feat: improve drag-and-drop feel in network diagram editor

Grip icons on draggable toolbar items, press effect on drag start,
dashed border overlay with 'Drop to add' text when dragging over canvas.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/network/NetworkCanvas.tsx

@@ -24,6 +24,8 @@ interface NetworkCanvasProps {
   onEdgeSelect: (edgeId: string | null) => void
   onDrop: (event: React.DragEvent) => void
   onDragOver: (event: React.DragEvent) => void
+  onDragLeave?: (event: React.DragEvent) => void
+  isDragOver?: boolean
 }
 
 export function NetworkCanvas({
@@ -36,6 +38,8 @@ export function NetworkCanvas({
   onEdgeSelect,
   onDrop,
   onDragOver,
+  onDragLeave,
+  isDragOver,
 }: NetworkCanvasProps) {
   const handleSelectionChange = useCallback(({ nodes: selectedNodes, edges: selectedEdges }: { nodes: Node[]; edges: Edge[] }) => {
     if (selectedNodes.length === 1) {
@@ -56,32 +60,41 @@ export function NetworkCanvas({
   }, [onNodeSelect, onEdgeSelect])
 
   return (
-    <ReactFlow
-      nodes={nodes}
-      edges={edges}
-      onNodesChange={onNodesChange}
-      onEdgesChange={onEdgesChange}
-      onConnect={onConnect}
-      onSelectionChange={handleSelectionChange}
-      onPaneClick={handlePaneClick}
-      onDrop={onDrop}
-      onDragOver={onDragOver}
-      nodeTypes={nodeTypes}
-      edgeTypes={edgeTypes}
-      defaultEdgeOptions={{ type: 'connection' }}
-      deleteKeyCode={['Backspace', 'Delete']}
-      multiSelectionKeyCode="Shift"
-      fitView
-      className="bg-page"
-    >
-      <Background variant={BackgroundVariant.Dots} color="var(--color-border-default)" gap={20} size={1} />
-      <Controls className="!border-default !bg-card [&>button]:!border-default [&>button]:!bg-card [&>button]:!fill-text-primary" />
-      <MiniMap
-        nodeColor="var(--color-bg-elevated)"
-        maskColor="rgba(0,0,0,0.5)"
-        className="!border-default !bg-card"
-        position="bottom-right"
-      />
-    </ReactFlow>
+    <div className="relative h-full w-full" onDragLeave={onDragLeave}>
+      <ReactFlow
+        nodes={nodes}
+        edges={edges}
+        onNodesChange={onNodesChange}
+        onEdgesChange={onEdgesChange}
+        onConnect={onConnect}
+        onSelectionChange={handleSelectionChange}
+        onPaneClick={handlePaneClick}
+        onDrop={onDrop}
+        onDragOver={onDragOver}
+        nodeTypes={nodeTypes}
+        edgeTypes={edgeTypes}
+        defaultEdgeOptions={{ type: 'connection' }}
+        deleteKeyCode={['Backspace', 'Delete']}
+        multiSelectionKeyCode="Shift"
+        fitView
+        className="bg-page"
+      >
+        <Background variant={BackgroundVariant.Dots} color="var(--color-border-default)" gap={20} size={1} />
+        <Controls className="!border-default !bg-card [&>button]:!border-default [&>button]:!bg-card [&>button]:!fill-text-primary" />
+        <MiniMap
+          nodeColor="var(--color-bg-elevated)"
+          maskColor="rgba(0,0,0,0.5)"
+          className="!border-default !bg-card"
+          position="bottom-right"
+        />
+      </ReactFlow>
+      {isDragOver && (
+        <div className="pointer-events-none absolute inset-2 z-10 flex items-center justify-center rounded-lg border-2 border-dashed border-accent/30">
+          <span className="rounded-md bg-card/80 px-3 py-1.5 text-sm text-muted-foreground">
+            Drop to add
+          </span>
+        </div>
+      )}
+    </div>
   )
 }

