From 7c1930621561f4c52e1298f4c55cfc8ddedb3acd Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Tue, 26 Aug 2025 13:20:20 +0200
Subject: [PATCH 01/12] Serialize accessed derived state props

---
 .../class-wp-interactivity-api.php            | 40 ++++++++++++++++++-
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
index fdde5d429aa6b..630af8c9afc07 100644
--- a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -58,6 +58,18 @@ final class WP_Interactivity_API {
 	 */
 	private $config_data = array();
 
+	/**
+	 * Keeps track of all derived state props accessed during server-side rendering.
+	 *
+	 * This data is serialized and sent to the client as part of the interactivity
+	 * data, and is handled later in the client to support derived state props that
+	 * are lazily hydrated.
+	 *
+	 * @since 6.9.0
+	 * @var array
+	 */
+	private $derived_state_props_accessed = array();
+
 	/**
 	 * Flag that indicates whether the `data-wp-router-region` directive has
 	 * been found in the HTML and processed.
@@ -236,12 +248,17 @@ public function filter_script_module_interactivity_router_data( array $data ): a
 	 * interactivity stores and the configuration will be available using a `getConfig` utility.
 	 *
 	 * @since 6.7.0
+	 * @since 6.9.0 Serializes derived state props accessed during directive processing.
 	 *
 	 * @param array $data Data to filter.
 	 * @return array Data for the Interactivity API script module.
 	 */
 	public function filter_script_module_interactivity_data( array $data ): array {
-		if ( empty( $this->state_data ) && empty( $this->config_data ) ) {
+		if (
+			empty( $this->state_data ) &&
+			empty( $this->config_data ) &&
+			empty( $this->derived_state_props_accessed )
+		) {
 			return $data;
 		}
 
@@ -265,6 +282,16 @@ public function filter_script_module_interactivity_data( array $data ): array {
 			$data['state'] = $state;
 		}
 
+		$derived_props = array();
+		foreach ( $this->derived_state_props_accessed as $key => $value ) {
+			if ( ! empty( $value ) ) {
+				$derived_props[ $key ] = $value;
+			}
+		}
+		if ( ! empty( $derived_props ) ) {
+			$data['derivedStatePropsAccessed'] = $derived_props;
+		}
+
 		return $data;
 	}
 
@@ -598,7 +625,7 @@ private function evaluate( $directive_value ) {
 		// Extracts the value from the store using the reference path.
 		$path_segments = explode( '.', $path );
 		$current       = $store;
-		foreach ( $path_segments as $path_segment ) {
+		foreach ( $path_segments as $index => $path_segment ) {
 			/*
 			 * Special case for numeric arrays and strings. Add length
 			 * property mimicking JavaScript behavior.
@@ -647,6 +674,15 @@ private function evaluate( $directive_value ) {
 				array_push( $this->namespace_stack, $ns );
 				try {
 					$current = $current();
+
+					// Tracks derived state properties that are accessed during rendering.
+					$this->derived_state_props_accessed[ $ns ] = $this->derived_state_props_accessed[ $ns ] ?? array();
+
+					// Builds path for the current property and add it to tracking if not already present.
+					$current_path = implode( '.', array_slice( $path_segments, 0, $index + 1 ) );
+					if ( ! in_array( $current_path, $this->derived_state_props_accessed[ $ns ], true ) ) {
+						$this->derived_state_props_accessed[ $ns ][] = $current_path;
+					}
 				} catch ( Throwable $e ) {
 					_doing_it_wrong(
 						__METHOD__,

From 5cbb32444312f1e8c56d38fd1a5428cf161ba62d Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Wed, 27 Aug 2025 12:27:49 +0200
Subject: [PATCH 02/12] Add tests for accessed derived state props
 serialization

---
 .../interactivity-api/wpInteractivityAPI.php  | 93 +++++++++++++++++++
 1 file changed, 93 insertions(+)

diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
index 1aa9a7238e104..2754de55708d1 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
@@ -25,6 +25,7 @@ class Tests_Interactivity_API_WpInteractivityAPI extends WP_UnitTestCase {
 	public function set_up() {
 		parent::set_up();
 		$this->interactivity = new WP_Interactivity_API();
+		wp_default_script_modules();
 	}
 
