diff --git a/src/Integrations/Divi/Design/AssignRewrite.php b/src/Integrations/Divi/Design/AssignRewrite.php
new file mode 100644
index 0000000..ee25ec2
--- /dev/null
+++ b/src/Integrations/Divi/Design/AssignRewrite.php
@@ -0,0 +1,94 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Design;
+
+use JsonException;
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+use LIT\MCP\Integrations\Divi\BlockTree\GlobalInstance;
+use LIT\MCP\Integrations\Divi\BlockTree\Json;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeSummary;
+use LogicException;
+
+defined('ABSPATH') || exit;
+
+/**
+ * Mass assignment of a preset stack and group presets (lit/divi-presets-assign): every block of $module – optionally
+ * only those without an own preset (empty stack or only default IDs) or only those that use preset $onlyWithPresetId
+ * – gets $spec through PresetAssignment, the one choke point for preset assignments (D7). Local values that cover the
+ * assigned presets are noted, or removed with $clearOverrides (rulings R4, R5). A block that would not change stays
+ * untouched, so the call can be repeated. Pure PHP.
+ */
+final class AssignRewrite implements NodeRewrite
+{
+    /**
+     * @param array{preset?: mixed, group_presets?: mixed} $spec Already checked: PresetAssignment::apply() returned
+     *     no errors for it.
+     */
+    public function __construct(
+        private string $module,
+        private PresetAssignment $assignment,
+        private array $spec,
+        private bool $onlyWithoutPreset = false,
+        private ?string $onlyWithPresetId = null,
+        private bool $clearOverrides = false
+    ) {
+    }
+
+    /** @throws LogicException When $spec does not pass PresetAssignment (it was to be validated beforehand). */
+    public function rewrite(Block $block): ?array
+    {
+        if (! $this->selects($block)) {
+            return null;
+        }
+
+        $attrs = $block->attrs();
+        $result = $this->assignment->apply($this->module, $attrs, $this->spec, 'node');
+        if ($result['errors'] !== []) {
+            throw new LogicException('The preset assignment was not validated: ' . implode('; ', $result['errors']));
+        }
+
+        $new = $this->clearOverrides ? $this->assignment->clearOverrides($result['attrs']) : $result['attrs'];
+
+        return self::same($attrs, $new) ? null : $new;
+    }
+
+    public function notes(Block $block, string $nodeId): array
+    {
+        if ($this->clearOverrides) {
+            return [];
+        }
+
+        return $this->assignment->overrides()->describe($nodeId, $block->attrs(), $this->assignment->names());
+    }
+
+    public function concernsInstance(Block $instance): bool
+    {
+        return GlobalInstance::effectiveName($instance) === $this->module;
+    }
+
+    private function selects(Block $block): bool
+    {
+        if ($block->name() !== $this->module) {
+            return false;
+        }
+
+        $stack = NodeSummary::presetIds($block);
+        if ($this->onlyWithoutPreset && array_diff($stack, PresetUsageMatcher::DEFAULT_IDS) !== []) {
+            return false;
+        }
+
+        return $this->onlyWithPresetId === null || in_array($this->onlyWithPresetId, $stack, true);
+    }
+
+    /** @param array<string, mixed> $before @param array<string, mixed> $after */
+    private static function same(array $before, array $after): bool
+    {
+        try {
+            return Json::encode($before) === Json::encode($after);
+        } catch (JsonException) {
+            return false;
+        }
+    }
+}
diff --git a/src/Integrations/Divi/Design/DetachRewrite.php b/src/Integrations/Divi/Design/DetachRewrite.php
new file mode 100644
index 0000000..076bb10
--- /dev/null
+++ b/src/Integrations/Divi/Design/DetachRewrite.php
@@ -0,0 +1,146 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Design;
+
+use JsonException;
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+use LIT\MCP\Integrations\Divi\BlockTree\Json;
+
+defined('ABSPATH') || exit;
+
+/**
+ * Removes the references to preset $id from blocks (lit/divi-design-detach, ruling R10): a module preset from the
+ * modulePreset stack of the blocks of its module (an empty stack leaves no key, so Divi falls back to the default
+ * preset), a group preset from every groupPreset entry of its group (an empty entry, then an empty map is removed).
