diff --git a/.github/workflows/quality-php.yml b/.github/workflows/quality-php.yml
index 30b16ca..68e0566 100644
--- a/.github/workflows/quality-php.yml
+++ b/.github/workflows/quality-php.yml
@@ -5,10 +5,12 @@ on:
         paths:
             - 'composer.json'
             - 'blockparty-key-figure.php'
+            - 'includes/**'
     push:
         paths:
             - 'composer.json'
             - 'blockparty-key-figure.php'
+            - 'includes/**'
         branches:
             - main
 
diff --git a/blockparty-key-figure.php b/blockparty-key-figure.php
index e3b673a..0c4b82d 100644
--- a/blockparty-key-figure.php
+++ b/blockparty-key-figure.php
@@ -15,6 +15,8 @@
 
 namespace Blockparty\Key_Figure;
 
+use Blockparty\Key_Figure\Cli\MigrateFromKeyFigureBlockCommand;
+
 define( 'BLOCKPARTY_KEY_FIGURE_VERSION', '1.1.1' );
 define( 'BLOCKPARTY_KEY_FIGURE_URL', plugin_dir_url( __FILE__ ) );
 define( 'BLOCKPARTY_KEY_FIGURE_DIR', plugin_dir_path( __FILE__ ) );
@@ -55,4 +57,11 @@ function init() {
 	do_action( 'blockparty_key_figure_block_init' );
 }
 
-add_action( 'init', __NAMESPACE__ . '\\init' );
+add_action( 'init', __NAMESPACE__ . '\\init', 10, 0 );
+
+if ( defined( 'WP_CLI' ) && WP_CLI ) {
+	require_once __DIR__ . '/includes/Migration/KeyFigureBlockMigrator.php';
+	require_once __DIR__ . '/includes/Cli/MigrateFromKeyFigureBlockCommand.php';
+
+	\WP_CLI::add_command( 'blockparty key-figure migrate', MigrateFromKeyFigureBlockCommand::class );
+}
diff --git a/composer.json b/composer.json
index 0c9d846..1a66453 100644
--- a/composer.json
+++ b/composer.json
@@ -48,7 +48,11 @@
 		"vimeo/psalm": "^5.20",
 		"wp-coding-standards/wpcs": "^3.0"
 	},
-	"autoload": {},
+	"autoload": {
+		"psr-4": {
+			"Blockparty\\Key_Figure\\": "includes/"
+		}
+	},
 	"autoload-dev": {},
 	"scripts": {
 		"cs": "./vendor/bin/phpcs",
diff --git a/grumphp.yml b/grumphp.yml
index b7e5058..c0dd3a5 100644
--- a/grumphp.yml
+++ b/grumphp.yml
@@ -13,7 +13,7 @@ grumphp:
             jobs: ~
             triggered_by: ['php', 'phtml', 'php3', 'php4', 'php5', 'php7']
         phpcs:
-            standard: ['phpcs.xml.dist']
+            standard: ['phpcs.xml']
             triggered_by: [php]
         composer:
             no_check_all: true
diff --git a/includes/Cli/MigrateFromKeyFigureBlockCommand.php b/includes/Cli/MigrateFromKeyFigureBlockCommand.php
new file mode 100644
index 0000000..388be40
--- /dev/null
+++ b/includes/Cli/MigrateFromKeyFigureBlockCommand.php
@@ -0,0 +1,393 @@
+<?php
+/**
+ * WP-CLI command to migrate beapi/key-figure content.
+ *
+ * @package Blockparty\Key_Figure
+ */
+
+namespace Blockparty\Key_Figure\Cli;
+
+use Blockparty\Key_Figure\Migration\KeyFigureBlockMigrator;
+use WP_CLI;
+use WP_CLI_Command;
+
+/**
+ * Blockparty Key Figure WP-CLI commands.
+ */
+class MigrateFromKeyFigureBlockCommand extends WP_CLI_Command {
+
+	/**
+	 * Option holding the block widgets content.
+	 *
+	 * @var string
+	 */
+	const WIDGETS_OPTION = 'widget_block';
+
+	/**
+	 * Whether the content is reported without being saved.
