KB63 was here

src/ts/ui/fileEdit/fileEditUi/execution/ExecutionManager.scss

@@ -22,6 +22,17 @@
         padding: 4px 20px 4px 0px;
     }
     .move-wrap {
+        position: relative;
+        &.terminate .skull {
+            display: inline-block;
+        }
+        .skull {
+            display: none;
+            filter: drop-shadow(1px 1px 2px black);
+            &::before {
+                content: "💀";
+            }
+        }
         >.no-spill {
             height: 100%;
             width: 20px;

src/ts/ui/fileEdit/fileEditUi/execution/ExecutionManager.tsx

@@ -198,10 +198,12 @@ export const ExecutionManager: React.FC<{ initializedDataAuthorityData: Initiali
                     const gradientColors = containedColors.map((c, index) => `${c} ${(index) * step}% ${(index + 1) * step}%`).join(", ");
                     const gradientString = `linear-gradient(to bottom, ${gradientColors})`;
                     const futureMove = index >= executionContext.state.numAliveMoves;
-                    return [<div key={index} className="move-wrap">
+                    const classNames = "move-wrap" + (move.transition.extensions["plusplus"]?.["type"] === "terminate" ? " terminate" : "");
+                    return [<div key={index} className={classNames}>
                         <div className={"move" + (futureMove ? " future" : "")} style={{ background: gradientString } as React.CSSProperties} onClick={() => resetTrace(move)}>
                             <span className="label">
                                 {move.transition.displayName}
+                                <span className="skull" />
                             </span>
                         </div>
                     </div>];