add local storage in json for collection

src/lib/checklist.ts

@@ -18,27 +18,23 @@ export function loadChecklistV1(): Set<string> {
   }
 }
 
-// New storage (v2)
-export function loadChecklist(): ChecklistV2 {
+// Local-only helpers (kept for migration / fallback)
+export function loadChecklistLocal(): ChecklistV2 {
   if (typeof window === 'undefined') return {};
   try {
     const v2 = localStorage.getItem(CHECKLIST_KEY_V2);
     if (v2) return JSON.parse(v2) as ChecklistV2;
-    // migrate from v1 if present
     const v1 = loadChecklistV1();
     if (v1.size === 0) return {};
     const migrated: ChecklistV2 = {};
-    v1.forEach((id) => {
-      migrated[id] = { base: true };
-    });
-    saveChecklist(migrated);
+    v1.forEach((id) => { migrated[id] = { base: true }; });
     return migrated;
   } catch {
     return {};
   }
 }
 
-export function saveChecklist(state: ChecklistV2) {
+export function saveChecklistLocal(state: ChecklistV2) {
   if (typeof window === 'undefined') return;
   try {
     localStorage.setItem(CHECKLIST_KEY_V2, JSON.stringify(state));
@@ -46,3 +42,43 @@ export function saveChecklist(state: ChecklistV2) {
     // ignore
   }
 }
+
+// Server-backed persistence
+export async function loadChecklistServer(): Promise<ChecklistV2> {
+  try {
+    const res = await fetch('/api/checklist', { cache: 'no-store' });
+    if (!res.ok) throw new Error('failed');
+    const json = await res.json();
+    const serverData = (json?.data || {}) as ChecklistV2;
+    // If server is empty, try migrate from local and push
+    const hasServerData = serverData && Object.keys(serverData).length > 0;
+    if (!hasServerData && typeof window !== 'undefined') {
+      const local = loadChecklistLocal();
+      const hasLocal = Object.keys(local).length > 0;
+      if (hasLocal) {
+        await saveChecklistServer(local);
+        // Clear legacy keys after successful push
+        try { localStorage.removeItem(CHECKLIST_KEY_V2); } catch {}
+        try { localStorage.removeItem(CHECKLIST_KEY_V1); } catch {}
+        return local;
+      }
+    }
+    return serverData || {};
+  } catch {
+    // As a fallback (e.g., during dev with API not ready), use local
+    return loadChecklistLocal();
+  }
+}
+
+export async function saveChecklistServer(state: ChecklistV2): Promise<void> {
+  try {
+    await fetch('/api/checklist', {
+      method: 'PUT',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify(state),
+    });
+  } catch {
+    // best-effort: persist locally so user doesn't lose progress offline
+    saveChecklistLocal(state);
+  }
+}