Align backend plan with codebase

app/create/context/CreateFlowBackendSync.tsx

@@ -0,0 +1,72 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import {
+  fetchAuthSession,
+  fetchDraftFromServer,
+  saveDraftToServer,
+} from "../../../lib/create/api";
+import { useCreateFlow } from "./CreateFlowContext";
+
+const SYNC_ENABLED =
+  process.env.NEXT_PUBLIC_ENABLE_BACKEND_SYNC === "true";
+
+const DEBOUNCE_MS = 1000;
+
+/**
+ * When NEXT_PUBLIC_ENABLE_BACKEND_SYNC=true, loads the signed-in user's draft
+ * from the server and debounces saves. Anonymous users keep localStorage-only behavior.
+ */
+export function CreateFlowBackendSync() {
+  const { state, replaceState } = useCreateFlow();
+  const [hydrated, setHydrated] = useState(!SYNC_ENABLED);
+  const saveTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  useEffect(() => {
+    if (!SYNC_ENABLED) return;
+
+    let cancelled = false;
+
+    (async () => {
+      try {
+        const { user } = await fetchAuthSession();
+        if (cancelled || !user) {
+          setHydrated(true);
+          return;
+        }
+        const serverDraft = await fetchDraftFromServer();
+        if (cancelled) return;
+        if (serverDraft && Object.keys(serverDraft).length > 0) {
+          replaceState(serverDraft);
+        }
+      } finally {
+        if (!cancelled) setHydrated(true);
+      }
+    })();
+
+    return () => {
+      cancelled = true;
+    };
+  }, [replaceState]);
+
+  useEffect(() => {
+    if (!SYNC_ENABLED || !hydrated) return;
+
+    if (saveTimer.current) clearTimeout(saveTimer.current);
+
+    saveTimer.current = setTimeout(() => {
+      saveTimer.current = null;
+      void (async () => {
+        const { user } = await fetchAuthSession();
+        if (!user) return;
+        await saveDraftToServer(state);
+      })();
+    }, DEBOUNCE_MS);
+
+    return () => {
+      if (saveTimer.current) clearTimeout(saveTimer.current);
+    };
+  }, [state, hydrated]);
+
+  return null;
+}

app/create/context/CreateFlowContext.tsx

@@ -79,6 +79,11 @@ export function CreateFlowProvider({
     }));
   }, []);
 
+  const replaceState = useCallback((next: CreateFlowState) => {
+    setState(next);
+    writeStateToStorage(STORAGE_KEY, next);
+  }, []);
+
   const clearState = useCallback(() => {
     setState({});
     removeFromStorage(STORAGE_KEY);
@@ -89,6 +94,7 @@ export function CreateFlowProvider({
     state,
     currentStep,
     updateState,
+    replaceState,
     clearState,
   };