feat: [Page Builder] Config: Elemental configuration, allowed block types per page

[jsirish]

Implements #135

Configuration

• elemental.yml — Attaches ElementalAreasExtension to Page, enables CMS live preview
• elemental-blocks.yml — Per-page-type block whitelists:
  • Page: ContentBlock, TextBlock, HTMLBlock, ImageBlock (base only)
  • LandingPage: Full palette (18+ blocks including CTA, Quote, Gallery, Hero, etc.)
  • ErrorPage: No blocks allowed
  • HomePage (optional): Curated subset

How to override

Blocks are configured via YAML. Additional PageTypes can add their own allowed_elements list to elemental-blocks.yml.

[Copilot]

Pull request overview

Adds SilverStripe Elemental configuration to enable page-builder “blocks” and define per-page-type whitelists for which blocks can be added in the CMS (issue #135).

Changes:

• Introduces app/_config/elemental.yml to attach Elemental to Page and enable live preview.
• Introduces app/_config/elemental-blocks.yml to define allowed_elements per PageType (Page, LandingPage, ErrorPage, optional HomePage).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
app/_config/elemental.yml	Adds global Elemental config (extension + block defaults + live preview).
app/_config/elemental-blocks.yml	Adds per-page-type allowed_elements whitelists (including an optional HomePage override).

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[Copilot]

After: is written as a single scalar value containing commas (framework/*, cms/*, elemental/*). In YAML this won’t be treated as multiple ordering rules, so the config load order likely won’t behave as intended. Use a YAML list (multiple - entries) or a single After: target that matches an actual config name/anchor.

Suggested change

	After: framework/*, cms/*, elemental/*
	After:
	- framework/*
	- cms/*
	- elemental/*

[Copilot]

This config unconditionally references Elemental classes (e.g. DNADesign\Elemental\Extensions\ElementalAreasExtension, DNADesign\Elemental\Models\BaseElement), but composer.json in this repo doesn’t require the Elemental module. Without gating (e.g. Only: { moduleexists: 'dnadesign/silverstripe-elemental' }) this can break dev/build when the module isn’t installed.

[Copilot]

The block classes configured here (App\PageBuilder\Blocks\ContentBlock, TextBlock, HTMLBlock, ImageBlock) don’t exist anywhere in this repository (no App\PageBuilder code is present). As-is, these settings won’t take effect and may lead to missing/empty block options. Either add these block classes, correct the namespaces to match existing classes, or remove the config until the blocks exist.

Suggested change

	App\PageBuilder\Blocks\ContentBlock:
	allow_page_editing: true
	App\PageBuilder\Blocks\TextBlock:
	allow_page_editing: true
	App\PageBuilder\Blocks\HTMLBlock:
	allow_page_editing: true
	App\PageBuilder\Blocks\ImageBlock:
	allow_page_editing: true

[Copilot]

This file also unconditionally configures Elemental classes (allowed_elements includes DNADesign\Elemental\Models\* and many App\PageBuilder\Blocks\*), but the Elemental module isn’t declared in composer.json. Consider adding an Only: { moduleexists: 'dnadesign/silverstripe-elemental' } guard (or adding the dependency in this PR) to avoid config breaking when Elemental isn’t installed.

Suggested change

	Name: elemental-blocks
	Name: elemental-blocks
	Only:
	moduleexists: 'dnadesign/silverstripe-elemental'

[Copilot]

allowed_elements references many App\PageBuilder\Blocks\* classes (and App\PageBuilder\LandingPage) that do not exist anywhere in this repository. With no corresponding PHP classes, the CMS “Add Block” dialog can end up empty or erroring depending on how Elemental resolves the whitelist. Update this list to only include classes that actually exist in the codebase, or land the block/page classes in the same PR.

[Copilot]

The conditional config block for App\Page\HomePage uses only: (lowercase) and an 'exists' condition key, which doesn’t match the existing conditional config pattern used elsewhere in this repo (Only: with keys like moduleexists, e.g. app/_config/mimevalidator.yml). As written, this condition is likely ignored, so the HomePage whitelist may apply unexpectedly or never apply. Use the standard Only: casing and a supported condition (e.g. class/module existence).

Suggested change

	only:
	'exists': 'App\Page\HomePage'
	Only:
	classexists: App\Page\HomePage

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

---

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[Copilot]

If this file is intended to override defaults set in app/_config/elemental.yml (Name: elemental), After: elemental/* does not guarantee ordering relative to that named config. Consider using After: '#elemental' (or otherwise explicitly ordering against the app config name) so the per-page whitelists reliably apply last.

Suggested change

	After: elemental/*
	After: '#elemental'

[Copilot]

App\\PageBuilder\\LandingPage is configured here, but there is no LandingPage class under app/src in this repo. If the page type is expected to come from another module, ensure that module is required/autoloaded; otherwise this per-page whitelist will never take effect.

Suggested change

	App\PageBuilder\LandingPage:
	App\PageBuilder\LandingPage:
	only:
	'exists': 'App\PageBuilder\LandingPage'