diff --git a/.github/workflows/scheduled-ci.yml b/.github/workflows/scheduled-ci.yml
index c6718fd..129802b 100644
--- a/.github/workflows/scheduled-ci.yml
+++ b/.github/workflows/scheduled-ci.yml
@@ -8,4 +8,5 @@ on:
 
 jobs:
   scheduled-ci:
-    uses: builtnorth/.github/.github/workflows/composer-package-ci.yml@main
\ No newline at end of file
+    uses: builtnorth/.github/.github/workflows/composer-package-ci.yml@main
+    secrets: inherit
\ No newline at end of file
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 77bb23e..cedd6bf 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -8,3 +8,4 @@ on:
 jobs:
   ci:
     uses: builtnorth/.github/.github/workflows/composer-package-ci.yml@main
+    secrets: inherit
diff --git a/composer.json b/composer.json
index 12ad3f1..f04bedf 100644
--- a/composer.json
+++ b/composer.json
@@ -10,7 +10,7 @@
     }
   ],
   "require": {
-    "php": ">=8.1"
+    "php": ">=8.0"
   },
   "autoload": {
     "psr-4": {
diff --git a/docs/hooks-reference.md b/docs/hooks-reference.md
index ad09165..24a23c3 100644
--- a/docs/hooks-reference.md
+++ b/docs/hooks-reference.md
@@ -82,7 +82,7 @@ add_filter('wp_schema_framework_output_enabled', function($enabled) {
 Override the detected page context.
 
 **Parameters:**
-- `$context` (string) - Detected context ('home', 'singular', 'archive', 'search', 'error')
+- `$context` (string) - Detected context ('home', 'singular', 'attachment', 'archive', 'search', '404', 'unknown')
 
 **Usage:**
 ```php
@@ -167,7 +167,8 @@ Modify a specific schema piece by ID.
 
 **Usage:**
 ```php
-add_filter('wp_schema_framework_piece_id_#organization', function($piece, $context) {
+// Note: '#' is stripped from IDs when building the hook name, so '#organization' becomes 'organization'
+add_filter('wp_schema_framework_piece_id_organization', function($piece, $context) {
     $piece->set('telephone', '+1234567890');
     return $piece;
 }, 10, 2);
diff --git a/inc/App.php b/inc/App.php
index 82fd10f..9c30d29 100644
--- a/inc/App.php
+++ b/inc/App.php
@@ -4,6 +4,7 @@
 
 namespace BuiltNorth\WPSchema;
 
+use BuiltNorth\WPSchema\Contracts\SchemaProviderInterface;
 use BuiltNorth\WPSchema\Services\ProviderRegistry;
 use BuiltNorth\WPSchema\Services\GraphBuilder;
 use BuiltNorth\WPSchema\Services\OutputService;
@@ -60,12 +61,14 @@ public function init(): void
         
         // Initialize output hooks
         $this->output_service->init();
-        
+
+        // Mark initialized before firing the action so register_provider() works
+        // during wp_schema_framework_register_providers callbacks.
+        $this->initialized = true;
+
         // Allow plugins to register providers
         do_action('wp_schema_framework_register_providers', $this);
         
-        $this->initialized = true;
-        
         // Framework is ready
         do_action('wp_schema_framework_ready', $this);
         
@@ -120,16 +123,25 @@ private function register_core_providers(): void
     public static function register_provider(string $name, string $class_name): bool
     {
         $instance = self::instance();
-        
+
+        // Registry is only available after init(); return false instead of crashing.
+        if (!$instance->initialized) {
+            return false;
+        }
+
         if (!class_exists($class_name)) {
             return false;
         }
-        
+
+        if (!is_a($class_name, SchemaProviderInterface::class, true)) {
+            return false;
+        }
+
         try {
             $provider = new $class_name();
             $instance->registry->register($name, $provider);
             return true;
-        } catch (\Exception $e) {
+        } catch (\Throwable $e) {
             return false;
         }
     }
diff --git a/inc/Graph/SchemaGraph.php b/inc/Graph/SchemaGraph.php
index 53fef0e..05c21fa 100644
--- a/inc/Graph/SchemaGraph.php
+++ b/inc/Graph/SchemaGraph.php
@@ -169,7 +169,7 @@ public function to_json(): string
         
