add-middleware

name	add-middleware
description	Add a new Express middleware to this project and wire it up correctly. Use when the user asks to add middleware — rate limiting, request guards, validation, logging enrichment, custom auth checks, etc.

When the user asks to add middleware, follow these steps.

Step 1 — Create the file (src/middleware/<name>.middleware.ts)

Rules:

• Export named functions, not default exports — consistent with the barrel pattern.
• Type req, res, next as Request, Response, NextFunction from express. No any.
• Use the Pino logger from src/config/logger.ts if logging is needed — never console.*.
• Use config values from src/config/env.ts — never process.env directly.
• Throw from src/errors/ for error conditions and call next(error) — never res.status().json() directly.
• No floating promises — always await or .catch().

Auth guard pattern:

import type { Request, Response, NextFunction } from 'express';
import { AuthenticationError } from '../errors';

export const requireAdmin = (req: Request, _res: Response, next: NextFunction): void => {
    if (!req.user || req.user.role !== 'admin') {
        return next(new AuthenticationError('Admin access required'));
    }
    next();
};

Async middleware pattern:

import type { Request, Response, NextFunction } from 'express';
import { NotFoundError } from '../errors';
import logger from '../config/logger';

export const someAsyncGuard = async (req: Request, _res: Response, next: NextFunction): Promise<void> => {
    try {
        // async work
        next();
    } catch (error) {
        logger.error(error, 'someAsyncGuard failed');
        next(error);
    }
};

Rate limiter pattern (if adding a new limiter):

import rateLimit from 'express-rate-limit';

export const myLimiter = rateLimit({
    windowMs: 15 * 60 * 1000,
    max: 100,
    standardHeaders: true,
    legacyHeaders: false,
    message: { success: false, message: 'Too many requests' },
});

---

Step 2 — Export from the barrel (src/middleware/index.ts)

export { myMiddleware } from './<name>.middleware';

---

Step 3 — Apply it

App-wide (applies to every request) — add to src/app.ts in the correct position in the middleware chain. Order matters:

correlation → httpLogger → helmet → cors → json → cookie-parser → CSRF → [your middleware] → routes

Route-group-wide — add to the route constructor in src/routes/<name>.route.ts:

protected initializeRoutes(): void {
    this.router.use(myMiddleware);
    // then individual route definitions
}

Per-endpoint — add inline in the route definition:

this.router.post('/', limiter, protect, myMiddleware, createValidation, this.controller.createItem);

---

Step 4 — Verify

pnpm full-check

Fix every TypeScript and lint error before reporting done.