From dc7b924bda2667d57bbb9f8be6cd158dcdca5c18 Mon Sep 17 00:00:00 2001
From: Chris Huber <chris.huber@automattic.com>
Date: Mon, 9 Nov 2026 11:40:51 -0500
Subject: [PATCH] Carry the source div marker on description-list rows

Author type selectors such as `.intro dl div` are rewritten to the source
div tag marker, but the description-list block rendered its row wrappers
as plain divs, so the projected rule matched nothing. Persist the marker in
each row wrapper's className attribute, the same source identity other
converted elements carry, so saved markup stays editor-valid and the
rewritten selector matches.

Fixes #5235.
---
 .../DescriptionListBlockGenerator.php         |  7 ++-
 .../description-list-source-tag-selector.php  | 56 +++++++++++++++++++
 2 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 php-transformer/tests/unit/description-list-source-tag-selector.php

diff --git a/php-transformer/src/HtmlToBlocks/Generators/DescriptionListBlockGenerator.php b/php-transformer/src/HtmlToBlocks/Generators/DescriptionListBlockGenerator.php
index 5b501c354..e57f1112f 100644
--- a/php-transformer/src/HtmlToBlocks/Generators/DescriptionListBlockGenerator.php
+++ b/php-transformer/src/HtmlToBlocks/Generators/DescriptionListBlockGenerator.php
@@ -340,8 +340,13 @@ private function item(DOMElement $element): array
     /** @return array<string, mixed> */
     private function wrapper(DOMElement $element): array
     {
+        // Author type selectors such as `dl div` are rewritten to the source
+        // tag marker; persist it on the row so the projected rule still matches.
         $wrapper = array_filter(array(
-            'className' => $element->getAttribute('class'),
+            'className' => SourceDom::mergeClassNames(
+                $element->getAttribute('class'),
+                $this->session?->authorSelectorProjectionState()->tagMarker($element->tagName) ?? ''
+            ),
             'style' => $element->getAttribute('style'),
         ), static fn (mixed $value): bool => '' !== $value);
         $attributes = array();
diff --git a/php-transformer/tests/unit/description-list-source-tag-selector.php b/php-transformer/tests/unit/description-list-source-tag-selector.php
new file mode 100644
index 000000000..3862a03df
--- /dev/null
+++ b/php-transformer/tests/unit/description-list-source-tag-selector.php
@@ -0,0 +1,56 @@
+<?php
+declare(strict_types=1);
+
+require dirname(__DIR__, 2) . '/vendor/autoload.php';
+
+use Automattic\BlocksEngine\PhpTransformer\Css\CssSelectorMatcher;
+use Automattic\BlocksEngine\PhpTransformer\Css\CssStylesheetTransformer;
+use Automattic\BlocksEngine\PhpTransformer\HtmlToBlocks\HtmlTransformer;
+
+$assert = static function (bool $ok, string $message): void {
+    if ( ! $ok ) {
+        throw new RuntimeException($message);
+    }
+};
+
+// Author type selectors that reach description-list rows are rewritten to the
+// source div marker, so the generated rows must carry that marker to match.
+$html = '<style>.intro dl div{border-top:1px solid #ccc}dl + div{color:red}</style>'
+    . '<main><section class="intro"><dl><div><dt>Color story</dt><dd>Spring · Summer</dd></div><div><dt>Forms</dt><dd>Plates · Bowls</dd></div></dl><div>After</div></section></main>';
+$result = ( new HtmlTransformer() )->transform($html)->toArray();
+$assert('pass' === ($result['source_reports']['wp_block_validity']['status'] ?? null), 'Description-list rows with source markers stay editor-valid');
+
+$css = '';
+foreach ( $result['assets'] as $asset ) {
+    if ( 'author-css' === ($asset['source'] ?? '') ) {
+        $css .= (string) $asset['content'];
+    }
+}
+$projected = array();
+( new CssStylesheetTransformer() )->transformStyleRules($css, static function (string $selector, string $body) use (&$projected): string {
+    $projected[$body] = $selector;
+    return $selector . '{' . $body . '}';
+});
+
+$dom = new DOMDocument();
+$dom->loadHTML('<?xml encoding="UTF-8"><body>' . $result['serialized_blocks'] . '</body>', LIBXML_NOERROR);
+$xpath = new DOMXPath($dom);
+$rows = iterator_to_array($xpath->query('//dl/div'));
+$after = $xpath->query('//*[normalize-space(text())="After"]')->item(0);
+$assert(2 === count($rows) && $after instanceof DOMElement, 'Rows and the following sibling are rendered');
+
+foreach ( array(
+    'descendant row selector' => array( 'body' => 'border-top:1px solid #ccc', 'rows' => true, 'after' => false ),
+    'sibling selector stays rewritten' => array( 'body' => 'color:red', 'rows' => false, 'after' => true ),
+) as $case => $expected ) {
+    $selector = $projected[$expected['body']] ?? '';
+    $assert(1 !== preg_match('/(?:^|[\s>+~])div\b/', $selector), $case . ': the div type selector is rewritten to its source marker, got ' . $selector);
+    $parsed = CssSelectorMatcher::parse($selector);
+    $assert($parsed['supported'], $case . ': projected selector is matchable');
+    foreach ( $rows as $row ) {
+        $assert($expected['rows'] === CssSelectorMatcher::matches($row, $parsed)['matches'], $case . ': row match is ' . var_export($expected['rows'], true) . ' for ' . $selector . ' on ' . $dom->saveHTML($row));
+    }
+    $assert($expected['after'] === CssSelectorMatcher::matches($after, $parsed)['matches'], $case . ': following sibling match is ' . var_export($expected['after'], true));
+}
+
+echo "Description-list source tag selector passed\n";