         return json_encode(
             $schema_array,
-            JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE
+            JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS | JSON_HEX_QUOT
         ) ?: '';
     }
     
diff --git a/inc/Providers/ArticleProvider.php b/inc/Providers/ArticleProvider.php
index 5a829b4..1f73480 100644
--- a/inc/Providers/ArticleProvider.php
+++ b/inc/Providers/ArticleProvider.php
@@ -113,42 +113,72 @@ public function get_pieces(string $context): array
         if (!$post) {
             return [];
         }
-        
+
         // Get schema type
         $default_type = $this->get_default_schema_type($post->post_type);
         $schema_type = apply_filters('wp_schema_framework_post_type_override', $default_type, $post->ID, $post->post_type, $post);
-        
-        // Create article piece
+
         $article = new SchemaPiece('#article', $schema_type);
-        
+
         $article
             ->set('headline', $post->post_title)
             ->set('name', $post->post_title)
             ->set('url', get_permalink($post->ID))
             ->set('datePublished', get_the_date('c', $post->ID))
             ->set('dateModified', get_the_modified_date('c', $post->ID))
+            ->set('mainEntityOfPage', ['@type' => 'WebPage', '@id' => get_permalink($post->ID)])
+            ->set('inLanguage', get_bloginfo('language'))
             ->add_reference('author', '#author')
-            ->add_reference('publisher', '#organization');
-        
-        // Add description from filter or excerpt
+            ->add_reference('publisher', '#organization')
+            ->add_reference('isPartOf', '#website');
+
+        // Description from filter or excerpt
         $description = apply_filters('wp_schema_framework_post_description', '', $post->ID, $post);
         if ($description) {
             $article->set('description', $description);
         } elseif ($post->post_excerpt) {
             $article->set('description', wp_strip_all_tags($post->post_excerpt));
         }
-        
-        // Add featured image
-        if (has_post_thumbnail($post->ID)) {
-            $image_url = get_the_post_thumbnail_url($post->ID, 'full');
+
+        // Featured image with dimensions
+        $thumb_id = get_post_thumbnail_id($post->ID);
+        if ($thumb_id) {
+            $image_url = wp_get_attachment_image_url($thumb_id, 'full');
             if ($image_url) {
-                $article->set('image', [
-                    '@type' => 'ImageObject',
-                    'url' => $image_url,
-                ]);
+                $image_data = ['@type' => 'ImageObject', 'url' => $image_url];
+                $metadata = wp_get_attachment_metadata($thumb_id);
+                if (!empty($metadata['width'])) {
+                    $image_data['width'] = $metadata['width'];
+                }
+                if (!empty($metadata['height'])) {
+                    $image_data['height'] = $metadata['height'];
+                }
+                $article->set('image', $image_data);
             }
         }
-        
+
+        // Keywords from post tags
+        $tags = get_the_tags($post->ID);
+        if ($tags) {
+            $article->set('keywords', implode(', ', array_map(fn($tag) => $tag->name, $tags)));
+        }
+
+        // Article section from primary category
+        $categories = get_the_category($post->ID);
+        if ($categories) {
+            $article->set('articleSection', $categories[0]->name);
+        }
+
+        // Word count
+        $word_count = str_word_count(wp_strip_all_tags($post->post_content));
+        if ($word_count > 0) {
+            $article->set('wordCount', $word_count);
+        }
+
+        // Allow filtering — also gives polaris-seo a chance to add image fallback etc.
+        $data = apply_filters('wp_schema_framework_article_data', $article->to_array(), $post->ID, $post);
+        $article->from_array($data);
+
         return [$article];
     }
     
diff --git a/inc/Providers/MediaProvider.php b/inc/Providers/MediaProvider.php
index eb7a952..fe53084 100644
--- a/inc/Providers/MediaProvider.php
+++ b/inc/Providers/MediaProvider.php
@@ -19,8 +19,7 @@ class MediaProvider implements SchemaProviderInterface
 {
     public function can_provide(string $context): bool
     {
-        // Only provide for singular attachment pages
-        return $context === 'singular' && is_attachment();
+        return $context === 'attachment';
     }
     
