src/app/editor/[projectId]/FlowchartEditor.tsx

@@ -24,6 +24,7 @@ import ChoiceNode from '@/components/editor/nodes/ChoiceNode'
 import VariableNode from '@/components/editor/nodes/VariableNode'
 import ProjectSettingsModal from '@/components/editor/ProjectSettingsModal'
 import ConditionEditor from '@/components/editor/ConditionEditor'
+import ExportValidationModal, { type ValidationIssue } from '@/components/editor/ExportValidationModal'
 import { EditorProvider } from '@/components/editor/EditorContext'
 import Toast from '@/components/Toast'
 import type { FlowchartData, FlowchartNode, FlowchartEdge, Character, Variable, Condition } from '@/types/flowchart'
@@ -229,6 +230,8 @@ function FlowchartEditorInner({ projectId, initialData, needsMigration }: Flowch
   const [showSettings, setShowSettings] = useState(false)
   const [selectedEdgeId, setSelectedEdgeId] = useState<string | null>(null)
   const [toastMessage, setToastMessage] = useState<string | null>(migratedData.toastMessage)
+  const [validationIssues, setValidationIssues] = useState<ValidationIssue[] | null>(null)
+  const [warningNodeIds, setWarningNodeIds] = useState<Set<string>>(new Set())
 
   const handleAddCharacter = useCallback(
     (name: string, color: string): string => {
@@ -360,8 +363,92 @@ function FlowchartEditorInner({ projectId, initialData, needsMigration }: Flowch
     // TODO: Implement in US-034
   }, [])
 
+  const performExport = useCallback(() => {
+    // TODO: Actual export logic in US-035
+    setValidationIssues(null)
+    setWarningNodeIds(new Set())
+  }, [])
+
   const handleExport = useCallback(() => {
-    // TODO: Implement in US-035
+    const issues: ValidationIssue[] = []
+    const characterIds = new Set(characters.map((c) => c.id))
+    const variableIds = new Set(variables.map((v) => v.id))
+
+    // Scan nodes for undefined references
+    nodes.forEach((node) => {
+      if (node.type === 'dialogue' && node.data?.characterId) {
+        if (!characterIds.has(node.data.characterId)) {
+          issues.push({
+            nodeId: node.id,
+            nodeType: 'dialogue',
+            contentSnippet: node.data.text
+              ? `"${node.data.text.slice(0, 40)}${node.data.text.length > 40 ? '...' : ''}"`
+              : 'Empty dialogue',
+            undefinedReference: node.data.characterId,
+            referenceType: 'character',
+          })
+        }
+      }
+      if (node.type === 'variable' && node.data?.variableId) {
+        if (!variableIds.has(node.data.variableId)) {
+          issues.push({
+            nodeId: node.id,
+            nodeType: 'variable',
+            contentSnippet: node.data.variableName
+              ? `Variable: ${node.data.variableName}`
+              : 'Variable node',
+            undefinedReference: node.data.variableId,
+            referenceType: 'variable',
+          })
+        }
+      }
+      if (node.type === 'choice' && node.data?.options) {
+        node.data.options.forEach((opt: { id: string; label: string; condition?: { variableId?: string; variableName?: string } }) => {
+          if (opt.condition?.variableId && !variableIds.has(opt.condition.variableId)) {
+            issues.push({
+              nodeId: node.id,
+              nodeType: 'choice',
+              contentSnippet: opt.label
+                ? `Option: "${opt.label.slice(0, 30)}${opt.label.length > 30 ? '...' : ''}"`
+                : 'Choice option',
+              undefinedReference: opt.condition.variableId,
+              referenceType: 'variable',
+            })
+          }
+        })
+      }
+    })
+
+    // Scan edges for undefined variable references in conditions
+    edges.forEach((edge) => {
+      if (edge.data?.condition?.variableId && !variableIds.has(edge.data.condition.variableId)) {
+        issues.push({
+          nodeId: edge.id,
+          nodeType: 'edge',
+          contentSnippet: edge.data.condition.variableName
+            ? `Condition on: ${edge.data.condition.variableName}`
+            : 'Edge condition',
+          undefinedReference: edge.data.condition.variableId,
+          referenceType: 'variable',
+        })
+      }
+    })
+
+    if (issues.length === 0) {
+      performExport()
+    } else {
+      setValidationIssues(issues)
+      setWarningNodeIds(new Set(issues.map((i) => i.nodeId)))
+    }
+  }, [nodes, edges, characters, variables, performExport])
+
+  const handleExportAnyway = useCallback(() => {
+    performExport()
+  }, [performExport])
+
+  const handleExportCancel = useCallback(() => {
+    setValidationIssues(null)
+    setWarningNodeIds(new Set())
   }, [])
 
