WordPress admin

01Overview

Nucleo adds a top-level menu, "Nucleo AI", with 14 items to the dashboard.

Each item requires a WordPress capability. Pro items stay in the menu in Free, locked.

Almost all pages are React apps. The AI agents page is a PHP page.

The pages have no API of their own. They run the nucleo/* abilities through the WordPress Abilities REST API.

The document editor is a hidden page (nucleo-editor). It replaces Gutenberg only for posts with a Nucleo document.

The content model registers types, taxonomies and fields. The fields also appear in the native WordPress screens.

The Pro functions are in the Pro package. They manage the license, the updates and the Pro edition.

The Free package for WordPress.org follows the directory guidelines. Compared with the Free package downloaded from nucleowp.dev, it does not contain:

• the Kits, Performance and License items, the Critical CSS service tab and the CSS reduction options: no menu item is locked;
• the nc/html and nc/shortcode blocks and the perf.html.block quality rule;
• the nucleo/component-activate and nucleo/critical-request abilities;
• the language pack installation in the site import: the language is changed in Settings > General;
• the translation files: translate.wordpress.org provides them.

02Menu and access

Nucleo AI menu

What it does: registers the top-level menu nucleo ("Nucleo AI") and one submenu item for each item visible to the user.

How to use it: dashboard, "Nucleo AI" item at position 61. The items, in order:

In Free, the Pro items, and the items with at least one locked Pro tab, show the PRO tag.

The nucleo-quality item shows a red counter, only for users with edit_others_posts.

Permissions: the top-level item requires edit_posts. Each submenu item requires the capability in the table. If the capability is missing, the page responds with 403.

Edition: Free. In Free, the Pro items stay in the menu, locked.

Known limits: the capabilities in the table apply only to the interface. The abilities called by the pages check capability and edition on their own, and they can be stricter. See the Content model section.

Access rules

What it does: calculates for each item, tab and option a state among ok, hidden, locked, explain and readonly, with the reason (capability, feature, plugin, edition).

How to use it: the menu shows the items that are not hidden, with tabs and options already resolved. The pages read the same result.

Parameters: keys of a rule.

The checks run in this order: capability, feature, plugin, edition, write. The first missing condition wins.

Permissions: depends on the rule.

Edition: Free.

Known limits: Nucleo detects plugins from their active presence.

Locked items

What it does: shows the access state in the pages.

How to use it:

• locked: the content is blurred and inert under a tab with the buttons "Upgrade to Pro" and "I already have a key". Both lead to the License page.
• readonly: the content is visible with an information note.
• explain: the content is visible with a text that explains what is missing.
• Whole page locked: with the Pro package installed and no license, it shows "Nucleo Pro is installed but the license is not active.". Without the package, it shows "This page is available with Nucleo Pro.".

Permissions: none beyond those of the page.

Edition: Free.

Page boot data

What it does: passes the object window.nucleoAdmin to the admin pages, written inline before the pages script.

How to use it: the pages read these keys.

Parameters: filter nucleo/languages (list of language codes).

Permissions: none beyond those of the page.

Edition: Free.

Known limits: scripts load only on the Nucleo pages. Styles also load on the OAuth consent screen.

Running abilities from the pages

What it does: runs an ability from the browser. Pages and the editor use the same call.

How to use it: abilities annotated readonly are read with GET. The others use POST with body {input}.

GET /wp-abilities/v1/abilities/<name>/run?input[k]=v

POST /wp-abilities/v1/abilities/<name>/run
{"input": {…}}

The call does not throw exceptions. An error returns as {ok: false, error: {code, message}}.

Parameters: the ability name and input.

Permissions: those of the ability, with the WordPress cookie authentication.

Edition: Free.

Known limits: in the editor, if the readonly list is missing, the fallback list contains only nucleo/doc-get, nucleo/catalog-list, nucleo/catalog-get and nucleo/doc-texts.

03Admin pages

Overview (nucleo)

What it does: summarizes the site with documents, quality, recent activity, layouts and status.

