Gutenberg changed how WordPress content gets edited back in 2018, and full-site editing is the natural next step: applying the same block model to headers, footers, and templates, not just the content inside a post or page. We took an early experimental build for a spin on an internal test site to see whether it's ready for anything beyond curiosity.
`theme.json` is the centerpiece of the new approach, a single configuration file that defines a theme's color palette, typography scale, spacing units, and which of those options are exposed to editors in the block editor's UI. It's genuinely powerful once you understand it; a client's brand colors and type scale can be defined once and enforced consistently across every block on the site, rather than relying on a style guide document that editors may or may not follow when they're building a page. But the learning curve for agencies used to classic PHP templates is steeper than Gutenberg's initial rollout was, since `theme.json` replaces a lot of what used to live directly in `functions.php` and template files, and there isn't yet a large body of documentation or established convention to lean on the way there is for classic theme development.
Template parts, reusable chunks of a layout like a header or a footer defined as blocks rather than PHP includes, worked more smoothly than we expected, and editing a site-wide header directly in the same block editor used for post content is a genuinely nice unification of two previously separate editing experiences. Query loop blocks, which let an editor build a custom post listing entirely through the block editor rather than a PHP template, are promising but still limited; several query configurations we'd normally reach for in a classic theme's template code, particularly more complex filtering and sorting, aren't yet exposed through the block interface and still require a custom block or a PHP fallback.
The experimental build we tested is promising but clearly not production-ready, and we wouldn't recommend it for a client project yet. It's also worth watching for what it might mean for the page-builder plugin market; several clients currently paying for a third-party page builder specifically for the layout flexibility it offers over classic WordPress themes might find full-site editing covers the same ground natively once it matures, which would be a meaningful simplification for anyone currently maintaining both a page builder and a classic theme side by side. We'll be revisiting this once a stable release lands in WordPress core rather than as a separate experimental plugin.