+ * Nested references inside other presets are not blocks; the preset pipeline removes those. Pure PHP.
+ */
+final class DetachRewrite implements NodeRewrite
+{
+    public function __construct(private PresetScope $scope, private string $id)
+    {
+    }
+
+    public function rewrite(Block $block): ?array
+    {
+        if (! $block->isDivi()) {
+            return null;
+        }
+
+        return $this->scope->kind === PresetScope::MODULE
+            ? $this->withoutModulePreset($block)
+            : $this->withoutGroupPreset($block->attrs());
+    }
+
+    public function notes(Block $block, string $nodeId): array
+    {
+        return [];
+    }
+
+    public function concernsInstance(Block $instance): bool
+    {
+        return self::mentions($instance, $this->id);
+    }
+
+    /** @return array<string, mixed>|null */
+    private function withoutModulePreset(Block $block): ?array
+    {
+        $attrs = $block->attrs();
+        $stack = self::idList($attrs['modulePreset'] ?? null);
+        if ($block->name() !== $this->scope->name || ! in_array($this->id, $stack, true)) {
+            return null;
+        }
+
+        $rest = $this->without($stack);
+        if ($rest === []) {
+            unset($attrs['modulePreset']);
+        } else {
+            $attrs['modulePreset'] = $rest;
+        }
+
+        return $attrs;
+    }
+
+    /**
+     * @param array<string, mixed> $attrs
+     * @return array<string, mixed>|null
+     */
+    private function withoutGroupPreset(array $attrs): ?array
+    {
+        $groups = $attrs['groupPreset'] ?? null;
+        if (! is_array($groups)) {
+            return null;
+        }
+
+        $changed = false;
+        foreach ($groups as $groupId => $entry) {
+            if (! is_array($entry) || ($entry['groupName'] ?? null) !== $this->scope->name) {
+                continue;
+            }
+            $ids = self::idList($entry['presetId'] ?? null);
+            if (! in_array($this->id, $ids, true)) {
+                continue;
+            }
+
+            $changed = true;
+            $rest = $this->without($ids);
+            if ($rest === []) {
+                unset($groups[$groupId]);
+            } else {
+                $groups[$groupId]['presetId'] = $rest;
+            }
+        }
+
+        if (! $changed) {
+            return null;
+        }
+
+        if ($groups === []) {
+            unset($attrs['groupPreset']);
+        } else {
+            $attrs['groupPreset'] = $groups;
+        }
+
+        return $attrs;
+    }
+
+    /** @return list<mixed> The IDs of a stored stack: a list, the legacy single string, else none. */
+    private static function idList(mixed $value): array
+    {
+        if (is_string($value)) {
+            return [$value];
+        }
+
+        return is_array($value) ? array_values($value) : [];
+    }
+
+    /**
+     * @param array<array-key, mixed> $ids
+     * @return list<mixed>
+     */
+    private function without(array $ids): array
+    {
+        return array_values(array_filter($ids, fn (mixed $item): bool => $item !== $this->id));
+    }
+
+    /** Whether the attributes of $block or of any block below mention $id (fail closed on unencodable values). */
+    private static function mentions(Block $block, string $id): bool
+    {
+        try {
+            if (str_contains(Json::encode($block->attrs()), $id)) {
+                return true;
+            }
+        } catch (JsonException) {
+            return true;
+        }
+
+        foreach ($block->children() as $child) {
+            if (self::mentions($child, $id)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
diff --git a/src/Integrations/Divi/Design/NodeRewrite.php b/src/Integrations/Divi/Design/NodeRewrite.php
new file mode 100644
index 0000000..92aa8c8
--- /dev/null
+++ b/src/Integrations/Divi/Design/NodeRewrite.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+
+defined('ABSPATH') || exit;
+
+/**
+ * One change to the blocks of a tree (Etappe 4b): assigning a preset (AssignRewrite) or removing a reference to it
+ * (DetachRewrite). TreeRewrite applies it to every block of a page; the strategy only decides per block. Pure PHP.
