feat: {{link:ID}} placeholder via Divi's post_link_url dynamic content

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/Integrations/Divi/Compose/LinkTargets.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Compose;
+
+defined('ABSPATH') || exit;
+
+/**
+ * Entries {{link:<ID>}} may point to (E13a). Pure interface – WpLinkTargets asks WordPress.
+ */
+interface LinkTargets
+{
+    /** Post type of entry $id when it may be linked (exists, not trashed, readable); null otherwise. */
+    public function postTypeOf(int $id): ?string;
+}

src/Integrations/Divi/Compose/Placeholders.php

@@ -12,10 +12,10 @@ defined('ABSPATH') || exit;
 /**
  * Translates the placeholders of spec §5.4 into Divi's $variable(…)$ syntax:
  * {{color:primary|<Name>|gcid-…}}, {{var:<Name>|gvid-…}}, {{font:heading|body}},
- * {{post:title|…}}, {{field:<meta_key>}}. A placeholder must be the whole value (D9); unknown
- * names fail with the list of existing ones, labels two entries share fail with their IDs
- * (ruling S13a, DesignSystem::colorIdFor/variableFor). The result is still checked by VariableRef
- * wherever it is written. Pure PHP.
+ * {{post:title|…}}, {{field:<meta_key>}}, {{link:<ID>}} (internal link, URL fields only – E13a).
+ * A placeholder must be the whole value (D9); unknown names fail with the list of existing ones,
+ * labels two entries share fail with their IDs (ruling S13a, DesignSystem::colorIdFor/variableFor).
+ * The result is still checked by VariableRef wherever it is written. Pure PHP.
  */
 final class Placeholders
 {
@@ -37,9 +37,10 @@ final class Placeholders
         'post_title', 'post_excerpt', 'post_date', 'post_modified_date', 'post_author', 'post_categories', 'post_tags',
     ];
 
-    private const PATTERN = '/^\{\{\s*(color|var|font|post|field)\s*:\s*([^{}]+?)\s*\}\}$/';
+    private const PATTERN = '/^\{\{\s*(color|var|font|post|field|link)\s*:\s*([^{}]+?)\s*\}\}$/';
 
-    public function __construct(private DesignSystem $design)
+    /** @param LinkTargets|null $links Entries {{link:…}} may point to; without them every link fails. */
+    public function __construct(private DesignSystem $design, private ?LinkTargets $links = null)
     {
     }
 
@@ -54,7 +55,7 @@ final class Placeholders
             if (str_contains($value, '{{')) {
                 throw new InvalidArgumentException(
                     'Platzhalter müssen allein im Wert stehen, z. B. "{{color:primary}}" (bekannt: color, var, font, '
-                        . 'post, field).'
+                        . 'post, field, link).'
                 );
             }
 
@@ -68,6 +69,7 @@ final class Placeholders
             'var' => $this->variable($name),
             'font' => $this->font($name),
             'post' => $this->post($name),
+            'link' => $this->link($name),
             default => $this->field($name),
         };
     }
@@ -152,6 +154,36 @@ final class Placeholders
         return VariableRef::serialize('content', $option, $settings);
     }
 
+    /**
+     * {{link:<ID>}} → Divi's own internal link post_link_url_<type> with settings.post_id (F27):
+     * rendered as get_permalink() at view time, so a draft target gets its pretty URL once published.
+     * Whether Divi offers that option (public post types only) VariableRef checks against the registry;
+     * that the value goes into a URL field and the target is readable (S37) the choke point checks again.
+     *
+     * @throws InvalidArgumentException
+     */
+    private function link(string $name): string
+    {
+        // FILTER_VALIDATE_INT: no id beyond PHP_INT_MAX that would saturate to another entry.
+        $id = preg_match('/^[1-9][0-9]{0,18}$/D', $name) === 1 ? filter_var($name, FILTER_VALIDATE_INT) : false;
+        if (! is_int($id)) {
+            throw new InvalidArgumentException(sprintf(
+                'Ungültige Beitrags-ID "%s" in {{link:…}} (positive Zahl erwartet, z. B. {{link:42}}).',
+                $name
+            ));
+        }
+
+        $type = $this->links?->postTypeOf($id);
+        if ($type === null) {
+            throw new InvalidArgumentException(sprintf(
+                'Eintrag %s für {{link:…}} gibt es nicht, er liegt im Papierkorb oder ist nicht lesbar.',
+                $name
+            ));
+        }
+
+        return VariableRef::serialize('content', 'post_link_url_' . $type, ['post_id' => $name]);
+    }
+
     private function field(string $name): string
     {
         if (preg_match(DynamicContentRules::META_KEY, $name) !== 1) {

