Disable Classic block: Control inserter support via filter

[yuliyan]

What?

Add a gutenberg_classic_block_supports_inserter filter to control whether the Classic block is available in the inserter. Defaults to false.

The previous post-content check is no longer necessary. Since we switched to registering the Classic block unconditionally in #77840, existing posts that use the Classic block will continue to work - we just don't allow new instances to be inserted.

Why?

Previously, the Classic block was made available in the inserter when the post being edited already contained one. For the experiment, we want a stricter default - hide the Classic block from the inserter, and let developers opt in explicitly.

How?

The Classic block's inserter visibility is now driven by a single PHP filter. The result is exposed to JS through the existing window.wp.needsClassicBlock flag, which the block reads via supports.inserter. The filter receives the post being edited (or null) so callbacks can decide based on context.

Testing Instructions

1. Open a post in the block editor with the "Disable Classic block" experiment enabled.
2. Confirm the Classic block is not in the inserter, even on posts that already contain a Classic block.
3. Add this snippet to a plugin or mu-plugins:

add_filter( 'gutenberg_classic_block_supports_inserter', '__return_true' );

Testing Instructions for Keyboard

Screenshots or screencast

N/A

Use of AI Tools

Cursor with Opus 4.7

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Co-authored-by: yuliyan <yuliyan@git.wordpress.org>
Co-authored-by: tyxla <tyxla@git.wordpress.org>

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[yuliyan]

The block is no longer registered conditionally, so this dependency doesn't need to be conditional either - editor is required whenever the Classic block can render, which is now always.

[tyxla]

Confirming the filter works well, and the block is hidden from the inserter (including in block visibility settings) by default, while existing Classic block instances continue to work regardless.

🚢

[tyxla]

I think this could use a dev note for the new filter, btw.

Especially considering that we're planning to remove the experimental wrapper before 7.1 ships.

[yuliyan]

Dev Note

Classic block: New filter to control inserter availability

The Classic block (core/freeform) no longer appears in the inserter by default. Whether it's available in the inserter is controlled by a new filter. Existing posts that contain a Classic block continue to render and can be edited as before.

New filter: gutenberg_classic_block_supports_inserter

/**
 * @param bool         $supports_inserter Whether the Classic block is available in the inserter.
 * @param WP_Post|null $post              The post being edited, or null if not in the post editor.
 */
apply_filters( 'gutenberg_classic_block_supports_inserter', false, $post );

The filter defaults to false, meaning the Classic block is hidden from the inserter by default. The result is exposed to JavaScript via the existing window.wp.needsClassicBlock flag, which the Classic block reads through its supports.inserter value.

Examples

Enable globally:

add_filter( 'gutenberg_classic_block_supports_inserter', '__return_true' );

Enable per post (e.g. only for pages):

add_filter(
	'gutenberg_classic_block_supports_inserter',
	function ( $supports, $post ) {
		return $supports || ( $post && 'page' === $post->post_type );
	},
	10,
	2
);

Enable for posts that already contain a Classic block (replicates the previous default behaviour):

add_filter(
	'gutenberg_classic_block_supports_inserter',
	function ( $supports, $post ) {
		if ( $supports || ! $post || empty( $post->post_content ) ) {
			return $supports;
		}

		foreach ( parse_blocks( $post->post_content ) as $block ) {
			$is_freeform = empty( $block['blockName'] ) || 'core/freeform' === $block['blockName'];

			if ( $is_freeform && '' !== trim( $block['innerHTML'] ) ) {
				return true;
			}
		}

		return $supports;
	},
	10,
	2
);

[yuliyan]

Posted a dev note for once the experiment wrapper is removed.

[Mamaduka]

Nice work!

Do we have a tracking issue related to this effort?

[tyxla]

@Mamaduka, there's been a fair amount of work on it this week.

Thanks - a tracking issue makes sense - we'll add one next week.