diff -r 48c4eec2b7e6 -r 8c2e4d02f4ef wp/wp-includes/class-wp-query.php
--- a/wp/wp-includes/class-wp-query.php	Fri Sep 05 18:40:08 2025 +0200
+++ b/wp/wp-includes/class-wp-query.php	Fri Sep 05 18:52:52 2025 +0200
@@ -442,6 +442,7 @@
 	 * via pre_get_posts hooks.
 	 *
 	 * @since 3.1.1
+	 * @var bool
 	 */
 	private $query_vars_changed = true;
 
@@ -474,6 +475,17 @@
 	private $compat_methods = array( 'init_query_flags', 'parse_tax_query' );
 
 	/**
+	 * The cache key generated by the query.
+	 *
+	 * The cache key is generated by the method ::generate_cache_key() after the
+	 * query has been normalized.
+	 *
+	 * @since 6.8.0
+	 * @var string
+	 */
+	private $query_cache_key = '';
+
+	/**
 	 * Resets query flags to false.
 	 *
 	 * The query flags are what page info WordPress was able to figure out.
@@ -1100,7 +1112,8 @@
 
 		if ( ! empty( $qv['post_type'] ) ) {
 			if ( is_array( $qv['post_type'] ) ) {
-				$qv['post_type'] = array_map( 'sanitize_key', $qv['post_type'] );
+				$qv['post_type'] = array_map( 'sanitize_key', array_unique( $qv['post_type'] ) );
+				sort( $qv['post_type'] );
 			} else {
 				$qv['post_type'] = sanitize_key( $qv['post_type'] );
 			}
@@ -1108,7 +1121,8 @@
 
 		if ( ! empty( $qv['post_status'] ) ) {
 			if ( is_array( $qv['post_status'] ) ) {
-				$qv['post_status'] = array_map( 'sanitize_key', $qv['post_status'] );
+				$qv['post_status'] = array_map( 'sanitize_key', array_unique( $qv['post_status'] ) );
+				sort( $qv['post_status'] );
 			} else {
 				$qv['post_status'] = preg_replace( '|[^a-z0-9_,-]|', '', $qv['post_status'] );
 			}
@@ -1181,9 +1195,12 @@
 
 				$term = $q[ $t->query_var ];
 
-				if ( is_array( $term ) ) {
-					$term = implode( ',', $term );
+				if ( ! is_array( $term ) ) {
+					$term = explode( ',', $term );
+					$term = array_map( 'trim', $term );
 				}
+				sort( $term );
+				$term = implode( ',', $term );
 
 				if ( str_contains( $term, '+' ) ) {
 					$terms = preg_split( '/[+]+/', $term );
@@ -1219,7 +1236,8 @@
 
 			$cat_array = preg_split( '/[,\s]+/', urldecode( $q['cat'] ) );
 			$cat_array = array_map( 'intval', $cat_array );
-			$q['cat']  = implode( ',', $cat_array );
+			sort( $cat_array );
+			$q['cat'] = implode( ',', $cat_array );
 
 			foreach ( $cat_array as $cat ) {
 				if ( $cat > 0 ) {
@@ -1261,7 +1279,8 @@
 
 		if ( ! empty( $q['category__in'] ) ) {
 			$q['category__in'] = array_map( 'absint', array_unique( (array) $q['category__in'] ) );
-			$tax_query[]       = array(
+			sort( $q['category__in'] );
+			$tax_query[] = array(
 				'taxonomy'         => 'category',
 				'terms'            => $q['category__in'],
 				'field'            => 'term_id',
@@ -1271,7 +1290,8 @@
 
 		if ( ! empty( $q['category__not_in'] ) ) {
 			$q['category__not_in'] = array_map( 'absint', array_unique( (array) $q['category__not_in'] ) );
-			$tax_query[]           = array(
+			sort( $q['category__not_in'] );
+			$tax_query[] = array(
 				'taxonomy'         => 'category',
 				'terms'            => $q['category__not_in'],
 				'operator'         => 'NOT IN',
@@ -1281,7 +1301,8 @@
 
 		if ( ! empty( $q['category__and'] ) ) {
 			$q['category__and'] = array_map( 'absint', array_unique( (array) $q['category__and'] ) );
-			$tax_query[]        = array(
+			sort( $q['category__and'] );
+			$tax_query[] = array(
 				'taxonomy'         => 'category',
 				'terms'            => $q['category__and'],
 				'field'            => 'term_id',
@@ -1299,10 +1320,12 @@
 
