With a monorepo with this kind of structure

.
├── api
│   └── index.js
└── web
    ├── index.html
    ├── main.css
    └── main.js

Assuming you changed the web/index.html and web/main.css files, in CI, how would you deploy only the web directory?

Vice versa if you only changed api/index.js only deploy the api, not the frontend.