 	public function charset_iso_8859_1() {
@@ -311,6 +312,98 @@ function () {
 
 		$this->assertSame( array( 'state' => array( 'myPlugin' => array( 'emptyArray' => array() ) ) ), $filter->get_args()[0][0] );
 	}
+	/**
+	 * Tests that derived state props invoked during directive evaluation are
+	 * serialized correctly.
+	 *
+	 * @ticket XXX
+	 */
+	public function test_invoked_derived_state_props_are_serialized() {
+		$returns_whatever = function () { 
+			return 'whatever';
+		};
+
+		$returns_array = function () {
+			return array( 'prop' => 'whatever' );
+		};
+
+		$filter = $this->get_script_data_filter_result(
+			function () use ( $returns_whatever, $returns_array ) {
+				$this->interactivity->state( 'pluginWithInvokedDerivedState', array(
+					'derivedProp' => $returns_whatever,
+					'nested'      => array (
+						'derivedProp'             => $returns_whatever,
+						'derivedPropReturnsArray' => $returns_array,
+					),
+				) );
+
+				$this->interactivity->state( 'pluginWithInvokedDerivedStateReturningArray', array(
+					'derivedProp' => $returns_whatever,
+					'nested'      => array (
+						'derivedProp'             => $returns_whatever,
+						'derivedPropReturnsArray' => $returns_array,
+					),
+				) );
+
+				$this->interactivity->state( 'pluginWithoutInvokedDerivedState', array(
+					'derivedProp' => $returns_whatever,
+					'nested'      => array (
+						'derivedProp' => $returns_whatever,
+					),
+				) );
+
+				$this->set_internal_context_stack( array() );
+				
+				// Multiple evaluations should be serialized only once.
+				$this->set_internal_namespace_stack( 'pluginWithInvokedDerivedState' );
+				$this->evaluate( 'state.derivedProp' );
+				$this->evaluate( 'state.derivedProp' );
+				$this->evaluate( 'state.nested.derivedProp' );
+				$this->evaluate( 'state.nested.derivedProp' );
+
+				// Only the path part that points to a derived state prop should be serialized.
+				$this->set_internal_namespace_stack( 'pluginWithInvokedDerivedStateReturningArray' );
+				$this->evaluate( 'state.nested.derivedProp.prop' );
+			}
+		);
+
+		$this->assertSame(
+			array(
+				'state'                     => array(
+					'pluginWithInvokedDerivedState'               => array(
+						'derivedProp' => $returns_whatever,
+						'nested'      => array (
+							'derivedProp'             => $returns_whatever,
+							'derivedPropReturnsArray' => $returns_array,
+						),
+					),
+					'pluginWithInvokedDerivedStateReturningArray' => array(
+						'derivedProp' => $returns_whatever,
+						'nested'      => array (
+							'derivedProp'             => $returns_whatever,
+							'derivedPropReturnsArray' => $returns_array,
+						),
+					),
+					'pluginWithoutInvokedDerivedState'            => array(
+						'derivedProp' => $returns_whatever,
+						'nested'      => array (
+							'derivedProp' => $returns_whatever,
+						),
+					),
+				),
+				'derivedStatePropsAccessed' => array(
+					'pluginWithInvokedDerivedState' => array(
+						'state.derivedProp',
+						'state.nested.derivedProp',
+					),
+					'pluginWithInvokedDerivedStateReturningArray' => array(
+						'state.nested.derivedProp',
+					),
+				)
+			),
+			$filter->get_args()[0][0]
+		);
+	}
 
 	/**
 	 * Tests that empty config objects are pruned from printed data.

From 063a1f5eec38476dce4641570066e07993a75234 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Wed, 27 Aug 2025 12:32:28 +0200
Subject: [PATCH 03/12] Make `data-wp-each-child` to include namespace and path

---
 .../interactivity-api/class-wp-interactivity-api.php        | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
index 630af8c9afc07..6d7e214eddcbc 100644
--- a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -1241,8 +1241,8 @@ private function data_wp_each_processor( WP_Interactivity_API_Directives_Process
 			}
 
 			// Extracts the namespace from the directive attribute value.
-			$namespace_value         = end( $this->namespace_stack );
-			list( $namespace_value ) = is_string( $attribute_value ) && ! empty( $attribute_value )
+			$namespace_value                = end( $this->namespace_stack );
+			list( $namespace_value, $path ) = is_string( $attribute_value ) && ! empty( $attribute_value )
 				? $this->extract_directive_value( $attribute_value, $namespace_value )
 				: array( $namespace_value, null );
 