+	 *
+	 * @var bool
+	 */
+	private bool $dry_run = false;
+
+	/**
+	 * Whether the markup is aligned with the current block output.
+	 *
+	 * @var bool
+	 */
+	private bool $modernize = true;
+
+	/**
+	 * Whether post revisions are migrated too.
+	 *
+	 * @var bool
+	 */
+	private bool $include_revisions = true;
+
+	/**
+	 * How many posts are read per batch.
+	 *
+	 * @var int
+	 */
+	private int $batch_size = 100;
+
+	/**
+	 * Post types to migrate, empty for all of them.
+	 *
+	 * @var string[]
+	 */
+	private array $post_types = [];
+
+	/**
+	 * How many posts were read.
+	 *
+	 * @var int
+	 */
+	private int $posts_scanned = 0;
+
+	/**
+	 * How many posts were migrated.
+	 *
+	 * @var int
+	 */
+	private int $posts_updated = 0;
+
+	/**
+	 * How many block widgets were migrated.
+	 *
+	 * @var int
+	 */
+	private int $widgets_updated = 0;
+
+	/**
+	 * Content migrator.
+	 *
+	 * @var KeyFigureBlockMigrator
+	 */
+	private KeyFigureBlockMigrator $migrator;
+
+	/**
+	 * Constructor.
+	 */
+	public function __construct() {
+		$this->migrator = new KeyFigureBlockMigrator();
+	}
+
+	/**
+	 * Migrate beapi/key-figure content to blockparty/key-figure.
+	 *
+	 * Rewrites the block name (`wp:beapi/key-figure`) and the BEM root class
+	 * (`wp-block-beapi-key-figure`) in post content and in block widgets. Unless
+	 * `--no-modernize` is used, the saved markup is also aligned with the current
+	 * block output so migrated blocks stay valid in the editor.
+	 *
+	 * Always targets a single site. On multisite, use the global `--url`
+	 * parameter to pick the site.
+	 *
+	 * ## OPTIONS
+	 *
+	 * [--dry-run]
+	 * : Report changes without updating the database.
+	 *
+	 * [--[no-]modernize]
+	 * : Align the markup with the current block output: `p` key wrapper and number data attributes. Default: true.
+	 *
+	 * [--skip-revisions]
+	 * : Leave post revisions untouched.
+	 *
+	 * [--post-type=<post-types>]
+	 * : Comma-separated list of post types to migrate. Default: every post type.
+	 *
+	 * [--posts-per-page=<number>]
+	 * : How many posts are read per batch. Default: 100.
+	 *
+	 * ## EXAMPLES
+	 *
+	 *     # Apply the migration.
+	 *     wp blockparty key-figure migrate
+	 *
+	 *     # Report what would change.
+	 *     wp blockparty key-figure migrate --dry-run
+	 *
+	 *     # Migrate one site of a network, revisions excluded.
+	 *     wp blockparty key-figure migrate --skip-revisions --url=example.com/site-2
+	 *
+	 *     # Only rename the block and its CSS classes.
+	 *     wp blockparty key-figure migrate --no-modernize
+	 *
+	 * @param string[]                   $args       Positional arguments.
+	 * @param array<string, bool|string> $assoc_args Associative arguments.
