How does "prefix" works? #1096

// server.js
await fastify.register(require('./routes/user.routes'), {prefix: '/user'});

// user.route.js contains:
const fp = require('fastify-plugin');

async function userRoutes(fastify, options) {
  fastify.get('/me', async (request, reply) => {
    if (!request.session || !request.session.user) {
      return reply.code(401).send({ error: 'Not authenticated' });
    }
    
    reply.send(request.session.user);
  });

  fastify.post('/logout', { preHandler: [fastify.authenticate] }, async (request, reply) => {
    if (request.session) {
      request.session.destroy();
    }
    reply.send({ message: 'Logged out' });
  });
}

module.exports = fp(userRoutes);

    "fastify": "^5.3.3",
    "fastify-plugin": "^5.0.1",
    "@fastify/cookie": "^11.0.2",
    "@fastify/cors": "^11.0.1",
    "@fastify/session": "^11.1.0",
    "@fastify/swagger": "^9.5.1",
    "@fastify/swagger-ui": "^5.2.2",