diff --git a/includes/class-static-site-importer-companion-plugin.php b/includes/class-static-site-importer-companion-plugin.php
index a50423c9..b68858b2 100644
--- a/includes/class-static-site-importer-companion-plugin.php
+++ b/includes/class-static-site-importer-companion-plugin.php
@@ -222,8 +222,13 @@ public static function scaffold( array $payload ) {
 		foreach ( $preserved as $island ) {
 			$files[ $plugin_slug . '/' . $island['relative_src'] ] = $island['content'];
 		}
+		$provider_form_runtime = file_get_contents( __DIR__ . '/class-static-site-importer-provider-form-runtime.php' ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Reads the plugin-owned runtime source carried into generated companions.
+		if ( ! is_string( $provider_form_runtime ) || '' === $provider_form_runtime ) {
+			return new WP_Error( 'static_site_importer_companion_plugin_provider_form_runtime_missing', 'Provider form runtime projection file is unavailable.' );
+		}
+		$files[ $plugin_slug . '/includes/class-static-site-importer-provider-form-runtime.php' ] = $provider_form_runtime;
 
-		$inventory_hash        = substr( hash( 'sha256', (string) wp_json_encode( array( $block_names, $preserved ) ) ), 0, 16 );
+		$inventory_hash        = substr( hash( 'sha256', (string) wp_json_encode( array( $block_names, $preserved, hash( 'sha256', $provider_form_runtime ) ) ) ), 0, 16 );
 		$registration_callback = str_replace( '-', '_', $plugin_slug ) . '_' . $inventory_hash . '_register_blocks';
 		$main_file             = $plugin_slug . '/' . $plugin_slug . '.php';
 		$files                 = array_merge(
@@ -678,6 +683,9 @@ private static function main_plugin_file(
 		$lines[] = sprintf( "define( '%s_DIR', plugin_dir_path( __FILE__ ) );", $const_prefix );
 		$lines[] = sprintf( "define( '%s_URL', plugin_dir_url( __FILE__ ) );", $const_prefix );
 		$lines[] = '';
+		$lines[] = "require_once __DIR__ . '/includes/class-static-site-importer-provider-form-runtime.php';";
+		$lines[] = 'Static_Site_Importer_Provider_Form_Runtime::register();';
+		$lines[] = '';
 		$lines[] = '/**';
 		$lines[] = ' * Register generated blocks from their metadata directories.';
 		$lines[] = ' */';
diff --git a/includes/class-static-site-importer-form-seeder.php b/includes/class-static-site-importer-form-seeder.php
index c1d3b005..b64976c8 100644
--- a/includes/class-static-site-importer-form-seeder.php
+++ b/includes/class-static-site-importer-form-seeder.php
@@ -11,6 +11,7 @@
 
 require_once __DIR__ . '/class-static-site-importer-computed-layout-strategy.php';
 require_once __DIR__ . '/class-static-site-importer-provider-layout-overlay.php';
+require_once __DIR__ . '/class-static-site-importer-provider-form-runtime.php';
 
 /**
  * Turns preserved <form> fallback metadata into working Jetpack Form blocks.
@@ -59,38 +60,18 @@ public static function register_runtime_bootstrap(): void {
 			add_action( 'jetpack_loaded', array( __CLASS__, 'bootstrap_jetpack_forms_runtime' ) );
 		}
 		if ( function_exists( 'add_filter' ) ) {
-			add_filter( 'grunion_contact_form_field_html', array( __CLASS__, 'project_provider_wrapper_classes' ) );
+			Static_Site_Importer_Provider_Form_Runtime::register();
 		}
 	}
 
-	/** Project source wrapper classes onto Jetpack's existing field wrapper. */
+	/** Move source submit presentation from Core's wrapper onto its button control. */
+	public static function project_provider_submit_presentation( string $html, array $block = array() ): string {
+		return Static_Site_Importer_Provider_Form_Runtime::project_submit_presentation( $html, $block );
+	}
+
+	/** Rebuild source input-only wrapper layers inside Jetpack's field shell. */
 	public static function project_provider_wrapper_classes( string $html ): string {
-		$projected = preg_replace_callback(
-			'/\bclass=(["\'])(.*?)\1/s',
-			static function ( array $matches ): string {
-				$classes = preg_split( '/\s+/', trim( $matches[2] ) );
-				if ( false === $classes ) {
-					$classes = array();
-				}
-				$is_wrapper = (bool) array_filter( $classes, static fn ( string $class_name ): bool => 1 === preg_match( '/^grunion-field-[A-Za-z0-9_-]+-wrap$/D', $class_name ) );
-				$output     = array();
-				foreach ( $classes as $class ) {
-					if ( str_starts_with( $class, 'ssi-source-wrapper--' ) ) {
-						if ( $is_wrapper && str_ends_with( $class, '-wrap' ) ) {
-							$source_class = substr( $class, strlen( 'ssi-source-wrapper--' ), -strlen( '-wrap' ) );
-							if ( 1 === preg_match( '/^[A-Za-z_][A-Za-z0-9_-]{0,79}$/D', $source_class ) ) {
-								$output[] = $source_class;
-							}
-						}
-						continue;
-					}
-					$output[] = $class;
-				}
-				return 'class=' . $matches[1] . implode( ' ', array_values( array_unique( $output ) ) ) . $matches[1];
-			},
-			$html
-		);
-		return is_string( $projected ) ? $projected : $html;
+		return Static_Site_Importer_Provider_Form_Runtime::project_wrapper_classes( $html );
 	}
 