How to use it: "Nucleo AI" → "Overview". The page loads nucleo/site-describe, nucleo/quality-scan (page: 1), nucleo/audit-list (limit: 5) and nucleo/layout-list. Only administrators also load nucleo/status and nucleo/settings-get.

• "New page" opens the New document dialog with type page.
• "Open the header editor" opens the first layout with area header. Without a layout, the button is disabled.
• "Rebuild the cache" (administrators only) calls nucleo/cache-rebuild.
• With zero documents, the first-run panel appears, with three tabs: Kit, AI agents and blank page. "Don't show again" calls nucleo/settings-set with onboarding.dismissed: true.

Permissions: edit_posts. The status sections require manage_options.

Edition: Free.

Known limits: users who are not administrators read "Versions, storage and conflicts are visible to administrators only.".

Pages (nucleo-documents)

What it does: lists pages and posts with status, language and SEO score.

How to use it: tabs page ("Pages") and post ("Posts"), chosen with ?tab=, default page. The page calls nucleo/doc-list and nucleo/quality-scan.

• Row menu: Edit, View, Text only (&view=texts) and Translate, with at least two languages.
• "New document" opens the New document dialog with the type of the tab.

Parameters: search by title, on the server. Filters by status and language, in the browser.

Permissions: edit_posts.

Edition: Free.

Known limits:

• 20 rows per page.
• The status and language filters apply only to the loaded page.
• The check boxes have no bulk actions.
• The "Text only" link adds &view=texts, and the editor opens the "Text only" view.

Layouts (nucleo-layouts)

What it does: manages the layouts by area and their display conditions.

How to use it: tabs by area header, footer, single, archive and popup, default header.

• "New layout" calls nucleo/doc-create with type nucleo_layout and opens the editor.
• "Conditions" opens a panel with "Show on", "Hide on" and "Priority". Saving calls nucleo/layout-conditions-set.
• "Which layout applies?" calls nucleo/layout-explain.
• The conflicts from nucleo/layout-list appear in a notice with "Change priority".
• The value search uses WordPress users, terms and content, with 8 results.

Parameters: 14 condition types.

Permissions: edit_theme_options.

Edition: Free. The language condition requires Polylang or WPML. Without them, the page shows "Language requires Polylang or WPML.".

Known limits: the popup activation and frequency fields are disabled ("Coming soon"). The conflict error shows "This layout was changed elsewhere" with Reload.

Global sections (nucleo-sections)

What it does: lists the reusable sections (nucleo_section) with the number of pages that use them.

How to use it: the page calls nucleo/doc-list with postType: nucleo_section and nucleo/section-list. "New section" opens the New document dialog.

Parameters: search in the browser.

Permissions: edit_theme_options.

Edition: Free.

Known limits: the row menu has only Edit.

Design system (nucleo-design)

What it does: edits the design tokens.

How to use it: tabs colors, typography, spacing, shapes and containers, default colors.

• The page loads nucleo/tokens-get. "Save" calls nucleo/tokens-set with only the changed tokens.
• Importing a font calls nucleo/fonts-import.
• "Revert changes" restores the saved values.

Parameters: see the Design tokens section.

Permissions: edit_theme_options.

Edition: Free.

Known limits:

• Only colors and typography are editable. Spacing, shapes and containers are read only.
• The contrast check uses the 4.5 threshold.
• An invalid hexadecimal color disables "Save".
• The page warns (beforeunload) if you leave with unsaved changes.

Kits (nucleo-kits)

Content model (nucleo-content)

What it does: edits content types, taxonomies and field groups.

How to use it: tabs postTypes, taxonomies, fieldGroups and json, default postTypes.

• The page loads nucleo/model-get.
• Additions, changes and removals change only the draft. The JSON tab applies the text to the draft.
• "Save" calls nucleo/model-validate. Without errors, it shows additions, removals and changes. Every destructive change must be checked.
• "Confirm" calls nucleo/model-set with confirm equal to the checked ids.

