Add Branding::enqueue_inline_css() so partner CSS can attach to any handle (#762)

Allows external integrations (e.g. pp-hosts guided tour, which runs on
the block editor, site editor, frontend, and non-PP admin screens) to
apply the partner branding custom CSS to their own stylesheets, instead
of being limited to the PP admin pages where Page::enqueue_styles()
runs.

The new method is idempotent per style handle, so the per-request
dedupe that previously lived on Page (via the
$branding_inline_styles_added static — needed because dashboard
widgets call enqueue_styles() multiple times per request) now lives
with the branding class itself and works for any handle.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ilicfilip

classes/admin/class-page.php

@@ -12,13 +12,6 @@
  */
 class Page {
 
-	/**
-	 * Whether the branding inline styles have been added.
-	 *
-	 * @var boolean
-	 */
-	protected static $branding_inline_styles_added = false;
-
 	/**
 	 * Constructor.
 	 */
@@ -285,10 +278,7 @@ public function enqueue_styles() {
 
 		\progress_planner()->get_admin__enqueue()->enqueue_style( 'progress-planner/variables-color' );
 		\progress_planner()->get_admin__enqueue()->enqueue_style( 'progress-planner/admin' );
-		if ( ! static::$branding_inline_styles_added ) {
-			\wp_add_inline_style( 'progress-planner/admin', \progress_planner()->get_ui__branding()->get_custom_css() );
-			static::$branding_inline_styles_added = true;
-		}
+		\progress_planner()->get_ui__branding()->enqueue_inline_css( 'progress-planner/admin' );
 		\progress_planner()->get_admin__enqueue()->enqueue_style( 'progress-planner/web-components/prpl-tooltip' );
 		\progress_planner()->get_admin__enqueue()->enqueue_style( 'progress-planner/web-components/prpl-install-plugin' );
 

classes/ui/class-branding.php

@@ -21,6 +21,13 @@ final class Branding {
 		'default' => 0,
 	];
 
+	/**
+	 * Style handles that have already received the branding inline CSS this request.
+	 *
+	 * @var array<string, bool>
+	 */
+	private static $inline_css_attached = [];
+
 	/**
 	 * Constructor.
 	 */
@@ -124,6 +131,30 @@ public function get_custom_css(): string {
 			: $this->get_api_data()['custom_css'];
 	}
 
+	/**
+	 * Attach the branding custom CSS to a registered/enqueued stylesheet.
+	 *
+	 * Idempotent per handle within a single request, so callers do not need to
+	 * track whether the CSS has already been added.
+	 *
+	 * @param string $handle The style handle to attach the inline CSS to.
+	 *
+	 * @return void
+	 */
+	public function enqueue_inline_css( string $handle ): void {
+		if ( isset( self::$inline_css_attached[ $handle ] ) ) {
+			return;
+		}
+		self::$inline_css_attached[ $handle ] = true;
+
+		$css = $this->get_custom_css();
+		if ( '' === $css ) {
+			return;
+		}
+
+		\wp_add_inline_style( $handle, $css );
+	}
+
 	/**
 	 * Get the admin-menu icon.
 	 *