 	/**
@@ -450,6 +431,13 @@ private static function seed_form( array $form, bool $available ): array {
 				$text              = self::control_text( $control );
 				$submit_text       = '' !== $text ? $text : $submit_text;
 				$has_source_submit = true;
+				if ( isset( $control['presentation']['style'] ) && is_array( $control['presentation']['style'] ) ) {
+					$submit_presentation['block_attrs']['style'] = $control['presentation']['style'];
+				}
+				if ( empty( $submit_presentation['classes'] ) && isset( $control['class'] ) && is_scalar( $control['class'] ) ) {
+					$submit_classes                 = preg_split( '/\s+/', trim( (string) $control['class'] ) );
+					$submit_presentation['classes'] = false === $submit_classes ? array() : $submit_classes;
+				}
 				if ( $has_topology ) {
 					$presentation_class             = isset( $presentation_roles[ $control_index ]['control'] ) ? self::presentation_node_class( $scope, $control_index, 'control' ) : '';
 					$field_blocks[ $control_index ] = self::submit_button_block( $submit_text, trim( self::layout_node_class( $scope, 'control-' . $control_index ) . ' ' . $presentation_class ), $submit_presentation );
@@ -541,10 +529,24 @@ private static function seed_form( array $form, bool $available ): array {
 		}
 		self::append_receipt_entries( $layout['receipt'], 'operations', array_merge( $radio_groups['operations'], $topology['operations'] ) );
 		self::append_receipt_entries( $layout['receipt'], 'losses', $control_attribute_losses );
-		$inner_blocks              = $layout['blocks'];
-		$form_attrs                = self::contact_form_attributes( $form, $scope );
-		$overlay_graph             = $provider_graph;
-		$overlay_graph['nodes']    = array_values( array_filter( $overlay_graph['nodes'] ?? array(), static fn ( $node ): bool => is_array( $node ) && ( 'form' === ( $node['id'] ?? '' ) || preg_match( '/^control-[0-9]+$/D', (string) ( $node['id'] ?? '' ) ) ) ) );
+		$inner_blocks           = $layout['blocks'];
+		$form_attrs             = self::contact_form_attributes( $form, $scope, $topology['form_classes'] );
+		$overlay_graph          = $provider_graph;
+		$overlay_graph['nodes'] = array_values( array_filter( $overlay_graph['nodes'] ?? array(), static fn ( $node ): bool => is_array( $node ) && ( 'form' === ( $node['id'] ?? '' ) || preg_match( '/^control-[0-9]+$/D', (string) ( $node['id'] ?? '' ) ) ) ) );
+		foreach ( $topology['overlay_node_targets'] as $target ) {
+			$merged = false;
+			foreach ( $overlay_graph['nodes'] as &$overlay_node ) {
+				if ( is_array( $overlay_node ) && ( $overlay_node['id'] ?? null ) === ( $target['id'] ?? null ) ) {
+					$overlay_node['layout'] = array_merge( is_array( $overlay_node['layout'] ?? null ) ? $overlay_node['layout'] : array(), $target['layout'] );
+					$merged                 = true;
+					break;
+				}
+			}
+			unset( $overlay_node );
+			if ( ! $merged ) {
+				$overlay_graph['nodes'][] = $target;
+			}
+		}
 		$overlay_graph['variants'] = array_merge( $overlay_graph['variants'] ?? array(), $topology['responsive_variant_targets'] );
 		$overlay_node_ids          = array_fill_keys( array_map( static fn( array $node ): string => (string) $node['id'], $overlay_graph['nodes'] ), true );
 		foreach ( $topology['responsive_variant_targets'] as $variant ) {
@@ -838,7 +840,7 @@ private static function labelled_fieldset_legends( array $form, array $nodes ):
 	 *
 	 * @param array<int,array<string,mixed>> $field_blocks
 	 * @param array<int,array<string,mixed>> $controls
-	 * @return array{blocks:array<int,array<string,mixed>>,losses:array<int,array<string,mixed>>,operations:array<int,array<string,mixed>>,represented_layout_nodes:array<int,string>,represented_topology_nodes:array<int,string>,responsive_variant_targets:array<int,array<string,mixed>>,native_visibility_targets:array<int,string>}|null
+	 * @return array{blocks:array<int,array<string,mixed>>,losses:array<int,array<string,mixed>>,operations:array<int,array<string,mixed>>,represented_layout_nodes:array<int,string>,represented_topology_nodes:array<int,string>,overlay_node_targets:array<int,array<string,mixed>>,responsive_variant_targets:array<int,array<string,mixed>>,native_visibility_targets:array<int,string>,form_classes:array<int,string>}|null
 	 */
 	private static function topology_inner_blocks( array $form, array $field_blocks, array $controls, array $suppressed_controls = array() ): ?array {
 		if ( ! isset( $form['control_topology'] ) ) {
@@ -848,8 +850,10 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 				'operations'                 => array(),
 				'represented_layout_nodes'   => array(),
 				'represented_topology_nodes' => array(),
+				'overlay_node_targets'       => array(),
 				'responsive_variant_targets' => array(),
 				'native_visibility_targets'  => array(),
+				'form_classes'               => array(),
 			);
 		}
 		$nodes = $form['control_topology']['nodes'] ?? null;
@@ -882,11 +886,13 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 		$operations                 = array();
 		$represented_layout_nodes   = array();
 		$represented_topology_nodes = array();
+		$overlay_node_targets       = array();
 		$responsive_variant_targets = array();
 		$native_visibility_targets  = array();
 		$layout_by_node             = array();
 		$layout_nodes_by_id         = array();
 		$variants_by_node           = array();
+		$form_classes               = array();
 		foreach ( $form['layout_graph']['nodes'] ?? array() as $layout_node ) {
 			if ( is_array( $layout_node ) && is_string( $layout_node['id'] ?? null ) ) {
 				$layout_by_node[ $layout_node['id'] ]     = is_array( $layout_node['layout'] ?? null ) ? $layout_node['layout'] : array();
@@ -898,15 +904,25 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 				$variants_by_node[ $variant['node'] ][] = $variant;
 			}
 		}
+		$collect_controls = static function ( array $node ) use ( &$collect_controls, $children ): array {
+			if ( 'control' === ( $node['kind'] ?? null ) ) {
+				return is_int( $node['control'] ?? null ) ? array( $node['control'] ) : array();
+			}
+			$controls = array();
+			foreach ( $children[ $node['id'] ?? '' ] ?? array() as $child ) {
+				$controls = array_merge( $controls, $collect_controls( $child ) );
+			}
+			return $controls;
+		};
 		foreach ( $nodes as $node ) {
 			if ( ! is_array( $node ) || 'wrapper' !== ( $node['kind'] ?? null ) || ! is_string( $node['id'] ?? null ) ) {
 				continue;
 			}
-			$direct_children = $children[ $node['id'] ] ?? array();
-			if ( 1 !== count( $direct_children ) || 'control' !== ( $direct_children[0]['kind'] ?? null ) ) {
+			$branch_controls = $collect_controls( $node );
+			if ( 1 !== count( $branch_controls ) ) {
 				continue;
 			}
-			$control_index = $direct_children[0]['control'] ?? null;
+			$control_index = $branch_controls[0];
 			$source_class  = trim( (string) ( $node['class'] ?? '' ) );
 			if ( ! is_int( $control_index ) || '' === $source_class || ! isset( $field_blocks[ $control_index ] ) || 'core/button' === ( $field_blocks[ $control_index ]['name'] ?? '' ) ) {
 				continue;
@@ -916,7 +932,8 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 			if ( false === $wrapper_classes ) {
 				$wrapper_classes = array();
 			}
-			$wrapper_markers                                      = implode( ' ', array_map( static fn ( string $class_name ): string => 'ssi-source-wrapper--' . $class_name, $wrapper_classes ) );
+			$layer           = min( 99, max( 0, (int) ( $node['depth'] ?? 0 ) ) );
+			$wrapper_markers = implode( ' ', array_map( static fn ( string $class_name ): string => 'ssi-source-wrapper-' . $layer . '--' . $class_name, $wrapper_classes ) );
 			$field_blocks[ $control_index ]['attrs']['className'] = trim( (string) ( $field_blocks[ $control_index ]['attrs']['className'] ?? '' ) . ' ' . $wrapper_markers . ' ' . $generated_class );
 			$operations[] = array(
 				'dimension'   => 'topology',
@@ -950,17 +967,45 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 				$represented_layout_nodes[] = $node['id'];
 			}
 		}
-		$collect_controls = static function ( array $node ) use ( &$collect_controls, $children ): array {
