adding backup and data perstance accross devices

src/syncService.js

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+/**
+ * syncService.js
+ *
+ * Thin wrapper around the /api/projects endpoints.
+ * All functions are fire-and-forget friendly: they never throw — they
+ * return { ok: true, data } or { ok: false, error }.
+ *
+ * The caller decides whether to surface the error to the user.
+ */
+
+const BASE = '/api';
+
+async function request(method, path, body) {
+  try {
+    const opts = {
+      method,
+      headers: { 'Content-Type': 'application/json' },
+    };
+    if (body !== undefined) opts.body = JSON.stringify(body);
+    const res = await fetch(`${BASE}${path}`, opts);
+    const data = await res.json().catch(() => null);
+    if (!res.ok) {
+      return { ok: false, error: data?.error ?? `HTTP ${res.status}` };
+    }
+    return { ok: true, data };
+  } catch (err) {
+    return { ok: false, error: err?.message ?? 'Network error' };
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+/**
+ * List all remote project summaries.
+ * Returns { ok, data: Array<{ id, title, lastEdited, chapterSummary }> }
+ */
+export async function listRemoteProjects() {
+  return request('GET', '/projects');
+}
+
+/**
+ * Fetch a single full project by id.
+ * Returns { ok, data: project }
+ */
+export async function loadRemoteProject(id) {
+  return request('GET', `/projects/${id}`);
+}
+
+/**
+ * Save (create or update) a project on the server.
+ * Returns { ok, data: summary }
+ */
+export async function saveRemoteProject(project) {
+  return request('PUT', `/projects/${project.id}`, project);
+}
+
+/**
+ * Delete a project from the server.
+ * Returns { ok }
+ */
+export async function deleteRemoteProject(id) {
+  return request('DELETE', `/projects/${id}`);
+}
+
+/**
+ * Check whether the server is reachable.
+ * Returns true / false.
+ */
+export async function isServerReachable() {
+  try {
+    const res = await fetch(`${BASE}/health`, { method: 'GET' });
+    return res.ok;
+  } catch {
+    return false;
+  }
+}