diff --git a/src/Integrations/Divi/Design/PresetUsageMatcher.php b/src/Integrations/Divi/Design/PresetUsageMatcher.php
new file mode 100644
index 0000000..1f892cd
--- /dev/null
+++ b/src/Integrations/Divi/Design/PresetUsageMatcher.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+use LIT\MCP\Integrations\Divi\BlockTree\MalformedMarkup;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeIndex;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeSummary;
+use LIT\MCP\Integrations\Divi\BlockTree\Parser;
+
+defined('ABSPATH') || exit;
+
+/**
+ * Whether post content uses a preset (spec §6.4, formats §3 "Verweise in Blöcken"), fail closed:
+ * - module preset $id: a block of the module with $id in its modulePreset stack (array or legacy string);
+ *   the default preset additionally reaches every block of the module without an own preset ("" / "default" /
+ *   "_initial" mean the default, GlobalPreset::is_preset_id_as_default);
+ * - group preset $id: a block with $id in groupPreset.<attr>.presetId whose groupName is the group;
+ * - markup the parser rejects counts as a use.
+ * Pure PHP.
+ */
+final class PresetUsageMatcher
+{
+    private const DEFAULT_IDS = ['', 'default', '_initial'];
+
+    public function __construct(private Parser $parser = new Parser())
+    {
+    }
+
+    public function uses(string $content, PresetScope $scope, string $id, bool $isDefault): bool
+    {
+        try {
+            $index = NodeIndex::build($this->parser->parse($content));
+        } catch (MalformedMarkup) {
+            return true;
+        }
+
+        foreach ($index->entries() as $entry) {
+            if ($this->usesIn($entry['block'], $scope, $id, $isDefault)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private function usesIn(Block $block, PresetScope $scope, string $id, bool $isDefault): bool
+    {
+        if ($scope->kind === PresetScope::MODULE) {
+            return $this->usesModulePreset($block, $scope, $id, $isDefault);
+        }
+
+        return $this->usesGroupPreset($block->attrs(), $scope, $id);
+    }
+
+    private function usesModulePreset(Block $block, PresetScope $scope, string $id, bool $isDefault): bool
+    {
+        if ($block->name() !== $scope->name) {
+            return false;
+        }
+
+        $stack = NodeSummary::presetIds($block);
+        if (in_array($id, $stack, true)) {
+            return true;
+        }
+
+        return $isDefault && array_diff($stack, self::DEFAULT_IDS) === [];
+    }
+
+    /** @param array<string, mixed> $attrs */
+    private function usesGroupPreset(array $attrs, PresetScope $scope, string $id): bool
+    {
+        $groups = is_array($attrs['groupPreset'] ?? null) ? $attrs['groupPreset'] : [];
+        foreach ($groups as $group) {
+            if (! is_array($group) || ($group['groupName'] ?? null) !== $scope->name) {
+                continue;
+            }
+            if (in_array($id, (array) ($group['presetId'] ?? []), true)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
diff --git a/src/Integrations/Divi/Design/PresetUsageQuery.php b/src/Integrations/Divi/Design/PresetUsageQuery.php
new file mode 100644
index 0000000..ddac7c5
--- /dev/null
+++ b/src/Integrations/Divi/Design/PresetUsageQuery.php
@@ -0,0 +1,63 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Design;
+
+use InvalidArgumentException;
+use LIT\MCP\Integrations\Divi\Library\UsageQuery;
+
+defined('ABSPATH') || exit;
+
+/**
+ * The posts that use any of the presets $targets (GlobalUsages::reportFor()): candidates contain one of the IDs, a
+ * JSON escape of a letter (an escaped ID or key, fail closed like ruling P23) or – for a default module preset – a
+ * block of the module; PresetUsageMatcher decides per target.
+ */
+final class PresetUsageQuery implements UsageQuery
+{
+    private const ESCAPED_LETTER = '\\\\u00[4-7][0-9a-fA-F]';
+
+    /** @var list<array{scope: PresetScope, id: string, default: bool}> */
+    private array $targets;
+
+    /**
+     * @param list<array{scope: PresetScope, id: string, default: bool}> $targets
+     * @throws InvalidArgumentException Without targets.