     public function get_pieces(string $context): array
@@ -309,8 +308,8 @@ private function format_duration(int $seconds): string
     {
         $hours = floor($seconds / 3600);
         $minutes = floor(($seconds % 3600) / 60);
-        $seconds = $seconds % 60;
-        
+        $secs = $seconds % 60;
+
         $duration = 'PT';
         if ($hours > 0) {
             $duration .= $hours . 'H';
@@ -318,10 +317,10 @@ private function format_duration(int $seconds): string
         if ($minutes > 0) {
             $duration .= $minutes . 'M';
         }
-        if ($seconds > 0) {
-            $duration .= $seconds . 'S';
+        if ($secs > 0 || $duration === 'PT') {
+            $duration .= $secs . 'S';
         }
-        
+
         return $duration;
     }
 }
\ No newline at end of file
diff --git a/inc/Providers/WebPageProvider.php b/inc/Providers/WebPageProvider.php
index 3a4c6ff..680b140 100644
--- a/inc/Providers/WebPageProvider.php
+++ b/inc/Providers/WebPageProvider.php
@@ -53,15 +53,16 @@ public function get_pieces(string $context): array
                 ->set('name', get_bloginfo('name'))
                 ->set('headline', get_bloginfo('name'))
                 ->set('url', home_url())
+                ->set('inLanguage', get_bloginfo('language'))
                 ->add_reference('publisher', '#organization')
                 ->add_reference('isPartOf', '#website');
-            
+
             // Add description
             $description = get_bloginfo('description');
             if ($description) {
                 $webpage->set('description', $description);
             }
-            
+
             // If front page is a static page
             if (get_option('show_on_front') === 'page') {
                 $page_id = get_option('page_on_front');
@@ -69,31 +70,39 @@ public function get_pieces(string $context): array
                     $post = get_post($page_id);
                     if ($post) {
                         $webpage->set('headline', $post->post_title);
-                        
+
                         if ($post->post_excerpt) {
                             $webpage->set('description', wp_strip_all_tags($post->post_excerpt));
                         }
-                        
+
                         $webpage
                             ->set('datePublished', get_the_date('c', $page_id))
                             ->set('dateModified', get_the_modified_date('c', $page_id));
-                        
-                        if (has_post_thumbnail($page_id)) {
-                            $image_url = get_the_post_thumbnail_url($page_id, 'full');
+
+                        $thumb_id = get_post_thumbnail_id($page_id);
+                        if ($thumb_id) {
+                            $image_url = wp_get_attachment_image_url($thumb_id, 'full');
                             if ($image_url) {
-                                $webpage->set('image', [
-                                    '@type' => 'ImageObject',
-                                    'url' => $image_url,
-                                ]);
+                                $image_data = ['@type' => 'ImageObject', 'url' => $image_url];
+                                $metadata = wp_get_attachment_metadata($thumb_id);
+                                if (!empty($metadata['width'])) {
+                                    $image_data['width'] = $metadata['width'];
+                                }
+                                if (!empty($metadata['height'])) {
+                                    $image_data['height'] = $metadata['height'];
+                                }
+                                $webpage->set('image', $image_data);
                             }
                         }
                     }
                 }
             }
             
