fix(workflow): hide idle nested subflow end handles (#6976)

* fix(workflow): hide idle nested subflow end handles

* perf(workflow): avoid repeated subflow edge scans

* perf(workflow): stabilize subflow edge selector

---------

Co-authored-by: Bill Leoutsakos <billleoutsakos@Bills-MacBook-Pro.local>
Co-authored-by: Waleed Latif <walif6@gmail.com>

apps/docs/components/workflow-preview/docs-container-node.tsx

@@ -8,6 +8,7 @@ interface DocsContainerData {
   name: string
   blockType: string
   size?: { width: number; height: number }
+  parentId?: string
 }
 
 /**
@@ -24,6 +25,7 @@ export const DocsContainerNode = memo(function DocsContainerNode({
     name: data.name,
     width: data.size?.width,
     height: data.size?.height,
+    parentId: data.parentId,
     isPreview: true,
   }
 

apps/docs/components/workflow-preview/workflow-data.test.ts

@@ -0,0 +1,63 @@
+/**
+ * @vitest-environment node
+ */
+import { BLOCK_Z_BASE, CONTAINER_CHILD_Z_BASE, getEdgeZIndex } from '@sim/workflow-renderer'
+import { describe, expect, it } from 'vitest'
+import { type PreviewBlock, type PreviewWorkflow, toReactFlowElements } from './workflow-data'
+
+const block = (
+  overrides: Partial<PreviewBlock> & Pick<PreviewBlock, 'id' | 'type'>
+): PreviewBlock => ({
+  name: overrides.id,
+  bgColor: '#000000',
+  rows: [],
+  position: { x: 0, y: 0 },
+  ...overrides,
+})
+
+const workflow: PreviewWorkflow = {
+  id: 'nested-subflows',
+  name: 'Nested subflows',
+  blocks: [
+    block({ id: 'start', type: 'starter' }),
+    block({ id: 'loop', type: 'loop', size: { width: 500, height: 300 } }),
+    block({
+      id: 'parallel',
+      type: 'parallel',
+      parentId: 'loop',
+      position: { x: 24, y: 64 },
+      size: { width: 400, height: 200 },
+    }),
+    block({ id: 'agent', type: 'agent', parentId: 'loop', position: { x: 24, y: 140 } }),
+  ],
+  edges: [
+    { id: 'start-loop', source: 'start', target: 'loop' },
+    { id: 'loop-parallel', source: 'loop', target: 'parallel' },
+    { id: 'loop-agent', source: 'loop', target: 'agent' },
+  ],
+}
+
+describe('toReactFlowElements layering', () => {
+  it('places incoming edges on their container target layer', () => {
+    const { nodes, edges } = toReactFlowElements(workflow, false, {
+      highlightEdge: 'loop-parallel',
+    })
+    const nodeById = new Map(nodes.map((node) => [node.id, node]))
+    const edgeById = new Map(edges.map((edge) => [edge.id, edge]))
+
+    expect(nodeById.get('loop')?.zIndex).toBe(0)
+    expect(nodeById.get('parallel')?.zIndex).toBe(1)
+    expect(edgeById.get('start-loop')?.zIndex).toBe(0)
+    expect(edgeById.get('loop-parallel')?.zIndex).toBe(1)
+  })
+
+  it('keeps ordinary cards above normally layered edges', () => {
+    const { nodes, edges } = toReactFlowElements(workflow)
+    const nodeById = new Map(nodes.map((node) => [node.id, node]))
+    const edgeById = new Map(edges.map((edge) => [edge.id, edge]))
+
+    expect(nodeById.get('start')?.zIndex).toBe(BLOCK_Z_BASE)
+    expect(nodeById.get('agent')?.zIndex).toBe(CONTAINER_CHILD_Z_BASE)
+    expect(edgeById.get('loop-agent')?.zIndex).toBe(getEdgeZIndex(0))
+  })
+})

apps/docs/components/workflow-preview/workflow-data.ts

@@ -1,3 +1,9 @@
+import {
+  BLOCK_Z_BASE,
+  CONTAINER_CHILD_Z_BASE,
+  getEdgeZIndex,
+  getEdgeZIndexForTarget,
+} from '@sim/workflow-renderer'
 import { type Edge, type Node, Position } from 'reactflow'
 
 /**
@@ -61,6 +67,24 @@ export interface HighlightOptions {
   selectedBlock?: string
 }
 
+/** Semantic container depth used for z-order while docs positions stay flattened. */
+function getNestingDepth(block: PreviewBlock, blocksById: Map<string, PreviewBlock>): number {
+  let depth = 0
+  let parentId = block.parentId
+  const visited = new Set<string>()
+
+  while (parentId && !visited.has(parentId)) {
+    const parent = blocksById.get(parentId)
+    if (!parent) break
+
+    visited.add(parentId)
+    depth += 1
+    parentId = parent.parentId
+  }
+
+  return depth
+}
+
 /**
  * Converts a {@link PreviewWorkflow} to React Flow nodes and edges.
  *
@@ -81,6 +105,7 @@ export function toReactFlowElements(
 
   const nodes: Node[] = workflow.blocks.map((block, index) => {
     const isContainer = Boolean(block.size)
+    const nestingDepth = getNestingDepth(block, blocksById)
     // Nested blocks are authored relative to their container; render them at
     // absolute coordinates (not React Flow parentNode children) so the edges
     // between a container and its nested blocks render reliably and on top.
@@ -92,7 +117,7 @@ export function toReactFlowElements(
       id: block.id,
       type: isContainer ? 'previewContainer' : 'previewBlock',
       position,
-      zIndex: isContainer ? 0 : 1,
+      zIndex: isContainer ? nestingDepth : block.parentId ? CONTAINER_CHILD_Z_BASE : BLOCK_Z_BASE,
       ...(block.size ? { style: { width: block.size.width, height: block.size.height } } : {}),
       data: {
         name: block.name,
@@ -103,6 +128,7 @@ export function toReactFlowElements(
         tools: block.tools,
         hideTargetHandle: block.hideTargetHandle,
         size: block.size,
+        parentId: block.parentId,
         index,
         animate,
         isHighlighted: highlightBlock === block.id || selectedBlock === block.id,
@@ -127,6 +153,14 @@ export function toReactFlowElements(
     // so edges into and out of Loop/Parallel containers still connect.
     const sourceBlock = blocksById.get(e.source)
     const targetBlock = blocksById.get(e.target)
+    const parentContainer = blocksById.get(sourceBlock?.parentId ?? targetBlock?.parentId ?? '')
+    const baseZIndex = getEdgeZIndex(
+      parentContainer ? getNestingDepth(parentContainer, blocksById) : undefined,
+      { isHighlighted: isEdgeHighlight }
+    )
+    const targetContainerZIndex = targetBlock?.size
+      ? getNestingDepth(targetBlock, blocksById)
+      : undefined
     const sourceHandle =
       e.sourceHandle ?? (sourceBlock?.size ? `${sourceBlock.type}-end-source` : 'source')
     const targetHandle = targetBlock?.size ? undefined : 'target'
@@ -142,6 +176,7 @@ export function toReactFlowElements(
       },
       sourceHandle,
       targetHandle,
+      zIndex: getEdgeZIndexForTarget(baseZIndex, targetContainerZIndex),
       data: {
         animate,
         delay: animate ? sourceIndex * BLOCK_STAGGER + BLOCK_STAGGER : 0,