@@ -1267,7 +1267,7 @@ private function data_wp_each_processor( WP_Interactivity_API_Directives_Process
 				// Adds the `data-wp-each-child` to each top-level tag.
 				$i = new WP_Interactivity_API_Directives_Processor( $processed_item );
 				while ( $i->next_tag() ) {
-					$i->set_attribute( 'data-wp-each-child', true );
+					$i->set_attribute( 'data-wp-each-child', $namespace_value . '::' . $path );
 					$i->next_balanced_tag_closer_tag();
 				}
 				$processed_content .= $i->get_updated_html();

From fff193c715cf7108592332e95497207e748834e2 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Thu, 28 Aug 2025 11:45:20 +0200
Subject: [PATCH 04/12] Fix linting errors

---
 .../interactivity-api/wpInteractivityAPI.php  | 63 +++++++++++--------
 1 file changed, 36 insertions(+), 27 deletions(-)

diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
index 2754de55708d1..b68d602610bac 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
@@ -319,7 +319,7 @@ function () {
 	 * @ticket XXX
 	 */
 	public function test_invoked_derived_state_props_are_serialized() {
-		$returns_whatever = function () { 
+		$returns_whatever = function () {
 			return 'whatever';
 		};
 
@@ -329,31 +329,40 @@ public function test_invoked_derived_state_props_are_serialized() {
 
 		$filter = $this->get_script_data_filter_result(
 			function () use ( $returns_whatever, $returns_array ) {
-				$this->interactivity->state( 'pluginWithInvokedDerivedState', array(
-					'derivedProp' => $returns_whatever,
-					'nested'      => array (
-						'derivedProp'             => $returns_whatever,
-						'derivedPropReturnsArray' => $returns_array,
-					),
-				) );
+				$this->interactivity->state(
+					'pluginWithInvokedDerivedState',
+					array(
+						'derivedProp' => $returns_whatever,
+						'nested'      => array(
+							'derivedProp'             => $returns_whatever,
+							'derivedPropReturnsArray' => $returns_array,
+						),
+					)
+				);
 
-				$this->interactivity->state( 'pluginWithInvokedDerivedStateReturningArray', array(
-					'derivedProp' => $returns_whatever,
-					'nested'      => array (
-						'derivedProp'             => $returns_whatever,
-						'derivedPropReturnsArray' => $returns_array,
-					),
-				) );
+				$this->interactivity->state(
+					'pluginWithInvokedDerivedStateReturningArray',
+					array(
+						'derivedProp' => $returns_whatever,
+						'nested'      => array(
+							'derivedProp'             => $returns_whatever,
+							'derivedPropReturnsArray' => $returns_array,
+						),
+					)
+				);
 
-				$this->interactivity->state( 'pluginWithoutInvokedDerivedState', array(
-					'derivedProp' => $returns_whatever,
-					'nested'      => array (
+				$this->interactivity->state(
+					'pluginWithoutInvokedDerivedState',
+					array(
 						'derivedProp' => $returns_whatever,
-					),
-				) );
+						'nested'      => array(
+							'derivedProp' => $returns_whatever,
+						),
+					)
+				);
 
 				$this->set_internal_context_stack( array() );
-				
+
 				// Multiple evaluations should be serialized only once.
 				$this->set_internal_namespace_stack( 'pluginWithInvokedDerivedState' );
 				$this->evaluate( 'state.derivedProp' );
@@ -370,23 +379,23 @@ function () use ( $returns_whatever, $returns_array ) {
 		$this->assertSame(
 			array(
 				'state'                     => array(
-					'pluginWithInvokedDerivedState'               => array(
+					'pluginWithInvokedDerivedState'    => array(
 						'derivedProp' => $returns_whatever,
-						'nested'      => array (
+						'nested'      => array(
 							'derivedProp'             => $returns_whatever,
 							'derivedPropReturnsArray' => $returns_array,
 						),
 					),
 					'pluginWithInvokedDerivedStateReturningArray' => array(
 						'derivedProp' => $returns_whatever,
-						'nested'      => array (
+						'nested'      => array(
 							'derivedProp'             => $returns_whatever,
 							'derivedPropReturnsArray' => $returns_array,
 						),
 					),
-					'pluginWithoutInvokedDerivedState'            => array(
+					'pluginWithoutInvokedDerivedState' => array(
 						'derivedProp' => $returns_whatever,
-						'nested'      => array (
+						'nested'      => array(
 							'derivedProp' => $returns_whatever,
 						),
 					),
@@ -399,7 +408,7 @@ function () use ( $returns_whatever, $returns_array ) {
 					'pluginWithInvokedDerivedStateReturningArray' => array(
 						'state.nested.derivedProp',
 					),
-				)
+				),
 			),
 			$filter->get_args()[0][0]
 		);