-            // Add breadcrumb reference
-            $webpage->add_reference('breadcrumb', '#breadcrumb');
-            
+            // Only add breadcrumb reference if a BreadcrumbList will be in the graph
+            if (apply_filters('wp_schema_framework_has_breadcrumb', false)) {
+                $webpage->add_reference('breadcrumb', '#breadcrumb');
+            }
+
             // Allow filtering of homepage data
             $data = apply_filters('wp_schema_framework_homepage_data', $webpage->to_array());
             $data = apply_filters('wp_schema_framework_webpage_data', $data, 0, null);
@@ -121,10 +130,11 @@ public function get_pieces(string $context): array
             ->set('url', get_permalink($post->ID))
             ->set('datePublished', get_the_date('c', $post->ID))
             ->set('dateModified', get_the_modified_date('c', $post->ID))
+            ->set('inLanguage', get_bloginfo('language'))
             ->add_reference('author', '#author')
             ->add_reference('publisher', '#organization')
             ->add_reference('isPartOf', '#website');
-        
+
         // Add description from filter or excerpt
         $description = apply_filters('wp_schema_framework_post_description', '', $post->ID, $post);
         if ($description) {
@@ -132,21 +142,29 @@ public function get_pieces(string $context): array
         } elseif ($post->post_excerpt) {
             $webpage->set('description', wp_strip_all_tags($post->post_excerpt));
         }
-        
-        // Add featured image
-        if (has_post_thumbnail($post->ID)) {
-            $image_url = get_the_post_thumbnail_url($post->ID, 'full');
+
+        // Featured image with dimensions
+        $thumb_id = get_post_thumbnail_id($post->ID);
+        if ($thumb_id) {
+            $image_url = wp_get_attachment_image_url($thumb_id, 'full');
             if ($image_url) {
-                $webpage->set('image', [
-                    '@type' => 'ImageObject',
-                    'url' => $image_url,
-                ]);
+                $image_data = ['@type' => 'ImageObject', 'url' => $image_url];
+                $metadata = wp_get_attachment_metadata($thumb_id);
+                if (!empty($metadata['width'])) {
+                    $image_data['width'] = $metadata['width'];
+                }
+                if (!empty($metadata['height'])) {
+                    $image_data['height'] = $metadata['height'];
+                }
+                $webpage->set('image', $image_data);
             }
         }
         
-        // Add breadcrumb reference
-        $webpage->add_reference('breadcrumb', '#breadcrumb');
-        
+        // Only add breadcrumb reference if a BreadcrumbList will be in the graph
+        if (apply_filters('wp_schema_framework_has_breadcrumb', false)) {
+            $webpage->add_reference('breadcrumb', '#breadcrumb');
+        }
+
         // Allow filtering of webpage data
         $data = apply_filters('wp_schema_framework_webpage_data', $webpage->to_array(), $post->ID, $post);
         $webpage->from_array($data);
diff --git a/inc/Providers/WebsiteProvider.php b/inc/Providers/WebsiteProvider.php
index b39a62e..095717c 100644
--- a/inc/Providers/WebsiteProvider.php
+++ b/inc/Providers/WebsiteProvider.php
@@ -46,12 +46,18 @@ public function get_pieces(string $context): array
             ->set('name', get_bloginfo('name'))
             ->set('url', home_url('/'))
             ->add_reference('publisher', '#organization');
-        
+
         // Add description if available
         $description = get_bloginfo('description');
         if ($description) {
             $website->set('description', $description);
         }
+
+        // Language
+        $language = get_bloginfo('language');
+        if ($language) {
+            $website->set('inLanguage', $language);
+        }
         
         // Add search action on all pages for Google Sitelinks Searchbox
         $search_url = home_url('/?s={search_term_string}');
diff --git a/inc/Services/ContextDetector.php b/inc/Services/ContextDetector.php
index 6abcf88..19ff9d5 100644
--- a/inc/Services/ContextDetector.php
+++ b/inc/Services/ContextDetector.php
@@ -19,26 +19,22 @@ class ContextDetector
     public function get_current_context(): string
     {
         if (is_front_page()) {
-            return 'home';
+            $context = 'home';
+        } elseif (is_attachment()) {
+            $context = 'attachment';
+        } elseif (is_singular()) {
+            $context = 'singular';
+        } elseif (is_archive() || is_home()) {
+            $context = 'archive';
+        } elseif (is_search()) {
+            $context = 'search';
+        } elseif (is_404()) {
+            $context = '404';
+        } else {
+            $context = 'unknown';
         }
-        
-        if (is_singular()) {
-            return 'singular';
-        }
-        
-        if (is_archive() || is_home()) {
-            return 'archive';
-        }
-        
-        if (is_search()) {
-            return 'search';
-        }
-        
-        if (is_404()) {
-            return '404';
-        }
-        
-        return 'unknown';
+
+        return (string) apply_filters('wp_schema_framework_context', $context);
     }
     
     /**
diff --git a/inc/Services/GraphBuilder.php b/inc/Services/GraphBuilder.php
index 3d8c1d2..9a6fad8 100644
--- a/inc/Services/GraphBuilder.php
+++ b/inc/Services/GraphBuilder.php
@@ -40,7 +40,15 @@ public function build_for_context(string $context): SchemaGraph
         