+ */
+interface NodeRewrite
+{
+    /** The new attributes of $block, or null when it stays as it is (then there is no note either). */
+    public function rewrite(Block $block): ?array;
+
+    /**
+     * Notes on $block after rewrite() changed it (e.g. local values that cover the assigned preset).
+     *
+     * @param string $nodeId Path ID of $block (NodeIndex).
+     * @return list<string>
+     */
+    public function notes(Block $block, string $nodeId): array;
+
+    /** Whether the opaque global instance $instance would matter for this change (then it is reported as skipped). */
+    public function concernsInstance(Block $instance): bool;
+}
diff --git a/src/Integrations/Divi/Design/TreeRewrite.php b/src/Integrations/Divi/Design/TreeRewrite.php
new file mode 100644
index 0000000..86f068c
--- /dev/null
+++ b/src/Integrations/Divi/Design/TreeRewrite.php
@@ -0,0 +1,69 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeIndex;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeSummary;
+
+defined('ABSPATH') || exit;
+
+/**
+ * Applies a NodeRewrite to every block of a NodeIndex, in place (ruling R8): readable blocks are offered to
+ * rewrite(), a changed one gets its new attributes and then its notes; opaque blocks – global instances, blocks with
+ * unreadable attributes – are never offered and never changed, but listed as skipped when the strategy says the
+ * change concerns them (a global module is edited in its library entry). Pure PHP.
+ */
+final class TreeRewrite
+{
+    public function __construct(private NodeRewrite $rewrite)
+    {
+    }
+
+    /**
+     * @return array{changed: list<array{id: string, module: string, label: string}>, warnings: list<string>,
+     *               skipped: list<array{id: string, reason: string}>}
+     */
+    public function apply(NodeIndex $index): array
+    {
+        $changed = [];
+        $warnings = [];
+        $skipped = [];
+        foreach ($index->entries() as $entry) {
+            $id = $entry['id'];
+            $block = $entry['block'];
+
+            if ($block->isOpaque()) {
+                if ($this->rewrite->concernsInstance($block)) {
+                    $skipped[] = ['id' => $id, 'reason' => self::reason($block)];
+                }
+                continue;
+            }
+
+            $attrs = $this->rewrite->rewrite($block);
+            if ($attrs === null) {
+                continue;
+            }
+
+            $block->setAttrs($attrs);
+            $changed[] = ['id' => $id, 'module' => $block->name(), 'label' => NodeSummary::label($block)];
+            array_push($warnings, ...$this->rewrite->notes($block, $id));
+        }
+
+        return ['changed' => $changed, 'warnings' => $warnings, 'skipped' => $skipped];
+    }
+
+    private static function reason(Block $block): string
+    {
+        $ref = NodeSummary::globalRef($block);
+        if ($ref !== null) {
+            return sprintf('globales Modul – im Bibliothekseintrag %s ändern', $ref['id']);
+        }
+
+        return $block->isGlobal()
+            ? 'globales Modul ohne Bibliothekseintrag – im Divi-Builder prüfen'
+            : 'Attribute nicht lesbar – im Divi-Builder prüfen';
+    }
+}
diff --git a/tests/Unit/Integrations/Divi/Design/AssignRewriteTest.php b/tests/Unit/Integrations/Divi/Design/AssignRewriteTest.php
new file mode 100644
index 0000000..ac54c7d
--- /dev/null
+++ b/tests/Unit/Integrations/Divi/Design/AssignRewriteTest.php
@@ -0,0 +1,209 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeIndex;
+use LIT\MCP\Integrations\Divi\BlockTree\Parser;
+use LIT\MCP\Integrations\Divi\Design\AssignRewrite;
+use LIT\MCP\Integrations\Divi\Design\PresetAssignment;
+use LIT\MCP\Integrations\Divi\Design\PresetBook;
+use LogicException;
+use PHPUnit\Framework\TestCase;
+
+final class AssignRewriteTest extends TestCase