From 901a358d8913d9f37b5d61c7a88da2951a627ff8 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Fri, 5 Sep 2025 18:39:54 +0200
Subject: [PATCH 05/12] Update wp-each tests

---
 .../wpInteractivityAPI-wp-each.php            | 60 +++++++++----------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
index 0446fa461df14..42d05b18c9287 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
@@ -88,8 +88,8 @@ public function test_wp_each_simple_tags() {
 			'<template data-wp-each="myPlugin::state.list">' .
 				'<span data-wp-text="myPlugin::context.item"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">2</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -140,8 +140,8 @@ public function test_wp_each_merges_context_correctly() {
 				'<template data-wp-each="myPlugin::state.list">' .
 					'<span data-wp-bind--id="myPlugin::context.id" data-wp-text="myPlugin::context.item"></span>' .
 				'</template>' .
-				'<span data-wp-each-child id="some-id" data-wp-bind--id="myPlugin::context.id" data-wp-text="myPlugin::context.item">1</span>' .
-				'<span data-wp-each-child id="some-id" data-wp-bind--id="myPlugin::context.id" data-wp-text="myPlugin::context.item">2</span>' .
+				'<span data-wp-each-child="myPlugin::state.list" id="some-id" data-wp-bind--id="myPlugin::context.id" data-wp-text="myPlugin::context.item">1</span>' .
+				'<span data-wp-each-child="myPlugin::state.list" id="some-id" data-wp-bind--id="myPlugin::context.id" data-wp-text="myPlugin::context.item">2</span>' .
 				'<div id="after-wp-each" data-wp-bind--id="myPlugin::context.after" data-wp-text="myPlugin::context.item">New text</div>' .
 			'</div>';
 		$new      = $this->interactivity->process_directives( $original );
@@ -168,8 +168,8 @@ public function test_wp_each_gets_arrays_from_context() {
 				'<template data-wp-each="myPlugin::context.list">' .
 					'<span data-wp-text="myPlugin::context.item"></span>' .
 				'</template>' .
-				'<span data-wp-each-child data-wp-text="myPlugin::context.item">1</span>' .
-				'<span data-wp-each-child data-wp-text="myPlugin::context.item">2</span>' .
+				'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.item">1</span>' .
+				'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.item">2</span>' .
 				'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>' .
 			'</div>';
 		$new      = $this->interactivity->process_directives( $original );
@@ -196,8 +196,8 @@ public function test_wp_each_default_namespace() {
 				'<template data-wp-each="state.list">' .
 					'<span data-wp-text="context.item"></span>' .
 				'</template>' .
-				'<span data-wp-each-child data-wp-text="context.item">1</span>' .
-				'<span data-wp-each-child data-wp-text="context.item">2</span>' .
+				'<span data-wp-each-child="myPlugin::state.list" data-wp-text="context.item">1</span>' .
+				'<span data-wp-each-child="myPlugin::state.list" data-wp-text="context.item">2</span>' .
 				'<div id="after-wp-each" data-wp-bind--id="state.after">Text</div>' .
 			'</div>';
 		$new      = $this->interactivity->process_directives( $original );
@@ -223,10 +223,10 @@ public function test_wp_each_multiple_tags_per_item() {
 				'<span data-wp-text="myPlugin::context.item"></span>' .
 				'<span data-wp-text="myPlugin::context.item"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">2</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">2</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -251,10 +251,10 @@ public function test_wp_each_void_tags() {
 				'<img data-wp-bind--id="myPlugin::context.item">' .
 				'<img data-wp-bind--id="myPlugin::context.item">' .
 			'</template>' .
-			'<img data-wp-each-child id="1" data-wp-bind--id="myPlugin::context.item">' .
-			'<img data-wp-each-child id="1" data-wp-bind--id="myPlugin::context.item">' .
-			'<img data-wp-each-child id="2" data-wp-bind--id="myPlugin::context.item">' .
-			'<img data-wp-each-child id="2" data-wp-bind--id="myPlugin::context.item">' .