         // Apply filters for extensibility
         $graph->apply_filters($context);
-        
+
+        // Surface dangling references as error_log entries during development
+        if (defined('WP_DEBUG') && WP_DEBUG) {
+            foreach ($graph->validate_references() as $error) {
+                // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log
+                error_log('[WP Schema] ' . $error);
+            }
+        }
+
         return $graph;
     }
 }
\ No newline at end of file
diff --git a/inc/Services/OutputService.php b/inc/Services/OutputService.php
index 19fc639..c1da60c 100644
--- a/inc/Services/OutputService.php
+++ b/inc/Services/OutputService.php
@@ -83,7 +83,8 @@ private function output_graph($graph): void
         // Allow filtering of complete graph before output
         $graph_data = apply_filters('wp_schema_framework_graph', $graph_data);
         
-        $json = json_encode($graph_data, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
+        // JSON_HEX_TAG prevents </script> breakout inside <script type="application/ld+json">
+        $json = json_encode($graph_data, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS | JSON_HEX_QUOT);
         
         // Allow filtering of JSON string
         $json = apply_filters('wp_schema_framework_json_output', $json, $graph_data);
diff --git a/tests/AppTest.php b/tests/AppTest.php
index c43d160..1a280a4 100644
--- a/tests/AppTest.php
+++ b/tests/AppTest.php
@@ -127,11 +127,66 @@ public function testDoubleInitialization(): void
         WP_Mock::userFunction('do_action')->andReturn(null);
         WP_Mock::userFunction('add_filter')->andReturn(true);
         WP_Mock::userFunction('add_action')->andReturn(true);
-        
+
         $app = App::initialize();
         $app->init(); // Second initialization
-        
+
         // Should not throw an error
         $this->assertTrue($app->is_initialized());
     }
+
+    public function testRegisterProviderRejectsClassWithoutInterface(): void
+    {
+        WP_Mock::userFunction('do_action')->andReturn(null);
+        WP_Mock::userFunction('add_filter')->andReturn(true);
+        WP_Mock::userFunction('add_action')->andReturn(true);
+
+        App::initialize();
+
+        // A real class that exists but does NOT implement SchemaProviderInterface
+        $result = App::register_provider('bad_provider', \stdClass::class);
+
+        $this->assertFalse($result, 'Should reject class that does not implement SchemaProviderInterface');
+    }
+
+    public function testRegisterProviderHandlesThrowable(): void
+    {
+        WP_Mock::userFunction('do_action')->andReturn(null);
+        WP_Mock::userFunction('add_filter')->andReturn(true);
+        WP_Mock::userFunction('add_action')->andReturn(true);
+
+        App::initialize();
+
+        // Create a class whose constructor throws a TypeError (Throwable, not Exception)
+        $throwableClass = 'ThrowableProvider_' . uniqid();
+        eval("
+            class {$throwableClass} implements \\BuiltNorth\\WPSchema\\Contracts\\SchemaProviderInterface {
+                public function __construct() { throw new \\TypeError('Simulated type error'); }
+                public function can_provide(string \$context): bool { return false; }
+                public function get_pieces(string \$context): array { return []; }
+                public function get_priority(): int { return 10; }
+            }
+        ");
+
+        $result = App::register_provider('throwable_provider', $throwableClass);
+
+        $this->assertFalse($result, 'Should return false when constructor throws Throwable');
+    }
+
+    public function testRegisterProviderReturnsFalseBeforeInit(): void
+    {
+        // Do NOT call App::initialize() — should return false instead of crashing
+        $providerClass = 'PreInitProvider_' . uniqid();
+        eval("
+            class {$providerClass} implements \\BuiltNorth\\WPSchema\\Contracts\\SchemaProviderInterface {
+                public function can_provide(string \$context): bool { return false; }
+                public function get_pieces(string \$context): array { return []; }