+	 * @return void
+	 */
+	public function __invoke( $args, $assoc_args ): void {
+		$this->dry_run           = (bool) WP_CLI\Utils\get_flag_value( $assoc_args, 'dry-run', false );
+		$this->modernize         = (bool) WP_CLI\Utils\get_flag_value( $assoc_args, 'modernize', true );
+		$this->include_revisions = ! (bool) WP_CLI\Utils\get_flag_value( $assoc_args, 'skip-revisions', false );
+		$this->batch_size        = max( 1, (int) WP_CLI\Utils\get_flag_value( $assoc_args, 'posts-per-page', 100 ) );
+		$this->post_types        = $this->resolve_post_types( (string) WP_CLI\Utils\get_flag_value( $assoc_args, 'post-type', '' ) );
+
+		WP_CLI::log(
+			sprintf(
+				'Migrating site %1$d (%2$s)%3$s — post types: %4$s, revisions: %5$s, modernize: %6$s',
+				get_current_blog_id(),
+				home_url( '/' ),
+				$this->dry_run ? ' [dry-run]' : '',
+				empty( $this->post_types ) ? 'all' : implode( ', ', $this->post_types ),
+				$this->include_revisions ? 'yes' : 'no',
+				$this->modernize ? 'yes' : 'no'
+			)
+		);
+
+		$this->migrate_posts();
+		$this->migrate_widgets();
+
+		$this->print_summary();
+
+		if ( $this->migrator->skipped > 0 ) {
+			WP_CLI::warning( 'Some blocks were renamed without markup modernization because no number could be read from their markup. Check them in the editor.' );
+		}
+	}
+
+	/**
+	 * Migrate the post content of the current site.
+	 *
+	 * @return void
+	 */
+	private function migrate_posts(): void {
+		$after_id = 0;
+
+		while ( true ) {
+			$posts = $this->fetch_posts( $after_id );
+			$read  = count( $posts );
+
+			foreach ( $posts as $post ) {
+				$after_id = (int) $post->ID;
+				++$this->posts_scanned;
+
+				$content = $this->migrator->migrate_content( (string) $post->post_content, $this->modernize );
+
+				if ( null === $content ) {
+					continue;
+				}
+
+				++$this->posts_updated;
+
+				WP_CLI::log(
+					sprintf(
+						'%1$s post %2$d (%3$s)',
+						$this->dry_run ? '[dry-run]' : '[update]',
+						(int) $post->ID,
+						(string) $post->post_type
+					)
+				);
+
+				if ( ! $this->dry_run ) {
+					$this->save_post( $post, $content );
+				}
+			}
+
+			if ( $read < $this->batch_size ) {
+				return;
+			}
+		}
+	}
+
+	/**
+	 * Migrate the block widgets of the current site.
+	 *
+	 * @return void
+	 */
+	private function migrate_widgets(): void {
+		$widgets = get_option( self::WIDGETS_OPTION );
+
+		if ( ! is_array( $widgets ) ) {
+			return;
+		}
+
+		$updated = 0;
+
+		foreach ( $widgets as $key => $widget ) {
+			if ( ! is_array( $widget ) || ! isset( $widget['content'] ) || ! is_string( $widget['content'] ) ) {
+				continue;
+			}
+
+			$content = $this->migrator->migrate_content( $widget['content'], $this->modernize );
+
+			if ( null === $content ) {
+				continue;
+			}
+
+			$widget['content'] = $content;
+			$widgets[ $key ]   = $widget;
+			++$updated;
+			++$this->widgets_updated;
+
+			WP_CLI::log(
+				sprintf(
+					'%1$s block widget %2$s',
+					$this->dry_run ? '[dry-run]' : '[update]',
+					(string) $key
+				)
+			);
+		}
+
+		if ( $updated > 0 && ! $this->dry_run ) {
+			update_option( self::WIDGETS_OPTION, $widgets );
+		}
+	}
+
+	/**
+	 * Read the next batch of posts holding legacy markup.
+	 *
+	 * @param int $after_id Only read posts with a greater ID.
+	 * @return object[]
+	 */
+	private function fetch_posts( int $after_id ): array {
+		/** @var \wpdb $wpdb */
+		global $wpdb;
+
+		$sql = "SELECT ID, post_type, post_content FROM {$wpdb->posts} WHERE ID > %d AND ( post_content LIKE %s OR post_content LIKE %s )";
+
+		$values = [
+			$after_id,
+			'%' . $wpdb->esc_like( 'wp:' . KeyFigureBlockMigrator::LEGACY_BLOCK_NAME ) . '%',
+			'%' . $wpdb->esc_like( KeyFigureBlockMigrator::LEGACY_CLASS_ROOT ) . '%',
+		];
+
+		if ( ! $this->include_revisions ) {
+			$sql .= " AND post_type != 'revision'";
+		}
+
+		if ( ! empty( $this->post_types ) ) {
+			$sql   .= ' AND post_type IN ( ' . implode( ', ', array_fill( 0, count( $this->post_types ), '%s' ) ) . ' )';
+			$values = array_merge( $values, $this->post_types );
+		}
+
+		$sql     .= ' ORDER BY ID ASC LIMIT %d';
+		$values[] = $this->batch_size;
+
+		/** @var object[] $posts */
+		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared
+		$posts = $wpdb->get_results( $wpdb->prepare( $sql, $values ) );
+
+		return $posts;
+	}
+
+	/**
+	 * Save the migrated content of a single post.