-			if ( 'control' === ( $node['kind'] ?? null ) ) {
-				return is_int( $node['control'] ?? null ) ? array( $node['control'] ) : array();
+		$mapped_controls = array_keys( $field_blocks );
+		sort( $mapped_controls );
+		foreach ( $nodes as $node ) {
+			if ( ! is_array( $node ) || 'wrapper' !== ( $node['kind'] ?? null ) || '' === trim( (string) ( $node['class'] ?? '' ) ) ) {
+				continue;
 			}
-			$controls = array();
-			foreach ( $children[ $node['id'] ?? '' ] ?? array() as $child ) {
-				$controls = array_merge( $controls, $collect_controls( $child ) );
+			$branch_controls = $collect_controls( $node );
+			sort( $branch_controls );
+			if ( $mapped_controls !== $branch_controls || count( $children[ $node['id'] ] ?? array() ) < 2 ) {
+				continue;
 			}
-			return $controls;
-		};
-		$topology_by_id   = array();
+			$source_class = trim( (string) $node['class'] );
+			$class_tokens = preg_split( '/\s+/', $source_class );
+			if ( false === $class_tokens ) {
+				$class_tokens = array();
+			}
+			$facts       = array_merge( $layout_nodes_by_id[ $node['id'] ]['provenance'] ?? array(), ...array_map( static fn ( array $variant ): array => is_array( $variant['provenance'] ?? null ) ? $variant['provenance'] : array(), $variants_by_node[ $node['id'] ] ?? array() ) );
+			$class_owned = ! empty( $facts );
+			foreach ( $facts as $fact ) {
+				$selector = is_array( $fact ) && is_string( $fact['selector'] ?? null ) ? $fact['selector'] : '';
+				if ( ! preg_match( '/^(?:[a-z][a-z0-9-]*)?(?:\.[a-zA-Z][a-zA-Z0-9_-]*)+$/D', $selector ) || ! array_filter( $class_tokens, static fn ( string $class_name ): bool => '' !== $class_name && (bool) preg_match( '/\.' . preg_quote( $class_name, '/' ) . '(?![a-zA-Z0-9_-])/', $selector ) ) ) {
+					$class_owned = false;
+					break;
+				}
+			}
+			if ( ! $class_owned ) {
+				continue;
+			}
+			$form_classes                 = array_merge( $form_classes, $class_tokens );
+			$represented_layout_nodes[]   = $node['id'];
+			$represented_topology_nodes[] = $node['id'];
+			$operations[]                 = array(
+				'dimension'   => 'topology',
+				'strategy'    => 'provider_field_list_class_projection',
+				'target_hash' => hash( 'sha256', $node['id'] ),
+			);
+			break;
+		}
+		$topology_by_id = array();
 		foreach ( $nodes as $node ) {
 			if ( is_array( $node ) && is_string( $node['id'] ?? null ) ) {
 				$topology_by_id[ $node['id'] ] = $node;
@@ -981,6 +1026,7 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 				if ( ! is_array( $variant ) || ! is_array( $variant['condition'] ?? null ) || 'media' !== ( $variant['condition']['kind'] ?? null ) || ! is_string( $variant['condition']['query'] ?? null ) || 1 !== preg_match( '/^\((?:min|max)-(?:width|height): ?[0-9]+(?:\.[0-9]+)?(?:px|em|rem|vw|vh)\)$/D', $variant['condition']['query'] ) || ! is_string( $width ) || 1 !== preg_match( '/^(?:[0-9]+(?:\.[0-9]+)?|\.[0-9]+)%$/D', $width ) || ( array( 'width' ) !== array_keys( $patch ) && array( 'display', 'width' ) !== array_keys( $patch ) ) || ( isset( $patch['display'] ) && 'block' !== $patch['display'] ) ) {
 					return false;
 				}
+
 				$proven = false;
 				foreach ( $variant['provenance'] ?? array() as $fact ) {
 					if ( is_array( $fact ) && ( $fact['condition'] ?? null ) === $variant['condition'] && is_string( $fact['source_path'] ?? null ) && is_string( $fact['source_sha256'] ?? null ) && 1 === preg_match( '/^[a-f0-9]{64}$/D', $fact['source_sha256'] ) && is_string( $fact['selector'] ?? null ) && ! array_diff( array_keys( $patch ), $fact['properties'] ?? array() ) ) {
@@ -992,8 +1038,63 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 					return false;
 				}
 			}
+
 			return true;
 		};
+
+		$grid_span_width = static function ( mixed $columns, mixed $column ): ?string {
+			$columns = preg_replace( '/\s+/', '', is_string( $columns ) ? $columns : '' );
+			$column  = preg_replace( '/\s+/', '', is_string( $column ) ? $column : '' );
+			if ( ! is_string( $columns ) || ! is_string( $column ) || ! preg_match( '/^repeat\(([1-9][0-9]*),1fr\)$/D', $columns, $column_count ) || ! preg_match( '/^span([1-9][0-9]*)$/D', $column, $span ) || (int) $span[1] > (int) $column_count[1] ) {
+				return null;
+			}
+			return rtrim( rtrim( number_format( 100 * (int) $span[1] / (int) $column_count[1], 3, '.', '' ), '0' ), '.' ) . '%';
+		};
+		foreach ( $nodes as $node ) {
+			$id              = is_array( $node ) && 'wrapper' === ( $node['kind'] ?? null ) && is_string( $node['id'] ?? null ) ? $node['id'] : '';
+			$branch_controls = '' !== $id ? $collect_controls( $node ) : array();
+			$control_index   = 1 === count( $branch_controls ) ? $branch_controls[0] : null;
+			$layout_node     = $layout_nodes_by_id[ $id ] ?? null;
+			$layout_parent   = is_array( $layout_node ) && is_string( $layout_node['parent'] ?? null ) ? $layout_nodes_by_id[ $layout_node['parent'] ] ?? null : null;
+			$width           = is_array( $layout_node ) && is_array( $layout_parent ) ? $grid_span_width( $layout_parent['layout']['columns'] ?? null, $layout_node['layout']['column'] ?? null ) : null;
+			if ( ! is_int( $control_index ) || 'core/button' !== ( $field_blocks[ $control_index ]['name'] ?? '' ) || null === $width || ! $has_unconditional_proven_property( $layout_node, 'grid-column' ) || ! $has_unconditional_proven_property( $layout_parent, 'grid-template-columns' ) ) {
+				continue;
+			}
+			$target_variants = array();
+			$variants_safe   = true;
+			foreach ( $variants_by_node[ $id ] ?? array() as $variant ) {
+				$patch         = is_array( $variant['layout_patch'] ?? null ) ? $variant['layout_patch'] : array();
+				$variant_width = array( 'column' ) === array_keys( $patch ) ? $grid_span_width( $layout_parent['layout']['columns'] ?? null, $patch['column'] ) : null;
+				$proven        = false;
+				foreach ( $variant['provenance'] ?? array() as $fact ) {
+					if ( is_array( $fact ) && ( $fact['condition'] ?? null ) === ( $variant['condition'] ?? null ) && is_string( $fact['source_path'] ?? null ) && is_string( $fact['source_sha256'] ?? null ) && 1 === preg_match( '/^[a-f0-9]{64}$/D', $fact['source_sha256'] ) && in_array( 'grid-column', $fact['properties'] ?? array(), true ) ) {
+						$proven = true;
+						break;
+					}
+				}
+				if ( null === $variant_width || ! is_array( $variant['condition'] ?? null ) || 'media' !== ( $variant['condition']['kind'] ?? null ) || ! $proven ) {
+					$variants_safe = false;
+					break;
+				}
+				$variant['node']         = 'control-' . $control_index;
+				$variant['layout_patch'] = array( 'width' => $variant_width );
+				$target_variants[]       = $variant;
+			}
+			if ( ! $variants_safe ) {
+				continue;
+			}
+			$overlay_node_targets[]     = array(
+				'id'     => 'control-' . $control_index,
+				'layout' => array( 'width' => $width ),
+			);
+			$responsive_variant_targets = array_merge( $responsive_variant_targets, $target_variants );
+			$represented_layout_nodes[] = $id;
+			$operations[]               = array(
+				'dimension'   => 'layout',
+				'strategy'    => 'provider_grid_span_submit',
+				'target_hash' => hash( 'sha256', $id ),
+			);
+		}
 		foreach ( $nodes as $node ) {
 			$id = is_array( $node ) && 'control' === ( $node['kind'] ?? null ) && is_string( $node['id'] ?? null ) ? $node['id'] : '';
 			if ( '' === $id || 'none' !== ( $layout_by_node[ $id ]['display'] ?? null ) ) {
@@ -1224,8 +1325,10 @@ private static function topology_inner_blocks( array $form, array $field_blocks,
 			'operations'                 => $operations,
 			'represented_layout_nodes'   => array_values( array_unique( array_map( 'strval', $represented_layout_nodes ) ) ),
 			'represented_topology_nodes' => array_values( array_unique( array_map( 'strval', $represented_topology_nodes ) ) ),
+			'overlay_node_targets'       => $overlay_node_targets,
 			'responsive_variant_targets' => $responsive_variant_targets,
 			'native_visibility_targets'  => array_values( array_unique( array_map( 'strval', $native_visibility_targets ) ) ),
+			'form_classes'               => array_values( array_unique( $form_classes ) ),
 		);
 	}
 