 		if ( '' !== $q['tag'] && ! $this->is_singular && $this->query_vars_changed ) {
 			if ( str_contains( $q['tag'], ',' ) ) {
+				// @todo Handle normalizing `tag` query string.
 				$tags = preg_split( '/[,\r\n\t ]+/', $q['tag'] );
 				foreach ( (array) $tags as $tag ) {
 					$tag                 = sanitize_term_field( 'slug', $tag, 0, 'post_tag', 'db' );
 					$q['tag_slug__in'][] = $tag;
+					sort( $q['tag_slug__in'] );
 				}
 			} elseif ( preg_match( '/[+\r\n\t ]+/', $q['tag'] ) || ! empty( $q['cat'] ) ) {
 				$tags = preg_split( '/[+\r\n\t ]+/', $q['tag'] );
@@ -1313,6 +1336,7 @@
 			} else {
 				$q['tag']            = sanitize_term_field( 'slug', $q['tag'], 0, 'post_tag', 'db' );
 				$q['tag_slug__in'][] = $q['tag'];
+				sort( $q['tag_slug__in'] );
 			}
 		}
 
@@ -1326,7 +1350,8 @@
 
 		if ( ! empty( $q['tag__in'] ) ) {
 			$q['tag__in'] = array_map( 'absint', array_unique( (array) $q['tag__in'] ) );
-			$tax_query[]  = array(
+			sort( $q['tag__in'] );
+			$tax_query[] = array(
 				'taxonomy' => 'post_tag',
 				'terms'    => $q['tag__in'],
 			);
@@ -1334,7 +1359,8 @@
 
 		if ( ! empty( $q['tag__not_in'] ) ) {
 			$q['tag__not_in'] = array_map( 'absint', array_unique( (array) $q['tag__not_in'] ) );
-			$tax_query[]      = array(
+			sort( $q['tag__not_in'] );
+			$tax_query[] = array(
 				'taxonomy' => 'post_tag',
 				'terms'    => $q['tag__not_in'],
 				'operator' => 'NOT IN',
@@ -1343,7 +1369,8 @@
 
 		if ( ! empty( $q['tag__and'] ) ) {
 			$q['tag__and'] = array_map( 'absint', array_unique( (array) $q['tag__and'] ) );
-			$tax_query[]   = array(
+			sort( $q['tag__and'] );
+			$tax_query[] = array(
 				'taxonomy' => 'post_tag',
 				'terms'    => $q['tag__and'],
 				'operator' => 'AND',
@@ -1352,7 +1379,8 @@
 
 		if ( ! empty( $q['tag_slug__in'] ) ) {
 			$q['tag_slug__in'] = array_map( 'sanitize_title_for_query', array_unique( (array) $q['tag_slug__in'] ) );
-			$tax_query[]       = array(
+			sort( $q['tag_slug__in'] );
+			$tax_query[] = array(
 				'taxonomy' => 'post_tag',
 				'terms'    => $q['tag_slug__in'],
 				'field'    => 'slug',
@@ -1361,7 +1389,8 @@
 
 		if ( ! empty( $q['tag_slug__and'] ) ) {
 			$q['tag_slug__and'] = array_map( 'sanitize_title_for_query', array_unique( (array) $q['tag_slug__and'] ) );
-			$tax_query[]        = array(
+			sort( $q['tag_slug__and'] );
+			$tax_query[] = array(
 				'taxonomy' => 'post_tag',
 				'terms'    => $q['tag_slug__and'],
 				'field'    => 'slug',
@@ -1902,7 +1931,7 @@
 
 		// Set a flag if a 'pre_get_posts' hook changed the query vars.
 		$hash = md5( serialize( $this->query_vars ) );
-		if ( $hash != $this->query_vars_hash ) {
+		if ( $hash !== $this->query_vars_hash ) {
 			$this->query_vars_changed = true;
 			$this->query_vars_hash    = $hash;
 		}
@@ -2002,10 +2031,11 @@
 			}
 			$q['nopaging'] = false;
 		}
+
 		$q['posts_per_page'] = (int) $q['posts_per_page'];
 		if ( $q['posts_per_page'] < -1 ) {
 			$q['posts_per_page'] = abs( $q['posts_per_page'] );
-		} elseif ( 0 == $q['posts_per_page'] ) {
+		} elseif ( 0 === $q['posts_per_page'] ) {
 			$q['posts_per_page'] = 1;
 		}
 