+{
+    private const BUTTON = ['module' => 'divi/button', 'preset' => 'aaaaaaaaaa'];
+
+    /** PresetBookTest::stored() with settings in "CTA primär" (aaaaaaaaaa): background colour #111111. */
+    private static function stored(): array
+    {
+        $stored = PresetBookTest::stored();
+        $stored['module']['divi/button']['items']['aaaaaaaaaa']['attrs'] = [
+            'button' => ['decoration' => ['background' => ['desktop' => ['value' => ['color' => '#111111']]]]],
+        ];
+
+        return $stored;
+    }
+
+    private static function assignment(): PresetAssignment
+    {
+        return new PresetAssignment(
+            static fn (): PresetBook => PresetBook::fromDivi(self::stored()),
+            static fn (string $module): array => $module === 'divi/text'
+                ? ['content.decoration.bodyFont' => 'divi/font-body']
+                : [],
+            static fn (string $id): bool => preg_match('/^[a-z0-9]{10}$/D', $id) === 1
+        );
+    }
+
+    /** @return NodeIndex Blocks below s0.r0.c0 are m0, m1, … in the order of $inner. */
+    private static function index(string $inner): NodeIndex
+    {
+        return NodeIndex::build((new Parser())->parse(
+            '<!-- wp:divi/section --><!-- wp:divi/row --><!-- wp:divi/column -->' . $inner
+            . '<!-- /wp:divi/column --><!-- /wp:divi/row --><!-- /wp:divi/section -->'
+        ));
+    }
+
+    private static function node(NodeIndex $index, string $id): Block
+    {
+        $block = $index->find('s0.r0.c0.' . $id);
+        self::assertNotNull($block);
+
+        return $block;
+    }
+
+    public function testAssignsTheStackToBlocksOfTheModuleOnly(): void
+    {
+        $index = self::index('<!-- wp:divi/button /--><!-- wp:divi/text /-->');
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), ['preset' => ['aaaaaaaaaa', 'bbbbbbbbbb']]);
+
+        $button = $rewrite->rewrite(self::node($index, 'm0'));
+
+        self::assertSame(['aaaaaaaaaa', 'bbbbbbbbbb'], $button['modulePreset'] ?? null);
+        self::assertNull($rewrite->rewrite(self::node($index, 'm1')), 'another module');
+    }
+
+    public function testOnlyWithoutPresetSkipsBlocksWithAnExplicitPreset(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/button {"modulePreset":["bbbbbbbbbb"]} /-->'
+            . '<!-- wp:divi/button /-->'
+            . '<!-- wp:divi/button {"modulePreset":["default"]} /-->'
+        );
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), self::BUTTON, onlyWithoutPreset: true);
+
+        self::assertNull($rewrite->rewrite(self::node($index, 'm0')));
+        self::assertSame(['aaaaaaaaaa'], $rewrite->rewrite(self::node($index, 'm1'))['modulePreset'] ?? null);
+        self::assertSame(['aaaaaaaaaa'], $rewrite->rewrite(self::node($index, 'm2'))['modulePreset'] ?? null);
+    }
+
+    public function testOnlyWithPresetIdReplacesThatPreset(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/button {"modulePreset":["bbbbbbbbbb"]} /-->'
+            . '<!-- wp:divi/button {"modulePreset":["cccccccccc"]} /-->'
+            . '<!-- wp:divi/button /-->'
+        );
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), self::BUTTON, onlyWithPresetId: 'bbbbbbbbbb');
+
+        self::assertSame(['aaaaaaaaaa'], $rewrite->rewrite(self::node($index, 'm0'))['modulePreset'] ?? null);
+        self::assertNull($rewrite->rewrite(self::node($index, 'm1')), 'another preset');
+        self::assertNull($rewrite->rewrite(self::node($index, 'm2')), 'no preset at all');
+    }
+
+    public function testBothFiltersMustHold(): void
+    {
+        $index = self::index('<!-- wp:divi/button {"modulePreset":["bbbbbbbbbb"]} /-->');
+        $rewrite = new AssignRewrite(
+            'divi/button',
+            self::assignment(),
+            self::BUTTON,
+            onlyWithoutPreset: true,
