WordPress 6.9 Field Guide

WordPress 6.9 introduces block-level collaboration notes, enhanced drag-and-drop editing, and a new WP_Block_Processor for parsing block structures. The release adds new blocks (Math, Accordion, Terms Query), expands the Field API with 10+ field types, and improves DataViews with infinite scroll and custom layouts. Performance optimizations target LCP metrics through on-demand block styles and minified CSS. The Abilities API provides standardized AI integration, while the Interactivity API gains unique ID assignment and improved router support. PHP 8.5 receives beta support, UTF-8 handling becomes environment-independent, and the HTML API gets enhanced serialization. Email handling now supports inline images with cid: references, and apiVersion 3 becomes mandatory for blocks as the editor transitions to iframe architecture in WordPress 7.0.