The question presents on two levels . . . one much simpler than the other. The simpler level first; As agent of the Owner, you are authorized to make decisions for the Owner for purposes of expediting the project. When the contractor asks you for advice as to what should be done, you, as the agent of the Owner, are speaking as if you are the Owner. The Contractor is entitled to take what you say and rely on it as if the Owner said it. Bear that in mind when you administer contracts. That is the easy example The tougher example is your role as you put it "agent of the public". As such, you are vested with the responsibility to make building design decisions that foster the health, safety and welfare of the building using public. While those goals are generally concurrent, as you might imagine, there could be times when they are in conflict. While it is true that the Architect shoulders a unique form of professional liability that the contractor does not, it isn't accurate to say that the contractor has no liability for faulty construction. In your hypothetical, you suggest that the parties recognize that the ". . . . building design, if built as-drawn, will create an unsafe condition . . . .". That by itself presents a problem. If the building as designed would be unsafe, the Architect has some liability. Given that it was discovered before construction, that liability may be limited to the cost of a re-design that does not suffer that malady, but the fact that the design itself would create an unsafe condition if constructed is a problem for the Architect.