+            onlyWithPresetId: 'bbbbbbbbbb'
+        );
+
+        self::assertNull($rewrite->rewrite(self::node($index, 'm0')));
+    }
+
+    public function testRunningAgainChangesNothing(): void
+    {
+        $index = self::index('<!-- wp:divi/button {"modulePreset":["aaaaaaaaaa"],"x":1} /-->');
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), self::BUTTON);
+
+        self::assertNull($rewrite->rewrite(self::node($index, 'm0')));
+    }
+
+    public function testGroupPresetsAreAssignedThroughTheKeyOfTheGroup(): void
+    {
+        $index = self::index('<!-- wp:divi/text /-->');
+        $rewrite = new AssignRewrite(
+            'divi/text',
+            self::assignment(),
+            ['group_presets' => ['font-body' => 'Lesetext']]
+        );
+
+        $attrs = $rewrite->rewrite(self::node($index, 'm0'));
+
+        self::assertSame(
+            ['presetId' => ['gggggggggg'], 'groupName' => 'divi/font-body'],
+            $attrs['groupPreset']['content.decoration.bodyFont'] ?? null
+        );
+        self::assertArrayNotHasKey('modulePreset', $attrs);
+    }
+
+    public function testNotesDescribeWhatTheAssignedPresetCovers(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/button {"button":{"decoration":{"background":{"desktop":{"value":{"color":"#ff0000"}}}}}} /-->'
+            . '<!-- wp:divi/button {"button":{"decoration":{"background":{"desktop":{"value":{"color":"#111111"}}}}}} /-->'
+        );
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), self::BUTTON);
+
+        $different = self::node($index, 'm0');
+        $different->setAttrs($rewrite->rewrite($different) ?? []);
+        $notes = $rewrite->notes($different, 's0.r0.c0.m0');
+
+        self::assertCount(1, $notes);
+        self::assertStringContainsString('s0.r0.c0.m0: lokale Werte überdecken „CTA primär“', $notes[0]);
+        self::assertStringContainsString('clear_overrides: true entfernt sie.', $notes[0]);
+
+        $same = self::node($index, 'm1');
+        $same->setAttrs($rewrite->rewrite($same) ?? []);
+        self::assertSame([], $rewrite->notes($same, 's0.r0.c0.m1'), 'the same value covers nothing');
+    }
+
+    public function testClearOverridesRemovesTheCoveredValuesAndHasNoNotes(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/button {"button":{"decoration":{"background":{"desktop":{"value":{"color":"#ff0000"}}}}}} /-->'
+        );
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), self::BUTTON, clearOverrides: true);
+        $block = self::node($index, 'm0');
+
+        $attrs = $rewrite->rewrite($block);
+
+        self::assertSame(['aaaaaaaaaa'], $attrs['modulePreset'] ?? null);
+        self::assertArrayNotHasKey('button', $attrs, 'the local value and its empty parents are gone');
+        $block->setAttrs($attrs);
+        self::assertSame([], $rewrite->notes($block, 's0.r0.c0.m0'));
+    }
+
+    public function testClearOverridesAloneAlsoChangesABlockThatAlreadyHasThePreset(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/button {"modulePreset":["aaaaaaaaaa"],"button":{"decoration":{"background":'
+            . '{"desktop":{"value":{"color":"#ff0000"}}}}}} /-->'
+        );
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), self::BUTTON, clearOverrides: true);
+
+        $attrs = $rewrite->rewrite(self::node($index, 'm0'));
+
+        self::assertSame(['modulePreset' => ['aaaaaaaaaa']], $attrs);
+    }
+
+    public function testAnUnvalidatedSpecIsALogicError(): void
+    {
+        $index = self::index('<!-- wp:divi/button /-->');
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), ['preset' => 'Gibt es nicht']);
+
+        $this->expectException(LogicException::class);
+
+        $rewrite->rewrite(self::node($index, 'm0'));
+    }
+
