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1

（可选）调研你现有的 API 设计模式

如果你不确定你的 Express API 是如何构建的，或者不清楚应该参考哪些模式，可以先使用 Ask Devin 来了解情况：你也可以使用 DeepWiki 来探索具有类似模式的开源 API——例如搜索 Express + Prisma + Zod 示例，查看其他项目如何组织路由处理程序和验证逻辑。你还可以直接从 Ask Devin 启动 Devin 会话，它会自动继承前面获取的所有上下文信息。
2

为 Devin 指定你的 OpenAPI 规范

首先告诉 Devin 规范文件位于何处，以及要实现哪个资源。Devin 会读取 YAML 中的每个路径、schema 和错误定义，然后与现有的 Express 路由进行交叉比对，自动匹配既有约定。下面是 Devin 能处理的这类规范的一个节选——针对 bookings 资源的标准 OpenAPI 3.0 定义：
# openapi/bookings-v2.yaml (excerpt)
openapi: "3.0.3"
info:
  title: Bookings API
  version: "2.0.0"
paths:
  /api/v2/bookings:
    get:
      summary: List bookings
      parameters:
        - name: page
          in: query
          schema: { type: integer, default: 1 }
        - name: startDate
          in: query
          schema: { type: string, format: date }
        - name: endDate
          in: query
          schema: { type: string, format: date }
      responses:
        "200":
          description: Paginated list of bookings
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/BookingListResponse"
    post:
      summary: Create a booking
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/CreateBookingInput"
      responses:
        "201":
          description: Booking created
        "409":
          description: Time slot conflict
  /api/v2/bookings/{id}/confirm:
    post:
      summary: Confirm a booking
      responses:
        "200":
          description: Booking confirmed
        "422":
          description: Booking already cancelled
components:
  schemas:
    CreateBookingInput:
      type: object
      required: [title, startTime, endTime, roomId]
      properties:
        title:
          type: string
          maxLength: 200
        startTime:
          type: string
          format: date-time
        endTime:
          type: string
          format: date-time
        roomId:
          type: string
          format: uuid
If your spec isn’t checked into the repo yet, paste it directly into the session or attach the YAML/JSON file when starting.
3

Devin matches your Express patterns

The single most impactful thing you can do is reference a well-implemented resource in your codebase. Devin studies that code and replicates the folder structure, naming conventions, middleware chain, and error handling — so the new endpoints look like they were written by the same developer.For example, Devin reads src/api/v2/users/router.ts and produces a matching bookings router:
// src/api/v2/bookings/router.ts  (generated by Devin)
import { Router } from "express";
import { authenticate } from "@/middleware/auth";
import { validate } from "@/middleware/validate";
import { BookingsController } from "./controller";
import {
  createBookingSchema,
  updateBookingSchema,
  listBookingsQuerySchema,
} from "./schemas";

const router = Router();
const ctrl = new BookingsController();

router.use(authenticate);

router.get("/", validate({ query: listBookingsQuerySchema }), ctrl.list);
router.post("/", validate({ body: createBookingSchema }), ctrl.create);
router.get("/:id", ctrl.getById);
router.patch("/:id", validate({ body: updateBookingSchema }), ctrl.update);
router.delete("/:id", ctrl.softDelete);
router.post("/:id/confirm", ctrl.confirm);
router.post("/:id/cancel", ctrl.cancel);

export default router;
Devin also derives Zod schemas directly from the OpenAPI component definitions, so request validation stays in sync with the spec:
// src/api/v2/bookings/schemas.ts  (generated by Devin)
import { z } from "zod";

export const createBookingSchema = z.object({
  title: z.string().max(200),
  startTime: z.string().datetime(),
  endTime: z.string().datetime(),
  roomId: z.string().uuid(),
  notes: z.string().max(1000).optional(),
});

export const updateBookingSchema = createBookingSchema.partial();

export const listBookingsQuerySchema = z.object({
  page: z.coerce.number().int().positive().default(1),
  limit: z.coerce.number().int().min(1).max(100).default(20),
  startDate: z.string().date().optional(),
  endDate: z.string().date().optional(),
});
请确保你的仓库设置中包含测试数据库配置和所有所需的环境变量，以便 Devin 能够在本地运行完整的测试套件。如果你的 API 需要凭据 (数据库 URL、JWT 密钥等) ，请在开始会话前将其添加为 Secrets，或在会话期间通过聊天提供。
4

Devin delivers a tested PR

Devin reads the spec, studies your existing code, and implements each endpoint to match both the OpenAPI contract and your Express codebase conventions. Here’s what a typical PR looks like:
feat: Implement /api/v2/bookings endpoints from OpenAPI spec

src/api/v2/bookings/
  router.ts              (Express route definitions + middleware)
  controller.ts          (request handling)
  service.ts             (business logic)
  repository.ts          (Prisma queries)
  schemas.ts             (Zod validation from spec)
prisma/migrations/
  20260219_add_bookings/  (migration)
src/__tests__/
  bookings.integration.ts (Supertest tests)
Devin runs the Supertest suite before opening the PR:
  /api/v2/bookings
    GET /
      passes returns paginated bookings (42ms)
      passes filters by date range (38ms)
      passes returns 401 without auth (8ms)
    POST /
      passes creates booking with valid data (61ms)
      passes returns 400 for missing required fields (12ms)
      passes returns 409 for overlapping time slot (29ms)
    PATCH /:id
      passes updates booking fields (22ms)
      passes returns 404 for non-existent booking (9ms)
    POST /:id/confirm
      passes transitions status to confirmed (18ms)
      passes returns 422 for already-cancelled booking (11ms)

  16 passing (412ms)
5

在规范未涵盖的内容上进行迭代

The OpenAPI 规范定义了接口契约，但很少涵盖业务规则、授权逻辑或性能要求。使用后续提示来补充这些空白：
6

使用 Devin Review 审查此 PR

一旦 Devin 创建 PR，使用 Devin Review 来审查实现。Devin Review 可以发现诸如缺少错误处理、响应格式不一致，或者端点与规范不匹配之类的问题。如果 Devin Review 指出了问题，你可以使用 Autofix 让 Devin 自动修复这些被标记的问题——它会开启一个后续会话，应用修复，并推送更新后的提交，而你无需手动逐一描述每项更改。