@@ -1309,15 +1412,12 @@ private static function field_block_from_control( string $tag, string $type, arr
 			);
 		} elseif ( ! in_array( $lookup, array( 'checkbox', 'radio' ), true ) ) {
 			$input_attrs  = array(
-				'style'     => array( 'border' => array( 'style' => 'solid' ) ),
-				'className' => $control_class,
+				'style' => array( 'border' => array( 'style' => 'solid' ) ),
 			);
 			$source_class = isset( $control['class'] ) && is_scalar( $control['class'] ) ? trim( (string) $control['class'] ) : '';
 			$input_class  = trim( $source_class . ' ' . $control_class );
 			if ( '' !== $input_class ) {
 				$input_attrs['className'] = $input_class;
-			} else {
-				unset( $input_attrs['className'] );
 			}
 			if ( '' !== $placeholder ) {
 				$input_attrs['placeholder'] = $placeholder;
@@ -1412,19 +1512,26 @@ private static function receipt_loss_requires_gate( array $loss ): bool {
 	 * @return array<string, mixed>
 	 */
 	private static function submit_button_block( string $text, string $class_name = '', array $presentation = array() ): array {
-		$source_classes = isset( $presentation['classes'] ) && is_array( $presentation['classes'] ) ? implode( ' ', array_filter( $presentation['classes'], 'is_string' ) ) : '';
-		$class_name     = trim( 'form-button-submit is-submit ' . $source_classes . ' ' . $class_name );
+		$source_classes = isset( $presentation['classes'] ) && is_array( $presentation['classes'] ) ? array_filter( $presentation['classes'], 'is_string' ) : array();
+		$source_markers = implode( ' ', array_map( static fn ( string $source_class ): string => 'ssi-source-submit--' . $source_class, $source_classes ) );
+		$block_style    = isset( $presentation['block_attrs']['style'] ) && is_array( $presentation['block_attrs']['style'] ) ? $presentation['block_attrs']['style'] : array();
+		$class_name     = trim( 'form-button-submit is-submit ' . $source_markers . ' ' . ( empty( $block_style ) ? '' : 'ssi-provider-submit-presentation' ) . ' ' . $class_name );
+		$attrs          = array(
+			'tagName'   => 'button',
+			'type'      => 'submit',
+			'lock'      => array(
+				'remove' => true,
+			),
+			'className' => $class_name,
+			'metadata'  => array( 'name' => 'Submit button' ),
+		);
+		// The source governs this button through its own classes and stylesheet,
+		// so the block does not claim those styles as attributes. Claiming them
+		// made the saved markup disagree with core's save() output, which is
+		// what marked every imported form dirty in the editor.
 		return array(
 			'name'    => 'core/button',
-			'attrs'   => array(
-				'tagName'   => 'button',
-				'type'      => 'submit',
-				'lock'      => array(
-					'remove' => true,
-				),
-				'className' => $class_name,
-				'metadata'  => array( 'name' => 'Submit button' ),
-			),
+			'attrs'   => $attrs,
 			'content' => '' !== trim( $text ) ? trim( $text ) : 'Submit',
 			'wrapper' => 'submit',
 		);
@@ -1454,13 +1561,13 @@ private static function context_block_markup( array $form, string $position ): s
 	 * @param array<string, mixed> $form Validated form row.
 	 * @return array<string, mixed>
 	 */
-	private static function contact_form_attributes( array $form, string $scope = '' ): array {
+	private static function contact_form_attributes( array $form, string $scope = '', array $topology_classes = array() ): array {
 		$attrs    = array();
 		$metadata = isset( $form['form'] ) && is_array( $form['form'] ) ? $form['form'] : array();
 		$action   = isset( $metadata['action'] ) && is_scalar( $metadata['action'] ) ? trim( (string) $metadata['action'] ) : '';
 		$class    = isset( $metadata['class'] ) && is_scalar( $metadata['class'] ) ? trim( (string) $metadata['class'] ) : '';
 
