From 37dbf5f35f63ba13be0f48ea357c38056a64c775 Mon Sep 17 00:00:00 2001
From: Matt Hillsdon <matt.hillsdon@microbit.org>
Date: Tue, 9 Jun 2026 15:03:51 +0100
Subject: [PATCH] fix: don't allow disconnecting shadow blocks (#9964)

---
 packages/blockly/core/shortcut_items.ts         |  4 +++-
 .../blockly/tests/mocha/shortcut_items_test.js  | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/packages/blockly/core/shortcut_items.ts b/packages/blockly/core/shortcut_items.ts
index 9775ec86d..3d7bdc979 100644
--- a/packages/blockly/core/shortcut_items.ts
+++ b/packages/blockly/core/shortcut_items.ts
@@ -940,10 +940,12 @@ export function registerDisconnectBlock() {
   const disconnectShortcut: ShortcutRegistry.KeyboardShortcut = {
     name: names.DISCONNECT,
     preconditionFn: (workspace, scope) => {
+      const focused = scope.focusedNode;
       const result =
         !workspace.isDragging() &&
         !workspace.isReadOnly() &&
-        scope.focusedNode instanceof BlockSvg;
+        focused instanceof BlockSvg &&
+        !focused.isShadow();
 
       if (!result) {
         workspace.getAudioManager().playErrorBeep();
diff --git a/packages/blockly/tests/mocha/shortcut_items_test.js b/packages/blockly/tests/mocha/shortcut_items_test.js
index 503079c4c..33fa180ac 100644
--- a/packages/blockly/tests/mocha/shortcut_items_test.js
+++ b/packages/blockly/tests/mocha/shortcut_items_test.js
@@ -1036,6 +1036,23 @@ suite('Keyboard Shortcut Items', function () {
       assert.deepEqual(bounds, this.blockE.getBoundingRectangle());
     });
 
+    test('Does nothing for a shadow block', function () {
+      this.blockH.setShadow(true);
+      Blockly.getFocusManager().focusNode(this.blockH);
+      assert.isTrue(this.blockH.outputConnection.isConnected());
+
+      this.injectionDiv.dispatchEvent(
+        createKeyDownEvent(Blockly.utils.KeyCodes.X),
+      );
+
+      // The shadow should remain connected to its parent input.
+      assert.isTrue(this.blockH.outputConnection.isConnected());
+      assert.strictEqual(
+        Blockly.getFocusManager().getFocusedNode(),
+        this.blockH,
+      );
+    });
+
     test('Disconnects child blocks when triggered on top stack block', function () {
       Blockly.getFocusManager().focusNode(this.blockB);
       assert.isTrue(this.blockB.nextConnection.isConnected());