Fix make_clickable corrupting existing anchor tags (#2517)

Author: obenland

.github/changelog/2517-from-description

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Fix make_clickable corrupting existing anchor tags in ActivityPub content

includes/class-sanitize.php

@@ -191,7 +191,11 @@ public static function webfinger( $value ) {
 	 * @return string The converted content.
 	 */
 	public static function content( $content ) {
-		$content = \make_clickable( $content );
+		// Only make URLs clickable if no anchor tags exist, to avoid corrupting existing links.
+		if ( false === \strpos( $content, '<a ' ) ) {
+			$content = \make_clickable( $content );
+		}
+
 		$content = \wpautop( $content );
 		$content = \wp_kses_post( $content );
 

tests/phpunit/tests/includes/class-test-sanitize.php

@@ -231,6 +231,20 @@ public function test_content_urls() {
 		$this->assertStringContainsString( '<a href="https://example.com"', $result );
 	}
 
+	/**
+	 * Test content sanitization preserves existing links with Mastodon-style spans.
+	 *
+	 * @covers ::content
+	 */
+	public function test_content_preserves_existing_links() {
+		$content = '<p><a href="https://www.example.com/path/to/article?param=value&amp;utm_source=mastodon" target="_blank" rel="nofollow noopener" translate="no"><span class="invisible">https://www.</span><span class="ellipsis">example.com/path/to/art</span><span class="invisible">icle?param=value&amp;utm_source=mastodon</span></a></p>';
+		$result  = Sanitize::content( $content );
+
+		// Should preserve existing link structure without double-linking.
+		$this->assertSame( 1, \substr_count( $result, '<a ' ), 'Should have exactly one anchor tag' );
+		$this->assertStringContainsString( 'href="https://www.example.com/path/', $result );
+	}
+
 	/**
 	 * Test content sanitization with empty content.
 	 *