[2706] Fix children position on re-open

Bug: #2706

CHANGELOG.adoc

@@ -128,8 +128,9 @@ It uses our algorithm instead of elk.js to perform the arrange-all.
 - https://github.com/eclipse-sirius/sirius-web/issues/2640[#2640] [diagram] Compute the handle position on diagram conversion, which happens every time a diagram refresh payload is received.
 - https://github.com/eclipse-sirius/sirius-web/issues/2647[#2647] [diagram] Split border shorthand CSS properties into non-shorthand properties for list nodes.
 Make some border node transparent when the node is in a list node in the convert engine.
-- https://github.com/eclipse-sirius/sirius-web/issues/2646[#2646] [diagram] Fix an issue where the palette was re rendering too much.
+- https://github.com/eclipse-sirius/sirius-web/issues/2646[#2646] [diagram] Fix an issue where the palette was re-rendering too much.
 - https://github.com/eclipse-sirius/sirius-web/issues/2685[#2685] [diagram] Fix direct edit of edge labels with F2.
+- https://github.com/eclipse-sirius/sirius-web/issues/[#2706] [diagram] Fix an issue where node children were not correctly positioned.
 
 === New Features
 

packages/diagrams/frontend/sirius-components-diagrams-reactflow/src/converter/RectangleNodeConverterHandler.ts

@@ -51,7 +51,8 @@ const toRectangularNode = (
   } = gqlNode;
 
   const connectionHandles: ConnectionHandle[] = convertHandles(gqlNode, gqlEdges);
-  const isNew = gqlDiagram.layoutData.nodeLayoutData.find((nodeLayoutData) => nodeLayoutData.id === id) === undefined;
+  const nodeLayoutData = gqlDiagram.layoutData.nodeLayoutData.find((data) => data.id === id);
+  const isNew = nodeLayoutData === undefined;
 
   const data: RectangularNodeData = {
     targetObjectId,
@@ -124,7 +125,6 @@ const toRectangularNode = (
     node.parentNode = gqlParentNode.id;
   }
 
-  const nodeLayoutData = gqlDiagram.layoutData.nodeLayoutData.filter((data) => data.id === id)[0];
   if (nodeLayoutData) {
     const {
       position,

packages/diagrams/frontend/sirius-components-diagrams-reactflow/src/renderer/layout/RectangleNodeLayoutHandler.ts

@@ -92,7 +92,7 @@ export class RectangleNodeLayoutHandler implements INodeLayoutHandler<Rectangula
     // Update children position to be under the label and at the right padding.
     directNodesChildren.forEach((child, index) => {
       const previousNode = (previousDiagram?.nodes ?? []).find((previouseNode) => previouseNode.id === child.id);
-      const previousPosition = computePreviousPosition(previousNode, node);
+      const previousPosition = computePreviousPosition(previousNode, child);
       const createdNode = newlyAddedNode?.id === child.id ? newlyAddedNode : undefined;
 
       if (!!createdNode) {