+     */
+    public function __construct(array $targets, private PresetUsageMatcher $matcher = new PresetUsageMatcher())
+    {
+        if ($targets === []) {
+            throw new InvalidArgumentException('PresetUsageQuery needs at least one preset.');
+        }
+        $this->targets = array_values($targets);
+    }
+
+    public function candidateCondition(\wpdb $db): string
+    {
+        $likes = [];
+        foreach ($this->targets as $target) {
+            $likes[] = '%' . $db->esc_like($target['id']) . '%';
+            if ($target['default'] && $target['scope']->kind === PresetScope::MODULE) {
+                $likes[] = '%' . $db->esc_like('wp:' . $target['scope']->name . ' ') . '%';
+            }
+        }
+        $likes = array_values(array_unique($likes));
+
+        return (string) $db->prepare(
+            '(' . str_repeat('post_content LIKE %s OR ', count($likes)) . 'post_content REGEXP %s)',
+            ...array_merge($likes, [self::ESCAPED_LETTER])
+        );
+    }
+
+    public function matches(string $content): bool
+    {
+        foreach ($this->targets as $target) {
+            if ($this->matcher->uses($content, $target['scope'], $target['id'], $target['default'])) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
diff --git a/tests/Unit/Integrations/Divi/Design/PresetUsageMatcherTest.php b/tests/Unit/Integrations/Divi/Design/PresetUsageMatcherTest.php
new file mode 100644
index 0000000..a2dddd9
--- /dev/null
+++ b/tests/Unit/Integrations/Divi/Design/PresetUsageMatcherTest.php
@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\Design\PresetScope;
+use LIT\MCP\Integrations\Divi\Design\PresetUsageMatcher;
+use PHPUnit\Framework\TestCase;
+
+final class PresetUsageMatcherTest extends TestCase
+{
+    private const BUTTON = '<!-- wp:divi/section --><!-- wp:divi/row --><!-- wp:divi/column -->'
+        . '<!-- wp:divi/button %s /--><!-- /wp:divi/column --><!-- /wp:divi/row --><!-- /wp:divi/section -->';
+
+    private static function page(string $buttonAttrs): string
+    {
+        return sprintf(self::BUTTON, $buttonAttrs);
+    }
+
+    public function testModulePresetInTheStack(): void
+    {
+        $matcher = new PresetUsageMatcher();
+        $button = new PresetScope('module', 'divi/button');
+
+        self::assertTrue($matcher->uses(self::page('{"modulePreset":["aaaaaaaaaa"]}'), $button, 'aaaaaaaaaa', false));
+        self::assertTrue($matcher->uses(self::page('{"modulePreset":["x","aaaaaaaaaa"]}'), $button, 'aaaaaaaaaa', false));
+        self::assertTrue($matcher->uses(self::page('{"modulePreset":"aaaaaaaaaa"}'), $button, 'aaaaaaaaaa', false));
+        self::assertFalse($matcher->uses(self::page('{"modulePreset":["bbbbbbbbbb"]}'), $button, 'aaaaaaaaaa', false));
+        self::assertFalse(
+            $matcher->uses(self::page('{"modulePreset":["aaaaaaaaaa"]}'), new PresetScope('module', 'divi/text'), 'aaaaaaaaaa', false),
+            'an ID of another module does not count'
+        );
+    }
+
+    public function testDefaultModulePresetReachesModulesWithoutOwnPreset(): void
+    {
+        $matcher = new PresetUsageMatcher();
+        $button = new PresetScope('module', 'divi/button');
+
+        self::assertTrue($matcher->uses(self::page('{}'), $button, 'dddddddddd', true));
+        self::assertTrue($matcher->uses(self::page('{"modulePreset":["default"]}'), $button, 'dddddddddd', true));
+        self::assertFalse($matcher->uses(self::page('{"modulePreset":["aaaaaaaaaa"]}'), $button, 'dddddddddd', true));
