Prevent backup post from being deleted when HPOS is authoritative

plugins/woocommerce/changelog/fix-42746

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fix
+
+Add some safeguards against programmatic removal of orders due to sync when HPOS is active.

plugins/woocommerce/src/Internal/DataStores/Orders/DataSynchronizer.php

@@ -105,6 +105,7 @@ class DataSynchronizer implements BatchProcessorInterface {
 	 * Class constructor.
 	 */
 	public function __construct() {
+		self::add_filter( 'pre_delete_post', array( $this, 'maybe_prevent_deletion_of_post' ), 10, 2 );
 		self::add_action( 'deleted_post', array( $this, 'handle_deleted_post' ), 10, 2 );
 		self::add_action( 'woocommerce_new_order', array( $this, 'handle_updated_order' ), 100 );
 		self::add_action( 'woocommerce_refund_created', array( $this, 'handle_updated_order' ), 100 );
@@ -901,6 +902,26 @@ public function get_description(): string {
 		return 'Synchronizes orders between posts and custom order tables.';
 	}
 
+	/**
+	 * Prevents deletion of order backup posts (regardless of sync setting) when HPOS is authoritative and the order
+	 * still exists in HPOS.
+	 * This should help with edge cases where wp_delete_post() would delete the HPOS record too or backfill would sync
+	 * incorrect data from an order with no metadata from the posts table.
+	 *
+	 * @since 8.8.0
+	 *
+	 * @param WP_Post|false|null $delete Whether to go forward with deletion.
+	 * @param WP_Post            $post   Post object.
+	 * @return WP_Post|false|null
+	 */
+	private function maybe_prevent_deletion_of_post( $delete, $post ) {
+		if ( self::PLACEHOLDER_ORDER_POST_TYPE !== $post->post_type && $this->custom_orders_table_is_authoritative() && $this->data_store->order_exists( $post->ID ) ) {
+			$delete = false;
+		}
+
+		return $delete;
+	}
+
 	/**
 	 * Handle the 'deleted_post' action.
 	 *

plugins/woocommerce/tests/php/src/Internal/DataStores/Orders/DataSynchronizerTests.php

@@ -206,13 +206,24 @@ public function test_status_syncs_correctly_after_order_creation() {
 	 * change should propagate across to the other table.
 	 */
 	public function test_order_deletions_propagate_with_sync_enabled(): void {
-		// Sync enabled and COT authoritative.
+		// Sync enabled.
 		update_option( $this->sut::ORDERS_DATA_SYNC_ENABLED_OPTION, 'yes' );
+
+		// COT authoritative.
 		update_option( CustomOrdersTableController::CUSTOM_ORDERS_TABLE_USAGE_ENABLED_OPTION, 'yes' );
+		$order = OrderHelper::create_order();
 
+		// Deleting the backup post while COT is authoritative shouldn't delete the COT version.
+		wp_delete_post( $order->get_id(), true );
+		$this->assertNotFalse( wc_get_order( $order->get_id() ) );
+
+		// Deleting the backup post while posts is authoritative should delete everything.
+		update_option( CustomOrdersTableController::CUSTOM_ORDERS_TABLE_USAGE_ENABLED_OPTION, 'no' );
 		$order = OrderHelper::create_order();
 		wp_delete_post( $order->get_id(), true );
+		$this->assertFalse( wc_get_order( $order->get_id() ) );
 
+		update_option( CustomOrdersTableController::CUSTOM_ORDERS_TABLE_USAGE_ENABLED_OPTION, 'yes' );
 		$this->assertFalse(
 			wc_get_order( $order->get_id() ),
 			'After the order post record was deleted, the order was also deleted from COT.'