feat: block publish if unresolved answer stub nodes exist

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

frontend/src/pages/TreeEditorPage.tsx

@@ -5,7 +5,7 @@ import { Undo2, Redo2, Save, CheckCircle2, Monitor, FileText, Code2, LayoutList,
 import { getMonacoEditor } from '@/components/tree-editor/code-mode'
 import { treesApi } from '@/api/trees'
 import { treeMarkdownApi } from '@/api/treeMarkdown'
-import type { TreeCreate, TreeUpdate, TreeStatus } from '@/types'
+import type { TreeCreate, TreeUpdate, TreeStatus, TreeStructure } from '@/types'
 import { useTreeEditorStore, useTreeEditorTemporal } from '@/store/treeEditorStore'
 import { TreeEditorLayout } from '@/components/tree-editor/TreeEditorLayout'
 import { ValidationSummary } from '@/components/tree-editor/ValidationSummary'
@@ -15,6 +15,12 @@ import { cn, safeGetItem } from '@/lib/utils'
 import { toast } from '@/lib/toast'
 import { FlowAnalyticsPanel } from '@/components/analytics/FlowAnalyticsPanel'
 
+/** Recursively check if any node in the tree has type 'answer' */
+function hasAnswerNodes(node: TreeStructure): boolean {
+  if (node.type === 'answer') return true
+  return (node.children || []).some(hasAnswerNodes)
+}
+
 export function TreeEditorPage() {
   const { id } = useParams<{ id: string }>()
   const navigate = useNavigate()
@@ -292,6 +298,14 @@ export function TreeEditorPage() {
         return
       }
 
+      // Block publish if any answer placeholder nodes remain
+      const currentStructure = useTreeEditorStore.getState().treeStructure
+      if (currentStructure && hasAnswerNodes(currentStructure)) {
+        toast.error('Resolve all answer placeholders before publishing. Click each dashed stub card to assign a type.')
+        setSaving(false)
+        return
+      }
+
       // Validate tree structure
       const errors = validate()
       const hasErrors = errors.some(e => e.severity === 'error')