-		$attrs['className'] = trim( $class . ' ' . $scope );
+		$attrs['className'] = implode( ' ', array_filter( array( $class, implode( ' ', array_filter( $topology_classes, 'is_string' ) ), $scope ), static fn ( string $value ): bool => '' !== trim( $value ) ) );
 
 		if ( '' !== $action && 0 === stripos( $action, 'mailto:' ) ) {
 			$recipient = trim( substr( $action, 7 ) );
diff --git a/includes/class-static-site-importer-provider-form-runtime.php b/includes/class-static-site-importer-provider-form-runtime.php
new file mode 100644
index 00000000..a1cd0f83
--- /dev/null
+++ b/includes/class-static-site-importer-provider-form-runtime.php
@@ -0,0 +1,134 @@
+<?php
+/**
+ * Runtime presentation projection for materialized provider forms.
+ *
+ * @package StaticSiteImporter
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+if ( class_exists( 'Static_Site_Importer_Provider_Form_Runtime', false ) ) {
+	return;
+}
+
+/** Keeps source form presentation attached to provider-rendered controls. */
+final class Static_Site_Importer_Provider_Form_Runtime {
+	/** Whether hooks have already been registered in this request. */
+	private static bool $registered = false;
+
+	/** Register inert-unless-marked provider projection hooks. */
+	public static function register(): void {
+		if ( self::$registered || ! function_exists( 'add_filter' ) ) {
+			return;
+		}
+		self::$registered = true;
+		add_filter( 'grunion_contact_form_field_html', array( __CLASS__, 'project_wrapper_classes' ) );
+		add_filter( 'render_block_core/button', array( __CLASS__, 'project_submit_presentation' ), 10, 2 );
+	}
+
+	/** Move source submit presentation from Core's wrapper onto its button control. */
+	public static function project_submit_presentation( string $html, array $block = array() ): string {
+		$class_name = isset( $block['attrs']['className'] ) && is_string( $block['attrs']['className'] ) ? $block['attrs']['className'] : '';
+		if ( ! str_contains( $class_name, 'ssi-source-submit--' ) ) {
+			return $html;
+		}
+		$source_classes = array();
+		$projected      = preg_replace_callback(
+			'/\bclass=(["\'])(.*?)\1/s',
+			static function ( array $matches ) use ( &$source_classes ): string {
+				$classes = preg_split( '/\s+/', trim( $matches[2] ) );
+				$classes = false === $classes ? array() : $classes;
+				$output  = array();
+				foreach ( $classes as $candidate ) {
+					if ( preg_match( '/^ssi-source-submit--([A-Za-z_][A-Za-z0-9_-]{0,79})$/D', $candidate, $marker ) ) {
+						$source_classes[] = $marker[1];
+						continue;
+					}
+					$output[] = $candidate;
+				}
+				return 'class=' . $matches[1] . implode( ' ', $output ) . $matches[1];
+			},
+			$html,
+			1
+		);
+		if ( ! is_string( $projected ) || empty( $source_classes ) ) {
+			return $html;
+		}
+		$source_classes = array_values( array_unique( $source_classes ) );
+		$projected      = preg_replace_callback(
+			'/<button\b([^>]*)>/is',
+			static function ( array $matches ) use ( $source_classes ): string {
+				$attributes = $matches[1];
+				if ( preg_match( '/\bclass=(["\'])(.*?)\1/is', $attributes ) ) {
+					$attributes = preg_replace( '/\bclass=(["\'])(.*?)\1/is', 'class=$1$2 ' . implode( ' ', $source_classes ) . '$1', $attributes, 1 ) ?? $attributes;
+				} else {
+					$attributes .= ' class="' . implode( ' ', $source_classes ) . '"';
+				}
+				if ( preg_match( '/\bstyle=(["\'])(.*?)\1/is', $attributes ) ) {
+					$attributes = preg_replace( '/\bstyle=(["\'])(.*?)\1/is', 'style=$1$2;min-height:0$1', $attributes, 1 ) ?? $attributes;
+				} else {
+					$attributes .= ' style="min-height:0"';
+				}
+				return '<button' . $attributes . '>';
+			},
+			$projected,
+			1
+		);
+		return is_string( $projected ) ? $projected : $html;
+	}
+
+	/** Rebuild source input-only wrapper layers inside Jetpack's field shell. */
+	public static function project_wrapper_classes( string $html ): string {
+		$wrapper_layers = array();
+		$projected      = preg_replace_callback(
+			'/\bclass=(["\'])(.*?)\1/s',
+			static function ( array $matches ) use ( &$wrapper_layers ): string {
+				$classes    = preg_split( '/\s+/', trim( $matches[2] ) );
+				$classes    = false === $classes ? array() : $classes;
+				$is_wrapper = (bool) array_filter( $classes, static fn ( string $class_name ): bool => 1 === preg_match( '/^grunion-field-[A-Za-z0-9_-]+-wrap$/D', $class_name ) );
+				$output     = array();
+				foreach ( $classes as $class_name ) {
+					if ( preg_match( '/^ssi-source-wrapper-([0-9]{1,2})--([A-Za-z_][A-Za-z0-9_-]{0,79})-wrap$/D', $class_name, $marker ) ) {
+						if ( $is_wrapper ) {
+							$wrapper_layers[ (int) $marker[1] ][] = $marker[2];
+						}
+						continue;
+					}
+					if ( str_starts_with( $class_name, 'ssi-source-wrapper--' ) ) {
+						if ( $is_wrapper && str_ends_with( $class_name, '-wrap' ) ) {
+							$source_class = substr( $class_name, strlen( 'ssi-source-wrapper--' ), -strlen( '-wrap' ) );
+							if ( 1 === preg_match( '/^[A-Za-z_][A-Za-z0-9_-]{0,79}$/D', $source_class ) ) {
+								$wrapper_layers[0][] = $source_class;
+							}
+						}
+						continue;
+					}
+					$output[] = $class_name;
+				}
+				return 'class=' . $matches[1] . implode( ' ', array_values( array_unique( $output ) ) ) . $matches[1];
+			},
+			$html
+		);
+		if ( ! is_string( $projected ) || empty( $wrapper_layers ) ) {
+			return is_string( $projected ) ? $projected : $html;
+		}
+
+		ksort( $wrapper_layers );
+		$open  = '';
+		$close = '';
+		foreach ( $wrapper_layers as $classes ) {
+			$classes = array_values( array_unique( $classes ) );
+			$open   .= '<div class="' . implode( ' ', $classes ) . '">';
+			$close   = '</div>' . $close;
+		}
+		$wrapped = preg_replace_callback(
+			'/<input\b[^>]*>|<textarea\b[^>]*>.*?<\/textarea>|<select\b[^>]*>.*?<\/select>/is',
+			static fn ( array $control_match ): string => $open . $control_match[0] . $close,
+			$projected,
+			1
+		);
+		return is_string( $wrapped ) ? $wrapped : $projected;
+	}
+}
diff --git a/tests/form-materializer-smoke.php b/tests/form-materializer-smoke.php
index da195134..dd30397a 100644
--- a/tests/form-materializer-smoke.php
+++ b/tests/form-materializer-smoke.php
@@ -266,7 +266,7 @@ public function is_registered( string $name ): bool {
 					array( 'tag' => 'input', 'type' => 'radio', 'name' => 'format', 'label' => 'In person', 'options' => array( 'In person', 'Online' ) ),
 					array( 'tag' => 'input', 'type' => 'checkbox', 'name' => 'updates', 'label' => 'Send me updates' ),
 					array( 'tag' => 'textarea', 'type' => 'textarea', 'name' => 'message', 'label' => 'Message' ),
-					array( 'tag' => 'button', 'type' => 'submit', 'label' => 'Send message' ),
+					array( 'tag' => 'button', 'type' => 'submit', 'class' => 'source-submit', 'label' => 'Send message', 'presentation' => array( 'style' => array( 'spacing' => array( 'padding' => array( 'top' => '11px', 'bottom' => '11px' ) ) ) ) ),
 				),
 			),
 		),
@@ -290,6 +290,23 @@ public function is_registered( string $name ): bool {
 	$assert( str_contains( $markup, 'wp:jetpack/field-textarea' ), 'markup-field-textarea' );
 	$assert( str_contains( $markup, 'wp:button' ) && ! str_contains( $markup, 'wp:jetpack/button' ), 'markup-canonical-core-submit-button' );
 	$assert( 1 === substr_count( $markup, '<!-- wp:button ' ) && str_contains( $markup, '<button type="submit" class="wp-block-button__link wp-element-button">Send message</button>' ), 'source-submit-control-emits-one-canonical-button' );
+	$assert( str_contains( $markup, 'form-button-submit is-submit ssi-source-submit--source-submit ssi-provider-submit-presentation' ), 'source-submit-control-presentation-projects-onto-core-button' );
+	// The source stylesheet governs this button, so the block claims no style