+                public function get_priority(): int { return 10; }
+            }
+        ");
+
+        $result = App::register_provider('pre_init_provider', $providerClass);
+
+        $this->assertFalse($result, 'register_provider should return false safely when called before init()');
+    }
 }
\ No newline at end of file
diff --git a/tests/Services/ContextDetectorTest.php b/tests/Services/ContextDetectorTest.php
new file mode 100644
index 0000000..6529884
--- /dev/null
+++ b/tests/Services/ContextDetectorTest.php
@@ -0,0 +1,163 @@
+<?php
+
+declare(strict_types=1);
+
+namespace BuiltNorth\WPSchema\Tests\Services;
+
+use BuiltNorth\WPSchema\Services\ContextDetector;
+use BuiltNorth\WPSchema\Tests\TestCase;
+use WP_Mock;
+
+/**
+ * Tests for ContextDetector service
+ */
+class ContextDetectorTest extends TestCase
+{
+    private ContextDetector $detector;
+
+    public function setUp(): void
+    {
+        parent::setUp();
+        $this->detector = new ContextDetector();
+    }
+
+    /**
+     * Test attachment context is returned for attachment pages (before singular)
+     */
+    public function test_attachment_context_detected(): void
+    {
+        WP_Mock::userFunction('is_front_page')->andReturn(false);
+        WP_Mock::userFunction('is_attachment')->andReturn(true);
+        WP_Mock::onFilter('wp_schema_framework_context')
+            ->with('attachment')
+            ->reply('attachment');
+
+        $context = $this->detector->get_current_context();
+
+        $this->assertSame('attachment', $context);
+    }
+
+    /**
+     * Test singular context is not returned for attachments (attachment takes priority)
+     */
+    public function test_attachment_does_not_fall_through_to_singular(): void
+    {
+        WP_Mock::userFunction('is_front_page')->andReturn(false);
+        WP_Mock::userFunction('is_attachment')->andReturn(true);
+        WP_Mock::onFilter('wp_schema_framework_context')
+            ->with('attachment')
+            ->reply('attachment');
+
+        $context = $this->detector->get_current_context();
+
+        $this->assertNotSame('singular', $context);
+    }
+
+    /**
+     * Test singular context for non-attachment singular pages
+     */
+    public function test_singular_context_for_posts(): void
+    {
+        WP_Mock::userFunction('is_front_page')->andReturn(false);
+        WP_Mock::userFunction('is_attachment')->andReturn(false);
+        WP_Mock::userFunction('is_singular')->andReturn(true);
+        WP_Mock::onFilter('wp_schema_framework_context')
+            ->with('singular')
+            ->reply('singular');
+
+        $context = $this->detector->get_current_context();
+
+        $this->assertSame('singular', $context);
+    }
+
+    /**
+     * Test that wp_schema_framework_context filter is applied
+     */
+    public function test_context_filter_is_applied(): void
+    {
+        WP_Mock::userFunction('is_front_page')->andReturn(true);
+        WP_Mock::onFilter('wp_schema_framework_context')
+            ->with('home')
+            ->reply('custom_context');
+
+        $context = $this->detector->get_current_context();
+
+        $this->assertSame('custom_context', $context);
+    }
+
+    /**
+     * Test that context filter receives the detected context as its argument
+     */
+    public function test_context_filter_receives_detected_context(): void
+    {
+        WP_Mock::userFunction('is_front_page')->andReturn(false);
+        WP_Mock::userFunction('is_attachment')->andReturn(false);
+        WP_Mock::userFunction('is_singular')->andReturn(false);
+        WP_Mock::userFunction('is_archive')->andReturn(false);
+        WP_Mock::userFunction('is_home')->andReturn(false);
+        WP_Mock::userFunction('is_search')->andReturn(false);
+        WP_Mock::userFunction('is_404')->andReturn(false);
+
+        WP_Mock::onFilter('wp_schema_framework_context')
+            ->with('unknown')
+            ->reply('unknown');
+
+        $context = $this->detector->get_current_context();
+
+        $this->assertSame('unknown', $context);
+    }
+
+    /**
+     * Test 404 context
+     */
+    public function test_404_context(): void
+    {
