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

@@ -22,6 +22,8 @@ import ReactFlow, {
 import { nanoid } from 'nanoid'
 import 'reactflow/dist/style.css'
 import Toolbar from '@/components/editor/Toolbar'
+import Toast from '@/components/Toast'
+import { createClient } from '@/lib/supabase/client'
 import DialogueNode from '@/components/editor/nodes/DialogueNode'
 import ChoiceNode from '@/components/editor/nodes/ChoiceNode'
 import VariableNode from '@/components/editor/nodes/VariableNode'
@@ -166,6 +168,8 @@ function FlowchartEditorInner({ projectId, initialData }: FlowchartEditorProps)
 
   const [contextMenu, setContextMenu] = useState<ContextMenuState>(null)
   const [conditionEditor, setConditionEditor] = useState<ConditionEditorState>(null)
+  const [isSaving, setIsSaving] = useState(false)
+  const [toast, setToast] = useState<{ message: string; type: 'success' | 'error' } | null>(null)
 
   // Check for saved draft on initial render (lazy initialization)
   const [draftState, setDraftState] = useState<{
@@ -308,9 +312,43 @@ function FlowchartEditorInner({ projectId, initialData }: FlowchartEditorProps)
     setNodes((nodes) => [...nodes, newNode])
   }, [getViewportCenter, setNodes])
 
-  const handleSave = useCallback(() => {
-    // TODO: Implement in US-034
-  }, [])
+  const handleSave = useCallback(async () => {
+    if (isSaving) return
+
+    setIsSaving(true)
+
+    try {
+      const supabase = createClient()
+
+      // Convert React Flow state to FlowchartData
+      const flowchartData: FlowchartData = {
+        nodes: fromReactFlowNodes(nodes),
+        edges: fromReactFlowEdges(edges),
+      }
+
+      const { error } = await supabase
+        .from('projects')
+        .update({
+          flowchart_data: flowchartData,
+          updated_at: new Date().toISOString(),
+        })
+        .eq('id', projectId)
+
+      if (error) {
+        throw error
+      }
+
+      // Clear LocalStorage draft after successful save
+      clearDraft(projectId)
+
+      setToast({ message: 'Project saved successfully', type: 'success' })
+    } catch (error) {
+      console.error('Failed to save project:', error)
+      setToast({ message: 'Failed to save project. Please try again.', type: 'error' })
+    } finally {
+      setIsSaving(false)
+    }
+  }, [isSaving, nodes, edges, projectId])
 
   const handleExport = useCallback(() => {
     // TODO: Implement in US-035
@@ -509,6 +547,7 @@ function FlowchartEditorInner({ projectId, initialData }: FlowchartEditorProps)
         onSave={handleSave}
         onExport={handleExport}
         onImport={handleImport}
+        isSaving={isSaving}
       />
       <div className="flex-1">
         <ReactFlow
@@ -586,6 +625,15 @@ function FlowchartEditorInner({ projectId, initialData }: FlowchartEditorProps)
           </div>
         </div>
       )}
+
+      {/* Toast notification */}
+      {toast && (
+        <Toast
+          message={toast.message}
+          type={toast.type}
+          onClose={() => setToast(null)}
+        />
+      )}
     </div>
   )
 }

src/components/editor/Toolbar.tsx

@@ -7,6 +7,7 @@ type ToolbarProps = {
   onSave: () => void
   onExport: () => void
   onImport: () => void
+  isSaving?: boolean
 }
 
 export default function Toolbar({
@@ -16,6 +17,7 @@ export default function Toolbar({
   onSave,
   onExport,
   onImport,
+  isSaving = false,
 }: ToolbarProps) {
   return (
     <div className="flex items-center justify-between border-b border-zinc-200 bg-zinc-50 px-4 py-2 dark:border-zinc-700 dark:bg-zinc-800">
@@ -46,9 +48,32 @@ export default function Toolbar({
       <div className="flex items-center gap-2">
         <button
           onClick={onSave}
-          className="rounded border border-zinc-300 bg-white px-3 py-1.5 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"
+          disabled={isSaving}
+          className="flex items-center gap-1.5 rounded border border-zinc-300 bg-white px-3 py-1.5 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 disabled:cursor-not-allowed disabled:opacity-50 dark:border-zinc-600 dark:bg-zinc-700 dark:text-zinc-200 dark:hover:bg-zinc-600 dark:focus:ring-offset-zinc-800"
         >
-          Save
+          {isSaving && (
+            <svg
+              className="h-4 w-4 animate-spin"
+              xmlns="http://www.w3.org/2000/svg"
+              fill="none"
+              viewBox="0 0 24 24"
+            >
+              <circle
+                className="opacity-25"
+                cx="12"
+                cy="12"
+                r="10"
+                stroke="currentColor"
+                strokeWidth="4"
+              />
+              <path
+                className="opacity-75"
+                fill="currentColor"
+                d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"
+              />
+            </svg>
+          )}
+          {isSaving ? 'Saving...' : 'Save'}
         </button>
         <button
           onClick={onExport}