View config: port changes for WordPress 7.2

[oandregal]

Related to: https://core.trac.wordpress.org/ticket/66229#ticket

This is a continuation of https://core.trac.wordpress.org/ticket/65516 which landed view config endpoint for 7.1. It exists to track which changes we need to land in WordPress 7.2 version.

Some of these changes are conditional to enable the site editor v2.

Gutenberg PR: ​https://github.com/WordPress/gutenberg/pull/82138
Trac ticket: https://core.trac.wordpress.org/ticket/65981

Use of AI Tools
AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Fable
Used for: Porting the server-side change from the Gutenberg PR. Reviewed and edited by me.

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See ​GitHub Pull Requests for Code Review in the Core Handbook for more details.

The status and discussion groups of the default post type form used to be summarized by the field sharing their id (status, and the composite discussion field from @wordpress/fields). A combined form field no longer resolves its own id against the field definitions, so the summary field is declared through layout.summary instead. Without it, the groups would be summarized by their first child (status is unchanged, but discussion would show comment_status alone).

Gutenberg PR: ​https://github.com/WordPress/gutenberg/pull/82175

## Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Fable
Used for: Porting the server-side change and its unit test from the Gutenberg PR. Reviewed and edited by me.

Committed at https://core.trac.wordpress.org/changeset/63434

Trac ticket: https://core.trac.wordpress.org/ticket/65981

Adds descriptions to the styles property of the table layout schema in the view config REST controller and to the ColumnStyle properties (width, maxWidth, minWidth, align). The styles description notes that the styles apply to the columns listed in the view fields and not to the primary column (title, media, and description fields), which takes the width the other columns leave over. No behavior changes.

# Backports

Gutenberg PRs:

• ​https://github.com/WordPress/gutenberg/pull/82238

## Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Fable
Used for: Porting the server-side change from the Gutenberg PR. Reviewed and edited by me.

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See ​GitHub Pull Requests for Code Review in the Core Handbook for more details.

Committed at https://core.trac.wordpress.org/changeset/63436

Trac ticket: https://core.trac.wordpress.org/ticket/65981

Adds a boolean showPlaceholderIfEmpty property to the panel form layout in the view config REST schema. When true, the panel summary shows the field's placeholder instead of its render output when the value is undefined, null, or an empty string. It is false by default, so existing forms are unchanged. Schema only, no behavior changes on the server.

# Backports

Gutenberg PRs:

• ​https://github.com/WordPress/gutenberg/pull/82527

## Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Fable
Used for: Porting the server-side change from the Gutenberg PR.
Reviewed and edited by me.

Committed at https://core.trac.wordpress.org/changeset/63530

Removes the active, slug, and theme fields from the default view of the wp_template entity in view-config.php. Those fields were rendered by the template activation experiment, which has been removed from the editor (​https://github.com/WordPress/gutenberg/pull/82241). No field with those ids is registered for templates anymore, so the entries do nothing. DataViews drops unknown ids from view.fields, so there is no change in what the Templates page shows: title, description, and author.

# Backports

Gutenberg PRs:

• ​https://github.com/WordPress/gutenberg/pull/82602

## Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Fable
Used for: Tracing the history of the fields and porting the change from the Gutenberg PR. Reviewed and edited by me.

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See ​GitHub Pull Requests for Code Review in the Core Handbook for more details.

Committed at https://core.trac.wordpress.org/changeset/63551

Adds a base view configuration for the root/site entity, served by GET /wp/v2/view-config?kind=root&name=site. It provides the form the site editor's Identity screen renders over the site settings: a regular layout with labels on top, and the site title, tagline, logo, and icon fields. Only the form is defined, since the site settings are a singleton record that is never listed in a view. The Identity screen of the site editor reads this form from the endpoint once the @wordpress/edit-site package is updated, so plugins can adjust it through the get_entity_view_config_root_site filter.

This affects a stable screen of the site editor, so it is separate from the view configuration changes that wait on the site editor v2 experiment.

# Backports

Gutenberg PRs:

• ​https://github.com/WordPress/gutenberg/pull/82692

## Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Fable
Used for: Porting the server-side change from the Gutenberg PR. Reviewed and edited by me.

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See ​GitHub Pull Requests for Code Review in the Core Handbook for more details.

Committed at https://core.trac.wordpress.org/changeset/63578