fix(data): 清理旧数据并保护服务端写入

apps/web/lib/server-data.ts

@@ -1,4 +1,4 @@
-import { api } from './api';
+import { api, ApiRequestError } from './api';
 
 export type ServerDataKey =
   | 'products-overview'
@@ -19,13 +19,72 @@ export type ServerDataKey =
 interface ServerDataResponse<T> {
   key: ServerDataKey;
   value: T | null;
+  version: string | null;
+}
+
+type ServerDataConflictBody<T> = {
+  code: 'APP_DATA_CONFLICT';
+  key: ServerDataKey;
+  currentValue: T | null;
+  currentVersion: string | null;
+};
+
+const serverDataVersions = new Map<ServerDataKey, string | null>();
+
+export class ServerDataConflictError<T = unknown> extends Error {
+  constructor(
+    public readonly key: ServerDataKey,
+    public readonly currentValue: T | null,
+    public readonly currentVersion: string | null,
+  ) {
+    super('Server data was changed by another user. Reload before saving again.');
+    this.name = 'ServerDataConflictError';
+  }
 }
 
 export async function loadServerData<T>(key: ServerDataKey): Promise<T | null> {
   const res = await api.get<ServerDataResponse<T>>(`/data/${key}`);
+  serverDataVersions.set(key, res.version ?? null);
   return res.value;
 }
 
 export async function saveServerData<T>(key: ServerDataKey, value: T): Promise<void> {
-  await api.put(`/data/${key}`, { value });
+  const payload: { value: T; version?: string | null } = { value };
+  if (serverDataVersions.has(key)) {
+    payload.version = serverDataVersions.get(key) ?? null;
+  }
+
+  try {
+    const res = await api.put<ServerDataResponse<T>>(`/data/${key}`, payload);
+    serverDataVersions.set(key, res.version ?? null);
+  } catch (error) {
+    if (
+      error instanceof ApiRequestError &&
+      error.status === 409 &&
+      isServerDataConflictBody<T>(error.body, key)
+    ) {
+      throw new ServerDataConflictError(
+        error.body.key,
+        error.body.currentValue,
+        error.body.currentVersion,
+      );
+    }
+    throw error;
+  }
+}
+
+function isServerDataConflictBody<T>(
+  body: unknown,
+  key: ServerDataKey,
+): body is ServerDataConflictBody<T> {
+  return (
+    typeof body === 'object' &&
+    body !== null &&
+    (body as { code?: unknown }).code === 'APP_DATA_CONFLICT' &&
+    (body as { key?: unknown }).key === key &&
+    ('currentVersion' in body
+      ? typeof (body as { currentVersion?: unknown }).currentVersion === 'string' ||
+        (body as { currentVersion?: unknown }).currentVersion === null
+      : true)
+  );
 }