fix: bound render-summary strings, restore postdata globals, drain buffers

Review fix round 1 for lit/page-render-summary: extract shared Text::shorten()
(reused by NodeSummary), replace data: URIs with a short marker, prefer
data-src/data-lazy-src over placeholder src, dedup nested p/li/blockquote
text and ignore script/style/noscript content, restore every setup_postdata
global (not just $post), drain output buffers robustly around the_content,
and disclose that rendering can trigger oEmbed/network requests.

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

src/Abilities/Text.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Abilities;
+
+/**
+ * Small text helper shared by every summary that must stay bounded in size (outlines, node
+ * summaries, the rendered-page excerpt): extracts are a fixed-size preview, never an unbounded
+ * copy of user/plugin content. Pure PHP.
+ */
+final class Text
+{
+    /** Shortens to at most $max characters (multi-byte aware), appending an ellipsis. */
+    public static function shorten(string $text, int $max): string
+    {
+        return mb_strlen($text) > $max ? rtrim(mb_substr($text, 0, $max - 1)) . '…' : $text;
+    }
+}

src/Integrations/Divi/BlockTree/NodeSummary.php

@@ -4,6 +4,8 @@ declare(strict_types=1);
 
 namespace LIT\MCP\Integrations\Divi\BlockTree;
 
+use LIT\MCP\Abilities\Text;
+
 /**
  * Short human-readable facts about a node for the outline: admin label, first text,
  * preset IDs, column layout. Pure PHP.
@@ -36,7 +38,7 @@ final class NodeSummary
         foreach ($paths as $path) {
             $text = self::textOf(AttrMap::desktop($block->attrs(), $path));
             if ($text !== '') {
-                return self::shorten($text, $max);
+                return Text::shorten($text, $max);
             }
         }
 
@@ -130,9 +132,4 @@ final class NodeSummary
 
         return $index === false ? count(self::PRIORITY) : (int) $index;
     }
-
-    private static function shorten(string $text, int $max): string
-    {
-        return mb_strlen($text) > $max ? rtrim(mb_substr($text, 0, $max - 1)) . '…' : $text;
-    }
 }

src/Integrations/WordPress/Render/PageRenderSummaryAbility.php

@@ -34,8 +34,10 @@ final class PageRenderSummaryAbility implements Ability
     {
         return 'Rendert den Inhaltsbereich eines Eintrags wie im Frontend und liefert einen strukturierten Auszug: '
             . 'Überschriften, Texte, Links, Bilder mit Alt-Text und Warnungen (Hierarchie-Sprünge, fehlende '
-            . 'Alt-Texte). Header, Footer und Theme-Builder-Vorlagen sind nicht enthalten. Gut zum Prüfen nach '
-            . 'Änderungen.';
+            . 'Alt-Texte). Header, Footer und Theme-Builder-Vorlagen sind nicht enthalten. Das Rendern führt die '
+            . 'üblichen Inhalts-Filter aus (Shortcodes, Divi, andere Plugins) und kann dabei Netzwerkanfragen '
+            . 'auslösen, z. B. oEmbed-Abrufe, die von WordPress oder anderen Plugins zwischengespeichert werden. '
+            . 'Gut zum Prüfen nach Änderungen.';
     }
 
     public function inputSchema(): array
@@ -90,7 +92,11 @@ final class PageRenderSummaryAbility implements Ability
             return $post;
         }
 
-        $notes = ['Nur der Inhaltsbereich; Header, Footer und Theme-Builder-Vorlagen fehlen.'];
+        $notes = [
+            'Nur der Inhaltsbereich; Header, Footer und Theme-Builder-Vorlagen fehlen.',
+            'Das Rendern führt Plugin-/Theme-Filter aus (Shortcodes, oEmbed u. Ä.) und kann dabei '
+                . 'Netzwerkanfragen auslösen, die von WordPress oder anderen Plugins zwischengespeichert werden.',
+        ];
         if ((string) $post->post_password !== '') {
             $notes[] = 'Der Eintrag ist passwortgeschützt; Besucher sehen zuerst das Passwortformular.';
         }