+        WP_Mock::userFunction('is_front_page')->andReturn(false);
+        WP_Mock::userFunction('is_attachment')->andReturn(false);
+        WP_Mock::userFunction('is_singular')->andReturn(false);
+        WP_Mock::userFunction('is_archive')->andReturn(false);
+        WP_Mock::userFunction('is_home')->andReturn(false);
+        WP_Mock::userFunction('is_search')->andReturn(false);
+        WP_Mock::userFunction('is_404')->andReturn(true);
+        WP_Mock::onFilter('wp_schema_framework_context')
+            ->with('404')
+            ->reply('404');
+
+        $context = $this->detector->get_current_context();
+
+        $this->assertSame('404', $context);
+    }
+
+    /**
+     * Test should_generate_schema returns false for 404 and unknown
+     */
+    public function test_should_not_generate_schema_for_404(): void
+    {
+        WP_Mock::onFilter('wp_schema_framework_output_enabled')
+            ->with(true)
+            ->reply(true);
+        WP_Mock::userFunction('is_admin')->andReturn(false);
+        WP_Mock::userFunction('is_feed')->andReturn(false);
+        WP_Mock::userFunction('is_robots')->andReturn(false);
+        WP_Mock::userFunction('is_trackback')->andReturn(false);
+
+        $this->assertFalse($this->detector->should_generate_schema('404'));
+        $this->assertFalse($this->detector->should_generate_schema('unknown'));
+    }
+
+    /**
+     * Test should_generate_schema returns true for attachment context
+     */
+    public function test_should_generate_schema_for_attachment(): void
+    {
+        WP_Mock::onFilter('wp_schema_framework_output_enabled')
+            ->with(true)
+            ->reply(true);
+        WP_Mock::userFunction('is_admin')->andReturn(false);
+        WP_Mock::userFunction('is_feed')->andReturn(false);
+        WP_Mock::userFunction('is_robots')->andReturn(false);
+        WP_Mock::userFunction('is_trackback')->andReturn(false);
+
+        $this->assertTrue($this->detector->should_generate_schema('attachment'));
+    }
+}
diff --git a/tests/Services/OutputServiceTest.php b/tests/Services/OutputServiceTest.php
new file mode 100644
index 0000000..7535039
--- /dev/null
+++ b/tests/Services/OutputServiceTest.php
@@ -0,0 +1,157 @@
+<?php
+
+declare(strict_types=1);
+
+namespace BuiltNorth\WPSchema\Tests\Services;
+
+use BuiltNorth\WPSchema\Services\OutputService;
+use BuiltNorth\WPSchema\Services\GraphBuilder;
+use BuiltNorth\WPSchema\Services\ContextDetector;
+use BuiltNorth\WPSchema\Graph\SchemaGraph;
+use BuiltNorth\WPSchema\Graph\SchemaPiece;
+use BuiltNorth\WPSchema\Tests\TestCase;
+use WP_Mock;
+use Mockery;
+
+/**
+ * Tests for OutputService — focused on JSON-LD escaping
+ */
+class OutputServiceTest extends TestCase
+{
+    /**
+     * Test JSON output escapes </script> sequences (JSON_HEX_TAG)
+     */
+    public function test_json_output_escapes_script_closing_tag(): void
+    {
+        $piece = new SchemaPiece('#test', 'Article');
+        $piece->set('name', 'Title with </script> tag');
+
+        $graph = Mockery::mock(SchemaGraph::class);
+        $graph->shouldReceive('is_empty')->andReturn(false);
+        $graph->shouldReceive('get_pieces')->andReturn([$piece]);
+
+        $graph_builder = Mockery::mock(GraphBuilder::class);
+        $graph_builder->shouldReceive('build_for_context')->andReturn($graph);
+
+        $context_detector = Mockery::mock(ContextDetector::class);
+        $context_detector->shouldReceive('get_current_context')->andReturn('singular');
+        $context_detector->shouldReceive('should_generate_schema')->with('singular')->andReturn(true);
+
+        WP_Mock::userFunction('do_action')->andReturn(null);
+        WP_Mock::userFunction('apply_filters')
+            ->andReturnUsing(function ($hook, $value) {
+                return $value;
+            });
+
+        $service = new OutputService($graph_builder, $context_detector);
+
+        ob_start();
+        $service->output_schema();
+        $output = ob_get_clean();
+
+        // Extract just the JSON content (between the script tags, before the closing </script>)
+        preg_match('/<script type="application\/ld\+json">(.*?)<\/script>/s', $output, $matches);