   const handleImport = useCallback(() => {
@@ -394,6 +481,19 @@ function FlowchartEditorInner({ projectId, initialData, needsMigration }: Flowch
     [setEdges]
   )
 
+  // Apply warning styles to nodes with undefined references
+  const styledNodes = useMemo(
+    () =>
+      warningNodeIds.size === 0
+        ? nodes
+        : nodes.map((node) =>
+            warningNodeIds.has(node.id)
+              ? { ...node, className: 'export-warning-node' }
+              : node
+          ),
+    [nodes, warningNodeIds]
+  )
+
   // Get the selected edge's condition data
   const selectedEdge = useMemo(
     () => (selectedEdgeId ? edges.find((e) => e.id === selectedEdgeId) : null),
@@ -414,7 +514,7 @@ function FlowchartEditorInner({ projectId, initialData, needsMigration }: Flowch
         />
         <div className="flex-1">
           <ReactFlow
-            nodes={nodes}
+            nodes={styledNodes}
             edges={edges}
             nodeTypes={nodeTypes}
             onNodesChange={onNodesChange}
@@ -449,6 +549,13 @@ function FlowchartEditorInner({ projectId, initialData, needsMigration }: Flowch
             onClose={() => setSelectedEdgeId(null)}
           />
         )}
+        {validationIssues && (
+          <ExportValidationModal
+            issues={validationIssues}
+            onExportAnyway={handleExportAnyway}
+            onCancel={handleExportCancel}
+          />
+        )}
         {toastMessage && (
           <Toast
             message={toastMessage}

src/app/globals.css

@@ -24,3 +24,16 @@ body {
   color: var(--foreground);
   font-family: Arial, Helvetica, sans-serif;
 }
+
+/* Export validation warning highlighting for React Flow nodes */
+.react-flow__node.export-warning-node {
+  outline: 3px solid #f97316;
+  outline-offset: 2px;
+  border-radius: 6px;
+  animation: pulse-warning 1.5s ease-in-out infinite;
+}
+
+@keyframes pulse-warning {
+  0%, 100% { outline-color: #f97316; }
+  50% { outline-color: #fb923c; }
+}