+			'<img data-wp-each-child="myPlugin::state.list" id="1" data-wp-bind--id="myPlugin::context.item">' .
+			'<img data-wp-each-child="myPlugin::state.list" id="1" data-wp-bind--id="myPlugin::context.item">' .
+			'<img data-wp-each-child="myPlugin::state.list" id="2" data-wp-bind--id="myPlugin::context.item">' .
+			'<img data-wp-each-child="myPlugin::state.list" id="2" data-wp-bind--id="myPlugin::context.item">' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -280,10 +280,10 @@ public function test_wp_each_void_and_non_void_tags() {
 				'<img data-wp-bind--id="myPlugin::context.item">' .
 				'<span data-wp-text="myPlugin::context.item"></span>' .
 			'</template>' .
-			'<img data-wp-each-child id="1" data-wp-bind--id="myPlugin::context.item">' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">1</span>' .
-			'<img data-wp-each-child id="2" data-wp-bind--id="myPlugin::context.item">' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">2</span>' .
+			'<img data-wp-each-child="myPlugin::state.list" id="1" data-wp-bind--id="myPlugin::context.item">' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">1</span>' .
+			'<img data-wp-each-child="myPlugin::state.list" id="2" data-wp-bind--id="myPlugin::context.item">' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">2</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -310,10 +310,10 @@ public function test_wp_each_nested_tags() {
 					'id: <span data-wp-text="myPlugin::context.item"></span>' .
 				'</div>' .
 			'</template>' .
-			'<div data-wp-each-child id="1" data-wp-bind--id="myPlugin::context.item">' .
+			'<div data-wp-each-child="myPlugin::state.list" id="1" data-wp-bind--id="myPlugin::context.item">' .
 				'id: <span data-wp-text="myPlugin::context.item">1</span>' .
 			'</div>' .
-			'<div data-wp-each-child id="2" data-wp-bind--id="myPlugin::context.item">' .
+			'<div data-wp-each-child="myPlugin::state.list" id="2" data-wp-bind--id="myPlugin::context.item">' .
 				'id: <span data-wp-text="myPlugin::context.item">2</span>' .
 			'</div>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
@@ -355,10 +355,10 @@ public function test_wp_each_nested_item_properties() {
 				'<span data-wp-text="myPlugin::context.item.id"></span>' .
 				'<span data-wp-text="myPlugin::context.item.name"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item.id">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item.name">one</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item.id">2</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item.name">two</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item.id">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item.name">one</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item.id">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item.name">two</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -381,8 +381,8 @@ public function test_wp_each_different_item_names() {
 			'<template data-wp-each--myitem="myPlugin::state.list">' .
 				'<span data-wp-text="myPlugin::context.myitem"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.myitem">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.myitem">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.myitem">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.myitem">2</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -406,8 +406,8 @@ public function test_wp_each_different_item_names_transforms_camelcase() {
 			'<template data-wp-each--my-item="myPlugin::state.list">' .
 				'<span data-wp-text="myPlugin::context.myItem"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.myItem">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.myItem">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.myItem">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.myItem">2</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );

