diff --git a/cms/core/class/CodePressCMS.php b/cms/core/class/CodePressCMS.php
index 8766b84..e9c291f 100644
--- a/cms/core/class/CodePressCMS.php
+++ b/cms/core/class/CodePressCMS.php
@@ -540,6 +540,7 @@ class CodePressCMS {
      * Parse Markdown content to HTML using League CommonMark
      * 
      * @param string $content Raw Markdown content
+     * @param string $actualFilePath Path to the source file (used for display name fallback)
      * @return array Parsed content with title and body
      */
     public function parseMarkdown($content, $actualFilePath = '') {
diff --git a/cms/core/class/ContentAPI.php b/cms/core/class/ContentAPI.php
index 0064e8b..d0ff27f 100644
--- a/cms/core/class/ContentAPI.php
+++ b/cms/core/class/ContentAPI.php
@@ -1,5 +1,12 @@
 <?php
 
+/**
+ * Content API for PHP content files
+ *
+ * Provides a safe, read-only interface for PHP content files to access
+ * CMS data (pages, menu, config, navigation, translations, search).
+ * Only instantiated inside parsePHP() — never exposed via URL.
+ */
 class ContentAPI
 {
     private CodePressCMS $cms;
@@ -9,11 +16,22 @@ class ContentAPI
         $this->cms = $cms;
     }
 
+    /**
+     * Get all pages as a flat array of path => title pairs
+     *
+     * @return array Associative array like ['index' => 'Home', 'over-ons' => 'Over ons']
+     */
     public function getAllPages(): array
     {
         return $this->cms->getAllPageTitles();
     }
 
+    /**
+     * Get a single page by path, including title, content, layout, and metadata
+     *
+     * @param string $path Page path without extension (e.g. 'over-ons' or 'blog/post-1')
+     * @return array|null Page data or null if not found
+     */
     public function getPage(string $path): ?array
     {
         $contentDir = $this->cms->config['content_dir'];
@@ -60,11 +78,23 @@ class ContentAPI
         ];
     }
 
+    /**
+     * Get the navigation menu structure
+     *
+     * @return array Hierarchical menu array with 'title', 'path', 'children', 'active' keys
+     */
     public function getMenu(): array
     {
         return $this->cms->getMenu();
     }
 
+    /**
+     * Get a config value using dot notation
+     *
+     * @param string $key Config key, e.g. 'site_title' or 'features.search'
+     * @param mixed $default Default value if key is not found
+     * @return mixed Config value or default
+     */
     public function getConfig(string $key, $default = null)
     {
         $keys = explode('.', $key);
@@ -80,11 +110,24 @@ class ContentAPI
         return $value;
     }
 
+    /**
+     * Get the current language code (e.g. 'nl' or 'en')
+     *
+     * @return string
+     */
     public function getCurrentLanguage(): string
     {
         return $this->cms->currentLanguage;
     }
 
+    /**
+     * Build a URL for a page, optionally with a specific language and extra params
+     *
+     * @param string $page Page path (default 'index')
+     * @param string|null $lang Language code (defaults to current language)
+     * @param array $params Additional query parameters
+     * @return string URL string starting with '?'
+     */
     public function buildUrl(string $page = 'index', ?string $lang = null, array $params = []): string
     {
         $lang = $lang ?? $this->getCurrentLanguage();
@@ -95,6 +138,12 @@ class ContentAPI
         return '?' . $query;
     }
 
+    /**
+     * Check if a page exists at the given path
+     *
+     * @param string $path Page path without extension
+     * @return bool
+     */
     public function pageExists(string $path): bool
     {
         $contentDir = $this->cms->config['content_dir'];
@@ -106,17 +155,32 @@ class ContentAPI
             || file_exists($basePath . '.html');
     }
 
+    /**
+     * Get the title of the currently viewed page
+     *
+     * @return string
+     */
     public function getCurrentPageTitle(): string
     {
         $page = $this->cms->getPage();
         return $page['title'] ?? '';
     }
 
+    /**
+     * Get the path of the currently viewed page
+     *
+     * @return string
+     */
     public function getCurrentPagePath(): string
     {
         return $_GET['page'] ?? $this->cms->config['default_page'];
     }
 
+    /**
+     * Check if the current page is the homepage
+     *
+     * @return bool
+     */
     public function isHomepage(): bool
     {
         $defaultPage = $this->cms->config['default_page'] ?? 'index';
@@ -124,21 +188,42 @@ class ContentAPI
         return $currentPage === $defaultPage;
     }
 
+    /**
+     * Translate a language key using the current language
+     *
+     * @param string $key Language key
+     * @return string Translated text
+     */
     public function t(string $key): string
     {
         return $this->cms->t($key);
     }
 
+    /**
+     * Get the site title from config
+     *
+     * @return string
+     */
     public function getSiteTitle(): string
     {
         return $this->cms->config['site_title'] ?? 'CodePress';
     }
 
+    /**
+     * Get all available language codes
+     *
+     * @return array Language codes like ['nl', 'en']
+     */
     public function getAvailableLanguages(): array
     {
         return $this->cms->getAvailableLanguages();
     }
 
+    /**
+     * Get search results for the current search query
+     *
+     * @return array Search results, or empty array if not searching
+     */
     public function getSearchResults(): array
     {
         if (isset($_GET['search'])) {
@@ -147,6 +232,11 @@ class ContentAPI
         return [];
     }
 
+    /**
+     * Check if a search is currently active
+     *
+     * @return bool
+     */
     public function isSearching(): bool
     {
         return isset($_GET['search']);
diff --git a/public/admin.php b/public/admin.php
index eca4bbb..ba37b28 100644
--- a/public/admin.php
+++ b/public/admin.php
@@ -1374,6 +1374,16 @@ function handleUsers(AdminAuth $auth, array $config): void
     require __DIR__ . '/../admin/templates/layout.php';
 }
 
+/**
+ * Render the admin guide page from a markdown file
+ *
+ * Reads the guide file for the selected language, renders it through
+ * CommonMark (with HeadingPermalink IDs moved to heading elements for
+ * working deep links), and outputs it via the admin layout.
+ *
+ * @param AdminAuth $auth Admin authentication instance
+ * @param array $config Site configuration
+ */
 function handleGuide(AdminAuth $auth, array $config): void
 {
     $user = $auth->getCurrentUser();