+    public function testGlobalInstancesOfTheModuleConcernTheRewrite(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/global-layout {"globalModule":"1058","blockName":"divi/button"} /-->'
+            . '<!-- wp:divi/global-layout {"globalModule":"1059","blockName":"divi/text"} /-->'
+        );
+        $rewrite = new AssignRewrite('divi/button', self::assignment(), self::BUTTON);
+
+        self::assertTrue($rewrite->concernsInstance(self::node($index, 'g0')));
+        self::assertFalse($rewrite->concernsInstance(self::node($index, 'g1')));
+    }
+}
diff --git a/tests/Unit/Integrations/Divi/Design/DetachRewriteTest.php b/tests/Unit/Integrations/Divi/Design/DetachRewriteTest.php
new file mode 100644
index 0000000..51d9d5e
--- /dev/null
+++ b/tests/Unit/Integrations/Divi/Design/DetachRewriteTest.php
@@ -0,0 +1,117 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeIndex;
+use LIT\MCP\Integrations\Divi\BlockTree\Parser;
+use LIT\MCP\Integrations\Divi\Design\DetachRewrite;
+use LIT\MCP\Integrations\Divi\Design\PresetScope;
+use PHPUnit\Framework\TestCase;
+
+final class DetachRewriteTest extends TestCase
+{
+    /** @return NodeIndex Blocks below s0.r0.c0 are m0, m1, … (g0, … for instances) in the order of $inner. */
+    private static function index(string $inner): NodeIndex
+    {
+        return NodeIndex::build((new Parser())->parse(
+            '<!-- wp:divi/section --><!-- wp:divi/row --><!-- wp:divi/column -->' . $inner
+            . '<!-- /wp:divi/column --><!-- /wp:divi/row --><!-- /wp:divi/section -->'
+        ));
+    }
+
+    private static function node(NodeIndex $index, string $id): Block
+    {
+        $block = $index->find('s0.r0.c0.' . $id);
+        self::assertNotNull($block);
+
+        return $block;
+    }
+
+    public function testRemovesAModulePresetFromTheStack(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/button {"modulePreset":["aaaaaaaaaa","bbbbbbbbbb"]} /-->'
+            . '<!-- wp:divi/button {"modulePreset":["aaaaaaaaaa"],"x":1} /-->'
+            . '<!-- wp:divi/text {"modulePreset":["aaaaaaaaaa"]} /-->'
+            . '<!-- wp:divi/button {"modulePreset":"aaaaaaaaaa"} /-->'
+            . '<!-- wp:divi/button {"modulePreset":["cccccccccc"]} /-->'
+        );
+        $rewrite = new DetachRewrite(new PresetScope('module', 'divi/button'), 'aaaaaaaaaa');
+
+        self::assertSame(['modulePreset' => ['bbbbbbbbbb']], $rewrite->rewrite(self::node($index, 'm0')));
+        self::assertSame(['x' => 1], $rewrite->rewrite(self::node($index, 'm1')), 'an empty stack leaves no key');
+        self::assertNull($rewrite->rewrite(self::node($index, 'm2')), 'another module');
+        self::assertSame([], $rewrite->rewrite(self::node($index, 'm3')), 'legacy string form');
+        self::assertNull($rewrite->rewrite(self::node($index, 'm4')), 'the ID is not in the stack');
+    }
+
+    public function testRemovesAGroupPresetFromEveryEntryOfTheGroup(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/text {"groupPreset":{'
+            . '"content.decoration.bodyFont":{"presetId":["gggggggggg","hhhhhhhhhh"],"groupName":"divi/font-body"},'
+            . '"module.decoration.spacing":{"presetId":["gggggggggg"],"groupName":"divi/spacing"}}} /-->'
+            . '<!-- wp:divi/text {"groupPreset":{"content.decoration.bodyFont":'
+            . '{"presetId":["gggggggggg"],"groupName":"divi/font-body"}},"x":1} /-->'
+            . '<!-- wp:divi/text {"groupPreset":{"module.decoration.spacing":'
+            . '{"presetId":["gggggggggg"],"groupName":"divi/spacing"}}} /-->'
+            . '<!-- wp:core/paragraph {"groupPreset":{"content.decoration.bodyFont":'
+            . '{"presetId":["gggggggggg"],"groupName":"divi/font-body"}}} /-->'
+        );
+        $rewrite = new DetachRewrite(new PresetScope('group', 'divi/font-body'), 'gggggggggg');
+
+        $first = $rewrite->rewrite(self::node($index, 'm0'));