+	// attribute it would then have to reproduce in saved markup. That agreement
+	// with core's save() output is what keeps imported forms clean in the editor.
+	$submit_attrs = array();
+	foreach ( parse_blocks( $markup ) as $parsed_form ) {
+		$collect = static function ( array $blocks, callable $collect ) use ( &$submit_attrs ): void {
+			foreach ( $blocks as $parsed ) {
+				if ( 'core/button' === ( $parsed['blockName'] ?? '' ) ) {
+					$submit_attrs[] = $parsed['attrs'] ?? array();
+				}
+				$collect( $parsed['innerBlocks'] ?? array(), $collect );
+			}
+		};
+		$collect( array( $parsed_form ), $collect );
+	}
+	$assert( 1 === count( $submit_attrs ) && ! array_key_exists( 'style', $submit_attrs[0] ), 'source-submit-block-claims-no-unrenderable-style-attribute', wp_json_encode( $submit_attrs ) );
 	$assert( str_contains( $markup, 'hello@example.com' ), 'markup-mailto-recipient' );
 	$assert( str_contains( $markup, '"options":["Sales","Support"]' ), 'markup-select-options' );
 	$assert( 1 === preg_match( '/<div class="wp-block-jetpack-contact-form form contact ssi-form-[a-f0-9]{12}">/', $markup ), 'markup-contact-form-wrapper-and-source-classes' );
@@ -404,6 +421,44 @@ public function is_registered( string $name ): bool {
 	$assert( ! empty( Static_Site_Importer_Entity_Materializer_Registry::validate_forms_manifest( $unsafe_presentation )['errors'] ) && ! empty( Static_Site_Importer_Entity_Materializer_Registry::validate_forms_manifest( $oversized_presentation )['errors'] ), 'form-presentation-contract-rejects-unsafe-or-unbounded-input' );
 	$topology_seed_repeat = Static_Site_Importer_Form_Seeder::seed( array( 'forms' => $validated_topology['forms'] ) );
 	$assert( $topology_markup === (string) ( $topology_seed_repeat['forms'][0]['block_markup'] ?? '' ), 'provider-layout-classes-are-stable-for-identical-source-form' );
+	$field_list_form = $topology_form['forms'][0];
+	foreach ( $field_list_form['control_topology']['nodes'] as &$field_list_node ) {
+		++$field_list_node['depth'];
+		if ( null === ( $field_list_node['parent'] ?? null ) ) {
+			$field_list_node['parent'] = 'wrapper-4';
+		}
+	}
+	unset( $field_list_node );
+	array_unshift( $field_list_form['control_topology']['nodes'], array( 'id' => 'wrapper-4', 'kind' => 'wrapper', 'parent' => null, 'order' => 0, 'depth' => 0, 'tag' => 'div', 'class' => 'field-list' ) );
+	$field_list_form['layout_graph']['nodes'][0]['parent'] = 'wrapper-4';
+	array_unshift( $field_list_form['layout_graph']['nodes'], array( 'id' => 'wrapper-4', 'kind' => 'container', 'parent' => null, 'order' => 0, 'source' => array( 'tag' => 'div', 'classes' => array( 'field-list' ) ), 'layout' => array(), 'provenance' => array() ) );
+	$field_list_form['layout_graph']['variants'][] = array( 'node' => 'wrapper-4', 'condition' => array( 'kind' => 'media', 'query' => '(max-width: 48rem)' ), 'layout_patch' => array( 'display' => 'flex', 'direction' => 'column', 'gap' => '2rem' ), 'precedence' => array( 'display' => array( 'source_order' => 1, 'specificity' => 10, 'important' => false ), 'flex-direction' => array( 'source_order' => 1, 'specificity' => 10, 'important' => false ), 'gap' => array( 'source_order' => 1, 'specificity' => 10, 'important' => false ) ), 'provenance' => array( array( 'source_path' => 'assets/form.css', 'source_sha256' => str_repeat( 'f', 64 ), 'selector' => '.field-list', 'condition' => array( 'kind' => 'media', 'query' => '(max-width: 48rem)' ), 'properties' => array( 'display', 'flex-direction', 'gap' ) ) ) );
+	$field_list_validation = Static_Site_Importer_Entity_Materializer_Registry::validate_forms_manifest( array( 'forms' => array( $field_list_form ) ) );
+	$field_list_row = Static_Site_Importer_Form_Seeder::seed( array( 'forms' => $field_list_validation['forms'] ?? array() ) )['forms'][0] ?? array();
+	$assert( str_contains( (string) ( $field_list_row['block_markup'] ?? '' ), 'form contact field-list ssi-form-' ) && in_array( 'provider_field_list_class_projection', array_column( $field_list_row['computed_layout_receipt']['operations'] ?? array(), 'strategy' ), true ) && ! in_array( 'responsive_layout_ownership', array_column( $field_list_row['computed_layout_receipt']['losses'] ?? array(), 'reason_code' ), true ), 'class-owned-field-list-wrapper-projects-onto-provider-container', wp_json_encode( array( 'validation' => $field_list_validation, 'row' => $field_list_row ) ) );
+
+	$grid_submit_form = array(
+		'selector' => 'form.grid-submit',
+		'controls' => array( array( 'tag' => 'input', 'type' => 'email', 'name' => 'email', 'label' => 'Email' ), array( 'tag' => 'button', 'type' => 'submit', 'label' => 'Send' ) ),
+		'control_topology' => array(
+			'schema' => 'generic/form-control-topology/v1', 'max_depth' => 8, 'max_nodes' => 128, 'truncated' => false,
+			'nodes' => array(
+				array( 'id' => 'control-0', 'kind' => 'control', 'parent' => null, 'order' => 0, 'depth' => 0, 'control' => 0 ),
+				array( 'id' => 'wrapper-0', 'kind' => 'wrapper', 'parent' => null, 'order' => 1, 'depth' => 0, 'tag' => 'div' ),
+				array( 'id' => 'control-1', 'kind' => 'control', 'parent' => 'wrapper-0', 'order' => 0, 'depth' => 1, 'control' => 1 ),
+			),
+		),
+		'layout_graph' => $v2_layout_graph( array(
+			array( 'id' => 'form', 'kind' => 'container', 'parent' => null, 'order' => 0, 'source' => array( 'tag' => 'form', 'classes' => array( 'grid-submit' ) ), 'layout' => array( 'display' => 'grid', 'columns' => 'repeat(12, 1fr)' ), 'provenance' => array( array( 'source_path' => 'assets/form.css', 'source_sha256' => str_repeat( 'a', 64 ), 'selector' => '.grid-submit', 'condition' => null, 'properties' => array( 'display', 'grid-template-columns' ) ) ) ),
+			array( 'id' => 'wrapper-0', 'kind' => 'container', 'parent' => 'form', 'order' => 1, 'source' => array( 'tag' => 'div', 'classes' => array( 'submit-cell' ) ), 'layout' => array( 'column' => 'span 4' ), 'provenance' => array( array( 'source_path' => 'assets/form.css', 'source_sha256' => str_repeat( 'a', 64 ), 'selector' => '.submit-cell', 'condition' => null, 'properties' => array( 'grid-column' ) ) ) ),
+		) ),
+	);
+	$grid_submit_condition = array( 'kind' => 'media', 'query' => '(max-width: 767px)' );
+	$grid_submit_form['layout_graph']['variants'][] = array( 'node' => 'wrapper-0', 'condition' => $grid_submit_condition, 'layout_patch' => array( 'column' => 'span 12' ), 'precedence' => array( 'grid-column' => array( 'source_order' => 2, 'specificity' => 10, 'important' => false ) ), 'provenance' => array( array( 'source_path' => 'assets/form.css', 'source_sha256' => str_repeat( 'b', 64 ), 'selector' => '.submit-cell', 'condition' => $grid_submit_condition, 'properties' => array( 'grid-column' ) ) ) );
+	$grid_submit_validation = Static_Site_Importer_Entity_Materializer_Registry::validate_forms_manifest( array( 'forms' => array( $grid_submit_form ) ) );
+	$grid_submit_row = Static_Site_Importer_Form_Seeder::seed( array( 'forms' => $grid_submit_validation['forms'] ?? array() ) )['forms'][0] ?? array();
+	$grid_submit_css = (string) ( $grid_submit_row['provider_layout_overlay_css']['css'] ?? '' );
+	$assert( empty( $grid_submit_validation['errors'] ) && 'mapped' === ( $grid_submit_row['status'] ?? '' ) && in_array( 'provider_grid_span_submit', array_column( $grid_submit_row['computed_layout_receipt']['operations'] ?? array(), 'strategy' ), true ) && str_contains( $grid_submit_css, 'width:33.333%' ) && str_contains( $grid_submit_css, '@media (max-width: 767px)' ) && str_contains( $grid_submit_css, 'width:100%' ), 'proven-grid-span-submit-transposes-to-responsive-provider-width', wp_json_encode( array( 'validation' => $grid_submit_validation, 'row' => $grid_submit_row ) ) );
 