src/components/editor/ExportValidationModal.tsx

@@ -0,0 +1,131 @@
+'use client'
+
+export type ValidationIssue = {
+  nodeId: string
+  nodeType: 'dialogue' | 'choice' | 'variable' | 'edge'
+  contentSnippet: string
+  undefinedReference: string
+  referenceType: 'character' | 'variable'
+}
+
+type ExportValidationModalProps = {
+  issues: ValidationIssue[]
+  onExportAnyway: () => void
+  onCancel: () => void
+}
+
+export default function ExportValidationModal({
+  issues,
+  onExportAnyway,
+  onCancel,
+}: ExportValidationModalProps) {
+  const characterIssues = issues.filter((i) => i.referenceType === 'character')
+  const variableIssues = issues.filter((i) => i.referenceType === 'variable')
+
+  return (
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
+      <div className="mx-4 w-full max-w-lg rounded-lg bg-white shadow-xl dark:bg-zinc-800">
+        <div className="border-b border-zinc-200 px-6 py-4 dark:border-zinc-700">
+          <div className="flex items-center gap-2">
+            <svg
+              className="h-5 w-5 text-orange-500"
+              fill="none"
+              viewBox="0 0 24 24"
+              stroke="currentColor"
+            >
+              <path
+                strokeLinecap="round"
+                strokeLinejoin="round"
+                strokeWidth={2}
+                d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-2.5L13.732 4c-.77-.833-1.964-.833-2.732 0L4.082 16.5c-.77.833.192 2.5 1.732 2.5z"
+              />
+            </svg>
+            <h2 className="text-lg font-semibold text-zinc-900 dark:text-zinc-100">
+              Export Validation Issues
+            </h2>
+          </div>
+          <p className="mt-1 text-sm text-zinc-500 dark:text-zinc-400">
+            {issues.length} undefined reference{issues.length !== 1 ? 's' : ''} found. These nodes/edges reference characters or variables that no longer exist.
+          </p>
+        </div>
+
+        <div className="max-h-[50vh] overflow-y-auto px-6 py-4">
+          {characterIssues.length > 0 && (
+            <div className="mb-4">
+              <h3 className="mb-2 text-sm font-medium text-zinc-700 dark:text-zinc-300">
+                Undefined Characters
+              </h3>
+              <ul className="space-y-2">
+                {characterIssues.map((issue, idx) => (
+                  <li
+                    key={`char-${idx}`}
+                    className="rounded border border-orange-200 bg-orange-50 p-3 dark:border-orange-800 dark:bg-orange-950"
+                  >
+                    <div className="flex items-start justify-between gap-2">
+                      <div className="min-w-0">
+                        <span className="inline-block rounded bg-blue-100 px-1.5 py-0.5 text-xs font-medium text-blue-700 dark:bg-blue-900 dark:text-blue-300">
+                          {issue.nodeType}
+                        </span>
+                        <p className="mt-1 truncate text-sm text-zinc-700 dark:text-zinc-300">
+                          {issue.contentSnippet}
+                        </p>
+                      </div>
+                      <span className="shrink-0 text-xs text-orange-600 dark:text-orange-400">
+                        ID: {issue.undefinedReference.slice(0, 8)}...
+                      </span>
+                    </div>
+                  </li>
+                ))}
+              </ul>
+            </div>
+          )}
+
+          {variableIssues.length > 0 && (
+            <div>
+              <h3 className="mb-2 text-sm font-medium text-zinc-700 dark:text-zinc-300">
+                Undefined Variables
+              </h3>
+              <ul className="space-y-2">
+                {variableIssues.map((issue, idx) => (
+                  <li
+                    key={`var-${idx}`}
+                    className="rounded border border-orange-200 bg-orange-50 p-3 dark:border-orange-800 dark:bg-orange-950"
+                  >
+                    <div className="flex items-start justify-between gap-2">
+                      <div className="min-w-0">
+                        <span className="inline-block rounded bg-blue-100 px-1.5 py-0.5 text-xs font-medium text-blue-700 dark:bg-blue-900 dark:text-blue-300">
+                          {issue.nodeType}
+                        </span>
+                        <p className="mt-1 truncate text-sm text-zinc-700 dark:text-zinc-300">
+                          {issue.contentSnippet}
+                        </p>
+                      </div>
+                      <span className="shrink-0 text-xs text-orange-600 dark:text-orange-400">
+                        ID: {issue.undefinedReference.slice(0, 8)}...
+                      </span>
+                    </div>
+                  </li>
+                ))}
+              </ul>
+            </div>
+          )}
+        </div>
+
+        <div className="flex justify-end gap-3 border-t border-zinc-200 px-6 py-4 dark:border-zinc-700">
+          <button
+            onClick={onCancel}
+            className="rounded border border-zinc-300 bg-white px-4 py-2 text-sm font-medium text-zinc-700 hover:bg-zinc-50 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 dark:border-zinc-600 dark:bg-zinc-700 dark:text-zinc-200 dark:hover:bg-zinc-600 dark:focus:ring-offset-zinc-800"
+          >
+            Cancel
+          </button>
+          <button
+            onClick={onExportAnyway}
+            className="rounded bg-orange-500 px-4 py-2 text-sm font-medium text-white hover:bg-orange-600 focus:outline-none focus:ring-2 focus:ring-orange-500 focus:ring-offset-2 dark:focus:ring-offset-zinc-800"
+          >
+            Export anyway
+          </button>
+        </div>
+      </div>
+    </div>
+  )
+}