Add per-block Fediverse visibility toggle

[pfefferle]

Fixes #2076

Prepares for Block Visibility in WordPress 7.0.

Proposed changes:

• Add a "Fediverse ⁂" panel to the block inspector sidebar with a "Share to the Fediverse" toggle for every block
• When disabled, the block is excluded from federated content but remains visible on the site
• Store the setting in metadata.blockVisibility.fediverse — piggybacks on the new WordPress 7.0 block visibility metadata structure
• Filter hidden blocks during ActivityPub content rendering via render_block filter (only active during AP content generation)
• Also exclude hidden blocks from reply URL extraction and media attachment extraction
• Disable core block visibility (viewport hiding) on the Federated Reply block since it is semantic

Other information:

• Have you written new tests for your changes, if applicable?

Testing instructions:

• Install and activate the latest Gutenberg plugin (22.7+)
• Create or edit a post with multiple blocks (paragraphs, images, etc.)
• Select any block and open the "Fediverse ⁂" panel in the block inspector sidebar
• Toggle "Share to the Fediverse" off for one or more blocks
• Save/publish the post
• Open the Fediverse preview — the hidden blocks should not appear
• Verify hidden blocks still appear normally on the site's frontend
• Test with image blocks: hidden images should not appear as ActivityPub attachments
• Test with the Federated Reply block: verify the viewport visibility controls (Show/Hide) do not appear in the block toolbar

Changelog entry

• Automatically create a changelog entry from the details below.

Changelog Entry Details

Significance

• Patch
• Minor
• Major

Type

• Added - for new features
• Changed - for changes in existing functionality
• Deprecated - for soon-to-be removed features
• Removed - for now removed features
• Fixed - for any bug fixes
• Security - in case of vulnerabilities

Message

Add per-block Fediverse visibility toggle to control which blocks are shared to Mastodon and other Fediverse platforms.

[Copilot]

Pull request overview

Adds an editor-facing “Share to the Fediverse” per-block toggle and enforces it during ActivityPub rendering so authors can exclude specific blocks from federated content without affecting on-site display.

Changes:

• Introduces a block editor plugin that writes metadata.blockVisibility.fediverse per block via a new Inspector “Fediverse ⁂” panel.
• Filters hidden blocks out of ActivityPub-rendered HTML and excludes them from reply URL + media attachment extraction.
• Disables core visibility UI on the Federated Reply block (supports.visibility: false) and adds the needed JS dependency.

Reviewed changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/reply/block.json	Disables core visibility controls for the Federated Reply block.
src/block-visibility/plugin.js	Adds the Inspector toggle and persists the setting into block metadata.
src/block-visibility/block.json	Provides build metadata for the editor plugin bundle.
includes/class-blocks.php	Adds render-time filtering for hidden blocks during ActivityPub content generation.
includes/transformer/class-post.php	Skips hidden blocks when extracting in-reply-to URLs and media attachments.
package.json	Adds @wordpress/hooks for the new editor plugin code.
package-lock.json	Locks the new dependency.
.github/changelog/block-visibility-fediverse	Changelog entry for the new feature.
build/*	Build artifacts (not code-reviewed).

Comments suppressed due to low confidence (2)

includes/class-blocks.php:1016

• filter_blocks_hidden_from_fediverse() / is_block_hidden_from_fediverse() introduce new filtering logic that affects all ActivityPub content rendering. There are existing PHPUnit tests for Activitypub\Blocks (e.g., reply link generation and import transformations), but no coverage for this new visibility behavior; please add tests for both helper methods (visible by default, hidden when metadata.blockVisibility.fediverse is false, and filtering returns an empty string when hidden).

	/**
	 * Strip blocks not marked for federation during content rendering.
	 *
	 * @since unreleased
	 *
	 * @param string $block_content The rendered block content.
	 * @param array  $block         The parsed block data.
	 *
	 * @return string The block content, or empty string if hidden.
	 */
	public static function maybe_hide_block( $block_content, $block ) {
		if ( ! self::is_federated( $block ) ) {
			return '';
		}

		return $block_content;
	}

	/**
	 * Whether a block should be included in federated content.
	 *
	 * Checks `metadata.blockVisibility.fediverse`. Defaults to true.
	 *
	 * @since unreleased
	 *
	 * @param array $block The parsed block data.
	 *
	 * @return bool True if the block should be federated.
	 */
	public static function is_federated( $block ) {
		$visibility = $block['attrs']['metadata']['blockVisibility']['fediverse'] ?? true;

		return false !== $visibility;
	}

	/**
	 * Generate HTML @ link for reply block.
	 *
	 * @param string $block_content The block content.

includes/class-blocks.php:960

• In add_post_transformation_callbacks(), generate_reply_link is added whenever the first block is activitypub/reply, even if that reply block is hidden from the Fediverse. In that case the block will be removed later by filter_blocks_hidden_from_fediverse, but generate_reply_link() can still run first and perform remote fetches unnecessarily. Consider skipping the render_block_activitypub/reply filter when the first reply block is hidden (e.g., check self::is_block_hidden_from_fediverse( $blocks[0] ) before adding the filter).

		// Only transform reply link if it's the first block in the post.
		$blocks = \parse_blocks( $post->post_content );
		if ( ! empty( $blocks ) && 'activitypub/reply' === $blocks[0]['blockName'] ) {
			\add_filter( 'render_block_activitypub/reply', array( self::class, 'generate_reply_link' ), 10, 2 );
		}

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