Parameters: see the Model format section.

Permissions: the item and the abilities nucleo/model-get, nucleo/model-validate and nucleo/model-set require manage_options.

Edition: Free. In Free, the field types relation and repeater and the taxonomy location are disabled.

Known limits: the page warns (beforeunload) if you leave with unsaved changes.

Quality and SEO (nucleo-quality)

What it does: scans the site and shows the problems for each page.

How to use it: tabs issues, pages, overrides and rules, default issues.

• The scan calls nucleo/quality-scan page by page, until next is null.
• If no scan has ever run, the page offers "Start the first scan".
• A click on a title opens the details with nucleo/quality-check.

Permissions: edit_posts. Without edit_others_posts, the page is read only and the issues and overrides tabs disappear. The rules tab requires edit_theme_options.

Edition: Free.

Known limits: the overrides tab shows "Not available yet". The rules tab is a static table of 19 rules. The full rules are in the Quality engine section.

Performance (nucleo-performance)

AI agents (nucleo-agents)

What it does: connects MCP agents to the site. It shows the MCP server URL, the registered OAuth clients, the active tokens, the dynamic registration switch, the allowed domains and the .htaccess rule for the Authorization header.

How to use it: the page shows the URL rest_url('nucleo/v1/mcp') and the quick setups for Claude Desktop and Claude Code.

{"mcpServers":{"nucleo":{"url":"<server URL>"}}}

# adds the Nucleo MCP server to Claude Code
claude mcp add --transport http nucleo <server URL>

The page also shows the STDIO alternative, from the terminal:

# MCP server over STDIO with the given user's permissions
wp nucleo mcp --user=<login>

• The client table shows name, type (pre Pre-registered, cimd Metadata document, dcr Dynamic registration; with the "Confidential" label if it has a secret), who authorized it, date, last use, active access tokens and scope.
• "Add agent" creates a pre-registered client (kind = pre). The client_id appears only once.
• "Add confidential agent" creates a client with a client secret. The secret appears only once, on the next page, together with the client_id; the database keeps only the hash.
• "Save domains" saves the list of allowed domains (nucleo_oauth_domains). Empty list: no limit. Clients added by hand are not subject to the list.
• "Write the .htaccess rule" appears if agent requests reach the site without the Authorization header. It writes a Nucleo block into the .htaccess of the root that passes the header to PHP.
• "Revoke tokens" sets revoked = 2 on the client's tokens that are still active. The client stays.
• "Delete" removes the client and all its tokens, after confirmation.
• The switch saves the nucleo_oauth_dcr option.

Parameters: "Add agent" and "Add confidential agent".

Permissions: manage_options for the page and for each action. Each form has a nonce.

Edition: Free.

Known limits: errors when adding: missing_name, name_too_long, invalid_redirect and save_failed. The confidential client's secret stays in a transient for 60 seconds. If the OAuth tables are missing, the page installs them.

AI activity (nucleo-activity)

What it does: shows the log of ability operations and lets you undo them.

How to use it: the page loads nucleo/audit-list with limit: 200.

• Filters in the browser: agent, user, action, document text and "Only errors".
• "Restore" appears on the successful entries of doc-patch, doc-texts-set, doc-publish, doc-rollback and doc-translate. It calls nucleo/doc-revisions, takes the second-to-last revision and, after confirmation, calls nucleo/doc-rollback.

Permissions: edit_posts. Without edit_others_posts, the page is read only, shows only your own entries and "Restore" disappears.

Edition: Free.

Known limits: 25 entries per page, from the last 200. "Restore" always returns to the second-to-last revision of the document, not to the one before the selected entry.

Tools (nucleo-tools)

What it does: exports and imports the site, rebuilds the cache and shows the system status.

