Federated Reply block: embed original post on frontend

[jeherve]

What

The Federated reply block is very useful for a site to become a real actor on the Fediverse. Once we publish a post using that block, our reply looks good on the Fediverse. I was wondering if we could embed the original post instead of "only" rendering a link to that post:

wordpress-activitypub/includes/class-blocks.php

Lines 301 to 326 in 9beea62

	/**
	* Render the reply block.
	*
	* @param array $attrs The block attributes.
	*
	* @return string The HTML to render.
	*/
	public static function render_reply_block( $attrs ) {
	/**
	* Filter the reply block.
	*
	* @param string $html The HTML to render.
	* @param array $attrs The block attributes.
	*/
	return apply_filters(
	'activitypub_reply_block',
	sprintf(
	'<p><a title="%2$s" aria-label="%2$s" href="%1$s" class="u-in-reply-to" target="_blank">%3$s</a></p>',
	esc_url( $attrs['url'] ),
	esc_attr__( 'This post is a response to the referenced content.', 'activitypub' ),
	// translators: %s is the URL of the post being replied to.
	sprintf( __( '&#8620;%s', 'activitypub' ), \str_replace( array( 'https://', 'http://' ), '', $attrs['url'] ) )
	),
	$attrs
	);
	}

Why

This would allow readers that consume the site content from the site, and not from the Fediverse, to read the original post right away, without having to click, and thus have all the context of the conversation in one place, just like folks on the Fediverse experience.

How

I know that Fediverse embeds are a bit tricky, but maybe we could start with some support for Mastodon, based off the learnings from this trac ticket.