src/Integrations/WordPress/Render/PageRenderer.php

@@ -9,28 +9,60 @@ use WP_Post;
 /**
  * Renders the content area of an entry in-process, like the front end does for the_content
  * (Divi 5 renders its blocks there – verified in DDEV). Header, footer and Theme Builder
- * layouts are not part of it. Not final so abilities can be unit-tested with a mock.
+ * layouts are not part of it. Rendering runs every plugin's/theme's content filters and
+ * shortcodes exactly as the front end would, which can trigger network requests (e.g. oEmbed
+ * lookups) that get cached by WordPress or other plugins as a side effect. Not final so
+ * abilities can be unit-tested with a mock.
  */
 class PageRenderer
 {
+    /**
+     * Globals setup_postdata() populates from the post loop (WP_Query::the_post()); all of
+     * them are restored to their pre-render value afterwards, not just $post itself.
+     */
+    private const POSTDATA_GLOBALS = ['id', 'authordata', 'pages', 'page', 'more', 'numpages', 'multipage'];
+
     public function render(WP_Post $post): string
     {
-        $previous = $GLOBALS['post'] ?? null;
+        $previousPost = $GLOBALS['post'] ?? null;
+        $previousGlobals = [];
+        foreach (self::POSTDATA_GLOBALS as $name) {
+            $previousGlobals[$name] = $GLOBALS[$name] ?? null;
+        }
+
         $GLOBALS['post'] = $post;
-        setup_postdata($post);
+        $level = ob_get_level();
         ob_start();
         try {
+            setup_postdata($post);
             $html = (string) apply_filters('the_content', (string) $post->post_content);
         } finally {
-            $echoed = (string) ob_get_clean();
-            $GLOBALS['post'] = $previous;
-            if ($previous instanceof WP_Post) {
-                setup_postdata($previous);
-            } else {
-                wp_reset_postdata();
+            $echoed = self::drain($level);
+            $GLOBALS['post'] = $previousPost;
+            foreach ($previousGlobals as $name => $value) {
+                $GLOBALS[$name] = $value;
             }
         }
 
         return $echoed . $html;
     }
+
+    /**
+     * Pops every output buffer opened while rendering, including one a rogue shortcode/filter
+     * left open (drained here instead of leaking into the caller) – but never one it already
+     * closed for us: the loop only pops down to the level recorded before our own ob_start(),
+     * so a filter that closes one buffer too many simply loses whatever was already echoed
+     * (nothing left to drain) rather than us popping a buffer that belongs to the caller.
+     * Buffers are combined in the order their content was written (innermost popped first,
+     * then prepended) so a leaked nested buffer's output stays after what came before it.
+     */
+    private static function drain(int $level): string
+    {
+        $output = '';
+        while (ob_get_level() > $level) {
+            $output = (string) ob_get_clean() . $output;
+        }
+
+        return $output;
+    }
 }

src/Integrations/WordPress/Render/RenderSummary.php

@@ -6,15 +6,34 @@ namespace LIT\MCP\Integrations\WordPress\Render;
 
 use DOMDocument;
 use DOMElement;
+use DOMNode;
 use DOMXPath;
+use LIT\MCP\Abilities\Text;
 
 /**
  * Structured excerpt of rendered HTML (spec §5.7 lit/page-render-summary): headings, text
- * blocks, links, images with alt text and the obvious problems. Pure PHP (ext-dom).
+ * blocks, links, images with alt text and the obvious problems. Every extracted string is
+ * bounded in length through the shared Text::shorten() helper (also used by
+ * Divi\BlockTree\NodeSummary) – a rendered page can otherwise embed arbitrarily large text,
+ * a huge inline data: URI, or a long tracking URL, none of which belong in an MCP response.
+ * Pure PHP (ext-dom).
  */
 final class RenderSummary
 {
     private const TEXT_LIMIT = 300;
+    private const HEADING_LIMIT = 200;
+    private const LINK_TEXT_LIMIT = 150;
+    private const ALT_LIMIT = 200;
+    private const URL_LIMIT = 300;
+
+    private const HEADING_TAGS = ['h1', 'h2', 'h3', 'h4', 'h5', 'h6'];
+    private const TEXT_TAGS = ['p', 'li', 'blockquote'];
+
+    /** Never real page content: script/style source and noscript fallback markup. */
+    private const IGNORED_ANCESTORS = ['script', 'style', 'noscript'];
+
+    /** Attributes lazy-load libraries put the real image URL in; `src` is then a placeholder. */
+    private const LAZY_SRC_ATTRIBUTES = ['data-src', 'data-lazy-src'];
 