@@ -2037,6 +2067,15 @@
 			case 'id=>parent':
 				$fields = "{$wpdb->posts}.ID, {$wpdb->posts}.post_parent";
 				break;
+			case '':
+				/*
+				 * Set the default to 'all'.
+				 *
+				 * This is used in `WP_Query::the_post` to determine if the
+				 * entire post object has been queried.
+				 */
+				$q['fields'] = 'all';
+				// Falls through.
 			default:
 				$fields = "{$wpdb->posts}.*";
 		}
@@ -2185,8 +2224,11 @@
 			$where          .= " AND {$wpdb->posts}.post_name = '" . $q['attachment'] . "'";
 		} elseif ( is_array( $q['post_name__in'] ) && ! empty( $q['post_name__in'] ) ) {
 			$q['post_name__in'] = array_map( 'sanitize_title_for_query', $q['post_name__in'] );
-			$post_name__in      = "'" . implode( "','", $q['post_name__in'] ) . "'";
-			$where             .= " AND {$wpdb->posts}.post_name IN ($post_name__in)";
+			// Duplicate array before sorting to allow for the orderby clause.
+			$post_name__in_for_where = array_unique( $q['post_name__in'] );
+			sort( $post_name__in_for_where );
+			$post_name__in = "'" . implode( "','", $post_name__in_for_where ) . "'";
+			$where        .= " AND {$wpdb->posts}.post_name IN ($post_name__in)";
 		}
 
 		// If an attachment is requested by number, let it supersede any post number.
@@ -2198,9 +2240,14 @@
 		if ( $q['p'] ) {
 			$where .= " AND {$wpdb->posts}.ID = " . $q['p'];
 		} elseif ( $q['post__in'] ) {
-			$post__in = implode( ',', array_map( 'absint', $q['post__in'] ) );
+			// Duplicate array before sorting to allow for the orderby clause.
+			$post__in_for_where = $q['post__in'];
+			$post__in_for_where = array_unique( array_map( 'absint', $post__in_for_where ) );
+			sort( $post__in_for_where );
+			$post__in = implode( ',', array_map( 'absint', $post__in_for_where ) );
 			$where   .= " AND {$wpdb->posts}.ID IN ($post__in)";
 		} elseif ( $q['post__not_in'] ) {
+			sort( $q['post__not_in'] );
 			$post__not_in = implode( ',', array_map( 'absint', $q['post__not_in'] ) );
 			$where       .= " AND {$wpdb->posts}.ID NOT IN ($post__not_in)";
 		}
@@ -2208,9 +2255,14 @@
 		if ( is_numeric( $q['post_parent'] ) ) {
 			$where .= $wpdb->prepare( " AND {$wpdb->posts}.post_parent = %d ", $q['post_parent'] );
 		} elseif ( $q['post_parent__in'] ) {
-			$post_parent__in = implode( ',', array_map( 'absint', $q['post_parent__in'] ) );
+			// Duplicate array before sorting to allow for the orderby clause.
+			$post_parent__in_for_where = $q['post_parent__in'];
+			$post_parent__in_for_where = array_unique( array_map( 'absint', $post_parent__in_for_where ) );
+			sort( $post_parent__in_for_where );
+			$post_parent__in = implode( ',', array_map( 'absint', $post_parent__in_for_where ) );
 			$where          .= " AND {$wpdb->posts}.post_parent IN ($post_parent__in)";
 		} elseif ( $q['post_parent__not_in'] ) {
+			sort( $q['post_parent__not_in'] );
 			$post_parent__not_in = implode( ',', array_map( 'absint', $q['post_parent__not_in'] ) );
 			$where              .= " AND {$wpdb->posts}.post_parent NOT IN ($post_parent__not_in)";
 		}
@@ -2340,6 +2392,7 @@
 		if ( ! empty( $q['author'] ) && '0' != $q['author'] ) {
 			$q['author'] = addslashes_gpc( '' . urldecode( $q['author'] ) );
 			$authors     = array_unique( array_map( 'intval', preg_split( '/[,\s]+/', $q['author'] ) ) );
+			sort( $authors );
 			foreach ( $authors as $author ) {
 				$key         = $author > 0 ? 'author__in' : 'author__not_in';
 				$q[ $key ][] = abs( $author );
@@ -2348,9 +2401,17 @@
 		}
 
