refactor: one VariableRef per composition, design lookups in DesignSystem (H3)

- DiviComposition::references() builds the one VariableRef with the entry's
  live map (S22/S31) and passes it to AttrWriter; Placeholders only needs the
  design system now, Placeholders::references() is gone (no reach-through).
- DesignSystem::colorIdFor()/variableFor() replace the dead colorId()/variable()
  and carry Placeholders' lookup incl. the S13a ambiguity check (byLabel moved,
  messages unchanged); isColorVariable() decides color vs content for {{var:}}.
- DesignSystem::colorReferenceIds() (VariableRef color names) and
  contentVariableIds() (DynamicContentRules design names) replace the two
  inline computations; same lists, same order.
Tests: fixtures/tests get the VariableRef from ComposeFixture::references() or
build it with the map; DesignSystemTest uses the new lookups (+2 tests).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

tests/Unit/Integrations/Divi/Compose/PlaceholdersTest.php

@@ -44,7 +44,7 @@ final class PlaceholdersTest extends TestCase
         self::assertSame($expected, $resolved);
         if ($expected !== $input) {
             // What placeholders produce passes the strict checker unchanged (ruling S1/S25).
-            self::assertSame($resolved, $placeholders->references()->canonical($resolved, ComposeFixture::sanitizer()));
+            self::assertSame($resolved, ComposeFixture::references()->canonical($resolved, ComposeFixture::sanitizer()));
         }
     }
 

tests/Unit/Integrations/Divi/Design/DesignSystemTest.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace LIT\MCP\Tests\Unit\Integrations\Divi\Design;
 
+use InvalidArgumentException;
 use LIT\MCP\Integrations\Divi\Design\DesignSystem;
 use LIT\MCP\Tests\Support\DiviFixtures;
 use PHPUnit\Framework\TestCase;
@@ -34,16 +35,53 @@ final class DesignSystemTest extends TestCase
         self::assertSame(['p-1' => 'Standard', 'p-2' => 'CTA primär', 'g-1' => 'Fließtext groß'], $design->presetNames());
     }
 
+    /** The name lists VariableRef/DynamicContentRules check references against (H3: one place). */
+    public function testReferenceNameLists(): void
+    {
+        $design = new DesignSystem(
+            [['id' => 'gcid-a', 'label' => 'A', 'value' => '#000']],
+            [
+                ['id' => 'gvid-c', 'type' => 'colors', 'label' => 'C', 'value' => '#fff'],
+                ['id' => 'gvid-t', 'type' => 'strings', 'label' => 'T', 'value' => 'x'],
+            ],
+            [],
+            ['heading' => '', 'body' => ''],
+            []
+        );
+
+        self::assertSame(['gcid-a', 'gvid-c'], $design->colorReferenceIds());
+        self::assertSame(['--et_global_heading_font', '--et_global_body_font', 'gvid-t'], $design->contentVariableIds());
+        self::assertTrue($design->isColorVariable('gvid-c'));
+        self::assertFalse($design->isColorVariable('gvid-t'));
+        self::assertFalse($design->isColorVariable('gcid-a'));
+    }
+
+    public function testLabelLookupsRefuseAmbiguousLabels(): void
+    {
+        $design = new DesignSystem(
+            [['id' => 'gcid-a', 'label' => 'Blau', 'value' => '#00f'], ['id' => 'gcid-b', 'label' => 'blau', 'value' => '#00e']],
+            [],
+            [],
+            ['heading' => '', 'body' => ''],
+            []
+        );
+
+        self::assertSame('gcid-b', $design->colorIdFor('gcid-b'));
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Name der globale Farbe "Blau" ist mehrdeutig; bitte die ID angeben: gcid-a, gcid-b.');
+        $design->colorIdFor('Blau');
+    }
+
     public function testLooksUpByAliasLabelOrId(): void
     {
         $design = DiviFixtures::designSystem();
 
-        self::assertSame('gcid-primary-color', $design->colorId('primary'));
-        self::assertSame('gcid-a1b2', $design->colorId('nachtblau'));
-        self::assertSame('gcid-a1b2', $design->colorId('gcid-a1b2'));
-        self::assertNull($design->colorId('secondary'));
-        self::assertNull($design->colorId('Alt'));
-        self::assertSame('gvid-s1', $design->variable('telefon')['id'] ?? null);
+        self::assertSame('gcid-primary-color', $design->colorIdFor('primary'));
+        self::assertSame('gcid-a1b2', $design->colorIdFor('nachtblau'));
+        self::assertSame('gcid-a1b2', $design->colorIdFor('gcid-a1b2'));
+        self::assertNull($design->colorIdFor('secondary'));
+        self::assertNull($design->colorIdFor('Alt'));
+        self::assertSame('gvid-s1', $design->variableFor('telefon'));
         self::assertSame('p-2', $design->modulePresetId('divi/button', 'cta PRIMÄR'));
         self::assertNull($design->modulePresetId('divi/text', 'Standard'));
         self::assertSame(['Standard', 'CTA primär'], $design->modulePresetNames('divi/button'));

tests/Unit/Integrations/Divi/Pages/DiviCompositionTest.php

@@ -71,6 +71,7 @@ final class DiviCompositionTest extends TestCase
         self::assertSame([7], $this->registryCalls, 'the registry is read once per post');
         self::assertSame($composition->attrWriter(), $composition->attrWriter());
         self::assertSame($composition->placeholders(), $composition->placeholders());
+        self::assertSame($composition->references(), $composition->references());
     }
 
     public function testWithoutAPostTheDefaultMapApplies(): void
@@ -97,6 +98,8 @@ final class DiviCompositionTest extends TestCase
         self::assertNotSame($base, $seven);
         self::assertNotSame($seven->placeholders(), $eight->placeholders());
         self::assertNotSame($base->placeholders(), $seven->placeholders());
+        self::assertNotSame($seven->references(), $eight->references());
+        self::assertNotSame($base->references(), $seven->references());
         self::assertSame([7, 8], $this->registryCalls);
     }
 

tests/Unit/Integrations/Divi/Pages/DiviWriterTest.php

@@ -91,7 +91,7 @@ final class DiviWriterTest extends TestCase
         $writer = $this->writer(Mockery::mock(DiviSaver::class), FakeChangeLog::forbidden());
         $page = $writer->page(['post_id' => 7, 'tree_rev' => Rev::of($content)]);
 
-        $writer->composition($page)->placeholders();
+        $writer->composition($page)->references();
 
         self::assertSame([7], $this->registryCalls, 'the live dynamic content map of post 7 (ruling S22)');
     }

tests/Unit/Integrations/Divi/Pages/DynamicContentMapTest.php

@@ -61,12 +61,13 @@ final class DynamicContentMapTest extends TestCase
         self::assertSame('select', $map['post_date']['date_format']);
         self::assertSame('text', $map['post_excerpt']['words']);
 
-        $placeholders = new Placeholders(DiviFixtures::designSystem(), $map);
+        $placeholders = new Placeholders(DiviFixtures::designSystem());
+        $references = new VariableRef(DiviFixtures::designSystem(), $map);
         foreach (array_keys(Placeholders::POST) as $key) {
             $reference = $placeholders->resolve('{{post:' . $key . '}}');
             self::assertSame(
                 $reference,
-                $placeholders->references()->canonical($reference, ComposeFixture::sanitizer()),
+                $references->canonical($reference, ComposeFixture::sanitizer()),
                 $key
             );
         }