fix: repair legacy embed className via WP-CLI - #149

Summary

Posts saved by Press This before PR #129 have core/embed blocks whose <figure> className is missing wp-block-embed-{provider} (e.g. wp-block-embed-youtube). Gutenberg's save() output for that block always includes this class when type/providerNameSlug attrs are set, so the mismatch fails block validation and shows "Block contains unexpected or invalid content" in the standard editor.

Adds a WP-CLI command that finds and repairs this specific mismatch in stored post content.

Fixes #131

Changes

includes/class-press-this-embed-repair.php (new)

Before:

// no repair mechanism existed

After:

class Press_This_Embed_Repair {
	public static function repair_content( $content ) {
		// parse_blocks(), find core/embed blocks with type + providerNameSlug
		// but missing wp-block-embed-{provider} in the figure class, append it,
		// serialize_blocks() back. Returns false if nothing needed fixing.
	}
}

Why: Isolated, pure content-rewrite logic that's easy to unit test without a live WP-CLI environment. Validates providerNameSlug against sanitize_html_class() before it touches HTML, since that value comes from stored post content, not a trusted source.

includes/class-press-this-cli-commands.php (new)

Before:

// no CLI commands existed in the plugin

After:

class Press_This_CLI_Commands {
	public function repair_embeds( $args, $assoc_args ) {
		// wp press-this repair-embeds [--dry-run] [--post-type=<type>]
		// batches posts via $wpdb LIKE query on post_content, pre-filters
		// with has_block(), repairs, wp_update_post()s only real changes
	}
}

Why: Explicit, auditable repair path with dry-run support, rather than silently rewriting content on every page load.

press-this-plugin.php

Before:

add_action( 'init', 'press_this_load_textdomain' );

After:

add_action( 'init', 'press_this_load_textdomain' );

if ( defined( 'WP_CLI' ) && WP_CLI ) {
	require_once __DIR__ . '/includes/class-press-this-cli-commands.php';
	WP_CLI::add_command( 'press-this', 'Press_This_CLI_Commands' );
}

Why: Registers the command only in a WP-CLI context, no overhead on regular requests.

Testing

Test 1: Legacy embed fails validation before repair

1. Create a post with <figure class="wp-block-embed is-type-video is-provider-youtube"> (missing the 4th class)
2. Open it in the standard editor
   Result: "Block contains unexpected or invalid content" shown, as reported in the issue

Test 2: Repair fixes it

1. Run wp press-this repair-embeds --dry-run, confirm it lists the post
2. Run wp press-this repair-embeds
3. Reload the post in the standard editor
   Result: embed renders normally, no validation warning. Re-running the command reports 0 posts repaired (idempotent).

Test 3: Unaffected content is left alone

1. Run the command against a post created after PR Fix YouTube and Vimeo embed previews not showing in editor #129, or one using the generic embed shape with no type/providerNameSlug attrs (the PHP get_suggested_content() path)
   Result: not touched, since neither is broken

Also ran full PHP unit suite (283 tests, all passing) and composer php:lint / composer php:compatibility clean.