     /**
      * @return array{headings: list<array{level: int, text: string}>, texts: list<string>,
@@ -34,32 +53,48 @@ final class RenderSummary
         $xpath = new DOMXPath($dom);
 
         $headings = [];
-        foreach (self::elements($xpath, '//h1|//h2|//h3|//h4|//h5|//h6', $max) as $element) {
-            $headings[] = ['level' => (int) substr($element->nodeName, 1), 'text' => self::text($element)];
-        }
-
-        $texts = [];
-        foreach (self::elements($xpath, '//p|//li|//blockquote', $max) as $element) {
+        $query = self::xpathFor(self::HEADING_TAGS, self::IGNORED_ANCESTORS);
+        foreach (self::elements($xpath, $query) as $element) {
             $text = self::text($element);
             if ($text !== '') {
-                $texts[] = mb_strlen($text) > self::TEXT_LIMIT
-                    ? mb_substr($text, 0, self::TEXT_LIMIT - 1) . '…'
-                    : $text;
+                $headings[] = [
+                    'level' => (int) substr($element->nodeName, 1),
+                    'text' => Text::shorten($text, self::HEADING_LIMIT),
+                ];
             }
         }
+        $headings = array_slice($headings, 0, $max);
+
+        // p/li/blockquote nested inside another one of these (a <p> inside a <li>, a nested
+        // list item, …) are excluded, otherwise their text would be extracted twice: once as
+        // part of the outer element's textContent, once again on its own.
+        $texts = [];
+        $query = self::xpathFor(self::TEXT_TAGS, array_merge(self::IGNORED_ANCESTORS, self::TEXT_TAGS));
+        foreach (self::elements($xpath, $query) as $element) {
+            $text = self::text($element);
+            if ($text !== '') {
+                $texts[] = Text::shorten($text, self::TEXT_LIMIT);
+            }
+        }
+        $texts = array_slice($texts, 0, $max);
 
         $links = [];
-        foreach (self::elements($xpath, '//a[@href]', $max) as $element) {
-            $links[] = ['text' => self::text($element), 'href' => $element->getAttribute('href')];
-        }
-
-        $images = [];
-        foreach (self::elements($xpath, '//img', $max) as $element) {
-            $images[] = [
-                'src' => $element->getAttribute('src'),
-                'alt' => $element->hasAttribute('alt') ? $element->getAttribute('alt') : null,
+        $query = self::xpathFor(['a[@href]'], self::IGNORED_ANCESTORS);
+        foreach (self::elements($xpath, $query) as $element) {
+            $links[] = [
+                'text' => Text::shorten(self::text($element), self::LINK_TEXT_LIMIT),
+                'href' => self::shortenUrl($element->getAttribute('href')),
             ];
         }
+        $links = array_slice($links, 0, $max);
+
+        $images = [];
+        $query = self::xpathFor(['img'], self::IGNORED_ANCESTORS);
+        foreach (self::elements($xpath, $query) as $element) {
+            $alt = $element->hasAttribute('alt') ? Text::shorten($element->getAttribute('alt'), self::ALT_LIMIT) : null;
+            $images[] = ['src' => self::shortenUrl(self::imageSrc($element)), 'alt' => $alt];
+        }
+        $images = array_slice($images, 0, $max);
 
         return [
             'headings' => $headings,
@@ -112,13 +147,25 @@ final class RenderSummary
         return $warnings;
     }
 
+    /** Builds an XPath union of $tags, each excluding descendants of $excludeAncestors. */
+    private static function xpathFor(array $tags, array $excludeAncestors): string
+    {
+        $conditions = array_map(
+            static fn (string $tag): string => "not(ancestor::{$tag})",
+            $excludeAncestors
+        );
+        $guard = $conditions === [] ? '' : '[' . implode(' and ', $conditions) . ']';
+
+        return implode(' | ', array_map(static fn (string $tag): string => "//{$tag}{$guard}", $tags));
+    }
+
     /** @return list<DOMElement> */
-    private static function elements(DOMXPath $xpath, string $query, int $max): array
+    private static function elements(DOMXPath $xpath, string $query): array
     {
         $nodes = $xpath->query($query);
         $elements = [];
         foreach ($nodes === false ? [] : $nodes as $node) {
-            if ($node instanceof DOMElement && count($elements) < $max) {
+            if ($node instanceof DOMElement) {
                 $elements[] = $node;
             }
         }
@@ -126,8 +173,63 @@ final class RenderSummary
         return $elements;
     }
 