+	 *
+	 * @param object $post    Row read from the posts table.
+	 * @param string $content Migrated content.
+	 * @return void
+	 */
+	private function save_post( object $post, string $content ): void {
+		/** @var \wpdb $wpdb */
+		global $wpdb;
+
+		// Revisions are content snapshots: writing them through wp_update_post()
+		// would run the whole insert pipeline (status transition, hooks) on them.
+		if ( 'revision' === $post->post_type ) {
+			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
+			$wpdb->update( $wpdb->posts, [ 'post_content' => $content ], [ 'ID' => (int) $post->ID ] );
+			clean_post_cache( (int) $post->ID );
+
+			return;
+		}
+
+		// wp_update_post() expects slashed data; without wp_slash(), block comment
+		// escapes like \u002d (for "--") become bare "u002d".
+		$updated = wp_update_post(
+			[
+				'ID'           => (int) $post->ID,
+				'post_content' => wp_slash( $content ),
+			],
+			true
+		);
+
+		if ( is_wp_error( $updated ) ) {
+			WP_CLI::warning(
+				sprintf(
+					'Failed to update post %1$d: %2$s',
+					(int) $post->ID,
+					$updated->get_error_message()
+				)
+			);
+		}
+	}
+
+	/**
+	 * Resolve the post types to migrate.
+	 *
+	 * @param string $raw Comma-separated post types from the CLI.
+	 * @return string[] Empty when every post type is migrated.
+	 */
+	private function resolve_post_types( string $raw ): array {
+		if ( '' === trim( $raw ) ) {
+			return [];
+		}
+
+		return array_values( array_filter( array_map( 'trim', explode( ',', $raw ) ) ) );
+	}
+
+	/**
+	 * Print migration counters as a CLI table.
+	 *
+	 * @return void
+	 */
+	private function print_summary(): void {
+		$updated_label = $this->dry_run ? 'would update' : 'updated';
+
+		WP_CLI::success( 'Done.' );
+
+		WP_CLI\Utils\format_items(
+			'table',
+			[
+				[
+					'metric' => 'Posts scanned',
+					'count'  => $this->posts_scanned,
+				],
+				[
+					'metric' => 'Posts ' . $updated_label,
+					'count'  => $this->posts_updated,
+				],
+				[
+					'metric' => 'Widgets ' . $updated_label,
+					'count'  => $this->widgets_updated,
+				],
+				[
+					'metric' => 'Blocks renamed',
+					'count'  => $this->migrator->renamed,
+				],
+				[
+					'metric' => 'Markup modernized',
+					'count'  => $this->migrator->modernized,
+				],
+				[
+					'metric' => 'Markup skipped',
+					'count'  => $this->migrator->skipped,
+				],
+			],
+			[ 'metric', 'count' ]
+		);
+	}
+}
diff --git a/includes/Migration/KeyFigureBlockMigrator.php b/includes/Migration/KeyFigureBlockMigrator.php
new file mode 100644
index 0000000..ce8274f
--- /dev/null
+++ b/includes/Migration/KeyFigureBlockMigrator.php
@@ -0,0 +1,279 @@
+<?php
+/**
+ * Converts beapi/key-figure content to blockparty/key-figure.
+ *
+ * @package Blockparty\Key_Figure
+ */
+
+namespace Blockparty\Key_Figure\Migration;
+
+/**
+ * Turns legacy beapi/key-figure markup into blockparty/key-figure markup.
