Which first? Carpet or carpentry?

[DappledThings]

Have a room currently bare floorboards and free-standing bookcases. Will be carpeting it and having built in bookshelves on 3 walls.

Will be asking both the carpenter and the carpet fitter their opinions too but what would you do? Carpet first and have shelves fitted into it or shelves first so carpet fitted to them?

Shelves first, especially if they will be painted. The carpet fitters will then fit the carpet to the shelves

Carpenter first: messier job out of the way, and built ins on top of carpet a bad idea in case of moths in particular

Thanks both. This was my instinct but wasn't sure if I was missing something.