When might a contract made by a mentally impaired$/$incompetent person be enforceable?

The impaired$/$incompetent person signs a second contract affirming that he understands the nature of the contrac

The impaired person has not been declared incompetent by a court.

The impaired$/$incompetent person was lucid at the time the contract was made.

The impaired$/$incompetent person has a court$-$appointed guardian, and that guardian is aware of the contract.