Form Error State Contract表单错误状态契约

Define labels, helper text, validation timing, inline errors, error summaries, submit states, server-failure recovery, mobile input behavior, and frontend state models for login, signup, checkout, settings, submission, filter, multi-step, and admin-edit forms.

为登录、注册、结账、设置、投稿、筛选、多步表单和后台编辑建立标签、帮助文本、验证时机、内联错误、错误摘要、提交状态、服务端失败恢复、移动输入和前端状态模型。