+    /**
+     * Real lazy-loaded images keep the true URL in data-src/data-lazy-src and only put a
+     * placeholder (often a tiny data: URI) in src – prefer the real URL when present.
+     */
+    private static function imageSrc(DOMElement $element): string
+    {
+        foreach (self::LAZY_SRC_ATTRIBUTES as $attribute) {
+            if ($element->hasAttribute($attribute) && trim($element->getAttribute($attribute)) !== '') {
+                return $element->getAttribute($attribute);
+            }
+        }
+
+        return $element->getAttribute('src');
+    }
+
+    /** A data: URI is replaced by a short marker instead of being truncated mid-payload. */
+    private static function shortenUrl(string $url): string
+    {
+        if (stripos($url, 'data:') === 0) {
+            return self::dataUriMarker($url);
+        }
+
+        return Text::shorten($url, self::URL_LIMIT);
+    }
+
+    private static function dataUriMarker(string $url): string
+    {
+        $mime = 'unknown';
+        if (preg_match('/^data:([^;,]*)/i', $url, $match) === 1 && $match[1] !== '') {
+            $mime = $match[1];
+        }
+
+        return sprintf('data:%s;… (%d Bytes)', $mime, strlen($url));
+    }
+
+    /** Text of the element, ignoring script/style/noscript content, whitespace-normalized. */
     private static function text(DOMElement $element): string
     {
-        return trim((string) preg_replace('/\s+/u', ' ', $element->textContent));
+        return trim((string) preg_replace('/\s+/u', ' ', self::plainText($element)));
+    }
+
+    private static function plainText(DOMNode $node): string
+    {
+        $text = '';
+        foreach ($node->childNodes as $child) {
+            if ($child->nodeType === XML_TEXT_NODE || $child->nodeType === XML_CDATA_SECTION_NODE) {
+                $text .= $child->nodeValue;
+                continue;
+            }
+
+            if ($child instanceof DOMElement && in_array(strtolower($child->nodeName), self::IGNORED_ANCESTORS, true)) {
+                continue;
+            }
+
+            $text .= self::plainText($child);
+        }
+
+        return $text;
     }
 }

tests/Unit/Integrations/WordPress/Render/PageRenderSummaryAbilityTest.php

@@ -42,6 +42,81 @@ final class PageRenderSummaryAbilityTest extends TestCase
         self::assertCount(2, RenderSummary::fromHtml(str_repeat('<p>x</p>', 5), 2)['texts']);
     }
 
