Jetpack Sync: Prevent syncing unchanged orders on save or update within a short window

projects/packages/sync/changelog/update-sync-hpos-orders-save-no-changes

@@ -0,0 +1,4 @@
+Significance: patch
+Type: changed
+
+Jetpack Sync: Prevent syncing unchanged orders on save within a short window.

projects/packages/sync/src/modules/class-woocommerce-hpos-orders.php

@@ -23,6 +23,16 @@ class WooCommerce_HPOS_Orders extends Module {
 	 */
 	const WOOCOMMERCE_SUBSCRIPTIONS_PATH = 'woocommerce-subscriptions/woocommerce-subscriptions.php';
 
+	/**
+	 * Cache key prefix for storing order checksums to avoid resyncing unchanged orders.
+	 */
+	const HPOS_CACHE_KEY = 'jetpack_sync_hpos_cache_key_';
+
+	/**
+	 * Cache expiration for storing order content signatures.
+	 */
+	const CACHE_EXPIRATION = 5 * MINUTE_IN_SECONDS;
+
 	/**
 	 * Order table name. There are four order tables (order, addresses, operational_data and meta), but for sync purposes we only care about the main table since it has the order ID.
 	 *
@@ -325,6 +335,34 @@ public function on_before_enqueue_order_save( $args ) {
 			return false;
 		}
 
+		$filtered = $this->filter_order_data( $order_object );
+
+		unset(
+			$filtered['date_modified']
+		);
+
+		// md5 of the date-stripped order payload to detect no-change saves (ignores timestamp-only changes)
+		$current_signature = md5( wp_json_encode( $filtered ) );
+		$cache_key         = self::HPOS_CACHE_KEY . $order_id;
+
+		$group = 'jetpack_sync_hpos';
+
+		$previous_signature = wp_using_ext_object_cache()
+		? wp_cache_get( $cache_key, $group )
+		: get_transient( $cache_key );
+
+		// If no substantive changes, skip enqueue.
+		if ( is_string( $previous_signature ) && hash_equals( $previous_signature, $current_signature ) ) {
+			return false;
+		}
+
+		// Remember current signature briefly to avoid "Update" or "Recalculate" clicks syncing again with no changes.
+		if ( wp_using_ext_object_cache() ) {
+			wp_cache_set( $cache_key, $current_signature, $group, self::CACHE_EXPIRATION );
+		} else {
+			set_transient( $cache_key, $current_signature, self::CACHE_EXPIRATION );
+		}
+
 		$processed[ $order_id ] = true;
 
 		return array( 'id' => $order_id );