diff --git a/includes/class-tmdo-logger.php b/includes/class-tmdo-logger.php
index 324cf38..feac105 100644
--- a/includes/class-tmdo-logger.php
+++ b/includes/class-tmdo-logger.php
@@ -16,6 +16,35 @@ if ( ! defined( 'ABSPATH' ) ) {
  */
 class TMDO_Logger {
 
+	/**
+	 * Request-scoped correlation id, lazily generated.
+	 *
+	 * @var string|null
+	 */
+	private static ?string $trace_id = null;
+
+	/**
+	 * Request-scoped UUIDv4 correlation id.
+	 *
+	 * Every audit row written during one request shares this value so a single
+	 * update_*_meta() call can be traced across entity groups.
+	 *
+	 * @return string UUIDv4.
+	 */
+	public static function trace_id(): string {
+		if ( null === self::$trace_id ) {
+			try {
+				$bytes = random_bytes( 16 );
+			} catch ( \Throwable $e ) {
+				$bytes = pack( 'H*', md5( (string) microtime( true ) . wp_generate_password( 16, false ) ) );
+			}
+			$bytes[6]       = chr( ( ord( $bytes[6] ) & 0x0f ) | 0x40 );
+			$bytes[8]       = chr( ( ord( $bytes[8] ) & 0x3f ) | 0x80 );
+			self::$trace_id = vsprintf( '%s%s-%s-%s-%s-%s%s%s', str_split( bin2hex( $bytes ), 4 ) );
+		}
+		return self::$trace_id;
+	}
+
 	/**
 	 * Log an INFO-level event (event-based signature, used by v2.0.0 engine code).
 	 *