How to use it:

• "Download zip" calls nucleo/site-export and downloads the file nucleo-export-YYYY-MM-DD.zip.
• The import accepts a .zip or several .json files. It first calls nucleo/site-import with dryRun: true and shows the preview. "Import" repeats the call with dryRun: false.
• "Overwrite changes made on the site" sets force after a confirmation with the list of files.
• "Rebuild all" calls nucleo/cache-rebuild. The status comes from nucleo/status, with "Copy report".

Parameters: see the Import, export and sync section.

Permissions: manage_options.

Edition: Free.

Settings (nucleo-settings)

What it does: edits the Nucleo options. The keys are described in the Settings section.

How to use it: tabs editor, performance, service ("Critical CSS service"), captcha, integrations and agents, chosen with ?tab=, default editor.

• The page loads nucleo/settings-get. "Save changes" calls nucleo/settings-set with only the group of the active tab.
• integrations shows the detected plugins, read only. agents links to the AI agents page.

Parameters: see the Settings section.

Permissions: manage_options.

Edition: Free. The service tab is Pro: in Free it shows the Pro block.

Known limits: the service key and the captcha secret never return to the browser. A field left empty is not sent and keeps the saved value.

License (nucleo-license)

What it does: shows the license state, the plans and the activation and deactivation forms.

How to use it: the page shows one of these states.

In the active state, the expiry shows a yellow notice from 0 to 30 days and a red one if it has passed, with "Renew". The activation form is described in the License activation section.

Parameters: filter nucleo/license_plans, with a list of plans {id, name, price, period, sites, description, recommended, url}.

Permissions: manage_options.

Edition: Free. Activation and deactivation exist only in the Pro package.

Known limits: the key reaches the browser masked: 12 dots plus the last 4 characters.

New document dialog

What it does: creates a blank document and opens the editor.

How to use it: buttons "New page", "New document" and "New section". "Create and open the editor" calls nucleo/doc-create with title, postType, a blank document and publish.

Parameters: title (required), type page or post (if the page does not set it), "Publish now" (only with publish_pages).

Permissions: those of nucleo/doc-create.

Edition: Free.

Known limits: the starting point "From kit template" is disabled ("Not available yet").

Translation dialog

04Document editor

Editor page (nucleo-editor)

What it does: mounts the React editor of the Nucleo document of a post.

How to use it: admin.php?page=nucleo-editor&post=<ID>. The page does not appear in the menu. The title is "Nucleo editor".

Parameters: post (ID of the post, in the query string).

Permissions: the page requires edit_posts. Rendering requires edit_post on the post, otherwise it responds with 403.

Edition: Free.

Known limits: below 1024 px of width, the editor forces the "Text only" view.

Starting a document

What it does: creates the Nucleo document for a post that does not have one.

How to use it: if nucleo/doc-get responds not_found, the editor shows "This content has no Nucleo document yet". "Start with Nucleo" calls nucleo/doc-create with a blank document, with a section as the root.

Permissions: those of nucleo/doc-create.

Edition: Free.

Known limits: if the post already has content, the editor warns that paragraphs, headings and lists become text blocks. Images and other elements do not carry over. Nucleo keeps a copy of the original text. The "Open in the WordPress editor" button opens the classic WordPress editor.

Gutenberg and post.php

What it does: opens the Nucleo editor in place of Gutenberg only for posts with a Nucleo document.

How to use it:

• For Nucleo posts, the WordPress block editor does not open. The edit link leads to the Nucleo editor.
• post.php?action=edit on a Nucleo layout or section redirects to the Nucleo editor.
• post.php on another Nucleo page stays open, with title, custom fields and publishing. The classic editor disappears and the notice "Open the Nucleo editor" appears.
• A draft Nucleo page with blocking quality issues does not go online from post.php, from the block editor or by scheduling. The REST API responds quality_blocking; post.php keeps the previous status.

Permissions: those of WordPress for post.php.

Edition: Free.

Known limits: after saving a Nucleo page from post.php, the edit link stays on post.php.

Preview

What it does: builds the document in memory, without saving it, and shows it in an isolated frame.