From a04465145964745d370a0199ff9c1ab8e6b5c739 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Fri, 5 Sep 2025 21:24:00 +0200
Subject: [PATCH 06/12] Fix data-wp-each-child value assignment

---
 .../class-wp-interactivity-api.php            | 15 ++++-
 .../wpInteractivityAPI-wp-each.php            | 56 +++++++++----------
 2 files changed, 41 insertions(+), 30 deletions(-)

diff --git a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
index 6d7e214eddcbc..b16147236ee20 100644
--- a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -1196,6 +1196,7 @@ private function data_wp_router_region_processor( WP_Interactivity_API_Directive
 	 * `template` tag.
 	 *
 	 * @since 6.5.0
+	 * @since 6.9.0 Include the list path in the rendered `data-wp-each-child` directives.
 	 *
 	 * @param WP_Interactivity_API_Directives_Processor $p               The directives processor instance.
 	 * @param string                                    $mode            Whether the processing is entering or exiting the tag.
@@ -1264,10 +1265,20 @@ private function data_wp_each_processor( WP_Interactivity_API_Directives_Process
 					return;
 				}
 
-				// Adds the `data-wp-each-child` to each top-level tag.
+				/*
+				 * Adds the `data-wp-each-child` directive to each top-level tag
+				 * rendered by this `data-wp-each` directive. The value is the
+				 * `data-wp-each` directive's namespace and path.
+				 *
+				 * Nested `data-wp-each` directives could render
+				 * `data-wp-each-child` elements at the top level as well, and
+				 * they should be ignored.
+				 */
 				$i = new WP_Interactivity_API_Directives_Processor( $processed_item );
 				while ( $i->next_tag() ) {
-					$i->set_attribute( 'data-wp-each-child', $namespace_value . '::' . $path );
+					if ( ! $i->get_attribute( 'data-wp-each-child' ) ) {
+						$i->set_attribute( 'data-wp-each-child', $namespace_value . '::' . $path );
+					}
 					$i->next_balanced_tag_closer_tag();
 				}
 				$processed_content .= $i->get_updated_html();
diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
index 42d05b18c9287..d3de768e21cae 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
@@ -473,18 +473,18 @@ public function test_wp_each_nested_template_tags() {
 					'<span data-wp-text="myPlugin::context.item2"></span>' .
 				'</template>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item1">1</span>' .
-			'<template data-wp-each-child data-wp-each--item2="myPlugin::state.list2">' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item1">1</span>' .
+			'<template data-wp-each-child="myPlugin::state.list" data-wp-each--item2="myPlugin::state.list2">' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">4</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item1">2</span>' .
-			'<template data-wp-each-child data-wp-each--item2="myPlugin::state.list2">' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item1">2</span>' .
+			'<template data-wp-each-child="myPlugin::state.list" data-wp-each--item2="myPlugin::state.list2">' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -515,22 +515,22 @@ public function test_wp_each_directly_nested_template_tags() {
 					'<span data-wp-text="myPlugin::context.item2"></span>' .
 				'</template>' .
 			'</template>' .
-			'<template data-wp-each-child data-wp-each--item2="myPlugin::state.list2">' .
+			'<template data-wp-each-child="myPlugin::state.list" data-wp-each--item2="myPlugin::state.list2">' .
 				'<span data-wp-text="myPlugin::context.item1"></span>' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item1">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item1">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">4</span>' .
-			'<template data-wp-each-child data-wp-each--item2="myPlugin::state.list2">' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
+			'<template data-wp-each-child="myPlugin::state.list" data-wp-each--item2="myPlugin::state.list2">' .
 				'<span data-wp-text="myPlugin::context.item1"></span>' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item1">2</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item1">2</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item2">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -559,16 +559,16 @@ public function test_wp_each_nested_template_tags_using_previous_item_as_list()
 					'<span data-wp-text="myPlugin::context.number"></span>' .
 				'</template>' .
 			'</template>' .
-			'<template data-wp-each-child data-wp-each--number="myPlugin::context.list">' .
+			'<template data-wp-each-child="myPlugin::state.list2" data-wp-each--number="myPlugin::context.list">' .
 				'<span data-wp-text="myPlugin::context.number"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.number">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.number">2</span>' .
-			'<template data-wp-each-child data-wp-each--number="myPlugin::context.list">' .
+			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">1</span>' .
+			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">2</span>' .
+			'<template data-wp-each-child="myPlugin::state.list2" data-wp-each--number="myPlugin::context.list">' .
 				'<span data-wp-text="myPlugin::context.number"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.number">3</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.number">4</span>' .
+			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">3</span>' .
+			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">4</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -671,15 +671,15 @@ public function test_wp_each_doesnt_process_with_manual_server_directive_process
 			'<template data-wp-each="myPlugin::state.list">' .
 				'<span data-wp-text="myPlugin::context.item"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">2</span>' .
 			'<div data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$expected = '' .
 			'<template data-wp-each="myPlugin::state.list">' .
 				'<span data-wp-text="myPlugin::context.item"></span>' .
 			'</template>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">1</span>' .
-			'<span data-wp-each-child data-wp-text="myPlugin::context.item">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item">2</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );

From 8985e108dbcb94c4a8fbf832c37e73f4fe1210b5 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Wed, 15 Oct 2025 17:03:56 +0200
Subject: [PATCH 07/12] Fix ticket number

---
 tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
index b68d602610bac..4a2ba509b773d 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
@@ -316,7 +316,7 @@ function () {
 	 * Tests that derived state props invoked during directive evaluation are
 	 * serialized correctly.
 	 *
-	 * @ticket XXX
+	 * @ticket 63898
 	 */
 	public function test_invoked_derived_state_props_are_serialized() {
 		$returns_whatever = function () {

From bbe8791e42b510360d53d97e7c2f9c46ebd29ec5 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Thu, 16 Oct 2025 12:35:16 +0200
Subject: [PATCH 08/12] Set the value of all `data-wp-each-child` to the top
 most `data-wp-each` element

