In most cases, they will be working for the developer. You should be very careful to ensure that your interests are protected before signing a contract of purchase and sale. It is a good idea to consult your lawyer or notary public before signing a binding agreement. Do not assume that because you have bought a house in the past you know how agency relationships work today. Industry standards changed in 1994.
Court rulings can also lead to changes in practice and disclosure over time.
Even the specifics of a particular transaction can affect an agent's legal relationship to you. In most cases, your salesperson's service has no direct cost to you. Real estate salespersons usually do not charge buyers a fee. They are paid out of the transaction. The seller or seller's salesperson receives a commission, and the fee is shared with the buyer's salesperson.