address comments

Author: icecrasher321

apps/sim/app/workspace/[workspaceId]/w/[workflowId]/workflow.tsx

@@ -246,7 +246,7 @@ const WorkflowContent = React.memo(
     const [selectedEdges, setSelectedEdges] = useState<SelectedEdgesMap>(new Map())
     const [isErrorConnectionDrag, setIsErrorConnectionDrag] = useState(false)
     const canvasContainerRef = useRef<HTMLDivElement>(null)
-    const selectedIdsRef = useRef<string[] | null>(null)
+    const displayNodesRef = useRef<Node[]>([])
     const embeddedFitFrameRef = useRef<number | null>(null)
     const hasCompletedInitialEmbeddedFitRef = useRef(false)
     const canvasMode = useCanvasModeStore((state) => state.mode)
@@ -2477,6 +2477,10 @@ const WorkflowContent = React.memo(
     // Local state for nodes - allows smooth drag without store updates on every frame
     const [displayNodes, setDisplayNodes] = useState<Node[]>([])
 
+    useEffect(() => {
+      displayNodesRef.current = displayNodes
+    }, [displayNodes])
+
     useEffect(() => {
       // Check for pending selection (from paste/duplicate), otherwise preserve existing selection
       if (pendingSelection && pendingSelection.length > 0) {
@@ -2709,17 +2713,17 @@ const WorkflowContent = React.memo(
     /** Handles node changes - applies changes and resolves parent-child selection conflicts. */
     const onNodesChange = useCallback(
       (changes: NodeChange[]) => {
-        selectedIdsRef.current = null
-        setDisplayNodes((nds) => {
-          const updated = applyNodeChanges(changes, nds)
-          const hasSelectionChange = changes.some((c) => c.type === 'select')
-          if (!hasSelectionChange) return updated
-          const resolved = resolveParentChildSelectionConflicts(updated, blocks)
-          selectedIdsRef.current = resolved.filter((node) => node.selected).map((node) => node.id)
-          return resolved
-        })
-        const selectedIds = selectedIdsRef.current as string[] | null
-        if (selectedIds !== null) {
+        const updated = applyNodeChanges(changes, displayNodesRef.current)
+        const hasSelectionChange = changes.some((c) => c.type === 'select')
+        const nextNodes = hasSelectionChange
+          ? resolveParentChildSelectionConflicts(updated, blocks)
+          : updated
+
+        displayNodesRef.current = nextNodes
+        setDisplayNodes(nextNodes)
+
+        if (hasSelectionChange) {
+          const selectedIds = nextNodes.filter((node) => node.selected).map((node) => node.id)
           syncPanelWithSelection(selectedIds)
         }
 
@@ -3610,22 +3614,22 @@ const WorkflowContent = React.memo(
     const handleNodeClick = useCallback(
       (event: React.MouseEvent, node: Node) => {
         const isMultiSelect = event.shiftKey || event.metaKey || event.ctrlKey
-        selectedIdsRef.current = null
-        setDisplayNodes((nodes) => {
-          const updated = nodes.map((n) => ({
-            ...n,
-            selected: isMultiSelect ? (n.id === node.id ? true : n.selected) : n.id === node.id,
-          }))
-          const resolved = resolveParentChildSelectionConflicts(updated, blocks)
-          selectedIdsRef.current = resolved
-            .filter((selectedNode) => selectedNode.selected)
-            .map((selectedNode) => selectedNode.id)
-          return resolved
-        })
-        const selectedIds = selectedIdsRef.current as string[] | null
-        if (selectedIds !== null) {
-          syncPanelWithSelection(selectedIds)
-        }
+        const updated = displayNodesRef.current.map((currentNode) => ({
+          ...currentNode,
+          selected: isMultiSelect
+            ? currentNode.id === node.id
+              ? true
+              : currentNode.selected
+            : currentNode.id === node.id,
+        }))
+        const resolved = resolveParentChildSelectionConflicts(updated, blocks)
+        const selectedIds = resolved
+          .filter((selectedNode) => selectedNode.selected)
+          .map((selectedNode) => selectedNode.id)
+
+        displayNodesRef.current = resolved
+        setDisplayNodes(resolved)
+        syncPanelWithSelection(selectedIds)
       },
       [blocks]
     )