---
 .../class-wp-interactivity-api.php            |  6 ++--
 .../wpInteractivityAPI-wp-each.php            | 32 +++++++++----------
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
index b16147236ee20..289be13cedb8d 100644
--- a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -1272,13 +1272,11 @@ private function data_wp_each_processor( WP_Interactivity_API_Directives_Process
 				 *
 				 * Nested `data-wp-each` directives could render
 				 * `data-wp-each-child` elements at the top level as well, and
-				 * they should be ignored.
+				 * they should be overwritten.
 				 */
 				$i = new WP_Interactivity_API_Directives_Processor( $processed_item );
 				while ( $i->next_tag() ) {
-					if ( ! $i->get_attribute( 'data-wp-each-child' ) ) {
-						$i->set_attribute( 'data-wp-each-child', $namespace_value . '::' . $path );
-					}
+					$i->set_attribute( 'data-wp-each-child', $namespace_value . '::' . $path );
 					$i->next_balanced_tag_closer_tag();
 				}
 				$processed_content .= $i->get_updated_html();
diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
index d3de768e21cae..f0952dfabea89 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI-wp-each.php
@@ -477,14 +477,14 @@ public function test_wp_each_nested_template_tags() {
 			'<template data-wp-each-child="myPlugin::state.list" data-wp-each--item2="myPlugin::state.list2">' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">4</span>' .
 			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item1">2</span>' .
 			'<template data-wp-each-child="myPlugin::state.list" data-wp-each--item2="myPlugin::state.list2">' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">4</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -519,18 +519,18 @@ public function test_wp_each_directly_nested_template_tags() {
 				'<span data-wp-text="myPlugin::context.item1"></span>' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">1</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">1</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item1">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item1">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">4</span>' .
 			'<template data-wp-each-child="myPlugin::state.list" data-wp-each--item2="myPlugin::state.list2">' .
 				'<span data-wp-text="myPlugin::context.item1"></span>' .
 				'<span data-wp-text="myPlugin::context.item2"></span>' .
 			'</template>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">2</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">3</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item1">2</span>' .
-			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.item2">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item1">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item1">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list" data-wp-text="myPlugin::context.item2">4</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );
@@ -562,13 +562,13 @@ public function test_wp_each_nested_template_tags_using_previous_item_as_list()
 			'<template data-wp-each-child="myPlugin::state.list2" data-wp-each--number="myPlugin::context.list">' .
 				'<span data-wp-text="myPlugin::context.number"></span>' .
 			'</template>' .
-			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">1</span>' .
-			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">2</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.number">1</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.number">2</span>' .
 			'<template data-wp-each-child="myPlugin::state.list2" data-wp-each--number="myPlugin::context.list">' .
 				'<span data-wp-text="myPlugin::context.number"></span>' .
 			'</template>' .
-			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">3</span>' .
-			'<span data-wp-each-child="myPlugin::context.list" data-wp-text="myPlugin::context.number">4</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.number">3</span>' .
+			'<span data-wp-each-child="myPlugin::state.list2" data-wp-text="myPlugin::context.number">4</span>' .
 			'<div id="after-wp-each" data-wp-bind--id="myPlugin::state.after">Text</div>';
 		$new      = $this->interactivity->process_directives( $original );
 		$this->assertSame( $expected, $new );

From 78659e83fd482982c2231cdd7acfb909ca42d1aa Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Fri, 17 Oct 2025 10:32:44 +0200
Subject: [PATCH 09/12] Add missing since tags to comments

---
 .../interactivity-api/class-wp-interactivity-api.php     | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
index 289be13cedb8d..dd6fbad0bce86 100644
--- a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -675,7 +675,12 @@ private function evaluate( $directive_value ) {
 				try {
 					$current = $current();
 
-					// Tracks derived state properties that are accessed during rendering.
+					/*
+					 * Tracks derived state properties that are accessed during
+					 * rendering.
+					 *
+					 * @since 6.9.0
+					 */
 					$this->derived_state_props_accessed[ $ns ] = $this->derived_state_props_accessed[ $ns ] ?? array();
 
 					// Builds path for the current property and add it to tracking if not already present.
@@ -1273,6 +1278,8 @@ private function data_wp_each_processor( WP_Interactivity_API_Directives_Process
 				 * Nested `data-wp-each` directives could render
 				 * `data-wp-each-child` elements at the top level as well, and
 				 * they should be overwritten.
+				 *
+				 * @since 6.9.0
 				 */
 				$i = new WP_Interactivity_API_Directives_Processor( $processed_item );
 				while ( $i->next_tag() ) {

From 09f9a227c5d0958bfcc2f98dc03997471092b72c Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Fri, 17 Oct 2025 10:58:41 +0200
Subject: [PATCH 10/12] Change `derivedStatePropsAccessed` to
 `derivedStateClosures`

