Many buyers assume a builder's showroom representative is a neutral guide through the process, but that person's obligation runs to the builder who employs them. Your own agent can flag terms in the purchase agreement, including deposit handling and the structural warranty, that a builder's representative has no incentive to raise.
There is generally no added cost to you for bringing your own agent on a new construction purchase, since the builder typically pays commission on the same basis whether you are represented or not. Confirm that arrangement with your agent before you visit a builder's showroom.
A lawyer should still review the final purchase agreement before you sign, regardless of who represents you during the shopping process. Get your hand-reviewed valuation from Joel Dyck.