frontend/src/components/network/panels/DeviceToolbar.tsx

@@ -1,5 +1,5 @@
 import { useState, useMemo, useCallback } from 'react'
-import { Search, Plus, ChevronDown, ChevronRight, X, LayoutGrid } from 'lucide-react'
+import { Search, Plus, ChevronDown, ChevronRight, X, LayoutGrid, GripVertical } from 'lucide-react'
 import { getDeviceRenderConfig, CATEGORY_LABELS, CATEGORY_ORDER } from '../nodes/deviceRegistry'
 import type { DeviceTypeResponse, DeviceTypeCreate } from '@/types'
 import { deviceTypesApi } from '@/api'
@@ -107,8 +107,9 @@ export function DeviceToolbar({ deviceTypes, onDeviceTypesChange }: DeviceToolba
                         key={dt.id}
                         draggable
                         onDragStart={e => handleDragStart(e, dt)}
-                        className="flex cursor-grab items-center gap-2 rounded px-2 py-1.5 text-xs text-primary hover:bg-elevated active:cursor-grabbing"
+                        className="flex cursor-grab items-center gap-2 rounded px-2 py-1.5 text-xs text-primary hover:bg-elevated active:cursor-grabbing active:scale-[0.98] transition-transform"
                       >
+                        <GripVertical size={12} className="shrink-0 text-muted-foreground/50" />
                         <Icon size={14} style={{ color }} />
                         <span>{dt.label}</span>
                       </div>
@@ -140,8 +141,9 @@ export function DeviceToolbar({ deviceTypes, onDeviceTypesChange }: DeviceToolba
                 e.dataTransfer.setData('application/reactflow-group', JSON.stringify(item))
                 e.dataTransfer.effectAllowed = 'move'
               }}
-              className="flex cursor-grab items-center gap-2 rounded px-2 py-1.5 text-xs text-primary hover:bg-elevated active:cursor-grabbing"
+              className="flex cursor-grab items-center gap-2 rounded px-2 py-1.5 text-xs text-primary hover:bg-elevated active:cursor-grabbing active:scale-[0.98] transition-transform"
             >
+              <GripVertical size={12} className="shrink-0 text-muted-foreground/50" />
               <LayoutGrid size={14} className="text-muted-foreground" />
               <span>{item.label}</span>
             </div>

frontend/src/pages/NetworkDiagrams/DiagramEditor.tsx

@@ -50,6 +50,7 @@ function DiagramEditorInner() {
 
   const [deviceTypes, setDeviceTypes] = useState<DeviceTypeResponse[]>([])
   const [loading, setLoading] = useState(!!id)
+  const [isDragOver, setIsDragOver] = useState(false)
 
   useEffect(() => { isDirtyRef.current = isDirty }, [isDirty])
   useEffect(() => { diagramIdRef.current = diagramId }, [diagramId])
@@ -196,10 +197,18 @@ function DiagramEditorInner() {
   const onDragOver = useCallback((event: React.DragEvent) => {
     event.preventDefault()
     event.dataTransfer.dropEffect = 'move'
+    setIsDragOver(true)
+  }, [])
+
+  const onDragLeave = useCallback((event: React.DragEvent) => {
+    const relatedTarget = event.relatedTarget as HTMLElement | null
+    if (relatedTarget && (event.currentTarget as HTMLElement).contains(relatedTarget)) return
+    setIsDragOver(false)
   }, [])
 
   const onDrop = useCallback((event: React.DragEvent) => {
     event.preventDefault()
+    setIsDragOver(false)
 
     const position = screenToFlowPosition({ x: event.clientX, y: event.clientY })
 
@@ -415,6 +424,8 @@ function DiagramEditorInner() {
               onEdgeSelect={setSelectedEdgeId}
               onDrop={onDrop}
               onDragOver={onDragOver}
+              onDragLeave={onDragLeave}
+              isDragOver={isDragOver}
             />
           </div>
           <AIAssistPanel