 		if ( ! empty( $q['author__not_in'] ) ) {
-			$author__not_in = implode( ',', array_map( 'absint', array_unique( (array) $q['author__not_in'] ) ) );
+			if ( is_array( $q['author__not_in'] ) ) {
+				$q['author__not_in'] = array_unique( array_map( 'absint', $q['author__not_in'] ) );
+				sort( $q['author__not_in'] );
+			}
+			$author__not_in = implode( ',', (array) $q['author__not_in'] );
 			$where         .= " AND {$wpdb->posts}.post_author NOT IN ($author__not_in) ";
 		} elseif ( ! empty( $q['author__in'] ) ) {
+			if ( is_array( $q['author__in'] ) ) {
+				$q['author__in'] = array_unique( array_map( 'absint', $q['author__in'] ) );
+				sort( $q['author__in'] );
+			}
 			$author__in = implode( ',', array_map( 'absint', array_unique( (array) $q['author__in'] ) ) );
 			$where     .= " AND {$wpdb->posts}.post_author IN ($author__in) ";
 		}
@@ -2587,6 +2648,7 @@
 			if ( ! is_array( $q_status ) ) {
 				$q_status = explode( ',', $q_status );
 			}
+			sort( $q_status );
 			$r_status = array();
 			$p_status = array();
 			$e_status = array();
@@ -3294,7 +3356,7 @@
 			return $post_parents;
 		}
 
-		$is_unfiltered_query = $old_request == $this->request && "{$wpdb->posts}.*" === $fields;
+		$is_unfiltered_query = $old_request === $this->request && "{$wpdb->posts}.*" === $fields;
 
 		if ( null === $this->posts ) {
 			$split_the_query = (
@@ -3686,21 +3748,37 @@
 		global $post;
 
 		if ( ! $this->in_the_loop ) {
-			// Only prime the post cache for queries limited to the ID field.
-			$post_ids = array_filter( $this->posts, 'is_numeric' );
-			// Exclude any falsey values, such as 0.
-			$post_ids = array_filter( $post_ids );
-			if ( $post_ids ) {
+			if ( 'all' === $this->query_vars['fields'] ) {
+				// Full post objects queried.
+				$post_objects = $this->posts;
+			} else {
+				if ( 'ids' === $this->query_vars['fields'] ) {
+					// Post IDs queried.
+					$post_ids = $this->posts;
+				} else {
+					// Only partial objects queried, need to prime the cache for the loop.
+					$post_ids = array_reduce(
+						$this->posts,
+						function ( $carry, $post ) {
+							if ( isset( $post->ID ) ) {
+								$carry[] = $post->ID;
+							}
+
+							return $carry;
+						},
+						array()
+					);
+				}
 				_prime_post_caches( $post_ids, $this->query_vars['update_post_term_cache'], $this->query_vars['update_post_meta_cache'] );
+				$post_objects = array_map( 'get_post', $post_ids );
 			}
-			$post_objects = array_map( 'get_post', $this->posts );
 			update_post_author_caches( $post_objects );
 		}
 
 		$this->in_the_loop = true;
 		$this->before_loop = false;
 
-		if ( -1 == $this->current_post ) { // Loop has just started.
+		if ( -1 === $this->current_post ) { // Loop has just started.
 			/**
 			 * Fires once the loop is started.
 			 *
@@ -3712,6 +3790,24 @@
 		}
 
 		$post = $this->next_post();
+
+		// Ensure a full post object is available.
+		if ( 'all' !== $this->query_vars['fields'] ) {
+			if ( 'ids' === $this->query_vars['fields'] ) {
+				// Post IDs queried.
+				$post = get_post( $post );
+			} elseif ( isset( $post->ID ) ) {
+				/*
+				 * Partial objecct queried.
+				 *
+				 * The post object was queried with a partial set of
+				 * fields, populate the entire object for the loop.
+				 */
+				$post = get_post( $post->ID );
+			}
+		}
+
+		// Set up the global post object for the loop.
 		$this->setup_postdata( $post );
 	}
 