+ *
+ * @psalm-suppress MixedArgument
+ * @psalm-suppress MixedAssignment
+ * @psalm-suppress MixedArrayAccess
+ * @psalm-suppress MixedArrayAssignment
+ * @psalm-suppress MixedArgumentTypeCoercion
+ */
+class KeyFigureBlockMigrator {
+
+	/**
+	 * Block name used by the legacy beapi/key-figure-block plugin.
+	 *
+	 * @var string
+	 */
+	const LEGACY_BLOCK_NAME = 'beapi/key-figure';
+
+	/**
+	 * Block name used by this plugin.
+	 *
+	 * @var string
+	 */
+	const BLOCK_NAME = 'blockparty/key-figure';
+
+	/**
+	 * BEM root class generated by the legacy block name.
+	 *
+	 * @var string
+	 */
+	const LEGACY_CLASS_ROOT = 'wp-block-beapi-key-figure';
+
+	/**
+	 * BEM root class generated by the current block name.
+	 *
+	 * @var string
+	 */
+	const CLASS_ROOT = 'wp-block-blockparty-key-figure';
+
+	/**
+	 * How many blocks were renamed.
+	 *
+	 * @var int
+	 */
+	public int $renamed = 0;
+
+	/**
+	 * How many blocks had their markup aligned with the current block output.
+	 *
+	 * @var int
+	 */
+	public int $modernized = 0;
+
+	/**
+	 * How many blocks were renamed but could not be modernized.
+	 *
+	 * @var int
+	 */
+	public int $skipped = 0;
+
+	/**
+	 * Check whether a content string holds legacy key figure markup.
+	 *
+	 * @param string $content Post content, widget content or option value.
+	 * @return bool
+	 */
+	public function needs_migration( string $content ): bool {
+		return false !== strpos( $content, 'wp:' . self::LEGACY_BLOCK_NAME )
+			|| false !== strpos( $content, self::LEGACY_CLASS_ROOT );
+	}
+
+	/**
+	 * Rewrite a content string, or return null when there is nothing to do.
+	 *
+	 * @param string $content   Post content, widget content or option value.
+	 * @param bool   $modernize Whether to align the markup with the current block output.
+	 * @return string|null
+	 */
+	public function migrate_content( string $content, bool $modernize = true ): ?string {
+		if ( ! $this->needs_migration( $content ) ) {
+			return null;
+		}
+
+		/** @psalm-suppress MixedArgumentTypeCoercion */
+		$migrated = serialize_blocks( $this->migrate_blocks( parse_blocks( $content ), $modernize ) );
+
+		// Legacy classes also live outside of key figure blocks (core/html,
+		// classic content, theme markup), where only a rename is possible.
+		$migrated = $this->rename_markup( $migrated );
+
+		return $migrated === $content ? null : $migrated;
+	}
+
+	/**
+	 * Walk every block and convert the legacy ones.
+	 *
+	 * @param array $blocks    Parsed blocks.
+	 * @param bool  $modernize Whether to align the markup with the current block output.
+	 * @return array
+	 */
+	private function migrate_blocks( array $blocks, bool $modernize ): array {
+		foreach ( $blocks as $index => $block ) {
+			if ( self::LEGACY_BLOCK_NAME === ( $block['blockName'] ?? '' ) ) {
+				$blocks[ $index ] = $this->convert_block( $block, $modernize );
+				continue;
+			}
+
+			if ( is_array( $block['innerBlocks'] ?? null ) && [] !== $block['innerBlocks'] ) {
+				/** @var array $inner_blocks */
+				$inner_blocks         = $block['innerBlocks'];
+				$block['innerBlocks'] = $this->migrate_blocks( $inner_blocks, $modernize );
+				$blocks[ $index ]     = $block;
+			}
+		}
+
+		return $blocks;
+	}
+
+	/**
+	 * Convert a single legacy block.
+	 *
+	 * @param array $block     Legacy block.
+	 * @param bool  $modernize Whether to align the markup with the current block output.