+        self::assertSame(['hhhhhhhhhh'], $first['groupPreset']['content.decoration.bodyFont']['presetId'] ?? null);
+        self::assertSame(
+            ['presetId' => ['gggggggggg'], 'groupName' => 'divi/spacing'],
+            $first['groupPreset']['module.decoration.spacing'] ?? null,
+            'another group keeps its preset'
+        );
+        self::assertSame(['x' => 1], $rewrite->rewrite(self::node($index, 'm1')), 'empty entry and map are removed');
+        self::assertNull($rewrite->rewrite(self::node($index, 'm2')), 'the ID sits in another group');
+        self::assertNull($rewrite->rewrite(self::node($index, 'x0')), 'not a Divi block');
+    }
+
+    public function testAnUntouchedBlockStaysNull(): void
+    {
+        $index = self::index('<!-- wp:divi/button /--><!-- wp:divi/text {"groupPreset":{}} /-->');
+
+        self::assertNull(
+            (new DetachRewrite(new PresetScope('module', 'divi/button'), 'aaaaaaaaaa'))->rewrite(self::node($index, 'm0'))
+        );
+        self::assertNull(
+            (new DetachRewrite(new PresetScope('group', 'divi/font-body'), 'gggggggggg'))->rewrite(self::node($index, 'm1'))
+        );
+    }
+
+    public function testNotesAreEmpty(): void
+    {
+        $index = self::index('<!-- wp:divi/button /-->');
+
+        self::assertSame(
+            [],
+            (new DetachRewrite(new PresetScope('module', 'divi/button'), 'aaaaaaaaaa'))
+                ->notes(self::node($index, 'm0'), 's0.r0.c0.m0')
+        );
+    }
+
+    public function testInstancesThatMentionTheIdConcernTheRewrite(): void
+    {
+        $index = self::index(
+            '<!-- wp:divi/global-layout {"globalModule":"1058","blockName":"divi/button",'
+            . '"localAttrs":{"modulePreset":["aaaaaaaaaa"]}} /-->'
+            . '<!-- wp:divi/global-layout {"globalModule":"1059","blockName":"divi/section"} -->'
+            . '<!-- wp:divi/button {"modulePreset":["aaaaaaaaaa"],"globalParent":"1059"} /-->'
+            . '<!-- /wp:divi/global-layout -->'
+        );
+        $rewrite = new DetachRewrite(new PresetScope('module', 'divi/button'), 'aaaaaaaaaa');
+        $other = new DetachRewrite(new PresetScope('module', 'divi/button'), 'bbbbbbbbbb');
+
+        self::assertTrue($rewrite->concernsInstance(self::node($index, 'g0')), 'localAttrs');
+        self::assertTrue($rewrite->concernsInstance(self::node($index, 'g1')), 'snapshot of a child');
+        self::assertFalse($other->concernsInstance(self::node($index, 'g0')));
+    }
+}
diff --git a/tests/Unit/Integrations/Divi/Design/TreeRewriteTest.php b/tests/Unit/Integrations/Divi/Design/TreeRewriteTest.php
new file mode 100644
index 0000000..bcfabf3
--- /dev/null
+++ b/tests/Unit/Integrations/Divi/Design/TreeRewriteTest.php
@@ -0,0 +1,122 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Integrations\Divi\Design;
+
+use LIT\MCP\Integrations\Divi\BlockTree\Block;
+use LIT\MCP\Integrations\Divi\BlockTree\Document;
+use LIT\MCP\Integrations\Divi\BlockTree\GlobalInstance;
+use LIT\MCP\Integrations\Divi\BlockTree\NodeIndex;
+use LIT\MCP\Integrations\Divi\BlockTree\Parser;
+use LIT\MCP\Integrations\Divi\BlockTree\Serializer;
+use LIT\MCP\Integrations\Divi\Design\NodeRewrite;
+use LIT\MCP\Integrations\Divi\Design\TreeRewrite;
+use LIT\MCP\Tests\Unit\TestCase;
+
+final class TreeRewriteTest extends TestCase
+{
+    private static function document(string $inner): Document
+    {
+        return (new Parser())->parse(
+            '<!-- wp:divi/section --><!-- wp:divi/row --><!-- wp:divi/column -->' . $inner
+            . '<!-- /wp:divi/column --><!-- /wp:divi/row --><!-- /wp:divi/section -->'
+        );
+    }
+
+    /** Marks every divi/button; refuses opaque blocks, like the real strategies must never be offered one. */
+    private static function touchButtons(): NodeRewrite