@@ -3727,7 +3823,7 @@
 	public function have_posts() {
 		if ( $this->current_post + 1 < $this->post_count ) {
 			return true;
-		} elseif ( $this->current_post + 1 == $this->post_count && $this->post_count > 0 ) {
+		} elseif ( $this->current_post + 1 === $this->post_count && $this->post_count > 0 ) {
 			/**
 			 * Fires once the loop has ended.
 			 *
@@ -3736,6 +3832,7 @@
 			 * @param WP_Query $query The WP_Query instance (passed by reference).
 			 */
 			do_action_ref_array( 'loop_end', array( &$this ) );
+
 			// Do some cleaning up after the loop.
 			$this->rewind_posts();
 		} elseif ( 0 === $this->post_count ) {
@@ -3794,7 +3891,7 @@
 
 		$comment = $this->next_comment();
 
-		if ( 0 == $this->current_comment ) {
+		if ( 0 === $this->current_comment ) {
 			/**
 			 * Fires once the comment loop is started.
 			 *
@@ -3816,7 +3913,7 @@
 	public function have_comments() {
 		if ( $this->current_comment + 1 < $this->comment_count ) {
 			return true;
-		} elseif ( $this->current_comment + 1 == $this->comment_count ) {
+		} elseif ( $this->current_comment + 1 === $this->comment_count ) {
 			$this->rewind_comments();
 		}
 
@@ -4011,6 +4108,8 @@
 		if ( in_array( $name, $this->compat_fields, true ) ) {
 			return isset( $this->$name );
 		}
+
+		return false;
 	}
 
 	/**
@@ -4479,9 +4578,10 @@
 				if ( ! strpos( $pagepath, '/' ) ) {
 					continue;
 				}
+
 				$pagepath_obj = get_page_by_path( $pagepath );
 
-				if ( $pagepath_obj && ( $pagepath_obj->ID == $page_obj->ID ) ) {
+				if ( $pagepath_obj && ( $pagepath_obj->ID === $page_obj->ID ) ) {
 					return true;
 				}
 			}
@@ -4589,9 +4689,10 @@
 				if ( ! strpos( $postpath, '/' ) ) {
 					continue;
 				}
+
 				$postpath_obj = get_page_by_path( $postpath, OBJECT, $post_obj->post_type );
 
-				if ( $postpath_obj && ( $postpath_obj->ID == $post_obj->ID ) ) {
+				if ( $postpath_obj && ( $postpath_obj->ID === $post_obj->ID ) ) {
 					return true;
 				}
 			}
@@ -4899,6 +5000,33 @@
 		// Sort post types to ensure same cache key generation.
 		sort( $args['post_type'] );
 
+		/*
+		 * Sort arrays that can be used for ordering prior to cache key generation.
+		 *
+		 * These arrays are sorted in the query generator for the purposes of the
+		 * WHERE clause but the arguments are not modified as they can be used for
+		 * the orderby clase.
+		 *
+		 * Their use in the orderby clause will generate a different SQL query so
+		 * they can be sorted for the cache key generation.
+		 */
+		$sortable_arrays_with_int_values = array(
+			'post__in',
+			'post_parent__in',
+		);
+		foreach ( $sortable_arrays_with_int_values as $key ) {
+			if ( isset( $args[ $key ] ) && is_array( $args[ $key ] ) ) {
+				$args[ $key ] = array_unique( array_map( 'absint', $args[ $key ] ) );
+				sort( $args[ $key ] );
+			}
+		}
+
+		// Sort and unique the 'post_name__in' for cache key generation.
+		if ( isset( $args['post_name__in'] ) && is_array( $args['post_name__in'] ) ) {
+			$args['post_name__in'] = array_unique( $args['post_name__in'] );
+			sort( $args['post_name__in'] );
+		}
+
 		if ( isset( $args['post_status'] ) ) {
 			$args['post_status'] = (array) $args['post_status'];
 			// Sort post status to ensure same cache key generation.
@@ -4939,7 +5067,8 @@
 			$last_changed .= wp_cache_get_last_changed( 'terms' );
 		}
 
-		return "wp_query:$key:$last_changed";
+		$this->query_cache_key = "wp_query:$key:$last_changed";
+		return $this->query_cache_key;
 	}
 
 	/**