+        $json_content = $matches[1] ?? '';
+
+        // The literal </script> sequence must not appear unescaped inside the JSON content
+        $this->assertStringNotContainsString('</script>', $json_content, 'Raw </script> must be escaped inside JSON-LD content');
+        // JSON_HEX_TAG encodes < as < and > as >
+        $this->assertStringContainsString('\u003C', $json_content, 'JSON_HEX_TAG should encode < as \u003C');
+    }
+
+    /**
+     * Test JSON output escapes ampersands (JSON_HEX_AMP)
+     */
+    public function test_json_output_escapes_ampersands(): void
+    {
+        $piece = new SchemaPiece('#test', 'Organization');
+        $piece->set('name', 'Foo & Bar');
+
+        $graph = Mockery::mock(SchemaGraph::class);
+        $graph->shouldReceive('is_empty')->andReturn(false);
+        $graph->shouldReceive('get_pieces')->andReturn([$piece]);
+
+        $graph_builder = Mockery::mock(GraphBuilder::class);
+        $graph_builder->shouldReceive('build_for_context')->andReturn($graph);
+
+        $context_detector = Mockery::mock(ContextDetector::class);
+        $context_detector->shouldReceive('get_current_context')->andReturn('home');
+        $context_detector->shouldReceive('should_generate_schema')->with('home')->andReturn(true);
+
+        WP_Mock::userFunction('do_action')->andReturn(null);
+        WP_Mock::userFunction('apply_filters')
+            ->andReturnUsing(function ($hook, $value) {
+                return $value;
+            });
+
+        $service = new OutputService($graph_builder, $context_detector);
+
+        ob_start();
+        $service->output_schema();
+        $output = ob_get_clean();
+
+        $this->assertStringContainsString('\u0026', $output, 'JSON_HEX_AMP should encode & as \u0026');
+    }
+
+    /**
+     * Test output is wrapped in correct script tag
+     */
+    public function test_output_wrapped_in_ld_json_script_tag(): void
+    {
+        $piece = new SchemaPiece('#test', 'WebSite');
+        $piece->set('name', 'Test');
+
+        $graph = Mockery::mock(SchemaGraph::class);
+        $graph->shouldReceive('is_empty')->andReturn(false);
+        $graph->shouldReceive('get_pieces')->andReturn([$piece]);
+
+        $graph_builder = Mockery::mock(GraphBuilder::class);
+        $graph_builder->shouldReceive('build_for_context')->andReturn($graph);
+
+        $context_detector = Mockery::mock(ContextDetector::class);
+        $context_detector->shouldReceive('get_current_context')->andReturn('home');
+        $context_detector->shouldReceive('should_generate_schema')->with('home')->andReturn(true);
+
+        WP_Mock::userFunction('do_action')->andReturn(null);
+        WP_Mock::userFunction('apply_filters')
+            ->andReturnUsing(function ($hook, $value) {
+                return $value;
+            });
+
+        $service = new OutputService($graph_builder, $context_detector);
+
+        ob_start();
+        $service->output_schema();
+        $output = ob_get_clean();
+
+        $this->assertStringContainsString('<script type="application/ld+json">', $output);
+        $this->assertStringContainsString('</script>', $output);
+    }
+
+    /**
+     * Test nothing is output when graph is empty
+     */
+    public function test_no_output_when_graph_empty(): void
+    {
+        $graph = Mockery::mock(SchemaGraph::class);
+        $graph->shouldReceive('is_empty')->andReturn(true);
+
+        $graph_builder = Mockery::mock(GraphBuilder::class);
+        $graph_builder->shouldReceive('build_for_context')->andReturn($graph);
+
+        $context_detector = Mockery::mock(ContextDetector::class);
+        $context_detector->shouldReceive('get_current_context')->andReturn('home');
+        $context_detector->shouldReceive('should_generate_schema')->with('home')->andReturn(true);
+
+        WP_Mock::userFunction('do_action')->andReturn(null);
+        WP_Mock::userFunction('apply_filters')->andReturn(true);
+
+        $service = new OutputService($graph_builder, $context_detector);
+
+        ob_start();
+        $service->output_schema();
+        $output = ob_get_clean();
+
+        $this->assertEmpty($output);
+    }
+}