task-22(会话/菜单/权限): 定义 API 解包与错误归一化规则

envelope.ts 纯实现 unwrap(带 data 解包/success=false 抛错)、errorTextOf、
isUnauthorized(兼容 code/status/statusCode)、requestErrorMessage、loginRedirectTarget；
http.ts 复用 envelope 并对 HTTP200+code401 统一跳 /login?redirect=。

admin-frontend-vue/src/api/envelope.ts

@@ -0,0 +1,62 @@
+/** API 响应解包与错误归一化（任务 22）：纯函数，无框架依赖。 */
+
+export const REQUEST_FALLBACK_MESSAGE = '网络异常，请稍后重试'
+
+function textOf(value: Record<string, unknown>): string {
+  const message = value.message
+  const error = value.error
+  if (typeof message === 'string' && message.trim()) return message.trim()
+  if (typeof error === 'string' && error.trim()) return error.trim()
+  return ''
+}
+
+/**
+ * 统一解包 Java 响应：
+ * - success=false -> 抛错（取 message/error，空则“请求失败”）；
+ * - 带非空 data -> 返回 data；
+ * - 否则原样返回（允许 {item}/{items} 等信封由调用方再解）。
+ */
+export function unwrap<T>(payload: unknown): T {
+  const value = payload as Record<string, unknown> | null
+  if (!value || typeof value !== 'object') return payload as T
+  if (value.success === false) {
+    throw new Error(textOf(value) || '请求失败')
+  }
+  if ('data' in value && value.data !== null && value.data !== undefined) {
+    return value.data as T
+  }
+  return payload as T
+}
+
+/** 从任意负载取错误文案；缺省回退。 */
+export function errorTextOf(payload: unknown): string {
+  if (payload instanceof Error) return payload.message.trim() || REQUEST_FALLBACK_MESSAGE
+  if (payload && typeof payload === 'object') {
+    const text = textOf(payload as Record<string, unknown>)
+    if (text) return text
+  }
+  if (typeof payload === 'string' && payload.trim()) return payload.trim()
+  return REQUEST_FALLBACK_MESSAGE
+}
+
+/** 负载/状态码是否 401（未登录）。 */
+export function isUnauthorized(payload: unknown): boolean {
+  const record = payload as { status?: unknown; statusCode?: unknown; code?: unknown } | null
+  if (!record || typeof record !== 'object') return false
+  return [record.status, record.statusCode, record.code].some((v) => v === 401)
+}
+
+/** Axios 错误（带 response）或普通 Error 统一取可展示文案。 */
+export function requestErrorMessage(error: unknown): string {
+  const response = (error as { response?: { data?: unknown; status?: number } })?.response
+  if (response) {
+    const text = errorTextOf(response.data)
+    if (text) return text
+  }
+  return errorTextOf(error)
+}
+
+/** 当前地址作为登录跳转的 redirect 参数（encodeURIComponent 后）。 */
+export function loginRedirectTarget(location: { pathname: string; search: string }): string {
+  return encodeURIComponent(`${location.pathname}${location.search}`)
+}