+    public function testTruncatesLongExtractedStrings(): void
+    {
+        $longHeading = str_repeat('Ü', 250);
+        $longText = str_repeat('a', 400);
+        $longLinkText = str_repeat('b', 200);
+        $longHref = 'https://k.test/' . str_repeat('c', 400);
+        $longAlt = str_repeat('d', 300);
+        $html = "<h2>{$longHeading}</h2><p>{$longText}</p>"
+            . "<a href=\"{$longHref}\">{$longLinkText}</a>"
+            . "<img src=\"https://k.test/x.jpg\" alt=\"{$longAlt}\">";
+
+        $summary = RenderSummary::fromHtml($html);
+
+        self::assertSame(200, mb_strlen($summary['headings'][0]['text']));
+        self::assertStringEndsWith('…', $summary['headings'][0]['text']);
+        self::assertSame(300, mb_strlen($summary['texts'][0]));
+        self::assertStringEndsWith('…', $summary['texts'][0]);
+        self::assertSame(150, mb_strlen($summary['links'][0]['text']));
+        self::assertStringEndsWith('…', $summary['links'][0]['text']);
+        self::assertSame(300, mb_strlen($summary['links'][0]['href']));
+        self::assertStringEndsWith('…', $summary['links'][0]['href']);
+        self::assertSame(200, mb_strlen($summary['images'][0]['alt']));
+        self::assertStringEndsWith('…', $summary['images'][0]['alt']);
+    }
+
+    public function testRepresentsDataUrisAsAShortMarkerInsteadOfTruncatingThem(): void
+    {
+        $dataUri = 'data:image/png;base64,' . base64_encode(str_repeat('x', 5000));
+        $html = '<img src="' . $dataUri . '"><a href="' . $dataUri . '">Anhang</a>';
+
+        $summary = RenderSummary::fromHtml($html);
+
+        $marker = 'data:image/png;… (' . strlen($dataUri) . ' Bytes)';
+        self::assertSame($marker, $summary['images'][0]['src']);
+        self::assertSame($marker, $summary['links'][0]['href']);
+    }
+
+    public function testPrefersDataSrcOrDataLazySrcOverAPlaceholderSrc(): void
+    {
+        $html = '<img src="data:image/gif;base64,R0lGODlhAQABAAAAACw=" data-src="https://k.test/real.jpg" alt="Team">'
+            . '<img src="placeholder.gif" data-lazy-src="https://k.test/lazy.jpg">';
+
+        $summary = RenderSummary::fromHtml($html);
+
+        self::assertSame('https://k.test/real.jpg', $summary['images'][0]['src']);
+        self::assertSame('https://k.test/lazy.jpg', $summary['images'][1]['src']);
+    }
+
+    public function testWarnsAboutMultipleH1Headings(): void
+    {
+        $summary = RenderSummary::fromHtml('<h1>Erste</h1><h1>Zweite</h1>');
+
+        self::assertContains('2 Überschriften der Ebene h1 im Inhalt.', $summary['warnings']);
+    }
+
+    public function testDoesNotDuplicateTextFromNestedParagraphsListItemsOrBlockquotes(): void
+    {
+        $html = '<ul><li>Punkt <p>eingebettet</p></li></ul>'
+            . '<blockquote>Zitat <blockquote>innen</blockquote></blockquote>';
+
+        $summary = RenderSummary::fromHtml($html);
+
+        self::assertSame(['Punkt eingebettet', 'Zitat innen'], $summary['texts']);
+    }
+
+    public function testIgnoresScriptStyleAndNoscriptText(): void
+    {
+        $html = '<p>Sichtbar<script>var x = 1;</script><style>.a{color:red}</style>'
+            . '<noscript>Fallback</noscript> Ende</p>';
+
+        $summary = RenderSummary::fromHtml($html);
+
+        self::assertSame(['Sichtbar Ende'], $summary['texts']);
+    }
+
     public function testRendersTheEntryAndAddsNotes(): void
     {
         $post = new WP_Post(['ID' => 7, 'post_type' => 'page', 'post_password' => 'geheim']);
@@ -60,7 +135,7 @@ final class PageRenderSummaryAbilityTest extends TestCase
         self::assertSame(7, $result['post_id']);
         self::assertSame('https://k.test/start/', $result['url']);
         self::assertCount(2, $result['headings']);
-        self::assertCount(2, $result['notes']);
+        self::assertCount(3, $result['notes']);
         self::assertTrue($ability->isDirect());
         self::assertTrue($ability->annotations()['readonly']);
     }

tests/Unit/Integrations/WordPress/Render/PageRendererTest.php

@@ -13,20 +13,40 @@ use WP_Post;
 
 final class PageRendererTest extends TestCase
 {
+    private const POSTDATA_GLOBALS = ['id', 'authordata', 'pages', 'page', 'more', 'numpages', 'multipage'];
+
     protected function tearDown(): void
     {
         unset($GLOBALS['post']);
+        foreach (self::POSTDATA_GLOBALS as $name) {
+            unset($GLOBALS[$name]);
+        }
         parent::tearDown();
     }
 
