fix: Multi-layer protection against Twig rendering recursion

- Added render depth tracking in Plugin::render() with max depth of 5
- Strip shortcodes from content when in shortcode context
- Prevents any later do_shortcode() calls from triggering recursion

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

includes/Frontend/TemplateLoader.php

@@ -270,10 +270,19 @@ class TemplateLoader {
             $excerpt = get_the_excerpt( $post );
         }
 
+        // When skipping content filter, also strip shortcodes to prevent them from
+        // being processed by anything else that might call do_shortcode on the output.
+        if ( $skip_content_filter ) {
+            $content = strip_shortcodes( $post->post_content );
+            $content = wp_kses_post( $content );
+        } else {
+            $content = apply_filters( 'the_content', $post->post_content );
+        }
+
         $data = array(
             'id'        => $post->ID,
             'title'     => get_the_title( $post ),
-            'content'   => $skip_content_filter ? wp_kses_post( $post->post_content ) : apply_filters( 'the_content', $post->post_content ),
+            'content'   => $content,
             'excerpt'   => $excerpt,
             'permalink' => get_permalink( $post ),
             'thumbnail' => get_the_post_thumbnail_url( $post->ID, 'large' ),

includes/Plugin.php

@@ -55,6 +55,20 @@ final class Plugin {
      */
     private ?\Twig\Environment $twig = null;
 
+    /**
+     * Current Twig render depth to prevent infinite recursion.
+     *
+     * @var int
+     */
+    private static int $render_depth = 0;
+
+    /**
+     * Maximum allowed Twig render depth.
+     *
+     * @var int
+     */
+    private const MAX_RENDER_DEPTH = 5;
+
     /**
      * Post type instances.
      *
@@ -843,7 +857,20 @@ final class Plugin {
      * @return string Rendered template.
      */
     public function render( string $template, array $context = array() ): string {
-        return $this->twig->render( $template . '.twig', $context );
+        // Prevent infinite recursion in Twig rendering.
+        if ( self::$render_depth >= self::MAX_RENDER_DEPTH ) {
+            return '<!-- FediStream: render depth exceeded -->';
+        }
+
+        ++self::$render_depth;
+
+        try {
+            $result = $this->twig->render( $template . '.twig', $context );
+        } finally {
+            --self::$render_depth;
+        }
+
+        return $result;
     }
 
     /**