From 896653469aa6efb1909651714af09bc9ff049aaa Mon Sep 17 00:00:00 2001
From: Jonathan Desrosiers <359867+desrosj@users.noreply.github.com>
Date: Wed, 18 Mar 2026 19:46:16 -0400
Subject: [PATCH 1/2] Always run `build:gutenberg -- --dev`.

---
 Gruntfile.js             |  8 +++++++-
 tools/gutenberg/utils.js | 21 ++++++++++++++++-----
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/Gruntfile.js b/Gruntfile.js
index 8603635b28fbc..d6812d4024368 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -1594,7 +1594,13 @@ module.exports = function(grunt) {
 			args: [ 'tools/gutenberg/download.js' ],
 			opts: { stdio: 'inherit' }
 		}, function( error ) {
-			done( ! error );
+			if ( error ) {
+				done( false );
+				return;
+			}
+			grunt.option( 'dev', true );
+			grunt.task.run( 'build:gutenberg' );
+			done();
 		} );
 	} );
 
diff --git a/tools/gutenberg/utils.js b/tools/gutenberg/utils.js
index 2b30befd38735..a3167a3910793 100644
--- a/tools/gutenberg/utils.js
+++ b/tools/gutenberg/utils.js
@@ -42,13 +42,24 @@ function readGutenbergConfig() {
 }
 
 /**
- * Trigger a fresh download of the Gutenberg artifact by spawning download.js.
- * Exits the process if the download fails.
+ * Trigger a fresh download of the Gutenberg artifact by spawning download.js,
+ * then immediately copy the build to src/ so the files are in place before
+ * the build process runs copy:files.
+ * Exits the process if either step fails.
  */
 function downloadGutenberg() {
-	const result = spawnSync( 'node', [ path.join( __dirname, 'download.js' ) ], { stdio: 'inherit' } );
-	if ( result.status !== 0 ) {
-		process.exit( result.status ?? 1 );
+	const downloadResult = spawnSync( 'node', [ path.join( __dirname, 'download.js' ) ], { stdio: 'inherit' } );
+	if ( downloadResult.status !== 0 ) {
+		process.exit( downloadResult.status ?? 1 );
+	}
+
+	const copyResult = spawnSync(
+		'node',
+		[ path.join( __dirname, 'copy.js' ), '--build-dir=src' ],
+		{ stdio: 'inherit' }
+	);
+	if ( copyResult.status !== 0 ) {
+		process.exit( copyResult.status ?? 1 );
 	}
 }
 

From ec8e4c5a732875292720eae17614989c5f3895fe Mon Sep 17 00:00:00 2001
From: Jonathan Desrosiers <359867+desrosj@users.noreply.github.com>
Date: Wed, 18 Mar 2026 22:31:37 -0400
Subject: [PATCH 2/2] Ensure `build:gutenberg --dev` always runs.

---
 Gruntfile.js             | 18 +++++++++++++++---
 package.json             |  2 +-
 tools/gutenberg/utils.js | 13 ++++---------
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/Gruntfile.js b/Gruntfile.js
index 53d165bbb13cb..11f2db7a78ace 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -1611,9 +1611,21 @@ module.exports = function(grunt) {
 				done( false );
 				return;
 			}
-			grunt.option( 'dev', true );
-			grunt.task.run( 'build:gutenberg' );
-			done();
+			/*
+			 * Build block editor files into the src directory every time assets
+			 * are downloaded. This prevents failures when running from src
+			 * without running `build:dev` after those files were removed from
+			 * version control in https://core.trac.wordpress.org/changeset/61438.
+			 *
+			 * See https://core.trac.wordpress.org/ticket/64393.
+			 */
+			grunt.util.spawn( {
+				grunt: true,
+				args: [ 'build:gutenberg', '--dev' ],
+				opts: { stdio: 'inherit' }
+			}, function( buildError ) {
+				done( ! buildError );
+			} );
 		} );
 	} );
 
diff --git a/package.json b/package.json
index 9f67a45262806..3084630a2d726 100644
--- a/package.json
+++ b/package.json
@@ -141,7 +141,7 @@
 		"typecheck:php": "node ./tools/local-env/scripts/docker.js run --rm php composer phpstan",
 		"gutenberg:copy": "node tools/gutenberg/copy.js",
 		"gutenberg:verify": "node tools/gutenberg/utils.js",
-		"gutenberg:download": "node tools/gutenberg/download.js",
+		"gutenberg:download": "node tools/gutenberg/download.js && grunt build:gutenberg --dev",
 		"vendor:copy": "node tools/vendors/copy-vendors.js",
 		"sync-gutenberg-packages": "grunt sync-gutenberg-packages",
 		"postsync-gutenberg-packages": "grunt wp-packages:sync-stable-blocks && grunt build --dev && grunt build"
diff --git a/tools/gutenberg/utils.js b/tools/gutenberg/utils.js
index a3167a3910793..dc696d5e7bfd7 100644
--- a/tools/gutenberg/utils.js
+++ b/tools/gutenberg/utils.js
@@ -43,8 +43,7 @@ function readGutenbergConfig() {
 
 /**
  * Trigger a fresh download of the Gutenberg artifact by spawning download.js,
- * then immediately copy the build to src/ so the files are in place before
- * the build process runs copy:files.
+ * then run `grunt build:gutenberg --dev` to copy the build to src/.
  * Exits the process if either step fails.
  */
 function downloadGutenberg() {
@@ -53,13 +52,9 @@ function downloadGutenberg() {
 		process.exit( downloadResult.status ?? 1 );
 	}
 
-	const copyResult = spawnSync(
-		'node',
-		[ path.join( __dirname, 'copy.js' ), '--build-dir=src' ],
-		{ stdio: 'inherit' }
-	);
-	if ( copyResult.status !== 0 ) {
-		process.exit( copyResult.status ?? 1 );
+	const buildResult = spawnSync( 'grunt', [ 'build:gutenberg', '--dev' ], { stdio: 'inherit', shell: true } );
+	if ( buildResult.status !== 0 ) {
+		process.exit( buildResult.status ?? 1 );
 	}
 }