+    }
+
+    public function testGroupPresetById(): void
+    {
+        $matcher = new PresetUsageMatcher();
+        $group = new PresetScope('group', 'divi/font-body');
+        $attrs = '{"groupPreset":{"content.decoration.bodyFont":{"presetId":["gggggggggg"],"groupName":"divi/font-body"}}}';
+
+        self::assertTrue($matcher->uses(self::page($attrs), $group, 'gggggggggg', false));
+        self::assertFalse($matcher->uses(self::page($attrs), new PresetScope('group', 'divi/spacing'), 'gggggggggg', false));
+    }
+
+    public function testBrokenMarkupCountsAsUse(): void
+    {
+        self::assertTrue((new PresetUsageMatcher())->uses(
+            '<!-- wp:divi/section {"a": --><!-- /wp:divi/row -->',
+            new PresetScope('module', 'divi/button'),
+            'aaaaaaaaaa',
+            false
+        ));
+    }
+}
diff --git a/tests/Unit/Integrations/Divi/Design/PresetUsageQueryTest.php b/tests/Unit/Integrations/Divi/Design/PresetUsageQueryTest.php
new file mode 100644
index 0000000..8217a97
--- /dev/null
+++ b/tests/Unit/Integrations/Divi/Design/PresetUsageQueryTest.php
@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\Design\PresetScope;
+use LIT\MCP\Integrations\Divi\Design\PresetUsageQuery;
+use LIT\MCP\Tests\Unit\TestCase;
+use Mockery;
+
+final class PresetUsageQueryTest extends TestCase
+{
+    public function testCandidatesContainAnIdOrAJsonEscape(): void
+    {
+        $db = Mockery::mock(\wpdb::class);
+        $db->allows('esc_like')->andReturnUsing(static fn (string $text): string => $text);
+        $db->expects('prepare')
+            ->with(
+                '(post_content LIKE %s OR post_content LIKE %s OR post_content REGEXP %s)',
+                '%aaaaaaaaaa%',
+                '%gggggggggg%',
+                '\\\\u00[4-7][0-9a-fA-F]'
+            )
+            ->andReturn('(prepared)');
+
+        $query = new PresetUsageQuery([
+            ['scope' => new PresetScope('module', 'divi/button'), 'id' => 'aaaaaaaaaa', 'default' => false],
+            ['scope' => new PresetScope('group', 'divi/font-body'), 'id' => 'gggggggggg', 'default' => false],
+        ]);
+
+        self::assertSame('(prepared)', $query->candidateCondition($db));
+        self::assertTrue($query->matches('<!-- wp:divi/text {"groupPreset":{"content.decoration.bodyFont":'
+            . '{"presetId":["gggggggggg"],"groupName":"divi/font-body"}}} /-->'));
+        self::assertFalse($query->matches('<!-- wp:divi/text {} /-->'));
+    }
+
+    public function testADefaultModulePresetLooksForTheModule(): void
+    {
+        $db = Mockery::mock(\wpdb::class);
+        $db->allows('esc_like')->andReturnUsing(static fn (string $text): string => $text);
+        $db->expects('prepare')
+            ->with(
+                '(post_content LIKE %s OR post_content LIKE %s OR post_content REGEXP %s)',
+                '%dddddddddd%',
+                '%wp:divi/button %',
+                '\\\\u00[4-7][0-9a-fA-F]'
+            )
+            ->andReturn('(prepared)');
+
+        $query = new PresetUsageQuery([
+            ['scope' => new PresetScope('module', 'divi/button'), 'id' => 'dddddddddd', 'default' => true],
+        ]);
+
+        self::assertSame('(prepared)', $query->candidateCondition($db));
+        self::assertTrue($query->matches('<!-- wp:divi/button {} /-->'));
+    }
+
+    public function testNeedsATarget(): void
+    {
+        $this->expectException(\InvalidArgumentException::class);
+
+        new PresetUsageQuery([]);
+    }
+}