+	 * @return array
+	 */
+	private function convert_block( array $block, bool $modernize ): array {
+		$attrs        = is_array( $block['attrs'] ?? null ) ? (array) $block['attrs'] : [];
+		$inner_html   = $this->rename_markup( (string) ( $block['innerHTML'] ?? '' ) );
+		$inner_blocks = is_array( $block['innerBlocks'] ?? null ) ? (array) $block['innerBlocks'] : [];
+
+		/** @var array<int, string|null> $chunks */
+		$chunks        = is_array( $block['innerContent'] ?? null ) ? (array) $block['innerContent'] : [ $inner_html ];
+		$inner_content = [];
+
+		foreach ( $chunks as $chunk ) {
+			$inner_content[] = is_string( $chunk ) ? $this->rename_markup( $chunk ) : $chunk;
+		}
+
+		$block['blockName']    = self::BLOCK_NAME;
+		$block['innerHTML']    = $inner_html;
+		$block['innerContent'] = $inner_content;
+
+		++$this->renamed;
+
+		if ( ! $modernize || [] !== $inner_blocks ) {
+			return $block;
+		}
+
+		$modernized = $this->modernize_markup( $inner_html, $attrs );
+
+		if ( null === $modernized ) {
+			++$this->skipped;
+
+			return $block;
+		}
+
+		// Both values are read from the markup by the current block.
+		unset( $attrs['decimalSeparator'], $attrs['minimumFractionDigits'] );
+
+		$block['attrs']        = $attrs;
+		$block['innerHTML']    = $modernized;
+		$block['innerContent'] = [ $modernized ];
+
+		++$this->modernized;
+
+		return $block;
+	}
+
+	/**
+	 * Replace the legacy block name and BEM root class.
+	 *
+	 * @param string $markup Block delimiters and/or HTML.
+	 * @return string
+	 */
+	private function rename_markup( string $markup ): string {
+		$markup = (string) preg_replace(
+			'#(<!--\s*/?\s*)wp:' . preg_quote( self::LEGACY_BLOCK_NAME, '#' ) . '(?![\w/-])#',
+			'${1}wp:' . self::BLOCK_NAME,
+			$markup
+		);
+
+		return str_replace( self::LEGACY_CLASS_ROOT, self::CLASS_ROOT, $markup );
+	}
+
+	/**
+	 * Align renamed markup with the output of the current block.
+	 *
+	 * The legacy block stored the decimal options as block attributes and the
+	 * number already formatted, while the current block stores the options as
+	 * data attributes and formats the raw number on the front end.
+	 *
+	 * @param string $markup Renamed block markup.
+	 * @param array  $attrs  Legacy block attributes.
+	 * @return string|null Null when the number cannot be read from the markup.
+	 */
+	private function modernize_markup( string $markup, array $attrs ): ?string {
+		$number_pattern = sprintf(
+			'#<span((?:[^>]*\s)?class="[^"]*%s__number[^"]*"[^>]*)>(.*?)</span>#s',
+			preg_quote( self::CLASS_ROOT, '#' )
+		);
+
+		if ( ! preg_match( $number_pattern, $markup, $number ) ) {
+			return null;
+		}
+
+		if ( ! preg_match( '#\sdata-increment="([^"]*)"#', $number[1], $increment ) || '' === $increment[1] ) {
+			return null;
+		}
+
+		$number_attributes = $number[1];
+
+		if ( false === strpos( $number_attributes, 'data-decimal-separator' ) ) {
+			$number_attributes .= sprintf(
+				' data-decimal-separator="%s"',
+				esc_attr( (string) ( $attrs['decimalSeparator'] ?? 'none' ) )
+			);
+		}
+
+		if ( false === strpos( $number_attributes, 'data-minimum-fraction-digits' ) ) {
+			$number_attributes .= sprintf(
+				' data-minimum-fraction-digits="%s"',
+				esc_attr( (string) ( $attrs['minimumFractionDigits'] ?? '3' ) )
+			);
+		}
+
+		$markup = str_replace(
+			$number[0],
+			sprintf( '<span%1$s>%2$s</span>', $number_attributes, esc_html( $increment[1] ) ),
+			$markup
+		);
+
+		return $this->ensure_description( $this->convert_key_wrapper( $markup ) );
+	}
+
+	/**
+	 * Add the description paragraph that the current block always saves.
