fix: allow nav into collapsed block row via right arrow

packages/blockly/core/inputs/input.ts

@@ -375,7 +375,13 @@ export class Input {
   getRowId(): string {
     const inputs = this.getSourceBlock().inputList;
 
-    // The first input in a block has the same ID as its parent block.
+    // The first visible input shares the block's row id; this also covers
+    // the collapsed-input placeholder, since every other input is hidden.
+    if (this === inputs.find((i) => i.isVisible())) {
+      return (this.getSourceBlock() as BlockSvg).getRowId();
+    }
+
+    // Fallback when inputs[0] itself is hidden.
     if (this === inputs[0]) {
       return (this.getSourceBlock() as BlockSvg).getRowId();
     }

packages/blockly/core/keyboard_nav/navigation_policies/block_navigation_policy.ts

@@ -119,13 +119,12 @@ export class BlockNavigationPolicy implements INavigationPolicy<BlockSvg> {
  * @returns A list of navigable/focusable children of the given block.
  */
 function getBlockNavigationCandidates(block: BlockSvg): IFocusableNode[] {
-  // Collapsed blocks have no navigable children.
-  if (block.isCollapsed()) return [];
-
   const candidates: IFocusableNode[] = [];
 
   // Icons and open bubbles are navigable.
   for (const icon of block.getIcons()) {
+    // Icons hidden when the block is collapsed shouldn't be navigable.
+    if (block.isCollapsed() && !icon.isShownWhenCollapsed()) continue;
     candidates.push(icon);
     let bubble;
     if (

packages/blockly/tests/mocha/navigation_test.js

@@ -774,6 +774,24 @@ suite('Navigation', function () {
         const inNode = this.navigator.getFirstChild(this.blocks.buttonBlock);
         assert.isNull(inNode);
       });
+      test('reachesClickableFieldOnCollapsedInput', function () {
+        // Models a pattern where a clickable field is appended to
+        // COLLAPSED_INPUT_NAME when the block collapses.
+        const block = this.blocks.buttonBlock;
+        block.setCollapsed(true);
+        const input = block.getInput(Blockly.constants.COLLAPSED_INPUT_NAME);
+        const expandButton = new Blockly.FieldImage(
+          'https://www.gstatic.com/codesite/ph/images/star_on.gif',
+          16,
+          16,
+          'expand',
+          () => {},
+        );
+        input.appendField(expandButton);
+
+        const inNode = this.navigator.getInNode(block);
+        assert.equal(inNode, expandButton);
+      });
     });
 
     suite('Out', function () {