 	// V2 percentage facts replace only a complete, provenance-backed sibling row.
 	$deep_width_form = array(
@@ -571,9 +626,16 @@ public function is_registered( string $name ): bool {
 	$class_owned_seed = Static_Site_Importer_Form_Seeder::seed( array( 'forms' => array( $class_owned_form ) ) );
 	$class_owned_losses = $class_owned_seed['forms'][0]['computed_layout_receipt']['losses'] ?? array();
 	$class_owned_markup = (string) ( $class_owned_seed['forms'][0]['block_markup'] ?? '' );
-	$assert( ! in_array( 'provider_wrapper_layout_unrepresentable', array_column( $class_owned_losses, 'reason_code' ), true ) && str_contains( $class_owned_markup, 'ssi-source-wrapper\u002d\u002dfield' ), 'class-owned-single-field-layout-projects-with-its-provider-wrapper-hook', $class_owned_markup );
+	$assert( ! in_array( 'provider_wrapper_layout_unrepresentable', array_column( $class_owned_losses, 'reason_code' ), true ) && str_contains( $class_owned_markup, 'ssi-source-wrapper-1\u002d\u002dfield' ), 'class-owned-single-field-layout-projects-with-its-provider-wrapper-hook', $class_owned_markup );
 	$projected_wrapper = Static_Site_Importer_Form_Seeder::project_provider_wrapper_classes( '<div class="grunion-field-text-wrap ssi-source-wrapper--field-wrap"><input class="ssi-source-wrapper--field source-input"></div>' );
-	$assert( '<div class="grunion-field-text-wrap field"><input class="source-input"></div>' === $projected_wrapper, 'provider-runtime-projects-source-class-onto-existing-wrapper-only', $projected_wrapper );
+	$assert( '<div class="grunion-field-text-wrap"><div class="field"><input class="source-input"></div></div>' === $projected_wrapper, 'provider-runtime-rebuilds-source-wrapper-inside-field-shell', $projected_wrapper );
+	$layered_wrapper = Static_Site_Importer_Form_Seeder::project_provider_wrapper_classes( '<div class="grunion-field-text-wrap ssi-source-wrapper-6--carrier-wrap ssi-source-wrapper-8--input-shell-wrap"><label>Name</label><input class="source-input"></div>' );
+	$assert( '<div class="grunion-field-text-wrap"><label>Name</label><div class="carrier"><div class="input-shell"><input class="source-input"></div></div></div>' === $layered_wrapper, 'provider-runtime-preserves-ordered-input-wrapper-carriers-below-label', $layered_wrapper );
+	$projected_submit = Static_Site_Importer_Form_Seeder::project_provider_submit_presentation(
+		'<div class="wp-block-button ssi-source-submit--source-submit"><button class="wp-block-button__link">Send</button></div>',
+		array( 'attrs' => array( 'className' => 'wp-block-button ssi-source-submit--source-submit' ) )
+	);
+	$assert( '<div class="wp-block-button"><button class="wp-block-button__link source-submit" style="min-height:0">Send</button></div>' === $projected_submit, 'provider-runtime-projects-submit-classes-and-neutralizes-provider-minimum-height', $projected_submit );
 	$unproven_class_form = $class_owned_form;
 	$unproven_class_form['layout_graph']['nodes'][1]['provenance'] = array();
 	$unproven_class_seed = Static_Site_Importer_Form_Seeder::seed( array( 'forms' => array( $unproven_class_form ) ) );
@@ -904,7 +966,7 @@ static function ( array $adapters ): array {
 	$assert( 'woocommerce' === Static_Site_Importer_Entity_Materializer_Registry::provider_for( 'shop' ), 'shop-provider-unaffected-by-form-override' );
 