+	 *
+	 * @param string $markup Renamed block markup.
+	 * @return string
+	 */
+	private function ensure_description( string $markup ): string {
+		if ( false !== strpos( $markup, self::CLASS_ROOT . '__description' ) ) {
+			return $markup;
+		}
+
+		$paragraph = sprintf( '<p class="%s__description"></p>', self::CLASS_ROOT );
+		$wrapper   = strrpos( $markup, '</div>' );
+
+		if ( false === $wrapper ) {
+			return $markup . $paragraph;
+		}
+
+		return substr_replace( $markup, $paragraph, $wrapper, 0 );
+	}
+
+	/**
+	 * Turn the legacy `div` key wrapper into the `p` wrapper used since 1.1.0.
+	 *
+	 * @param string $markup Renamed block markup.
+	 * @return string
+	 */
+	private function convert_key_wrapper( string $markup ): string {
+		$pattern = sprintf(
+			'#<div((?:[^>]*\s)?class="[^"]*%s__key[^"]*"[^>]*)>((?:(?!<div)[\s\S])*?)</div>#',
+			preg_quote( self::CLASS_ROOT, '#' )
+		);
+
+		return (string) preg_replace( $pattern, '<p${1}>${2}</p>', $markup );
+	}
+}
diff --git a/phpcs.xml b/phpcs.xml
index 0937a2e..59e0898 100644
--- a/phpcs.xml
+++ b/phpcs.xml
@@ -7,6 +7,7 @@
 
     <!-- Scan all files in directory -->
     <file>blockparty-key-figure.php</file>
+    <file>./includes/</file>
 
     <exclude-pattern>./build/</exclude-pattern>
     <exclude-pattern>./node_modules/</exclude-pattern>
diff --git a/readme.txt b/readme.txt
index ea978a3..b6e22a9 100644
--- a/readme.txt
+++ b/readme.txt
@@ -23,6 +23,37 @@ This block allow to set a prefix, suffix and a number. It's possible to change t
 
 1. Block configuration in columns block
 
+== Migration from beapi/key-figure ==
+
+Content created with the legacy `beapi/key-figure-block` plugin still stores the old block name (`wp:beapi/key-figure`) and the old BEM root class (`wp-block-beapi-key-figure`). Those blocks are invalid in the editor until the content is rewritten, which the `wp blockparty key-figure migrate` WP-CLI command does.
+
+The command scans the post content of every post type (revisions and reusable blocks included) and the block widgets, then:
+
+1. Renames `wp:beapi/key-figure` to `wp:blockparty/key-figure`, keeping the block attributes.
+2. Renames `wp-block-beapi-key-figure` to `wp-block-blockparty-key-figure`, including the `__key`, `__prefix`, `__number`, `__suffix` and `__description` elements.
+3. Aligns the markup with the current block output, unless `--no-modernize` is used: `p` key wrapper (instead of `div`), `data-decimal-separator` and `data-minimum-fraction-digits` on the number, and the raw number as text since formatting now happens on the front end.
+
+It must be run manually on the server:
+
+    # Preview changes without writing to the database.
+    wp blockparty key-figure migrate --dry-run
+
+    # Apply the migration.
+    wp blockparty key-figure migrate
+
+    # Only rename the block and its CSS classes.
+    wp blockparty key-figure migrate --no-modernize
+
+    # Limit the migration to some post types, with a smaller batch size.
+    wp blockparty key-figure migrate --post-type=post,page --posts-per-page=20
+
+The command always targets a single site. On multisite, run it for each site with the native `--url` parameter:
+
+    wp blockparty key-figure migrate --url=example.com
+    wp blockparty key-figure migrate --url=example.com/site-2
+
+Run `wp help blockparty key-figure migrate` for the full list of options.
+
 == Changelog ==
 
 = 1.0.0 - 2024-04-02 =