---
 .../interactivity-api/class-wp-interactivity-api.php            | 2 +-
 tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
index dd6fbad0bce86..63266ee367d24 100644
--- a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -289,7 +289,7 @@ public function filter_script_module_interactivity_data( array $data ): array {
 			}
 		}
 		if ( ! empty( $derived_props ) ) {
-			$data['derivedStatePropsAccessed'] = $derived_props;
+			$data['derivedStateClosures'] = $derived_props;
 		}
 
 		return $data;
diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
index 4a2ba509b773d..84327f1b69ec4 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
@@ -400,7 +400,7 @@ function () use ( $returns_whatever, $returns_array ) {
 						),
 					),
 				),
-				'derivedStatePropsAccessed' => array(
+				'derivedStateClosures' => array(
 					'pluginWithInvokedDerivedState' => array(
 						'state.derivedProp',
 						'state.nested.derivedProp',

From f34b7e8a43a2768f8381a42c5e9725b954c152c0 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Fri, 17 Oct 2025 14:14:27 +0200
Subject: [PATCH 11/12] Fix phpcs warning

---
 tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
index 84327f1b69ec4..da305bfcc8779 100644
--- a/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
+++ b/tests/phpunit/tests/interactivity-api/wpInteractivityAPI.php
@@ -378,7 +378,7 @@ function () use ( $returns_whatever, $returns_array ) {
 
 		$this->assertSame(
 			array(
-				'state'                     => array(
+				'state'                => array(
 					'pluginWithInvokedDerivedState'    => array(
 						'derivedProp' => $returns_whatever,
 						'nested'      => array(

From 9d9244775db23d25ca863f1a49c58a2379b352d9 Mon Sep 17 00:00:00 2001
From: David <david.arenas@automattic.com>
Date: Fri, 17 Oct 2025 16:17:56 +0200
Subject: [PATCH 12/12] Rename derived_state_props_accessed to
 derived_state_closures

---
 .../class-wp-interactivity-api.php                 | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
index 63266ee367d24..2832efced6f61 100644
--- a/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
+++ b/src/wp-includes/interactivity-api/class-wp-interactivity-api.php
@@ -59,7 +59,7 @@ final class WP_Interactivity_API {
 	private $config_data = array();
 
 	/**
-	 * Keeps track of all derived state props accessed during server-side rendering.
+	 * Keeps track of all derived state closures accessed during server-side rendering.
 	 *
 	 * This data is serialized and sent to the client as part of the interactivity
 	 * data, and is handled later in the client to support derived state props that
@@ -68,7 +68,7 @@ final class WP_Interactivity_API {
 	 * @since 6.9.0
 	 * @var array
 	 */
-	private $derived_state_props_accessed = array();
+	private $derived_state_closures = array();
 
 	/**
 	 * Flag that indicates whether the `data-wp-router-region` directive has
@@ -257,7 +257,7 @@ public function filter_script_module_interactivity_data( array $data ): array {
 		if (
 			empty( $this->state_data ) &&
 			empty( $this->config_data ) &&
-			empty( $this->derived_state_props_accessed )
+			empty( $this->derived_state_closures )
 		) {
 			return $data;
 		}
@@ -283,7 +283,7 @@ public function filter_script_module_interactivity_data( array $data ): array {
 		}
 
 		$derived_props = array();
-		foreach ( $this->derived_state_props_accessed as $key => $value ) {
+		foreach ( $this->derived_state_closures as $key => $value ) {
 			if ( ! empty( $value ) ) {
 				$derived_props[ $key ] = $value;
 			}
@@ -681,12 +681,12 @@ private function evaluate( $directive_value ) {
 					 *
 					 * @since 6.9.0
 					 */
-					$this->derived_state_props_accessed[ $ns ] = $this->derived_state_props_accessed[ $ns ] ?? array();
+					$this->derived_state_closures[ $ns ] = $this->derived_state_closures[ $ns ] ?? array();
 
 					// Builds path for the current property and add it to tracking if not already present.
 					$current_path = implode( '.', array_slice( $path_segments, 0, $index + 1 ) );
-					if ( ! in_array( $current_path, $this->derived_state_props_accessed[ $ns ], true ) ) {
-						$this->derived_state_props_accessed[ $ns ][] = $current_path;
+					if ( ! in_array( $current_path, $this->derived_state_closures[ $ns ], true ) ) {
+						$this->derived_state_closures[ $ns ][] = $current_path;
 					}
 				} catch ( Throwable $e ) {
 					_doing_it_wrong(