fix(block-theme): remove MJML image-caption filter moved to newsletters plugin

[chickenn00dle]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

The MJML image-caption component attributes filter (setting align=left and padding=0) was duplicated identically in both the classic theme and block theme. This code has been moved into the newsletters plugin renderer as a default in Automattic/newspack-newsletters#2078, so the duplicate in this theme is no longer needed.

Depends on Automattic/newspack-newsletters#2078

Addresses https://linear.app/a8c/issue/NPPD-1316

How to test the changes in this Pull Request:

1. Apply fix(block-theme): override theme.json styles in the newsletter editor newspack-newsletters#2078 first
2. Activate the Newspack Classic Theme
3. Create a Newsletter post with all of the non-RDB blocks (I decided not to tackle these here as this one is already quite hairy) listed in this comment
4. Send a test email and verify the image caption is left-aligned with no extra padding — same as before this change

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR removes a now-duplicated MJML image-caption attribute filter from the theme, since the same default behavior has been moved into the Newspack Newsletters plugin renderer (per Automattic/newspack-newsletters#2078).

Changes:

• Removes the newspack_newsletters_mjml_component_attributes filter callback that forced align=left and padding=0 for the image-caption MJML component.

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[Copilot]

Removing the newspack_newsletters_mjml_component_attributes filter means sites running an older newspack-newsletters plugin (without the change from Automattic/newspack-newsletters#2078) will lose the left-aligned / zero-padding styling for image-caption in MJML output. Since the theme currently only checks class_exists( '\\Newspack_Newsletters' ) (no minimum version gating), consider keeping a small backward-compat shim: add the filter but only set align/padding when those attributes are not already present, so updated plugin versions are unaffected while older ones retain the previous behavior.

Suggested change

	add_action( 'newspack_newsletters_enqueue_block_editor_assets', 'newspack_newsletters_enqueue_editor_styles' );
	add_action( 'newspack_newsletters_enqueue_block_editor_assets', 'newspack_newsletters_enqueue_editor_styles' );
	/**
	* Backward-compatibility shim for older Newspack Newsletters versions.
	*
	* Ensures image captions keep the legacy left alignment and zero padding
	* when the plugin has not already provided those MJML attributes.
	*
	* @param array $attributes MJML component attributes.
	* @param string $component MJML component name.
	* @param null|mixed $block Optional block data passed by the filter.
	* @return array
	*/
	function newspack_newsletters_mjml_component_attributes_compat( $attributes, $component, $block = null ) {
	if ( 'image-caption' !== $component ) {
	return $attributes;
	}
	if ( empty( $attributes['align'] ) ) {
	$attributes['align'] = 'left';
	}
	if ( empty( $attributes['padding'] ) ) {
	$attributes['padding'] = '0px';
	}
	return $attributes;
	}
	add_filter( 'newspack_newsletters_mjml_component_attributes', 'newspack_newsletters_mjml_component_attributes_compat', 10, 3 );

[laurelfulford]

This one also looks good - this makes more sense than splitting this over both themes, given that both themes have left-aligned captions. Thanks @chickenn00dle!