Responses And Fields

• Removing or changing core fields breaks clients (including wp-admin).
• Prefer adding new fields or using _fields to limit response size.

register_rest_field

• Use for computed or custom fields.
• Provide get_callback, optional update_callback, and schema.
• Register on rest_api_init.

Raw vs rendered content

• For posts, content.rendered reflects filters (plugins like ToC inject HTML).
• Use ?context=edit (authenticated) to access content.raw.
• Combine with _fields=content.raw when you only need the editable body.

register_meta / register_post_meta / register_term_meta

• Use when the data is stored as meta.
• Set show_in_rest => true to expose under .meta.
• For object or array types, provide a JSON schema in show_in_rest.schema.

Links and embedding

• Add links with WP_REST_Response::add_link( $rel, $href, $attrs ).
• Use embeddable => true to allow _embed.
• Use IANA rels or a custom URI relation; CURIEs can be registered via rest_response_link_curies.