From b6db9fec8702482540e9ca63fc212c9c8dfdc71b Mon Sep 17 00:00:00 2001
From: Aaron Dodson <aaron.dodson@raspberrypi.org>
Date: Tue, 13 Jan 2026 15:13:55 -0800
Subject: [PATCH] feat: Add `IPathObject.updateReplacing()`

---
 core/block_svg.ts                      |  6 +-----
 core/renderers/common/i_path_object.ts |  9 +++++++++
 core/renderers/common/path_object.ts   | 11 +++++++++++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/core/block_svg.ts b/core/block_svg.ts
index 269081a6e..231af949d 100644
--- a/core/block_svg.ts
+++ b/core/block_svg.ts
@@ -1735,11 +1735,7 @@ export class BlockSvg
    * @internal
    */
   fadeForReplacement(add: boolean) {
-    if (add) {
-      this.addClass('blocklyReplaceable');
-    } else {
-      this.removeClass('blocklyReplaceable');
-    }
+    this.pathObject.updateReplacing?.(add);
   }
 
   /**
diff --git a/core/renderers/common/i_path_object.ts b/core/renderers/common/i_path_object.ts
index a68c3a411..a7379bbea 100644
--- a/core/renderers/common/i_path_object.ts
+++ b/core/renderers/common/i_path_object.ts
@@ -106,4 +106,13 @@ export interface IPathObject {
    * @param blockStyle The block style to use.
    */
   setStyle?(blockStyle: BlockStyle): void;
+
+  /**
+   * Add or remove styling indicating that a block will be bumped out and
+   * replaced by another block that is mid-move.
+   *
+   * @param replacing True if the block is at risk of being replaced, false
+   *     otherwise.
+   */
+  updateReplacing?(replacing: boolean): void;
 }
diff --git a/core/renderers/common/path_object.ts b/core/renderers/common/path_object.ts
index 50ea9252d..e6cb4962f 100644
--- a/core/renderers/common/path_object.ts
+++ b/core/renderers/common/path_object.ts
@@ -191,6 +191,17 @@ export class PathObject implements IPathObject {
     this.setClass_('blocklyDraggable', enable);
   }
 
+  /**
+   * Add or remove styling indicating that a block will be bumped out and
+   * replaced by another block that is mid-move.
+   *
+   * @param replacing True if the block is at risk of being replaced, false
+   *     otherwise.
+   */
+  updateReplacing(replacing: boolean) {
+    this.setClass_('blocklyReplaceable', replacing);
+  }
+
   /** Adds the given path as a connection highlight for the given connection. */
   addConnectionHighlight(
     connection: RenderedConnection,