-    public function testRendersTheContentFilterAndRestoresTheGlobalPost(): void
+    public function testRendersTheContentFilterAndRestoresGlobalPostAndPostdata(): void
     {
-        $previous = new WP_Post(['ID' => 1]);
-        $GLOBALS['post'] = $previous;
+        $previousPost = new WP_Post(['ID' => 1]);
+        $GLOBALS['post'] = $previousPost;
+        $GLOBALS['id'] = 1;
+        $GLOBALS['authordata'] = 'previous-author';
+        $GLOBALS['pages'] = ['previous'];
+        $GLOBALS['page'] = 1;
+        $GLOBALS['more'] = 1;
+        $GLOBALS['numpages'] = 1;
+        $GLOBALS['multipage'] = 0;
+
         $post = new WP_Post(['ID' => 7, 'post_content' => '<!-- wp:divi/section /-->']);
         $setup = [];
         Functions\when('setup_postdata')->alias(static function (WP_Post $p) use (&$setup): bool {
             $setup[] = $p->ID;
+            $GLOBALS['id'] = $p->ID;
+            $GLOBALS['authordata'] = 'author-of-' . $p->ID;
+            $GLOBALS['pages'] = ['page-of-' . $p->ID];
+            $GLOBALS['page'] = 2;
+            $GLOBALS['more'] = 0;
+            $GLOBALS['numpages'] = 3;
+            $GLOBALS['multipage'] = 1;
 
             return true;
         });
@@ -41,14 +61,20 @@ final class PageRendererTest extends TestCase
         $html = (new PageRenderer())->render($post);
 
         self::assertSame('<p>echoed</p><div class="et_pb_section"></div>', $html);
-        self::assertSame($previous, $GLOBALS['post']);
-        self::assertSame([7, 1], $setup);
+        self::assertSame([7], $setup);
+        self::assertSame($previousPost, $GLOBALS['post']);
+        self::assertSame(1, $GLOBALS['id']);
+        self::assertSame('previous-author', $GLOBALS['authordata']);
+        self::assertSame(['previous'], $GLOBALS['pages']);
+        self::assertSame(1, $GLOBALS['page']);
+        self::assertSame(1, $GLOBALS['more']);
+        self::assertSame(1, $GLOBALS['numpages']);
+        self::assertSame(0, $GLOBALS['multipage']);
     }
 
     public function testRestoresEvenWhenRenderingThrows(): void
     {
         Functions\when('setup_postdata')->justReturn(true);
-        Functions\expect('wp_reset_postdata')->once();
         Filters\expectApplied('the_content')->once()->andReturnUsing(static function (): string {
             throw new RuntimeException('module crashed');
         });
@@ -59,6 +85,47 @@ final class PageRendererTest extends TestCase
         } catch (RuntimeException) {
             self::assertArrayHasKey('post', $GLOBALS);
             self::assertNull($GLOBALS['post']);
+            foreach (self::POSTDATA_GLOBALS as $name) {
+                self::assertArrayHasKey($name, $GLOBALS);
+                self::assertNull($GLOBALS[$name]);
+            }
         }
     }
+
+    public function testDrainsAnExtraOutputBufferAShortcodeLeavesOpen(): void
+    {
+        Functions\when('setup_postdata')->justReturn(true);
+        Filters\expectApplied('the_content')->once()->andReturnUsing(static function (): string {
+            echo 'before-';
+            ob_start(); // a buggy shortcode opens a buffer and never closes it
+            echo 'leaked';
+
+            return 'html';
+        });
+        $levelBefore = ob_get_level();
+
+        $html = (new PageRenderer())->render(new WP_Post(['ID' => 7]));
+
+        self::assertSame('before-leakedhtml', $html);
+        self::assertSame($levelBefore, ob_get_level());
+    }
+
+    public function testToleratesAShortcodeThatClosesOneOutputBufferTooMany(): void
+    {
+        Functions\when('setup_postdata')->justReturn(true);
+        Filters\expectApplied('the_content')->once()->andReturnUsing(static function (): string {
+            ob_start(); // shortcode's own nested buffer
+            echo 'own';
+            ob_end_clean(); // correct: closes its own buffer
+            ob_end_clean(); // bug: also closes PageRenderer's buffer
+
+            return 'html';
+        });
+        $levelBefore = ob_get_level();
+
+        $html = (new PageRenderer())->render(new WP_Post(['ID' => 7]));
+
+        self::assertSame('html', $html);
+        self::assertSame($levelBefore, ob_get_level());
+    }
 }