feat: add FlowCanvasNode compact card for React Flow canvas

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/tree-editor/FlowCanvasNode.tsx

@@ -0,0 +1,154 @@
+import { memo } from 'react'
+import { Handle, Position, type NodeProps } from '@xyflow/react'
+import { HelpCircle, Zap, CheckCircle, ChevronDown, ChevronRight, AlertCircle } from 'lucide-react'
+import { cn } from '@/lib/utils'
+import type { TreeStructure, NodeType } from '@/types'
+
+const NODE_TYPE_CONFIG: Record<Exclude<NodeType, 'answer'>, {
+  icon: typeof HelpCircle
+  label: string
+  borderClass: string
+  badgeClass: string
+  minimapColor: string
+}> = {
+  decision: {
+    icon: HelpCircle,
+    label: 'Decision',
+    borderClass: 'border-l-4 border-l-blue-500',
+    badgeClass: 'bg-blue-500/20 text-blue-400',
+    minimapColor: '#3b82f6',
+  },
+  action: {
+    icon: Zap,
+    label: 'Action',
+    borderClass: 'border-l-4 border-l-yellow-500',
+    badgeClass: 'bg-yellow-500/20 text-yellow-400',
+    minimapColor: '#eab308',
+  },
+  solution: {
+    icon: CheckCircle,
+    label: 'Solution',
+    borderClass: 'border-l-4 border-l-green-500',
+    badgeClass: 'bg-green-500/20 text-green-400',
+    minimapColor: '#22c55e',
+  },
+}
+
+export interface FlowCanvasNodeData {
+  node: TreeStructure
+  hasChildren: boolean
+  isCollapsed: boolean
+  hasValidationErrors: boolean
+  isNew: boolean
+  onToggleCollapse: (nodeId: string) => void
+}
+
+function FlowCanvasNodeComponent({ data, selected }: NodeProps) {
+  const { node, hasChildren, isCollapsed, hasValidationErrors, isNew, onToggleCollapse } = data as unknown as FlowCanvasNodeData
+  const nodeType = node.type as Exclude<NodeType, 'answer'>
+  const config = NODE_TYPE_CONFIG[nodeType] ?? NODE_TYPE_CONFIG.decision
+  const Icon = config.icon
+
+  const title = node.type === 'decision'
+    ? (node.question || 'Untitled Decision')
+    : (node.title || `Untitled ${config.label}`)
+
+  const optionCount = node.options?.length ?? 0
+
+  return (
+    <>
+      {/* Target handle at top */}
+      <Handle type="target" position={Position.Top} className="!bg-border !w-2 !h-2 !border-0" />
+
+      <div
+        className={cn(
+          'w-[280px] rounded-xl border border-border bg-card shadow-sm cursor-pointer transition-all',
+          config.borderClass,
+          selected && 'ring-1 ring-primary shadow-md'
+        )}
+      >
+        {/* Header */}
+        <div className="flex items-center gap-2 px-3 py-2.5">
+          {/* Type badge */}
+          <span className={cn('flex h-5 w-5 shrink-0 items-center justify-center rounded', config.badgeClass)}>
+            <Icon className="h-3 w-3" />
+          </span>
+
+          {/* Title */}
+          <span className="flex-1 truncate text-sm font-heading font-medium text-foreground">
+            {title}
+          </span>
+
+          {/* Badges */}
+          {isNew && (
+            <span className="rounded-full bg-yellow-500/20 px-1.5 py-0.5 text-[10px] font-label text-yellow-400">
+              New
+            </span>
+          )}
+          {hasValidationErrors && (
+            <AlertCircle className="h-3.5 w-3.5 shrink-0 text-red-400" />
+          )}
+        </div>
+
+        {/* Decision options preview */}
+        {node.type === 'decision' && optionCount > 0 && (
+          <div className="border-t border-border px-3 py-1.5">
+            <div className="flex items-center gap-1.5 text-xs text-muted-foreground">
+              <span className="font-label">{optionCount} option{optionCount !== 1 ? 's' : ''}</span>
+            </div>
+            <div className="mt-1 space-y-0.5">
+              {node.options!.slice(0, 3).map((opt, i) => (
+                <div key={opt.id} className="truncate text-xs text-muted-foreground">
+                  <span className="font-label text-foreground/60">{String.fromCharCode(65 + i)}</span>{' '}
+                  {opt.label || '(empty)'}
+                </div>
+              ))}
+              {optionCount > 3 && (
+                <div className="text-xs text-muted-foreground">+{optionCount - 3} more</div>
+              )}
+            </div>
+          </div>
+        )}
+
+        {/* Description preview for action/solution */}
+        {(node.type === 'action' || node.type === 'solution') && node.description && (
+          <div className="border-t border-border px-3 py-1.5">
+            <div className="line-clamp-2 text-xs text-muted-foreground">{node.description}</div>
+          </div>
+        )}
+
+        {/* Collapse chevron */}
+        {hasChildren && (
+          <div className="flex justify-center border-t border-border py-1">
+            <button
+              type="button"
+              onClick={(e) => {
+                e.stopPropagation()
+                onToggleCollapse(node.id)
+              }}
+              className="flex items-center gap-1 rounded px-2 py-0.5 text-xs text-muted-foreground hover:bg-accent hover:text-foreground transition-colors"
+            >
+              {isCollapsed ? (
+                <>
+                  <ChevronRight className="h-3 w-3" />
+                  <span className="font-label">Expand</span>
+                </>
+              ) : (
+                <>
+                  <ChevronDown className="h-3 w-3" />
+                  <span className="font-label">Collapse</span>
+                </>
+              )}
+            </button>
+          </div>
+        )}
+      </div>
+
+      {/* Source handle at bottom */}
+      <Handle type="source" position={Position.Bottom} className="!bg-border !w-2 !h-2 !border-0" />
+    </>
+  )
+}
+
+export const FlowCanvasNode = memo(FlowCanvasNodeComponent)
+export { NODE_TYPE_CONFIG }