How to use it: 300 ms after the last change, the editor calls POST /nucleo/v1/preview with the postId of the page. The preview uses the post context: bindings, links and language. The frame receives HTML, CSS, the site's stylesheets and the token CSS. A click on an element selects the nearest node.

Permissions: edit_posts. With postId, also edit_post on the post.

Edition: Free.

Known limits: responses that arrive after a newer one are discarded.

Structure, insert and inspector

What it does: edits the document tree and the properties of the nodes.

How to use it: full view with three columns.

• Structure: a tree with Up, Down, Duplicate and Delete for each node except the root. Dragging: top quarter for before, bottom quarter for after, middle for inside. The drop is allowed only if the node accepts the type.
• Insert: a catalog searchable by name, title and description, grouped by category. The new node goes inside the chosen node if it accepts it, otherwise after it. Without a selection it goes to the end of the root. The new ids are n plus 7 base-36 characters.
• Inspector: tabs "Content", "Settings" and "Style", generated from the node type. The style tab has a breakpoint bar base, md, lg and xl, and shows the inherited value. The src field of nc/image opens the media library.

The catalog comes from nucleo/catalog-list and nucleo/catalog-get.

Permissions: edit_post on the post.

Edition: Free.

Known limits: the tree column is 200 to 520 px wide. The default is 260 px and is saved in the browser. Undo and Redo keep 100 steps in memory and reset after saving, restoring or reloading.

Text only view

What it does: shows all the texts of the document in a single form, in page order.

How to use it: "Complete" or "Text only" selector in the top bar. The view loads nucleo/doc-texts. "Save texts" calls nucleo/doc-texts-set with baseRevision.

Permissions: edit_post on the post.

Edition: Free.

Known limits: with unsaved structure changes, the save is rejected: "Save the structure changes first.". Going back to the "Text only" view does not discard unsaved texts. If editor.textOnlyRoles lists all the user's roles, the view is always the "Text only" view. The ?view=texts parameter opens the "Text only" view first (see the editor group).

Saving, publishing and conflicts

What it does: saves the changes as operations and publishes the document.

How to use it:

• The changes accumulate as set, move, remove, duplicate and insert operations.
• "Save" calls nucleo/doc-patch with baseRevision, ops and acknowledge.
• "Publish" saves the structure, then the texts changed in the "Text only" view, then calls nucleo/doc-publish.
• A quality problem with severity error blocks the save. To accept it, a reason is required, sent in acknowledge as {rule, node, reason}.
• With a conflict error, the editor shows "The document was changed elsewhere.", with Reload (discards the local changes) and Compare (opens the revisions).

Permissions: those of the abilities. nucleo/doc-publish uses the scope nucleo:publish.

Edition: Free.

Known limits: "Duplicate" saves at once, because the server reassigns the ids. With unsaved structure or text changes, the bar shows "Unsaved changes" and the browser asks for confirmation before leaving. Changes made during a save stay pending.

Revisions

What it does: lists the document revisions and restores a revision.

How to use it: "Revisions" button. It loads nucleo/doc-revisions and nucleo/audit-list (limit: 100), to show the agent that made each change. "Restore" asks for confirmation and calls nucleo/doc-rollback.

Permissions: those of the abilities.

Edition: Free.

Known limits: the latest revision has no "Restore".

Side panels

What it does: adds context tabs to the editor.

How to use it:

The Links tab reads the sources with nucleo/bind-fields. The Fields tab appears only if the type has field groups.

Permissions: those of the abilities.

Edition: Free. In Free, the Asset tab shows "The asset report is not available in the Free edition.".

Known limits: "Apply" in the Asset tab rewrites the whole list of rules with the added rule. The AI activity panel is a log: the editor does not generate content with AI.

Preview size and mockup

What it does: simulates devices in the preview.

How to use it: device buttons in the full view.

On mobile and tablet, the "Mockup" switch draws an iOS or Android frame with a status bar and an address bar.

Permissions: none.