 	if ( empty( $failures ) && in_array( '--emit-topology-markup', $argv ?? array(), true ) ) {
-		echo wp_json_encode( array( 'markup' => $topology_markup, 'depth_markup' => $deep_topology_markup, 'deep_width_markup' => $deep_width_markup, 'cara_markup' => $cara_grafted ) ) . "\n";
+		echo wp_json_encode( array( 'markup' => $topology_markup, 'styled_markup' => $markup, 'depth_markup' => $deep_topology_markup, 'deep_width_markup' => $deep_width_markup, 'cara_markup' => $cara_grafted ) ) . "\n";
 		exit( 0 );
 	}
 
diff --git a/tests/form-materializer-topology.test.mjs b/tests/form-materializer-topology.test.mjs
index 32944008..33a97430 100644
--- a/tests/form-materializer-topology.test.mjs
+++ b/tests/form-materializer-topology.test.mjs
@@ -78,7 +78,7 @@ test( 'provider-constrained topology emits nested fields and an editor-valid cor
 		cwd: process.cwd(),
 		encoding: 'utf8',
 	} );
-	const { markup, depth_markup: depthMarkup, deep_width_markup: deepWidthMarkup, cara_markup: caraMarkup } = JSON.parse( output );
+	const { markup, styled_markup: styledMarkup, depth_markup: depthMarkup, deep_width_markup: deepWidthMarkup, cara_markup: caraMarkup } = JSON.parse( output );
 	const warnings = [];
 	const originalWarn = console.warn;
 	const originalError = console.error;
@@ -115,6 +115,20 @@ test( 'provider-constrained topology emits nested fields and an editor-valid cor
 	assert.equal( coreButtons.length, 1 );
 	assert.equal( validateBlock( coreButtons[ 0 ] )[ 0 ], true );
 	assert.match( serialize( coreButtons ), /form-button-submit is-submit/ );
+	// A submit whose presentation comes from the source stylesheet must also be
+	// editor-valid: the block claims no style attribute, so its saved markup
+	// matches what core's save() produces.
+	const styledButtons = [];
+	const collectStyled = ( generatedBlocks ) => {
+		for ( const block of generatedBlocks ) {
+			if ( block.name === 'core/button' ) styledButtons.push( block );
+			collectStyled( block.innerBlocks );
+		}
+	};
+	collectStyled( parse( styledMarkup ) );
+	assert.equal( styledButtons.length, 1 );
+	assert.equal( validateBlock( styledButtons[ 0 ] )[ 0 ], true );
+	assert.equal( styledButtons[ 0 ].attributes.style, undefined );
 	const caraBlocks = parse( caraMarkup );
 	assert.equal( caraBlocks[ 0 ].name, 'core/heading' );
 	assert.equal( caraBlocks[ 1 ].name, 'core/paragraph' );
diff --git a/tests/smoke-companion-plugin.php b/tests/smoke-companion-plugin.php
index 593b8900..4f1cf8b0 100644
--- a/tests/smoke-companion-plugin.php
+++ b/tests/smoke-companion-plugin.php
@@ -31,6 +31,7 @@
 $GLOBALS['static_site_importer_companion_block_owners'] = array();
 $GLOBALS['ssi_companion_actions']     = array();
 $GLOBALS['ssi_companion_filters']     = array();
+$GLOBALS['ssi_companion_registered_filters'] = array();
 
 if ( ! class_exists( 'WP_Error' ) ) {
 	class WP_Error {
@@ -168,7 +169,9 @@ function add_action( string $hook, callable|string $callback ): void {
 }
 
 if ( ! function_exists( 'add_filter' ) ) {
-	function add_filter( string $hook, callable|string $callback ): void {}
+	function add_filter( string $hook, callable|string|array $callback, int $priority = 10, int $accepted_args = 1 ): void {
+		$GLOBALS['ssi_companion_registered_filters'][ $hook ][] = array( $callback, $priority, $accepted_args );
+	}
 }
 
 if ( ! function_exists( 'remove_filter' ) ) {
@@ -467,10 +470,12 @@ function update_option( string $name, mixed $value, bool $autoload = false ): bo
 	$assert( str_contains( $main, 'Plugin Name:' ), 'main-file-has-plugin-header' );
 	$assert( str_contains( $main, "add_filter( 'render_block'" ), 'main-file-scopes-island-enqueue' );
 	$assert( str_contains( $main, 'wp_enqueue_script' ), 'main-file-enqueues-island-js' );
+	$assert( str_contains( $main, "require_once __DIR__ . '/includes/class-static-site-importer-provider-form-runtime.php'" ) && str_contains( $main, 'Static_Site_Importer_Provider_Form_Runtime::register();' ), 'main-file-registers-carried-provider-form-runtime' );
+	$assert( isset( $files['ssi-example-site/includes/class-static-site-importer-provider-form-runtime.php'] ), 'provider-form-runtime-file-emitted' );
 
 	$assert( str_contains( $main, "register_block_type( SSI_EXAMPLE_SITE_" ) && str_contains( $main, "_DIR . 'blocks/' . \$block_dir )" ), 'main-file-registers-metadata-block-directory' );
 	$assert( str_contains( $main, "\$registered instanceof WP_Block_Type" ) && str_contains( $main, "static_site_importer_companion_block_owners" ) && str_contains( $main, "'plugin_file' => 'ssi-example-site/ssi-example-site.php'" ), 'main-file-records-owner-after-metadata-registration' );
-	$assert( ! str_contains( $main, 'Requires Plugins:' ) && ! str_contains( $main, 'Static_Site_Importer_' ) && ! str_contains( $main, 'Automattic\\BlocksEngine' ), 'generated-plugin-declares-no-importer-or-compiler-runtime-dependency' );
+	$assert( ! str_contains( $main, 'Requires Plugins:' ) && ! str_contains( $main, 'Automattic\\BlocksEngine' ), 'generated-plugin-declares-no-importer-or-compiler-runtime-dependency' );
 	$assert( ! str_contains( $main, 'block_specs' ) && ! str_contains( $main, 'render_callback' ) && ! str_contains( $main, "register_block_type( (string)" ), 'main-file-has-no-php-only-registration-fallback' );
 	$block_json = $files['ssi-example-site/blocks/custom-hero/block.json'] ?? '';
 	$assert( '' !== $block_json, 'metadata-block-json-emitted' );
@@ -772,6 +777,18 @@ function update_option( string $name, mixed $value, bool $autoload = false ): bo
 $assert( file_exists( WP_PLUGIN_DIR . '/ssi-example-site/blocks/custom-hero/render.php' ), 'install-writes-render-php-to-disk' );
 $assert( file_exists( WP_PLUGIN_DIR . '/ssi-example-site/blocks/custom-hero/block.json' ), 'install-emits-block-json' );
 $assert( file_exists( WP_PLUGIN_DIR . '/ssi-example-site/blocks/custom-hero/index.js' ), 'install-emits-declared-editor-asset' );
+$assert( file_exists( WP_PLUGIN_DIR . '/ssi-example-site/includes/class-static-site-importer-provider-form-runtime.php' ), 'install-writes-provider-form-runtime' );
+$assert( isset( $GLOBALS['ssi_companion_registered_filters']['grunion_contact_form_field_html'], $GLOBALS['ssi_companion_registered_filters']['render_block_core/button'] ), 'installed-companion-registers-provider-form-runtime-hooks' );
+$submit_filter = $GLOBALS['ssi_companion_registered_filters']['render_block_core/button'][0][0] ?? null;
+$projected_submit = is_callable( $submit_filter ) ? call_user_func(
+	$submit_filter,
+	'<div class="wp-block-button ssi-source-submit--source-submit"><button class="wp-block-button__link">Send</button></div>',
+	array( 'attrs' => array( 'className' => 'ssi-source-submit--source-submit' ) )
+) : '';
+$assert( str_contains( $projected_submit, 'class="wp-block-button"' ) && str_contains( $projected_submit, 'class="wp-block-button__link source-submit"' ), 'installed-companion-projects-submit-presentation-at-runtime' );
+$wrapper_filter = $GLOBALS['ssi_companion_registered_filters']['grunion_contact_form_field_html'][0][0] ?? null;
+$projected_wrapper = is_callable( $wrapper_filter ) ? call_user_func( $wrapper_filter, '<div class="grunion-field-text-wrap ssi-source-wrapper-2--source-box-wrap"><input type="text"></div>' ) : '';
+$assert( str_contains( $projected_wrapper, '<div class="source-box"><input type="text"></div>' ) && ! str_contains( $projected_wrapper, 'ssi-source-wrapper-' ), 'installed-companion-rebuilds-provider-input-wrapper-at-runtime' );
 $standalone_bootstrap = <<<'PHP'
 define( 'ABSPATH', __DIR__ . '/' );
 class WP_Block_Type {