src/Integrations/Divi/Compose/VariableRef.php

@@ -26,7 +26,8 @@ defined('ABSPATH') || exit;
  *   settings hue/saturation/lightness/opacity, numbers only.
  * - type "content": DynamicContentRules – the dynamic content map (ruling S22), custom_meta_<key>
  *   (S12/S29/S30), non-color global variables and theme fonts (S27); it also cleans each content
- *   setting. "enable_html" is always rejected here.
+ *   setting. "enable_html" is always rejected here. Internal links post_link_url_<type> ({{link:…}},
+ *   E13a) only in URL fields.
  * A dynamic content map of the wrong shape fails in the constructor with InvalidArgumentException.
  */
 final class VariableRef
@@ -232,6 +233,13 @@ final class VariableRef
      */
     private function contentSettings(string $name, array $settings, ValueSanitizer $sanitizer, bool $url): array
     {
+        if (! $url && str_starts_with($name, 'post_link_url_')) {
+            throw new InvalidArgumentException(sprintf(
+                '"%s" (Link auf einen Eintrag, {{link:…}}) nur in Link- und URL-Feldern.',
+                $name
+            ));
+        }
+
         $fields = $this->content->fieldsFor($name);
         $clean = [];
         foreach ($settings as $key => $value) {

src/Integrations/Divi/Pages/DiviComposition.php

@@ -6,6 +6,7 @@ namespace LIT\MCP\Integrations\Divi\Pages;
 
 use LIT\MCP\Integrations\Divi\Compose\AttrWriter;
 use LIT\MCP\Integrations\Divi\Compose\Composer;
+use LIT\MCP\Integrations\Divi\Compose\LinkTargets;
 use LIT\MCP\Integrations\Divi\Compose\MediaResolver;
 use LIT\MCP\Integrations\Divi\Compose\Placeholders;
 use LIT\MCP\Integrations\Divi\Compose\ShortformWriter;
@@ -45,7 +46,8 @@ class DiviComposition
         private DesignSystemReader $design,
         private ValueSanitizer $sanitizer = new WpValueSanitizer(),
         private MediaResolver $media = new WpMediaResolver(),
-        private DynamicContentMap $dynamicContent = new DynamicContentMap()
+        private DynamicContentMap $dynamicContent = new DynamicContentMap(),
+        private LinkTargets $links = new WpLinkTargets()
     ) {
     }
 
@@ -83,7 +85,7 @@ class DiviComposition
      */
     public function placeholders(): Placeholders
     {
-        return $this->placeholders ??= new Placeholders($this->design->read());
+        return $this->placeholders ??= new Placeholders($this->design->read(), $this->links);
     }
 
     /** The one choke point of this composition (ValueCleaner, rulings S1–S3, S7, S13, S28, S32). */

src/Integrations/Divi/Pages/WpLinkTargets.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Pages;
+
+use LIT\MCP\Integrations\Divi\Compose\LinkTargets;
+use WP_Post;
+
+defined('ABSPATH') || exit;
+
+/**
+ * {{link:<ID>}} targets from WordPress: the entry exists, lives (no trash, auto-draft or
+ * revision) and the current user may read it (read_post, like select_post settings, S37).
+ * Missing and unreadable entries give the same null (no existence oracle).
+ */
+final class WpLinkTargets implements LinkTargets
+{
+    private const DEAD = ['trash', 'auto-draft', 'inherit'];
+
+    public function postTypeOf(int $id): ?string
+    {
+        $post = get_post($id);
+        if (! $post instanceof WP_Post || in_array((string) $post->post_status, self::DEAD, true)) {
+            return null;
+        }
+
+        return current_user_can('read_post', $id) ? (string) $post->post_type : null;
+    }
+}