Edition: Free.

Known limits: the preview scale goes from 0.1 to 1.

Keyboard shortcuts

What it does: quick actions in the editor. Mod means Ctrl or ⌘.

How to use it:

Permissions: none.

Edition: Free.

Known limits: inside a text field only Mod+Z, Mod+Shift+Z and Mod+S work. Node actions do not apply to the root or without a selection.

05Settings

The settings are read with nucleo/settings-get and written with nucleo/settings-set. Both require manage_options and the scope nucleo:admin.

Saving is partial: groups and keys that are absent stay as they are. Each value is checked before writing. An error returns invalid_input and writes nothing.

editor group

What it does: saves the roles that use the "Text only" view as the default view.

How to use it: editor tab, field "Default view by role" for Editor, Author and Contributor.

Permissions: manage_options.

Edition: Free.

Known limits: an unknown role returns "Unknown role: <role>.". The value is saved and the editor uses it: if all the user's roles are in the list, the initial view is always the "Text only" view.

performance group

What it does: sets the WooCommerce cart fragments and the selectors to keep when reducing the CSS.

How to use it: performance tab. The safelist can also be edited from the Performance page.

Permissions: manage_options.

Edition: Free. The values are used only in the Pro package.

Known limits: reading also accepts a safelist saved as a string separated by spaces or commas.

service group

captcha group

What it does: chooses the captcha of the native forms (nc/native-form), one for the whole site.

How to use it: captcha tab. Each native form shows the captcha, unless settings.captcha: false is set on the form.

Parameters: option nucleo_captcha.

Permissions: manage_options.

Edition: Free.

Known limits: a threshold outside 0–1 returns "threshold" must be a number between 0 and 1.. The form details are in the Forms, dynamic data, components, bindings and media section.

onboarding group

What it does: hides the first-run panel of the Overview for the current user.

How to use it: "Don't show again" button of the Overview.

Permissions: manage_options, as for all of nucleo/settings-set.

Edition: Free.

Known limits: a user without manage_options cannot close the first-run panel, because the ability rejects the call.

Detected integrations

What it does: lists the plugins Nucleo recognizes and what it does with each one.

How to use it: integrations tab, field integrations of nucleo/settings-get. Recognized plugins: WooCommerce, Polylang, WPML, Yoast SEO, Rank Math, Contact Form 7, Complianz, Cookiebot, CookieYes and iubenda.

Permissions: manage_options.

Edition: Free.

Known limits: detection checks only that the plugin is present and does not verify versions. The details are in the Integrations section.

Options saved by this area

What it does: summarizes the WordPress options written by the backend.

Transients: nucleo_license_check (1 day), nucleo_license_flash_<user> (1 minute), nucleo_fields_errors_<user> (5 minutes), nucleo_oauth_secret_<user> (60 seconds) and nucleo_quality_badge.

Edition: Free, except nucleo_license.

06Content model and fields

Model format

What it does: describes content types, taxonomies and field groups in a JSON object.

How to use it: it is read with nucleo/model-get, checked with nucleo/model-validate, and saved with nucleo/model-set or from the Content model page. It is saved in the option nucleo_content_model.

Parameters: root {schema: 1, postTypes, taxonomies, fieldGroups}.

Field types: text, textarea, number, url, email, image, date, select, boolean, relation, repeater.

Slugs: ^[a-z][a-z0-9_-]*$.

Permissions: manage_options for the three abilities. The scope of nucleo/model-get and nucleo/model-validate is nucleo:read, that of nucleo/model-set is nucleo:design.

Edition: Free. relation, repeater and the taxonomy location are Pro.

Known limits: nucleo/model-set is partial. A postTypes, taxonomies or fieldGroups part not sent stays as it is. A part sent replaces the whole list.

Model validation

What it does: checks the model before saving.

How to use it: first the JSON schema (code schema), then the WordPress and edition rules.

Parameters: error codes, each with a path in JSON Pointer format.

Permissions: manage_options.

