fix: LXC/VM parent-child UX bugs with Proxmox container mode

- Don't create virtual edge when parent Proxmox is in container mode
  (containment is shown visually — edge was redundant and confusing)
- updateNode now syncs React Flow parentId/extent/position when
  data.parent_id changes, so nesting/un-nesting is immediate without
  requiring a save+reload
- Attaching to container: converts position to parent-relative coords
- Detaching from container: converts position back to absolute coords
  so the node escapes the container box immediately
- Ensure parent nodes precede children in array on attachment
  (React Flow rendering requirement)

frontend/src/App.tsx

@@ -258,10 +258,13 @@ export default function App() {
           )
           if (oldEdge) deleteEdge(oldEdge.id)
         }
-        // Create new virtual edge: LXC top → Proxmox bottom
+        // Create virtual edge only when parent is NOT in container mode
+        // (container mode shows containment visually — no edge needed)
         if (newParentId) {
-          // Pass type as extra field — canvasStore.onConnect casts to Connection & Partial<EdgeData>
-          onConnect({ source: editNodeId, sourceHandle: 'top', target: newParentId, targetHandle: 'bottom', type: 'virtual' } as unknown as Connection)
+          const parentNode = nodes.find((n) => n.id === newParentId)
+          if (!parentNode?.data.container_mode) {
+            onConnect({ source: editNodeId, sourceHandle: 'top', target: newParentId, targetHandle: 'bottom', type: 'virtual' } as unknown as Connection)
+          }
         }
       }
     }

frontend/src/stores/__tests__/canvasStore.test.ts

@@ -57,6 +57,57 @@ describe('canvasStore', () => {
     expect(node?.data.ip).toBe('10.0.0.1')
   })
 
+  it('updateNode setting parent_id on container-mode proxmox sets parentId and relative position', () => {
+    const proxmox = { ...makeNode('px1', { type: 'proxmox', container_mode: true }), position: { x: 100, y: 100 } }
+    const lxc = { ...makeNode('lxc1', { type: 'lxc' }), position: { x: 160, y: 180 } }
+    useCanvasStore.getState().addNode(proxmox)
+    useCanvasStore.getState().addNode(lxc)
+    useCanvasStore.getState().updateNode('lxc1', { parent_id: 'px1' })
+    const node = useCanvasStore.getState().nodes.find((n) => n.id === 'lxc1')
+    expect(node?.parentId).toBe('px1')
+    expect(node?.extent).toBe('parent')
+    // Position should be relative to parent (160-100=60, 180-100=80)
+    expect(node?.position.x).toBe(60)
+    expect(node?.position.y).toBe(80)
+  })
+
+  it('updateNode setting parent_id on non-container proxmox does NOT set React Flow parentId', () => {
+    const proxmox = { ...makeNode('px1', { type: 'proxmox', container_mode: false }), position: { x: 100, y: 100 } }
+    const lxc = { ...makeNode('lxc1', { type: 'lxc' }), position: { x: 160, y: 180 } }
+    useCanvasStore.getState().addNode(proxmox)
+    useCanvasStore.getState().addNode(lxc)
+    useCanvasStore.getState().updateNode('lxc1', { parent_id: 'px1' })
+    const node = useCanvasStore.getState().nodes.find((n) => n.id === 'lxc1')
+    expect(node?.parentId).toBeUndefined()
+    expect(node?.extent).toBeUndefined()
+  })
+
+  it('updateNode clearing parent_id converts position to absolute and clears parentId', () => {
+    const proxmox = { ...makeNode('px1', { type: 'proxmox', container_mode: true }), position: { x: 100, y: 100 } }
+    const lxc = { ...makeNode('lxc1', { type: 'lxc', parent_id: 'px1' }), position: { x: 30, y: 40 }, parentId: 'px1', extent: 'parent' as const }
+    useCanvasStore.getState().addNode(proxmox)
+    useCanvasStore.getState().addNode(lxc)
+    useCanvasStore.getState().updateNode('lxc1', { parent_id: undefined })
+    const node = useCanvasStore.getState().nodes.find((n) => n.id === 'lxc1')
+    expect(node?.parentId).toBeUndefined()
+    expect(node?.extent).toBeUndefined()
+    // Position should be absolute (100+30=130, 100+40=140)
+    expect(node?.position.x).toBe(130)
+    expect(node?.position.y).toBe(140)
+  })
+
+  it('updateNode with parent_id puts parents before children in array', () => {
+    const proxmox = { ...makeNode('px1', { type: 'proxmox', container_mode: true }), position: { x: 0, y: 0 } }
+    const lxc = { ...makeNode('lxc1', { type: 'lxc' }), position: { x: 10, y: 10 } }
+    useCanvasStore.getState().addNode(proxmox)
+    useCanvasStore.getState().addNode(lxc)
+    useCanvasStore.getState().updateNode('lxc1', { parent_id: 'px1' })
+    const { nodes } = useCanvasStore.getState()
+    const pxIdx = nodes.findIndex((n) => n.id === 'px1')
+    const lxcIdx = nodes.findIndex((n) => n.id === 'lxc1')
+    expect(pxIdx).toBeLessThan(lxcIdx)
+  })
+
   it('deleteNode removes node and its connected edges', () => {
     const store = useCanvasStore.getState()
     store.addNode(makeNode('n1'))

frontend/src/stores/canvasStore.ts

@@ -187,12 +187,47 @@ export const useCanvasStore = create<CanvasState>((set) => ({
     }),
 
   updateNode: (id, data) =>
-    set((state) => ({
-      nodes: state.nodes.map((n) =>
-        n.id === id ? { ...n, data: { ...n.data, ...data } } : n
-      ),
-      hasUnsavedChanges: true,
-    })),
+    set((state) => {
+      let nodes = state.nodes.map((n) => {
+        if (n.id !== id) return n
+        const updated: Node<NodeData> = { ...n, data: { ...n.data, ...data } }
+        if ('parent_id' in data) {
+          const newParentId = data.parent_id ?? undefined
+          if (!newParentId && n.parentId) {
+            // Detaching from a container: convert position back to absolute canvas coords
+            const parent = state.nodes.find((p) => p.id === n.parentId)
+            if (parent) {
+              updated.position = {
+                x: parent.position.x + n.position.x,
+                y: parent.position.y + n.position.y,
+              }
+            }
+            updated.parentId = undefined
+            updated.extent = undefined
+          } else if (newParentId && newParentId !== n.parentId) {
+            const parent = state.nodes.find((p) => p.id === newParentId)
+            if (parent?.data.container_mode) {
+              // Attaching to a container-mode Proxmox: nest visually
+              updated.parentId = newParentId
+              updated.extent = 'parent' as const
+              // Convert absolute position to parent-relative (keep node visible inside)
+              updated.position = {
+                x: Math.max(10, n.position.x - parent.position.x),
+                y: Math.max(10, n.position.y - parent.position.y),
+              }
+            }
+          }
+        }
+        return updated
+      })
+      // React Flow requires parent nodes to precede their children in the array
+      if ('parent_id' in data) {
+        const parents = nodes.filter((n) => !n.parentId)
+        const children = nodes.filter((n) => !!n.parentId)
+        nodes = [...parents, ...children]
+      }
+      return { nodes, hasUnsavedChanges: true }
+    }),
 
   deleteNode: (id) =>
     set((state) => {