page can be styled.', 'unsupervised-schedular' ),
+			$description,
+			esc_html__( 'Enrol by Sep 6, 2026', 'unsupervised-schedular' ),
 			esc_html__( 'Enrol', 'unsupervised-schedular' )
 		);
 	}

src/BlockRegistrar.php

@@ -160,7 +160,11 @@ class BlockRegistrar {
 	 * @param array<string, mixed> $attributes Block attributes.
 	 */
 	public function renderGroupClasses( array $attributes = [] ): string {
-		return $this->isEditorPreview() ? BlockPreview::groupClasses() : $this->groupClassPage->render( $attributes );
+		if ( ! $this->isEditorPreview() ) {
+			return $this->groupClassPage->render( $attributes );
+		}
+
+		return BlockPreview::groupClasses( Val::int( $attributes['offeringId'] ?? 0 ) > 0 );
 	}
 
 	/**