Edition: Free, with the Pro rules above.

Known limits: a slug already in the saved model, or registered by the model in the same request, does not count as registered by others. An error on a part not sent explains that this part must be sent too.

Destructive model changes

What it does: compares the saved model with the new one and finds the changes that lose data.

How to use it: the comparison returns added, removed, changed and destructive. The ids have the form postType:<slug>, taxonomy:<slug> or field:<group>/<key>.

Parameters: destructive changes.

Permissions: manage_options.

Edition: Free.

Known limits: the content count excludes automatic drafts and the trash.

Registering types, taxonomies and meta

What it does: registers the model's types, taxonomies and meta in WordPress.

How to use it: the registration is automatic on init, in the admin and on the public site. If the store is empty and the tokens are missing, it reads the option nucleo_content_model.

• Types and taxonomies have show_in_rest: true.
• Each field becomes a single meta with the REST schema of the type: number becomes number, boolean becomes boolean, image becomes integer, relation becomes integer or an array of integers, select becomes string or array, repeater becomes an array of objects. Others become string.

Permissions: none.

Edition: Free.

Known limits: a type or taxonomy already registered by other code is not registered. The origin becomes conflict.

Types allowed in the content and terms abilities

What it does: decides which types and taxonomies the content-* and terms-* abilities can read and write, and where they come from.

How to use it: a type is allowed if it is registered with show_ui.

• Excluded types: revision, attachment, nav_menu_item, custom_css, customize_changeset, oembed_cache, user_request, product, product_variation, and the prefixes nucleo_, wp_ and shop_.
• Excluded taxonomies: nav_menu, link_category, post_format, the prefixes nucleo_, wp_, product_ and pa_, and those without an allowed type.
• Origin (registeredBy): nucleo-model, wordpress, plugin-or-theme, conflict.

Permissions: with $editable, the inventory keeps only the types with edit_posts and the taxonomies with manage_terms.

Edition: Free.

Known limits: system pages cannot be trashed: the home page, the posts page, the privacy policy page and the WooCommerce pages (shop, cart, checkout, my account, terms). Details in nucleo/content-upsert and nucleo/terms-set.

Field panels

What it does: shows a panel for each field group in the edit screen of the type (post.php, post-new.php).

How to use it: the panel appears if the group has location.postType equal to the type. Saving happens with the post.

• repeater: rows with add, move and remove, with the max limit.
• image: choice from the media library.
• relation: search among WordPress content, with 10 results.

Parameters: POST field nucleo_fields[<key>], nonce nucleo_fields_nonce (action nucleo_fields).

Permissions: edit_post on the post. Saving skips autosaves and revisions.

Edition: Free. The relation and repeater fields exist only with a saved model in Pro.

Known limits: with an error, no field is saved. The errors appear as a "Fields not saved:" notice at the next load, for 5 minutes.

Term fields

Field values

What it does: validates, normalizes and saves the values of the model's fields on posts and terms.

How to use it: field panels, term fields, the Fields tab of the editor, nucleo/fields-get, nucleo/fields-set, nucleo/content-upsert and nucleo/terms-set.

Parameters: rules by type.

Permissions: those of the caller.

Edition: Free.

Known limits: saving is partial and all-or-nothing. Codes: unknown_field, required, invalid_value, too_many and too_few. An empty value deletes the meta. Only the fields of the Nucleo model are written: the fields of other plugins stay with those plugins.

07Site functions

Site options

What it does: reads and writes the title, tagline, home page, posts page, language, date and time formats, business data, icons, image formats and favicon.

How to use it: nucleo/site-options-set, the site import (key site of the site.json file) and nucleo/site-describe.

Parameters: supported keys.

Permissions: manage_options, scope nucleo:admin. Downloading the language requires install_languages (or WP-CLI without a user) and direct access to the files.

Edition: Free.

Known limits: errors invalid_input, page_not_found, same_page and language_unavailable. The language is applied last: if the package does not download, the other options stay written. For child pages, the slug is the path (services/consulting).

