fix: Hard main template rendering lock

- Added $rendering_main_template flag that blocks all other renders
- Reduced MAX_RENDER_DEPTH from 5 to 2
- template-wrapper.php passes is_main_template=true to enable hard lock
- Any render attempt during main template rendering is blocked

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

includes/Frontend/template-wrapper.php

@@ -60,7 +60,8 @@ get_header();
     if ( $template_name ) {
         try {
             // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
-            echo $plugin->render( $template_name, $context );
+            // Pass true for is_main_template to set the hard rendering lock.
+            echo $plugin->render( $template_name, $context, true );
         } catch ( \Exception $e ) {
             if ( WP_DEBUG ) {
                 echo '<div class="fedistream-error">';

includes/Plugin.php

@@ -64,10 +64,19 @@ final class Plugin {
 
     /**
      * Maximum allowed Twig render depth.
+     * Set to 2 to allow one level of nested includes but prevent deeper recursion.
      *
      * @var int
      */
-    private const MAX_RENDER_DEPTH = 5;
+    private const MAX_RENDER_DEPTH = 2;
+
+    /**
+     * Flag to track if we're currently rendering the main page template.
+     * This is a hard lock that prevents ANY other rendering.
+     *
+     * @var bool
+     */
+    private static bool $rendering_main_template = false;
 
     /**
      * Post type instances.
@@ -856,18 +865,32 @@ final class Plugin {
      * @param array  $context  Template context variables.
      * @return string Rendered template.
      */
-    public function render( string $template, array $context = array() ): string {
+    public function render( string $template, array $context = array(), bool $is_main_template = false ): string {
+        // If we're already rendering the main template, block any other renders.
+        if ( self::$rendering_main_template && ! $is_main_template ) {
+            return '<!-- FediStream: blocked during main template render -->';
+        }
+
         // Prevent infinite recursion in Twig rendering.
         if ( self::$render_depth >= self::MAX_RENDER_DEPTH ) {
             return '<!-- FediStream: render depth exceeded -->';
         }
 
+        // Set main template lock if this is the main template.
+        $was_main = self::$rendering_main_template;
+        if ( $is_main_template ) {
+            self::$rendering_main_template = true;
+        }
+
         ++self::$render_depth;
 
         try {
             $result = $this->twig->render( $template . '.twig', $context );
         } finally {
             --self::$render_depth;
+            if ( $is_main_template ) {
+                self::$rendering_main_template = $was_main;
+            }
         }
 
         return $result;