apps/sim/executor/dag/builder.test.ts

@@ -92,6 +92,57 @@ describe('DAGBuilder disabled subflow validation', () => {
     // Should not throw - loop is effectively disabled since all inner blocks are disabled
     expect(() => builder.build(workflow)).not.toThrow()
   })
+
+  it('does not mutate serialized loop config nodes during DAG build', () => {
+    const workflow: SerializedWorkflow = {
+      version: '1',
+      blocks: [
+        createBlock('start', BlockType.STARTER),
+        createBlock('loop-1', BlockType.LOOP),
+        { ...createBlock('inner-block', BlockType.FUNCTION), enabled: false },
+      ],
+      connections: [{ source: 'start', target: 'loop-1' }],
+      loops: {
+        'loop-1': {
+          id: 'loop-1',
+          nodes: ['inner-block'],
+          iterations: 3,
+        },
+      },
+      parallels: {},
+    }
+
+    const builder = new DAGBuilder()
+    builder.build(workflow)
+
+    expect(workflow.loops?.['loop-1']?.nodes).toEqual(['inner-block'])
+  })
+
+  it('does not mutate serialized parallel config nodes during DAG build', () => {
+    const workflow: SerializedWorkflow = {
+      version: '1',
+      blocks: [
+        createBlock('start', BlockType.STARTER),
+        createBlock('parallel-1', BlockType.PARALLEL),
+        { ...createBlock('inner-block', BlockType.FUNCTION), enabled: false },
+      ],
+      connections: [{ source: 'start', target: 'parallel-1' }],
+      loops: {},
+      parallels: {
+        'parallel-1': {
+          id: 'parallel-1',
+          nodes: ['inner-block'],
+          count: 2,
+          parallelType: 'count',
+        },
+      },
+    }
+
+    const builder = new DAGBuilder()
+    builder.build(workflow)
+
+    expect(workflow.parallels?.['parallel-1']?.nodes).toEqual(['inner-block'])
+  })
 })
 
 describe('DAGBuilder nested parallel support', () => {

apps/sim/executor/dag/builder.ts

@@ -113,13 +113,19 @@ export class DAGBuilder {
   private initializeConfigs(workflow: SerializedWorkflow, dag: DAG): void {
     if (workflow.loops) {
       for (const [loopId, loopConfig] of Object.entries(workflow.loops)) {
-        dag.loopConfigs.set(loopId, loopConfig)
+        dag.loopConfigs.set(loopId, {
+          ...loopConfig,
+          nodes: [...(loopConfig.nodes ?? [])],
+        })
       }
     }
 
     if (workflow.parallels) {
       for (const [parallelId, parallelConfig] of Object.entries(workflow.parallels)) {
-        dag.parallelConfigs.set(parallelId, parallelConfig)
+        dag.parallelConfigs.set(parallelId, {
+          ...parallelConfig,
+          nodes: [...(parallelConfig.nodes ?? [])],
+        })
       }
     }
   }

apps/sim/executor/orchestrators/parallel.ts

@@ -76,7 +76,10 @@ export class ParallelOrchestrator {
       items = resolved.items
       isEmpty = resolved.isEmpty ?? false
     } catch (error) {
-      const errorMessage = `Parallel Items did not resolve: ${error instanceof Error ? error.message : String(error)}`
+      const baseErrorMessage = error instanceof Error ? error.message : String(error)
+      const errorMessage = baseErrorMessage.startsWith('Parallel collection distribution is empty')
+        ? baseErrorMessage
+        : `Parallel Items did not resolve: ${baseErrorMessage}`
       logger.error(errorMessage, { parallelId, distribution: parallelConfig.distribution })
       await this.addParallelErrorLog(ctx, parallelId, errorMessage, {
         distribution: parallelConfig.distribution,