Navigation menus

What it does: creates a WordPress menu by slug, replaces its items and exports the menus.

How to use it: nucleo/menu-list, nucleo/menu-set, the site import and export.

Parameters: an item has a label and one of these targets.

children contains the child items.

Permissions: nucleo/menu-list requires edit_posts (scope nucleo:read). nucleo/menu-set requires edit_theme_options (scope nucleo:design).

Edition: Free.

Known limits:

• At most 3 levels.
• Errors: invalid_items and menu_target_missing.
• The targets are resolved before the old items are deleted: a missing target does not leave the menu half-done.
• After writing, the layouts that use the menu are rebuilt at once.
• The export skips items without a published target.

Site icons

What it does: saves SVG icons for the nc/icon block, next to the built-in set.

How to use it: nucleo/icons-set (adds, replaces, removes) or the icons key of the site options, which replaces everything. In the nc/icon block, a site icon wins over a built-in icon with the same name.

Parameters:

Permissions: manage_options, scope nucleo:admin.

Edition: Free.

Known limits:

• At most 300 icons.
• Allowed elements: svg, g, path, circle, ellipse, rect, line, polyline and polygon. Others are removed.
• fill and stroke values other than none become currentColor.
• The rendering adds width="24" height="24" focusable="false".
• An empty set deletes the option nucleo_icons.

Reported gaps

What it does: records what a design asks for and Nucleo cannot do, with the workaround used.

How to use it: nucleo/gap-report and nucleo/gap-list.

Parameters:

Permissions: nucleo/gap-report requires edit_pages (scope nucleo:write). nucleo/gap-list requires edit_posts (scope nucleo:read).

Edition: Free.

Known limits: the same pair block and need, without case, increases count and updates last and workaround. The last 200 gaps are kept.

Export, import and symbolic references

What it does: exports and imports the site as JSON files. It replaces the IDs with readable symbols (page:about-us, section:cta) and back.

How to use it: Tools page, nucleo/site-export, nucleo/site-import, wp nucleo export, wp nucleo import and wp nucleo sync.

Parameters: see the Import, export and sync section.

Permissions: manage_options, scope nucleo:admin.

Edition: Free.

Known limits: imported types: page, post, nucleo_layout and nucleo_section, in this order per folder: sections/, pages/, posts/, layouts/. Error codes: error, conflict, duplicate, not_json, invalid_document and quality_blocking. A value without a name stays numeric.

08Pro license and updates

Free and Pro packages

Active edition

License activation

License deactivation

License check

Active license and expiry

Pro plugin updates

09REST and admin-post actions

POST /nucleo/v1/preview

What it does: builds a document without saving it and returns the HTML, CSS and styles for the preview.

How to use it: the request body contains the document. The response contains the build result, plus the block and theme styles, if any, and the token CSS.

POST /wp-json/nucleo/v1/preview
{"document": {…}}

Parameters:

Permissions: edit_posts.

Edition: Free.

Known limits: a document that is not an object returns invalid_input with status 400. An invalid document returns a result with ok: false.

admin-post actions

What it does: handles the forms of AI agents and License through admin-post.php.

How to use it:

Parameters: each form has a nonce named after the action.

Permissions: manage_options. Without it, the response is 403.

Edition: Free for the OAuth actions, Pro for the license actions.

Known limits: the license actions exist only in the Pro package.

Other routes called by the backend

What it does: lists the REST routes used by the pages but registered outside this area.

How to use it:

• GET /nucleo/v1/kit-preview?kit=<id>: kit thumbnail. Requires edit_theme_options and the Pro edition. See the Kits section.
• /nucleo/v1/mcp: MCP server. See the AI agents section.
• WordPress routes: /wp/v2/search, /wp/v2/media/<id>, /wp/v2/users and /wp/v2/<taxonomy>.

Parameters: see the sections cited.

Permissions: see the sections cited.

Edition: see above.