§22 人类在环：审批流与四种模式

是Workflow多步？ ──是──▶ waitForApproval
   │否
是MCP服务器？ ──是──▶ elicitInput
   │否
是聊天交互？ ──是──▶ 要浏览器能力？ ──是──▶ onToolCall（客户端）
                         │否
                         └──▶ needsApproval（服务端）
    │否
简单确认 ──▶ State + WebSocket

processPayment: tool({
  description: "Process a payment",
  inputSchema: z.object({ amount: z.number(), recipient: z.string() }),
  needsApproval: async ({ amount }) => amount > 100, // 超 100 要批
  execute: async ({ amount, recipient }) => charge(amount, recipient),
}),

const userInput = await this.server.server.elicitInput({
  message: "By how much do you want to increase the counter?",
  requestedSchema: { type: "object", properties: { amount: { type: "number" } }, required: ["amount"] },
}, { relatedRequestId: extra.requestId });