diff --git a/common/includes/slack/trac/comment-handler.php b/common/includes/slack/trac/comment-handler.php
index ae47f599eb..86ee3b4ce1 100644
--- a/common/includes/slack/trac/comment-handler.php
+++ b/common/includes/slack/trac/comment-handler.php
@@ -23,6 +23,13 @@ class Comment_Handler {
 	 */
 	protected $keywords_added = array();
 
+	/**
+	 * Characters Trac's text wrapper breaks between, mirroring UnicodeTextWrapper::breakable_char_ranges.
+	 *
+	 * @var string
+	 */
+	const BREAKABLE_CHARS = '[\x{1100}-\x{11FF}\x{2E80}-\x{2EFF}\x{3000}-\x{30FF}\x{3130}-\x{319F}\x{31C0}-\x{31EF}\x{3200}-\x{4DBF}\x{4E00}-\x{9FFF}\x{A960}-\x{A97F}\x{AC00}-\x{D7FF}\x{F900}-\x{FAFF}\x{FE30}-\x{FE4F}\x{FF00}-\x{FFEF}\x{20000}-\x{3FFFF}]';
+
 	function __construct( \Dotorg\Slack\Send $send, array $email_message ) {
 		$this->send  = $send;
 		$this->lines = $email_message;
@@ -242,7 +249,22 @@ function process_message() {
 			while ( $lines && '' !== current( $lines ) ) {
 				$line = array_shift( $lines );
 
-				if ( preg_match( '~Attachment "([^"]+)" (added|removed)\.$~', $line, $matches ) ) { // * Attachment "test.txt" added/removed.
+				// Trac wraps long file names onto indented lines.
+				if ( 0 === strpos( $line, ' * Attachment "' ) ) {
+					while ( $lines && '' !== current( $lines ) && 0 !== strpos( current( $lines ), ' * ' ) ) {
+						$next_line = ltrim( array_shift( $lines ) );
+
+						// Trac also breaks between CJK characters, where there is no space to restore.
+						$cjk_break = preg_match( '/' . self::BREAKABLE_CHARS . '$/u', $line ) && preg_match( '/^' . self::BREAKABLE_CHARS . '/u', $next_line );
+
+						if ( '-' !== substr( $line, -1 ) && ! $cjk_break ) {
+							$line .= ' ';
+						}
+						$line .= $next_line;
+					}
+				}
+
+				if ( preg_match( '~Attachment "(.+)" (added|removed)\.$~', $line, $matches ) ) { // * Attachment "test.txt" added/removed.
 					$changes[] = "_*attachment:*_ `{$matches[1]}` {$matches[2]}";
 				} else {
 					if ( 0 === strpos( $line, ' * keywords:' ) ) {
diff --git a/common/includes/tests/slack/trac/comment-handler.php b/common/includes/tests/slack/trac/comment-handler.php
index 9cf7faf8a0..964944bbb4 100644
--- a/common/includes/tests/slack/trac/comment-handler.php
+++ b/common/includes/tests/slack/trac/comment-handler.php
@@ -67,7 +67,7 @@ public function test_last_line_is_kept( array $body, string $comment, array $cha
 	 */
 	public function data_last_line_is_kept(): array {
 		return array(
-			'comment'      => array(
+			'comment'                => array(
 				array(
 					'',
 					'Comment (by obenland):',
@@ -79,7 +79,7 @@ public function data_last_line_is_kept(): array {
 				"I started such a thread.\n\nSo it was closed.",
 				array(),
 			),
-			'changes only' => array(
+			'changes only'           => array(
 				array(
 					'Changes (by obenland):',
 					'',
@@ -92,6 +92,30 @@ public function data_last_line_is_kept(): array {
 					'_*status:*_ new => assigned',
 				),
 			),
+			'wrapped attachment'     => array(
+				array(
+					'Changes (by adamsilverstein):',
+					'',
+					' * Attachment "Monosnap Site Health - Info ‹ My... Website — WordPress',
+					' 2024-07-15 15-14-25.jpg" added.',
+				),
+				'',
+				array(
+					'_*attachment:*_ `Monosnap Site Health - Info ‹ My... Website — WordPress 2024-07-15 15-14-25.jpg` added',
+				),
+			),
+			'wrapped CJK attachment' => array(
+				array(
+					'Changes (by obenland):',
+					'',
+					' * Attachment "ワードプレスのサイトヘルス情報画面のスクリーンショット二〇二',
+					' 四年七月十五日撮影分.png" added.',
+				),
+				'',
+				array(
+					'_*attachment:*_ `ワードプレスのサイトヘルス情報画面のスクリーンショット二〇二四年七月十五日撮影分.png` added',
+				),
+			),
 		);
 	}
 }
diff --git a/svn.wordpress.org/bin/slack-trac-hook.php b/svn.wordpress.org/bin/slack-trac-hook.php
index 1493e5c92b..761677fa79 100644
--- a/svn.wordpress.org/bin/slack-trac-hook.php
+++ b/svn.wordpress.org/bin/slack-trac-hook.php
@@ -23,9 +23,17 @@
 	$ticket_url = $matches[2];
 	$ticket_base_url = $matches[3];
 	$ticket = $matches[4];
-	// Attachment notifcations use the ticket URL, check for attachment change line and process mail as comment on match.
-	$is_attachment = (bool) preg_grep( '/^ \* Attachment "([^"]+)"/', $lines );
-	$type = ( isset( $matches[5] ) || $is_attachment ) ? 'comment' : 'ticket';
+	// Attachment notifications use the ticket URL, but Trac sets In-Reply-To on all except new-ticket ones.
+	$is_reply = false;
+	foreach ( $lines as $header ) {
+		if ( '' === trim( $header ) ) {
+			break;
+		}
+		if ( 0 === stripos( $header, 'In-Reply-To:' ) ) {
+			$is_reply = true;
+		}
+	}
+	$type = ( isset( $matches[5] ) || $is_reply ) ? 'comment' : 'ticket'; // phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited -- WordPress isn't loaded here.
 	preg_match( '~^https?://([^.]+)\.trac~i', $ticket_base_url, $matches );
 	$trac = $matches[1];
 	break;