+    {
+        return new class implements NodeRewrite {
+            public function rewrite(Block $block): ?array
+            {
+                if ($block->isOpaque()) {
+                    throw new \LogicException('An opaque block was offered to rewrite().');
+                }
+
+                return $block->name() === 'divi/button' ? $block->attrs() + ['touched' => true] : null;
+            }
+
+            public function notes(Block $block, string $nodeId): array
+            {
+                return ['Hinweis ' . $nodeId];
+            }
+
+            public function concernsInstance(Block $instance): bool
+            {
+                return GlobalInstance::effectiveName($instance) === 'divi/button';
+            }
+        };
+    }
+
+    public function testChangesBlocksAndReportsThem(): void
+    {
+        $document = self::document(
+            '<!-- wp:divi/button {"module":{"meta":{"adminLabel":{"desktop":{"value":"Kaufen"}}}}} /-->'
+            . '<!-- wp:divi/text /--><!-- wp:divi/button /-->'
+        );
+
+        $result = (new TreeRewrite(self::touchButtons()))->apply(NodeIndex::build($document));
+
+        self::assertSame([
+            ['id' => 's0.r0.c0.m0', 'module' => 'divi/button', 'label' => 'Kaufen'],
+            ['id' => 's0.r0.c0.m2', 'module' => 'divi/button', 'label' => ''],
+        ], $result['changed']);
+        self::assertSame(['Hinweis s0.r0.c0.m0', 'Hinweis s0.r0.c0.m2'], $result['warnings']);
+        self::assertSame([], $result['skipped']);
+        self::assertSame(2, substr_count(Serializer::document($document), '"touched":true'));
+    }
+
+    public function testNothingToDoChangesNothing(): void
+    {
+        $document = self::document('<!-- wp:divi/text {"a":1} /-->');
+        $before = Serializer::document($document);
+
+        $result = (new TreeRewrite(self::touchButtons()))->apply(NodeIndex::build($document));
+
+        self::assertSame(['changed' => [], 'warnings' => [], 'skipped' => []], $result);
+        self::assertSame($before, Serializer::document($document));
+    }
+
+    public function testGlobalInstancesAreSkippedWithTheLibraryEntry(): void
+    {
+        $document = self::document(
+            '<!-- wp:divi/global-layout {"globalModule":"1058","blockName":"divi/button"} /-->'
+            . '<!-- wp:divi/global-layout {"globalModule":"1059","blockName":"divi/text"} /-->'
+        );
+        $before = Serializer::document($document);
+
+        $result = (new TreeRewrite(self::touchButtons()))->apply(NodeIndex::build($document));
+
+        self::assertSame([], $result['changed']);
+        self::assertSame(
+            [['id' => 's0.r0.c0.g0', 'reason' => 'globales Modul – im Bibliothekseintrag 1058 ändern']],
+            $result['skipped']
+        );
+        self::assertSame($before, Serializer::document($document), 'instances are never rewritten');
+    }
+
+    public function testBlocksWithUnreadableAttributesAreSkippedToo(): void
+    {
+        $document = self::document('<!-- wp:divi/button {"a":1,} /-->');
+
+        $result = (new TreeRewrite(self::touchButtons()))->apply(NodeIndex::build($document));
+
+        self::assertSame(
+            [['id' => 's0.r0.c0.m0', 'reason' => 'Attribute nicht lesbar – im Divi-Builder prüfen']],
+            $result['skipped']
+        );
+    }
+
+    public function testAGlobalLayoutWithoutLibraryEntryHasItsOwnReason(): void
+    {
+        $document = self::document('<!-- wp:divi/global-layout {"blockName":"divi/button"} /-->');
+
+        $result = (new TreeRewrite(self::touchButtons()))->apply(NodeIndex::build($document));
+
+        self::assertSame(
+            [['id' => 's0.r0.c0.g0', 'reason' => 'globales Modul ohne Bibliothekseintrag – im Divi-Builder prüfen']],
+            $result['skipped']
+        );
+    }
+}