feat: add React Flow UI foundation components for network diagrams

BaseNode (structured node shell with header/content/footer slots),
BaseHandle (styled connection handle), LabeledHandle (handle with
port label), NodeStatusIndicator (status border effect),
NodeTooltip (hover details via NodeToolbar).

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

frontend/src/components/network/ui/base-handle.tsx

@@ -0,0 +1,20 @@
+import type { ComponentProps } from 'react'
+import { Handle, type HandleProps } from '@xyflow/react'
+import { cn } from '@/lib/utils'
+
+export type BaseHandleProps = HandleProps
+
+export function BaseHandle({ className, children, ...props }: ComponentProps<typeof Handle>) {
+  return (
+    <Handle
+      {...props}
+      className={cn(
+        'h-[10px] w-[10px] rounded-full border border-default bg-elevated transition-opacity',
+        'opacity-0 group-hover:opacity-100',
+        className,
+      )}
+    >
+      {children}
+    </Handle>
+  )
+}

frontend/src/components/network/ui/base-node.tsx

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+import type { ComponentProps } from 'react'
+import { cn } from '@/lib/utils'
+
+export function BaseNode({ className, ...props }: ComponentProps<'div'>) {
+  return (
+    <div
+      className={cn(
+        'bg-card text-heading relative rounded-lg border border-default',
+        'transition-colors hover:border-hover',
+        'in-[.selected]:border-accent',
+        className,
+      )}
+      tabIndex={0}
+      {...props}
+    />
+  )
+}
+
+export function BaseNodeHeader({ className, ...props }: ComponentProps<'header'>) {
+  return (
+    <header
+      {...props}
+      className={cn('flex flex-row items-center gap-2 px-3 py-2', className)}
+    />
+  )
+}
+
+export function BaseNodeHeaderTitle({ className, ...props }: ComponentProps<'h3'>) {
+  return (
+    <h3
+      data-slot="base-node-title"
+      className={cn('select-none flex-1 text-xs font-semibold text-heading', className)}
+      {...props}
+    />
+  )
+}
+
+export function BaseNodeContent({ className, ...props }: ComponentProps<'div'>) {
+  return (
+    <div
+      data-slot="base-node-content"
+      className={cn('flex flex-col gap-y-1 px-3 pb-2', className)}
+      {...props}
+    />
+  )
+}
+
+export function BaseNodeFooter({ className, ...props }: ComponentProps<'div'>) {
+  return (
+    <div
+      data-slot="base-node-footer"
+      className={cn('flex flex-col items-center gap-y-1 border-t border-default px-3 pt-1.5 pb-2', className)}
+      {...props}
+    />
+  )
+}

frontend/src/components/network/ui/labeled-handle.tsx

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+import type { ComponentProps } from 'react'
+import { type HandleProps, Position } from '@xyflow/react'
+import { cn } from '@/lib/utils'
+import { BaseHandle } from './base-handle'
+
+const flexDirections: Record<string, string> = {
+  [Position.Top]: 'flex-col',
+  [Position.Right]: 'flex-row-reverse justify-end',
+  [Position.Bottom]: 'flex-col-reverse justify-end',
+  [Position.Left]: 'flex-row',
+}
+
+export function LabeledHandle({
+  className,
+  labelClassName,
+  handleClassName,
+  title,
+  position,
+  ...props
+}: HandleProps &
+  ComponentProps<'div'> & {
+    title: string
+    handleClassName?: string
+    labelClassName?: string
+  }) {
+  const { ref, ...handleProps } = props
+  return (
+    <div
+      title={title}
+      className={cn('relative flex items-center', flexDirections[position], className)}
+      ref={ref}
+    >
+      <BaseHandle position={position} className={handleClassName} {...handleProps} />
+      <label className={cn('text-muted-foreground text-[10px] font-mono px-1.5', labelClassName)}>
+        {title}
+      </label>
+    </div>
+  )
+}

frontend/src/components/network/ui/node-status-indicator.tsx

@@ -0,0 +1,43 @@
+import type { ReactNode } from 'react'
+import { cn } from '@/lib/utils'
+
+export type NodeStatus = 'online' | 'offline' | 'degraded' | 'unknown'
+
+const STATUS_BORDER_COLORS: Record<NodeStatus, string> = {
+  online: 'border-emerald-400',
+  offline: 'border-red-400',
+  degraded: 'border-yellow-400',
+  unknown: '',
+}
+
+const STATUS_GLOW: Record<NodeStatus, string> = {
+  online: 'shadow-[0_0_8px_rgba(52,211,153,0.3)]',
+  offline: 'shadow-[0_0_8px_rgba(248,113,113,0.3)]',
+  degraded: 'shadow-[0_0_8px_rgba(250,204,21,0.3)]',
+  unknown: '',
+}
+
+interface NodeStatusIndicatorProps {
+  status?: NodeStatus
+  children: ReactNode
+  className?: string
+}
+
+export function NodeStatusIndicator({ status = 'unknown', children, className }: NodeStatusIndicatorProps) {
+  if (status === 'unknown') {
+    return <>{children}</>
+  }
+
+  return (
+    <div
+      className={cn(
+        'rounded-lg border-2 transition-colors',
+        STATUS_BORDER_COLORS[status],
+        STATUS_GLOW[status],
+        className,
+      )}
+    >
+      {children}
+    </div>
+  )
+}

frontend/src/components/network/ui/node-tooltip.tsx

@@ -0,0 +1,77 @@
+import { createContext, useContext, useState, useCallback, type ReactNode, type ComponentProps } from 'react'
+import { NodeToolbar, type NodeToolbarProps } from '@xyflow/react'
+import { cn } from '@/lib/utils'
+
+interface NodeTooltipContextValue {
+  visible: boolean
+  show: () => void
+  hide: () => void
+}
+
+const NodeTooltipContext = createContext<NodeTooltipContextValue>({
+  visible: false,
+  show: () => {},
+  hide: () => {},
+})
+
+export function NodeTooltip({ children, ...props }: ComponentProps<'div'>) {
+  const [visible, setVisible] = useState(false)
+  const show = useCallback(() => setVisible(true), [])
+  const hide = useCallback(() => setVisible(false), [])
+
+  return (
+    <NodeTooltipContext.Provider value={{ visible, show, hide }}>
+      <div {...props}>{children}</div>
+    </NodeTooltipContext.Provider>
+  )
+}
+
+export function NodeTooltipTrigger({
+  children,
+  onMouseEnter,
+  onMouseLeave,
+  ...props
+}: ComponentProps<'div'>) {
+  const { show, hide } = useContext(NodeTooltipContext)
+
+  return (
+    <div
+      onMouseEnter={(e) => {
+        show()
+        onMouseEnter?.(e)
+      }}
+      onMouseLeave={(e) => {
+        hide()
+        onMouseLeave?.(e)
+      }}
+      {...props}
+    >
+      {children}
+    </div>
+  )
+}
+
+export function NodeTooltipContent({
+  className,
+  position,
+  children,
+  ...props
+}: Omit<NodeToolbarProps, 'children'> & { children: ReactNode }) {
+  const { visible } = useContext(NodeTooltipContext)
+
+  if (!visible) return null
+
+  return (
+    <NodeToolbar
+      position={position}
+      className={cn(
+        'rounded-lg border border-default bg-elevated px-3 py-2',
+        'pointer-events-none',
+        className,
+      )}
+      {...props}
+    >
+      {children}
+    </NodeToolbar>
+  )
+}